955 
FXSA20 KWBC 121810
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
209 PM EDT THU MAY 12 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

NOTE TO ALL USERS... NWS/WPC WILL BE TEMPORARILY SUSPENDING
SUPPORT TO SOUTH AMERICA O/A MAY 18.

FORECAST DISCUSSION FROM MAY 12/18 UTC: DISCUSSION NOT
ISSUED...NEXT TO BE DETERMINED.

DAVISON...WPC (USA)
$$

298 
FXSA20 KWBC 091747
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
146 PM EDT MON MAY 09 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAY 09/18 UTC: DISCUSSION NOT
ISSUED...NEXT TO BE DETERMINED.

DAVISON...WPC (USA)
$$

424 
FXSA20 KWBC 041555
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1154 AM EDT WED MAY 04 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAY 04/16 UTC: DISCUSSION NOT
ISSUED...NEXT TO BE DETERMINED.

DAVISON...WPC (USA)
$$

125 
FXSA20 KWBC 031707
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
106 PM EDT TUE MAY 03 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAY 03/18 UTC: UNDER THE INFLUENCE OF A
SHORT WAVE RIDGE TO THE WEST...A MID/UPPER LEVEL SHORT WAVE TROUGH
ON THE NORTHERN STREAM FLOW LIFTS ACROSS NORTHERN ARGENTINA/RIO DE
LA PLATA BASIN TO SOUTHERN BRASIL-PARAGUAY LATER THIS
AFTERNOON...WHERE IT ORGANIZES INTO A MID LEVEL LOW. AT 250
HPA...A SUBTROPICAL JET MAXIMA ROUNDING THE BASE OF THE UPPER
LEVEL TROUGH WILL COUPLE ON ITS DIVERGENT RIGHT EXIT REGION WITH A
NORTHERN POLAR JET OFF THE SOUTH COAST OF BRASIL. THIS WILL RESULT
IN A BROAD AREA OF UPPER DIVERGENCE AND ENVIRONMENTAL CONDITIONS
FAVORABLE FOR THE INSTENSIFICATION OF A FRONTAL LOW. THROUGH LATE
WEDNESDAY EVENING/EARLY ON THURSDAY THE SLOW TO EVOLVE MID/UPPER
LEVEL LOW WILL MEANDER EAST ACROSS SOUTHERN BRASIL TO THE WESTERN
ATLANTIC. BUT WHILE REMAINING CUT OFF FROM THE FLOW...IT WILL THEN
WEAKEN TO AN OPEN TROUGH EARLY ON FRIDAY.

AT LOW LEVELS...THE MID/UPPER LEVEL LOW IS INTERACTING WITH A
MEANDERING FRONT OVER NORTHERN SOUTH AMERICA...TRIGGERING
CYCLOGENESIS OVER SOUTHERN BRASIL. UNDER THE FAVORABLE INFLUENCE
OF THE UPPER LEVEL JETS...THE SURFACE LOW IS EXPECTED TO RAPIDLY
OCCLUDE THROUGH THIS EVENING. THIS...IN-TURN...WILL ALSO FAVOR A
SOUTHERLY JET ACROSS BOLIVIA TO PERU. THIS WILL DRIVE THE FRONT
NORTH ACROSS SAO PAULO-MATO GROSSO TO RONDONIA/NORTHERN BOLIVIA
LATER TODAY. ON WEDNESDAY THE FRONT ADVANCES ACROSS RIO DE
JANEIRO/MINAS GERAIS TO SOUTHERN AMAZONAS...WEAKENING TO A FRONTAL
SHEAR LINE ACROSS CENTRAL AMAZONAS TO NORTHERN JUNGLE OF
PERU/SOUTHERN COLOMBIA. THIS WILL PERSIST THROUGH THURSDAY...THEN
RAPIDLY WEAKEN OVER THE CONTINENT ON FRIDAY. THE REMAINING
PORTION...MEANWHILE...WHILE PERSIST OVER THE ATLANTIC INTO
NORTHERN RIO DE JANEIRO/ESPIRITO SANTO-MINAS GERAIS THROUGH THE
END OF THE WEEK. AS THE FRONTAL LOW OCCLUDES OVER SOUTHERN
BRASIL...IT WILL SUSTAIN A MOIST ONSHORE FLOW. IN THIS AREA THIS
WILL FAVOR HEAVY RAINFALL AMOUNTS DURING THE NEXT 48-60 HRS...WITH
ACCUMULATION OF 30-60MM/DAY AND MAXIMA OF 75-150MM/DAY. IN THIS
AREA...STORM TOTAL AMOUNTS OF 350-450 MM ARE HIGHLY LIKELY.
FURTHERMORE...AS THE FRONT SURGES ACROSS BOLIVIA TO ACRE/RONDONIA
IN BRASIL-SOUTHERN PERU EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
25-50MM THROUGH WEDNESDAY MORNING. ON WEDNESDAY TO THURSDAY THE
FOCUS OF THE ORGANIZED CONVECTION SHIFTS ALONG THE SHEAR LINE TO
THE NORTHERN JUNGLE OF PERU/EASTERN ECUADOR TO SOUTHERN
COLOMBIA...WITH MAXIMA OF 75-150MM. ON THURSDAY TO FIRDAY IT
WEAKENS TO MAXIMA OF 25-50MM

IN A TIGHT BELT OF MID LATITUDE WESTERLIES...PROGRESSIVE SHORT
WAVE PERTURBATIONS WILL POPULATE THE SOUTHERN STREAM FLOW. THESE
ARE TO PROPAGATE ACROSS THE DRAKE PASSAGE/SOUTHERN REGIONS OF
CHILE TO PATAGONIA IN ARGENTINA FROM TIME-TO-TIME. AS THESE TRACK
OVER WARMER THAN NORMAL WATERS OVER THE SOUTHEAST PACIFIC...THESE
PERTURBATIONS WILL ENHANCE MOISTURE TRANSPORT WHILE PROVIDING THE
DYNAMICAL SUPPORT. AT LOW LEVELS PROGRESSIVE FRONTAL LOWS ARE TO
ACCOMPANY THE MID/UPPER LEVEL PERTURBATIONS AS THEY STREAM ACROSS
THE SOUTHERN CONE...SUSTAINING A TIGHT GRADIENT AND STRONG
BOUNDARY LAYER WINDS. ON THE SOUTHERN ANDES OF CHILE AND TIERRA
DEL FUEGO THESE WILL ENHANCE TOPOGRAPHICAL ASCENT TO HELP SUSTAIN
HEAVY RAINFALL AMOUNTS. NOTE THAT THERE IS A STRONG CONSENSUS
AMONG THE DETERMINISTIC AND ENSEMBLE GUIDANCE THROUGH OUT THE
FORECAST CYCLE...LEADING TO HIGHER THAN NORMAL CONFIDENCE IN THE
FORECAST THROUGH THE MEDIUM RANGE PERIOD. OVER THE NEXT TWO DAYS
MAXIMA TO THE SOUTH OF TEMUCO/PUERTO MONTT WILL PEAK AT
30-60MM/DAY. ON FRIDAY...UNDER THE INFLUENCE OF A DEEPER/HIGHER
AMPLITUDE TROUGH...THIS INCREASES TO MAXIMA OF 50-100MM...WITH AN
ADDITIONAL 20-45MM/DAY DURING THE WEEKEND.

DAVISON...WPC (USA)
$$

868 
FXSA20 KWBC 021800
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EDT MON MAY 02 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAY 02/18 UTC: STEERED BY A MID/UPPER
LEVEL RIDGE TO THE WEST...A SHORT WAVE TROUGH LIFTS ACROSS
CENTRAL/NORTHERN ARGENTINA TO MID SECTIONS OF SOUTH AMERICA LATER
TODAY. THROUGH TUESDAY THIS WILL STRENGTHEN INTO A CLOSED LOW OVER
CORRIENTES/MISIONES IN NORTHERN ARGENTINA WHILE THE SHORT WAVE
TROUGH AMPLIFIES ACROSS PARAGUAY TO SOUTHEAST BOLIVIA. AT 250 HPA
A SUBTROPICAL JET MAXIMA ROUNDING THE BASE OF THE UPPER TROUGH
WILL THEN INTERACT WITH A NORTHERN POLAR JET IN SUPPORT OF A BROAD
AREA OF UPPER DIVERGENCE ON THE SOUTHERN STATES OF BRASIL. THROUGH
THURSDAY MORNING THE SLOW TO EVOLVE MID/UPPER LEVEL LOW WILL
MEANDER EAST ACROSS SOUTHERN BRASIL TO THE WESTERN ATLANTIC.
THROUGH FRIDAY AFTERNOON THE LOW WILL START TO WEAKEN TO AN OPEN
TROUGH WHILE MEANDERING EAST ACROSS 40W.

AT LOW LEVELS...THE UPPER LEVEL LOW WILL THEN INTERACT WITH A
MEANDERING FRONT EXTENDING ACROSS SOUTHERN BRASIL-PARAGUAY TO
CENTRAL BOLIVIA. UNDER THE CYCLOGENIC INFLUENCE OF THE MID LEVEL
VORTEX AND FAVORABLE UPPER LEVEL JET DYNAMICS A FRONTAL LOW
DEVELOPS ALONG THIS BOUNDARY BETWEEN SOUTHEAST PARAGUAY/MISIONES
IN ARGENTINA LATER TODAY/EARLY ON TUESDAY. THE LOW IS TO GRADUALLY
OCCLUDE WHILE DRIFTING TO THE EAST-NORTHEAST ACROSS THE SOUTHERN
STATES OF BRASIL. AS IT DEEPENS...THIS WILL FAVOR A MOIST ONSHORE
FLOW ACROSS RIO GRANDE DO SUL IN SOUTHERN BRASIL...WHILE OVER THE
CONTINENT IT WILL SUSTAIN A SOUTHERLY FLOW. THIS DRIVES THE FRONT
FARTHER NORTH ACROSS CENTRAL TO NORTHWEST BRASIL...WITH TRAILING
END WEAKENING TO A FRONTAL SHEAR LINE AS IT PUSHES NORTH ACROSS
AMAZONAS IN BRASIL TO SOUTHERN COLOMBIA/NORTHERN PERU LATER ON
WEDNESDAY EVENING. OVER SOUTHERN BRASIL THIS WILL SUSTAIN THREE
DAYS OF HEAVY RAINFALL...WITH THE DEEPENING LOW LIKELY TO RESULT
IN A TOPOGRAPHICALLY ENHANCED ECHO TRAINING PATTERN. STARTING
EARLY ON TUESDAY AND PERSISTING THROUGH THURSDAY...EXPECTING
RAINFALL AMOUNTS OF 20-40MM/DAY AND MAXIMA OF 75-150MM/DAY. IN
THIS AREA...STORM TOTAL AMOUNTS OF 350-450 MM ARE HIGHLY LIKELY.
FURTHERMORE...AS THE FRONT SURGES ACROSS BOLIVIA TO ACRE/RONDONIA
IN BRASIL-SOUTHERN PERU ON TUESDAY THROUGH WEDNESDAY EXPECTING
MAXIMA OF 25-50MM IN SCATTERED DEEP CONVECTION. LATER IN THE
WEEK...ACTIVITY CLUSTERING ALONG THE FRONTAL SHEAR LINE OVER
NORTHWEST BRASIL WILL SPREAD ACROSS NORTHERN PERU INTO SOUTHERN
COLOMBIA/EASTERN ECUADOR. MOST INTENSE...HOWEVER...IS EXPECTED ON
THE LEE OF THE ANDES BETWEEN SOUTHWEST COLOMBIA AND EASTERN
ECUADOR...WITH DAILY MAXIMA OF 75-150MM/DAY ON WEDNESDAY THROUGH
FRIDAY MORNING. IN THIS AREA CONDITIONS APPEAR FAVORABLE FOR AN
MCS TO FORM.

ON THE SOUTHERN STREAM FLOW...IN A TIGHT BELT OF MID LATITUDE
WESTERLIES...PROGRESSIVE MID LEVEL PERTURBATIONS ARE TO STREAM
ACROSS THE DRAKE PASSAGE/SOUTHERN REGIONS OF CHILE TO PATAGONIA IN
ARGENTINA FROM TIME-TO-TIME. TRACKING OVER WARMER THAN NORMAL
WATERS OVER THE SOUTH PACIFIC...THESE PERTURBATIONS WILL ENHANCE
MOISTURE TRANSPORT. AT LOW LEVELS PROGRESSIVE FRONTAL LOWS ARE TO
ACCOMPANY THE MID/UPPER LEVEL PERTURBATIONS AS THEY STREAM ACROSS
THE SOUTHERN CONE...SUSTAINING A TIGHT GRADIENT AND STRONG
BOUNDARY LAYER WINDS. ON THE SOUTHERN ANDES OF CHILE AND TIERRA
DEL FUEGO THESE WILL ENHANCE TOPOGRAPHICAL ASCENT TO HELP SUSTAIN
HEAVY RAINFALL AMOUNTS. NOTE THAT THERE IS A STRONG CONSENSUS
AMONG THE DETERMINISTIC AND ENSEMBLE GUIDANCE THROUGH OUT THE
FORECAST CYCLE...LEADING TO HIGHER THAN NORMAL CONFIDENCE IN THE
FORECAST THROUGH THE MEDIUM RANGE PERIOD.

DAVISON...WPC (USA)
$$

166 
FXSA20 KWBC 281632
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1231 PM EDT THU APR 28 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 28/17 UTC: IN A SINUSOIDAL
PATTERN...A RIDGE IS INITIALIZED OVER THE EASTERN PACIFIC WITH
AXIS SOUTH BETWEEN 80W/90W...WHILE TO THE EAST A BROAD TROUGH
EXTENDS OVER THE CONTINENT BETWEEN 70W-50W TO 20S. THE LATTER
SLOWLY RELOCATES TO THE WESTERN ATLANTIC THROUGH FRIDAY
AFTERNOON...WHERE IT BECOMES THE DOMINANT SYNOPTIC SCALE FEATURE.
MEANWHILE...UNDER THE INFLUENCE OF THE RIDGE TO THE WEST...SHORT
WAVE PERTURBATIONS ARE TO LIFT ACROSS THE SOUTHERN CONE AND FEED
INTO THE BROAD TROUGH TO THE EAST. THROUGH THE WEEKEND THE INFLOW
OF SHORT WAVE ENERGY WILL SUSTAIN THE NORTHWARD AMPLIFICATION OF A
SECONDARY TROUGH ACROSS ARGENTINA LATER ON SUNDAY. THROUGH MONDAY
THE TROUGH IS EXPECTED TO SPLIT IN TWO...SHEARING A SHORT WAVE
TROUGH OVER THE RIO DE LA PLATA BASIN/NORTHERN ARGENTINA. THIS
EVOLVES INTO A CLOSED LOW AS IT LIFTS ACROSS URUGUAY TO SOUTHERN
BRASIL EARLY NEXT WEEK.

AT LOW LEVELS...A POLAR RIDGE IS BUILDING NORTH ACROSS
ARGENTINA...WHILE TO THE EAST A BROAD TROUGH DOMINATES THE
CENTRAL/WESTERN SOUTH ATLANTIC. THE TROUGH ANCHOR ON AN INTENSE
936 HPA LOW NEAR THE SOUTH GEORGIA ISLANDS...WITH POLAR FRONT
SURGING ACROSS SOUTHERN BRASIL-PARAGUAY TO CENTRAL BOLIVIA LATER
THIS AFTERNOON. THE FRONT WILL REMAIN NEARLY STATIONARY OVER MID
SECTIONS OF SOUTH AMERICA THROUGH THE WEEKEND. BUT EARLY NEXT
WEEK...AS THE AFOREMENTIONED MID LEVEL SHORT WAVE TROUGH LIFTS
ACROSS ARGENTINA...THIS WILL STRENGTHEN THE BAROCLINIC BOUNDARY
WHILE TRIGGERING CYCLOGENESIS OVER SOUTHERN BRASIL. AS THE SURFACE
LOW DEEPENS...IT WILL DRIVE THE FRONT FARTHER NORTH ACROSS
BRASIL...SURGING ACROSS SAO PAULO-MATO GROSSO TO AMAZONAS ON
TUESDAY TO WEDNESDAY. OVER SOUTHERN BRASIL...THE FRONT WILL
INITIALLY FAVOR RAINFALL MAXIMA OF 30-60MM. THROUGH THE WEEKEND
THIS IS EXPECTED TO INTENSIFY...WITH MAXIMA INCREASING TO 40-80MM
IN POTENTIALLY SEVERE CONVECTION. MOST INTENSE...HOWEVER...IS
EXPECTED EARLY NEXT WEEK AS THE FRONT EXPERIENCES CYCLOGENESIS. ON
TUESDAY THIS COULD LEAD TO AN ECHO TRAINING PATTERN...WITH MAXIMA
SURGING TO 75-150MM. OTHER CONVECTION IS EXPECTED TO THE NORTH
ACROSS CENTRAL BOLIVIA...WHERE THE MAXIMA ALSO PEAKS AT 30-60MM
EARLY IN THE CYCLE. THIS...HOWEVER...RAPIDLY WEAKENS ON FRIDAY TO
SATURDAY.

SIMULTANEOUSLY...AS SHORT WAVE TROUGH REVOLVE AROUND THE RIDGE TO
THE WEST AND FEED INTO THE POLAR TROUGH TO THE EAST...THEY ARE TO
FAVOR PROGRESSIVE FRONTAL PERTURBATIONS. THESE LIFT ACROSS THE
SOUTHEAST PACIFIC TO THE SOUTHERN REGIONS OF CHILE/TIERRA DEL
FUEGO IN AN ALMOST DAILY BASIS. THE FRONTAL LOWS WILL ENHANCE THE
TRANSPORT OF SUBTROPICAL MOISTURE ACROSS THE SOUTHEAST
PACIFIC...FEEDING CONVECTIVE DEVELOPMENT TO THE SOUTH OF PUERTO
MONTT. ON FRIDAY AND SATURDAY THIS WILL RESULT IN RAINFALL AMOUNTS
OF 15-20MM/DAY...WHILE ON MONDAY AND TUESDAY IT IS TO INCREASE TO
25-50MM/DAY.

NORTH OVER THE CONTINENT...THE DOMINANT FEATURE IS A BROAD CELL OF
THE SUBTROPICAL RIDGE...WITH UPPER LEVEL AXIS ENVELOPING AREA TO
THE NORTH OF 20S. OVER THE EQUATOR...UPPER FLOW SPLITS BETWEEN
THIS AXIS AND A CELL OF THE SUBEQUATORIAL RIDGE OVER THE
CARIBBEAN/NORTHERN SOUTH AMERICA. THIS FAVORS AN UPPER DIVERGENT
PATTERN THAT IS VENTING DIURNAL CONVECTION OVER EQUATORIAL SOUTH
AMERICA. MOST ACTIVE IS CLUSTERING ALONG THE NORTH COAST OF BRASIL
INTO AMAPA-PARA-AMAZONAS TO THE NORTH AND WEST. GDI FORECAST OVER
THE NEXT FEW DAYS SHOWS AN ENHANCED POTENTIAL FOR MODERATE TO
HEAVY RAINFALL AMOUNTS...WITH ACTIVITY FLARING UP LATER IN THE DAY
INTO THE LATE EVENING HOURS.

DAVISON...WPC (USA)
$$

422 
FXSA20 KWBC 271732
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
132 PM EDT WED APR 27 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 27/18 UTC: THE GLOBAL MODELS
INITIALIZE A HIGH AMPLITUDE LONG WAVE TROUGH WITH AXIS TO THE
NORTH/NORTHWEST FROM THE WEDDELL SEA/ANTARCTIC PENINSULA TO MID
SECTIONS OF SOUTH AMERICA. A SUBTROPICAL AND A NORTHERN POLAR JET
MAXIMA ROUNDING THE BASE OF THE TROUGH COUPLED OVER THE WESTERN
ATLANTIC...SUSTAINING A BROAD AREA OF DIVERGENCE OFF THE COAST OF
ARGENTINA. THIS IS INDUCING THE RAPID INTENSIFICATION OF A SURFACE
LOW AS IT STREAMS TOWARDS THE SOUTH GEORGIA ISLANDS...WITH CLOSED
CIRCULATION EXPLOSIVELY INTENSIFYING FROM A 985 HPA LOW EARLY THIS
MORNING TO A 952 HPA LOW LATER THIS EVENING. EARLY ON THURSDAY
MORNING THE LOW REACHES PEAK INTENSITY...WITH CENTRAL PRESSURE
FORECAST TO DROP TO 936 HPA. THE INTENSE RATE OF INTENSIFICATION
WILL LEAD TO HURRICANE INTENSITY WINDS NORTH AND EAST OF THE
SURFACE LOW...WHILE INTENSE UPWARD VERTICAL MOTION IS LIKELY TO
RESULT IN EXTREME TURBULENCE.

THE BROAD SURFACE TROUGH AND THE DEEPENING LOW/METEOROLOGICAL BOMB
SUSTAINS A SURFACE FRONT OVER THE CONTINENT THAT MOVES NORTH
ACROSS URUGUAY TO SOUTHERN BRASIL/NORTHERN ARGENTINA LATER THIS
EVENING. ON THURSDAY...DRIVEN BY A POLAR RIDGE BUILDING ACROSS THE
SOUTHERN CONE...THE FRONT SURGES ACROSS PARAGUAY TO CENTRAL
BOLIVIA...WHERE IT IS EXPECTED TO STALL THROUGH THE END OF THE
WEEK. MEANWHILE...ACROSS URUGUAY TO RIO GRANDE DO SUL IN
BRASIL/CORRIENTES IN ARGENTINA THIS WILL SUSTAIN ORGANIZED DEEP
CONVECTION...WITH MAXIMA OF 75-150MM IN HIGHLY LIKELY SEVERE
THUNDERSTORMS. ON THURSDAY-FRIDAY EXPECTING MODERATE RAINFALL
AMOUNTS TO PERSIST ACROSS SOUTHERN BRASIL TO SOUTHEAST
PARAGUAY...WITH MAXIMA OF 20-35MM/DAY...WHILE OVER CENTRAL BOLIVIA
IT SURGES TO 30-60MM AS ENHANCED BY A SOUTHERLY LOW LEVEL JET
ACROSS PARAGUAY. OTHER PRECIPITATION IS EXPECTED ACROSS THE
SOUTHERN TO CENTRAL ANDES OF CHILE...WHERE THE BROAD TROUGH WILL
SUSTAIN HEAVY SNOWFALL AMOUNTS...WITH ACCUMULATION OF 15-30CM.

THROUGH THE WEEKEND...A MID/UPPER LEVEL SHORT WAVE TROUGH LIFTS
ACROSS THE SOUTHERN CONE. THROUGH SUNDAY MODELS FORECAST THIS
VORTEX TO DEEPEN AS IT LIFTS ALONG THE EASTERN FRINGES OF A BROAD
RIDGE TO THE WEST. THE MID/UPPER LEVEL TROUGH WILL THEN INTERACT
WITH THE AFOREMENTIONED FRONT AS IT MEANDERS ACROSS SOUTHERN
BRASIL-PARAGUAY. THIS WILL STRENGTHEN THE BAROCLINIC BOUNDARY AND
WOULD LIKELY TRIGGER ANOTHER ROUND OF ORGANIZED DEEP CONVECTION
ACROSS SOUTHERN BRASIL-MISIONES IN ARGENTINA AND SOUTHEAST
PARAGUAY. DURING THIS PERIOD THE CONSENSUS AMONG THE DETERMINISTIC
AND ENSEMBLE GUIDANCE IS HIGH...LEADING TO A HIGHER THAN NORMAL
CONFIDENCE IN THE FORECAST AS WE ENTER THE LONG RANGE PERIOD.

DAVISON...WPC (USA)
$$

971 
FXSA20 KWBC 261644
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1243 PM EDT TUE APR 26 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 26/17 UTC: CONSISTENT WITH PREVIOUS
FORECASTS...UNDER THE INFLUENCE OF A LONG WAVE RIDGE TO THE
WEST...A HIGH AMPLITUDE MID/UPPER LEVEL TROUGH IS FORECAST TO
AMPLIFY FROM THE ANTARCTIC PENINSULA TO MID SECTIONS OF SOUTH
AMERICA LATER TODAY. IN STRONG AGREEMENT...THE GLOBAL MODELS THEN
FORECAST THE HIGH AMPLITUDE TROUGH TO SLOWLY RELOCATE ACROSS THE
CONTINENT TO THE WESTERN ATLANTIC THROUGH THE EARLY MORNING HOURS
ON THURSDAY. THIS WILL THEN EVOLVE INTO A BROAD TROUGH WHILE
SLOWLY PULLING TO THE EAST-SOUTHEAST. MEANWHILE...AS IT ENTERS THE
CONTINENT...A SUBTROPICAL AND A NORTHERN POLAR JET MAXIMA ARE
FORECAST TO ROUND THE BASE OF THE LONG WAVE AXIS. AS THEY STREAM
ACROSS CHILE TO ARGENTINA THE JETS ARE FORECAST TO COUPLE OFF THE
COAST OF BUENOS AIRES...FAVORING A BROAD AREA OF UPPER DIVERGENCE.
UNDER THE INFLUENCE OF THE HIGH AMPLITUDE TROUGH AND FAVORABLE
UPPER LEVEL JET DYNAMICS...THE ENVIRONMENTAL CONDITIONS REMAIN
FAVORABLE FOR EXPLOSIVE CYCLOGENESIS (FORMATION OF A
METEOROLOGICAL BOMB)...WITH A 996 HPA LOW SOUTH OF BUENOS AIRES
PROVINCE LATER THIS EVENING...TO STRENGTHENT TO A 984 HPA LOW BY
DAYBREAK ON WEDNESDAY. THROUGH THE END OF THE DAY IT IS TO
MAINTAIN THE INTENSE RATE OF INTENSIFICATION...DEEPENING TO A 956
HPA LOW AS IT NEARS 50S 50W. THE SURFACE LOW REACHES MAXIMUM
INTENSITY OF 936 HPA AS IT NEARS THE SOUTH GEORGIA ISLAND EARLY ON
THURSDAY MORNING. AT LOW LEVELS THIS WILL LIKELY FAVOR HURRICANE
INTENSITY WINDS AS IT PROPAGATES TO THE SOUTHEAST...WHILE AT UPPER
LEVELS IT WOULD LEAD TO EXTREME AIRCRAFT TURBULENCE.

MEANWHILE...THIS WILL SUSTAIN A BROAD TROUGH ACROSS THE SOUTHERN
CONE...WITH FRONTAL LOWS TO REVOLVE AROUND THIS AXIS. A
PARTICULARLY STRONG LOW ENTERS SOUTHERN CHILE LATER THIS EVENING.
THIS WILL ACCELERATE ACROSS NORTHERN PATAGONIA TO THE WESTERN
ATLANTIC AS THE AFOREMENTIONED METEOROLOGICAL BOMB INTENSIFES
BETWEEN THE MALVINAS/FALKLAND AND THE SOUTH GEORGIA ISLANDS. OVER
THE CONTINENT THESE COMBINE IN SUPPORT OF A PROGRESSIVE FRONT THAT
ADVANCES ACROSS CENTRAL TO NORTHERN ARGENTINA/SOUTHERN BRASIL
LATER ON WEDNESDAY. DRIVEN BY A POLAR RIDGE TO THE SOUTH AND A
SOUTHERLY LOW LEVEL JET...THIS THEN SURGES ACROSS PARAGUAY TO
BOLIVIA ON THURSDAY...WHERE IT IS EXPECTED TO STALL THROUGH THE
END OF THE WEEK. OVER CHILE BETWEEN CONCEPCION AND ISLA DE CHILOE
TO THE SOUTH THIS WILL SUSTAIN MODERATE COASTAL CONVECTION WITH
ACCUMULATION OF 20-45MM THROUGH EARLY WEDNESDAY MORNING...WHILE
ACROSS THE CENTRAL AND SOUTHERN ANDES EXPECTING SNOWFALL AMOUNTS
OF NEARLY A METER PER DAY THROUGH THURSDAY MORNING. OVER THE RIO
DE LA PLATA BASIN/URUGUAY THIS WILL TRIGGER HEAVY SEVERE
CONVECTION...WITH ACCUMULATION OF 35-70MM. ON WEDNESDAY THIS
INCREASES TO 75-125MM WHILE BUILDING NORTH ACROSS URUGUAY TO
SOUTHERN BRASIL/CORRIENTES IN ARGENTINA. MODERATE TO HEAVY
CONVECTION WILL THEN PERSIST ACROSS PARA/RIO GRANDE DO SUL IN
SOUTHERN BRASIL AS WELL AS MISIONES IN ARGENTINA THROUGH THE END
OF THE WEEK. ACROSS CENTRAL BOLIVIA THE MOST INTENSE IS EXPECTED
ON THURSDAY...WITH MAXIMA OF 30-60MM. THIS WEAKENS AS IT SPREADS
NORTH ALONG THE SOUTHERN TO CENTRAL JUNGLE OF PERU...WITH MAXIMA
OF 20-35MM...BUT LATER IN THE WEEK COMBINES INTO A HEAVY RAINFALL
PRODUCING MCS BETWEEN THE NORTHERN JUNGLE OF PERU AND ECUADOR.

AS THE AFOREMENTIONED LONG WAVE TROUGH LIFTS ACROSS THE SOUTHERN
CONE...IT WILL PRESS AGAINST A BROAD CELL OF THE SUBTROPICAL RIDGE
TO THE NORTH...WITH THE LATTER EXTENDING WEST-TO-EAST BETWEEN
24S-08S...WHILE A CELL OF THE SUBEQUATORIAL RIDGE TO THE NORTH
DOMINATES THE FLOW ACROSS NORTHERN SOUTH AMERICA. THE DUAL
BARRELED RIDGE PATTERN WILL RESULT IN A BROAD AREA OF UPPER
DIVERGENCE ACROSS EQUATORIAL SOUTH AMERICA. THIS WILL VENT
CONVECTIVE DEVELOPMENT ACROSS NORTHERN BRASIL-THE
GUIANAS/VENEZUEAL TO COLOMBIA-NORTHERN PERU AND ECUADOR. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 15-25MM/DAY...WITH MAXIMA
INCREASING TO 25-50MM AS ENHANCED BY PERTURBATIONS IN THE LOW/MID
LEVEL EASTERLIES. OTHER CONVECTION IS EXPECTED ALONG THE NORTHEAST
COAST OF BRASIL BETWEEN ESPIRITO SANTO AND EASTERN BAHIA DUE TO
TRADE WINDS CONVERGENCE.

DAVISON...WPC (USA)
$$

769 
FXSA20 KWBC 251744
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
143 PM EDT MON APR 25 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

COR

FORECAST DISCUSSION FROM APR 25/18 UTC: AT MID/UPPER LEVELS...THE
GLOBAL MODELS INITIALIZE A HIGHLY AMPLIFIED SINUSOIDAL WAVE
PATTERN...WITH LONG WAVE RIDGE ALONG 110W/120W INDUCING THE
NORTHWARD AMPLIFICATION OF A TROUGH BETWEEN 100W AND THE
BELLINGSHAUSEN SEA TO THE NORTHERN REGIONS OF CHILE/MID SECTIONS
OF SOUTH AMERICA. EMBEDDED IN THIS FLOW...A STRONG VORTEX LIFTS
ACROSS THE SOUTHEAST PACIFIC TO THE SOUTHERN REGIONS OF CHILE
LATER TODAY. THIS WILL SLOWLY PULL ACROSS SOUTHERN CHILE/PATAGONIA
IN ARGENTINA TO THE WESTERN ATLANTIC LATER ON TUESDAY. STARTING ON
TUESDAY EVENING...AS IT MOVES SOUTH OF THE BUENOS AIRES
PROVINCE...THE VORTEX WILL EXPERIENCE A RAPID RATE OF
INTENSIFICATION AS ENHANCED BY COUPLED JETS ALOFT. AT LOW LEVELS
THIS PATTERN WILL LEAD TO BOMB CYCLOGENESIS OVER THE SOUTHWEST
ATLANTIC...WITH SURFACE LOW DEEPENING FROM A 996 HPA LOW JUST
SOUTH OF BUENOS AIRES ON TUESDAY EVENING...TO A 952 HPA LOW EAST
OF THE MALVINAS LATER ON WEDNESDAY. THE INTENSIFYING SURFACE
CYCLONE REACHES MAXIMUM INTENSITY ON THURSDAY AS IT MOVES NEAR THE
SOUTH GEORGIA ISLANDS. AT LOW LEVELS THIS WILL BE ACCOMPANIED BY
HURRICANE INTENSITY WINDS...PEAKING AT 65-70KT ON TUESDAY THROUGH
THURSDAY MORNING.

AS SUCCESSIVE FRONTAL PERTURBATIONS LIFT ACROSS THE SOUTHEAST
PACIFIC INTO THE SOUTHERN REGIONS OF CHILE...THIS WILL RESULT IN
SEVERAL DAYS OF INTENSE PRECIPITATION AMOUNTS. STARTING TODAY
EXPECTING RAINFALL MAXIMA OF 50-100MM...WHILE ON TUESDAY TO
WEDNESDAY EXPECTING ADDITIONAL AMOUNTS OF 20-45MM/DAY. ACROSS THE
SOUTHERN AND CENTRAL ANDES OF CHILE THIS WILL PHASE CHANGE TO
SOLID PRECIPITATION ON TUESDAY THROUGH WEDNESDAY...WITH
ACCUMULATION OF 20-35CM ON TUESDAY AND 15-30CM ON WEDNESDAY...FOR
STORM TOTAL AMOUNTS OF 1.5-2.0 METERS. OVER MID SECTIONS OF SOUTH
AMERICA...THE EVOLVING UPPER LEVEL PATTERN WILL HELP SUSTAIN A
STRONG BAROCLINIC BOUNDARY BETWEEN THE RIO DE LA PLATA BASIN AND
URUGUAY/NORTHERN ARGENTINA. STRONG UPPER LEVEL VERTICAL WIND SHEAR
WILL CONTRIBUTE TO ENHANCE HELICITY AND ROTATION TO LIKELY FAVOR
LONG LASTING SEVERE WEATHER PRODUCING THUNDERSTORMS ACROSS
URUGUAY-ENTRE RIOS AND PORTIONS OF CORRIENTES IN ARGENTINA.
INITIALLY EXPECTING RAINFALL AMOUNTS OF 75-150MM AS ENHANCED BY
THE UPPER LEVEL JET...WITH AN ADDITIONAL 35-70MM ON
TUESDAY...WHILE ON WEDNESDAY THE MAXIMA WEAKENS TO 25-50MM. A
DRYING TREND IS THEN EXPECTED ACROSS THE SOUTHERN CONE ON
THURSDAY...AS THE FRONTAL LOW BOMBS NEAR THE SOUTH GEORGIA ISLANDS
AND A POLAR RIDGE BUILDS ACROSS THE SOUTHERN CONE.

AS THE AFOREMENTIONED LONG WAVE TROUGH LIFTS ACROSS THE SOUTHERN
CONE...IT WILL PRESS AGAINST A BROAD CELL OF THE SUBTROPICAL RIDGE
TO THE NORTH...WITH THE LATTER EXTENDING WEST-TO-EAST BETWEEN
24S-08S...WHILE CELL OF THE SUBEQUATORIAL RIDGE TO THE NORTH
DOMINATES THE FLOW ACROSS NORTHERN SOUTH AMERICA. THE DUAL
BARRELED RIDGE PATTERN WILL RESULT IN A BROAD AREA OF UPPER
DIVERGENCE ACROSS EQUATORIAL SOUTH AMERICA. THIS WILL VENT
CONVECTIVE DEVELOPMENT ACROSS NORTHERN BRASIL-THE
GUIANAS/VENEZUEAL TO COLOMBIA-NORTHERN PERU AND ECUADOR. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 15-25MM/DAY...WITH MAXIMA
INCREASING TO 25-50MM AS ENHANCED BY PERTURBATIONS IN THE LOW/MID
LEVEL EASTERLIES. OTHER CONVECTION IS EXPECTED ALONG THE NORTHEAST
COAST OF BRASIL BETWEEN ESPIRITO SANTO AND EASTERN BAHIA...WHERE A
TRAILING SHEAR LINE AND TRADE WIND CONVERGENCE IS TO RESULT IN
AREAS OF MODERATE RAINFALL AMOUNTS.

DAVISON...WPC (USA)
$$

201 
FXSA20 KWBC 211649
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1248 PM EDT THU APR 21 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT DISCUSSION ON MONDAY APRIL 25.

FORECAST DISCUSSION FROM APR 21/16 UTC: PERSISTENT MID/UPPER LEVEL
RIDGE DOMINATES THE FLOW OVER THE PACIFIC BETWEEN 90W-120W WHILE
ANCHORING ON A MEANDERING MID LEVEL HIGH NEAR 35S 107W. AS THE
RIDGE HOLDS TO THE WEST...SHORT WAVE PERTURBATIONS STREAMING TO
THE SOUTH OF THIS AXIS WILL TEND TO AMPLIFY AS THEY LIFT ACROSS
THE SOUTHERN REGIONS OF CHILE INTO ARGENTINA. AT AN INTERVAL
RANGING BETWEEN 36-48 HRS...THE SUCCESSIVE SHORT WAVE
PERTURBATIONS WILL HELP SUSTAIN THE GRADUAL AMPLIFICATION OF A
LONG WAVE TROUGH ACROSS THE BELLINGSHAUSEN SEA INTO THE SOUTHERN
CONE THROUGH THE WEEKEND TO EARLY NEXT WEEK. THE EVOLVING LONG
WAVE AXIS WILL THEN FAVOR A LONG FETCH COLD ADVECTIVE PATTERN
ACROSS THE SOUTHEAST PACIFIC TO THE SOUTHERN CONE...WITH COLD
ANTARCTIC AIR ADVECTING ACROSS SOUTHERN CHILE TO PATAGONIA/LA
PAMPA IN ARGENTINA.

AT LOW LEVELS...PROGRESSIVE FRONTAL LOWS WILL LIFT ACROSS THE
SOUTHEAST PACIFIC TO THE SOUTHERN OF SOUTH AMERICA DURING THE NEXT
COUPLE OF DAYS...TO COMBINE IN SUPPORT OF A PERSISTENT BAROCLINIC
BOUNDARY ACROSS URUGUAY/NORTHERN ARGENTINA INTO SOUTHERN BRASIL.
THIS BOUNDARY WILL BE THE FOCUS OF LOW LEVEL MOISTURE CONVERGENCE
DURING THE NEXT THREE DAYS. THROUGH THE DAY TODAY INTO THE LATE
EVENING HOURS...UNDER THE INFLUENCE OF A SUBTROPICAL JET
MAXIMA...THIS WOULD LIKELY FAVOR HEAVY RAINFALL AMOUNTS ACROSS
CORRIENTES/MISIONES IN ARGENTINA-SOUTHEAST PARAGUAY INTO RIO
GRANDE DO SUL IN SOUTHERN BRASIL. IN THIS AREA EXPECTING MAXIMA OF
35-70MM IN POTENTIALLY SEVERE CONVECTION...WHILE ON FRIDAY TO
SATURDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 20-40MM.

THESE WILL BE FOLLOWED BY AN INTENSE FRONTAL LOW THAT REACHES THE
SOUTHERN REGIONS OF CHILE LATER ON FRIDAY...WITH AXIS EVOLVING
INTO A BROAD/DEEP OCCLUSION OVER THE SOUTHERN CONE/SOUTHWEST
ATLANTIC DURING THE WEEKEND. THE DEEPENING FRONTAL LOW AND THE
ENSUING PRESSURE GRADIENT WILL SUSTAIN STRONG BOUNDARY LAYER WINDS
35-60KT STARTING ON FRIDAY AND LASTING THROUGH SUNDAY. FAVORING
COLD ADVECTION OVER WARMER THAN NORMAL WATERS OFF THE SOUTH COAST
OF CHILE...THE ENSUING CONVECTIVE INSTABILITY WILL COMBINE WITH
TOPOGRAPHICAL LIFTING ACROSS THE SOUTHERN CONE TO TRIGGER HEAVY
RAINFALL AMOUNTS OVER CHILE BETWEEN CONCEPCION IN CENTRAL CHILE
AND ISLA DE CHILOE TO THE SOUTH. THIS INCREASES FROM 25-50MM
DURING THE DAY TODAY TO 35-70MM/DAY ON FRIDAY AND SATURDAY...AND
AGAIN ON MONDAY AS ANOTHER FRONTAL LOW LIFTS ACROSS THE SOUTHERN
CONE. OVER ARGENTINA MOST ACTIVE IS EXPECTED IN ASSOCIATION WITH
THE FRONTAL LOW TO THE SOUTH AS IT MEANDERS ACROSS PATAGONIA...BUT
LATER IN THE CYCLE IT WILL INTERACT WITH THE OLD/AFOREMENTIONED
BAROCLINIC BOUNDARY TO THE NORTH TO FAVOR HEAVY RAINFALL PRODUCING
MCS ACROSS URUGUAY-ENTRE RIOS/CORRIENTES IN ARGENTINA AND URUGUAY.
THROUGH EARLY NEXT WEEK THE ACTIVITY WILL THEN BUILD EAST AND
NORTH ACROSS SOUTHERN BRASIL...MEANWHILE TRIGGERING MAXIMA OF
75-125MM.

NORTH OVER THE CONTINENT...THE UPPER LEVEL FLOW SPLITS BETWEEN
CELL OF THE SUBTROPICAL RIDGE OVER BRASIL-BOLIVIA-PERU AND A CELL
OF THE SUBEQUATORIAL RIDE TO THE NORTH. AS THE UPPER FLOW SPLITS
BETWEEN THESE RIDGES...IT WILL RESULT IN A BROAD AREA OF UPPER
LEVEL DIVERGENCE OVER EQUATORIAL SOUTH AMERICA. THIS WILL VENT
CONVECTION TO THE NORTH AND IT IS LIKELY TO ENHANCE CONVECTION IN
ASSOCIATION OF EASTERLY WAVES STREAMING ALONG THE ATLANTIC
ITCZ/NEAR EQUATORIAL TROUGH. EARLY IN THE CYCLE THESE WILL SUSTAIN
A HEAVY RAINFALL PRODUCING MCS ACROSS AMAPA-NORTHERN PARA IN
BRASIL AND THE GUIANAS...WITH MAXIMA IN THIS AREA PEAKING AT
75-150MM THROUGH FRIDAY MORNING. FRIDAY AND SATURDAY EXPECTING AN
ADDITIONAL RAINFALL AMOUNTS OF 20-40MM. AS ACTIVITY ACROSS PARA IN
BRASIL WEAKENS...CONVECTION ACROSS NORTHERN AMAZONAS-RORAIMA TO
THE NORTHERN JUNGLE OF PERU IS EXPECTED TO INTENSIFY. THIS
INCREASES FROM 15-20MM/DAY EARLY IN THE CYCLE TO 20-45MM/DAY ON
SUNDAY THROUGH TUESDAY.

DAVISON...WPC (USA)
$$

051 
FXSA20 KWBC 191623
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1222 PM EDT TUE APR 19 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 19/16 UTC: UPPER LEVEL PATTERN OVER
NORTHERN SOUTH AMERICA REMAINS NEARLY UNCHANGED...WITH BROAD CELL
OF THE SUBTROPICAL RIDGE DOMINATING AREA TO THE NORTH OF 20S. THIS
IS EXPECTED TO PERSIST THROUGH THE MEDIUM RANGE PERIOD...WITH AXIS
WAXING AND WANING AS THE DAYS GO ON. AS THE RIDGE HOLDS OVER THE
CONTINENT...AT 250 HPA...IT IS TO STEER A SHORT WAVE TROUGH ACROSS
SOUTHERN/SOUTHEASTERN BRASIL TO OFF THE COAST INTO THE WESTERN
TROPICAL PACIFIC LATER TODAY. THIS IS A SLOW TO EVOLVE
FEATURE...WITH AXIS TO MEANDER EAST ACROSS 30W LATER ON THURSDAY.
ALSO AT 250 HPA...A SUBTROPICAL JET MAXIMA ACCOMPANIES THIS
PERTURBATION AS IT STREAMS ACROSS MID SECTIONS OF SOUTH AMERICA TO
THE WESTERN ATLANTIC. THE JET WILL TRAVERSE CONTINENTAL AREA
BETWEEN 20S-30S. THIS WILL ENHANCE VERTICAL WIND SHEAR ACROSS
NORTHERN ARGENTINA-PARAGUAY-SOUTHERN BRASIL...WHILE ALSO PROVIDING
THE VENTILATION ALOFT IN SUPPORT OF ORGANIZED DEEP CONVECTION.

MEANWHILE...THE UPPER LEVEL PERTURBATION AND JET MAXIMA...IN
INTERACTION WITH A MEANDERING FRONT OFF THE COAST OF
BRASIL...SUSTAINS THE INTENSIFICATION OF THE LOW LEVEL BAROCLINIC
BOUNDARY AND A PREFRONTAL SHEAR LINE ACROSS BAHIA IN NORTHEAST
BRASIL. THE SHEAR LINE WILL REMAIN WELL DEFINED DURING THE NEXT
TWO TO THREE DAYS...WHILE THE FRONT IS TO NEARLY DISSIPATE LATER
IN THE WEEK. MEANWHILE...CONVECTIVE CELLS BUILDING ALONG THE SHEAR
LINE WILL TRAIN ACROSS EASTERN BAHIA...FAVORING ADDITIONAL
RAINFALL AMOUNTS OF 35-70MM THROUGH WEDNESDAY MORNING. THIS WILL
THEN WEAKEN TO 20-30MM/DAY ON WEDNESDAY-THURSDAY...WITH
LIGHT/LOCALLY MODERATE COASTAL CONVECTION TO THEN PERSIST THROUGH
THE END OF THE WEEK.

FURTHERMORE...THE PERSISTENT CELL OF THE SUBTROPICAL RIDGE TO THE
NORTH WILL VENT DEEP CONVECTION ACROSS THE NORTHERN STATES OF
BRASIL AND EQUATORIAL PORTIONS OF SOUTH AMERICA. ACROSS NORTHERN
BRASIL...UNDER THE INFLUENCE OF A DIVERGENT PULSE OF THE MJO...THE
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE FOR HEAVY RAINFALL
PRODUCING MCS TO DEVELOP...WITH RAINFALL MAXIMA OF 35-70MM/DAY IN
ORGANIZED DEEP CONVECTION. THIS WILL PERSIST DURING THE NEXT THREE
DAYS...WITH ACTIVITY WEAKENING LATER IN THE WEEK. THIS IS TO ALSO
ENHANCE DEVELOPMENT ACROSS THE NORTHERN JUNGLE OF PERU INTO
EASTERN ECUADOR...TO RESULT IN MAXIMA OF 30-60MM ON TUESDAY
THROUGH WEDNESDAY...THEN GRADUALLY WEAKEN. THE MJO PULSE IS ALSO
ENHANCING ONSHORE WESTERLY FLOW ACROSS THE EASTERN PACIFIC INTO
ECUADOR/SOUTHWESTERN COLOMBIA. THIS FLOW WILL CONVERGE ALONG THE
WESTERN SLOPES OF THE NORTHERN ANDES TO FAVOR REGIONS OF MODERATE
TO HEAVY RAINFALL AMOUNTS. THIS...HOWEVER...WILL GRADUALLY WEAKEN
AS THE WEEK WEARS ON.

SOUTH OVER THE DOMAIN...A HIGH AMPLITUDE LONG WAVE TROUGH EXTENDS
NORTH FROM THE BELLINGSHAUSEN SEA TO THE CENTRAL REGIONS OF CHILE.
THROUGH WEDNESDAY MORNING THE TROUGH MEANDERS EAST ACROSS THE
SOUTHERN CONE TO THE ANTARCTIC PENINSULA AND OFF THE COAST OF
ARGENTINA. BUT AS IT PRESSES AGAINST A RIDGE TO THE EAST THE
TROUGH IS TO THEN SPLIT...WITH ITS SOUTHERN HALF TO ACCELERATE
ACROSS THE SOUTHERN CONE WHILE THE TRAILING NORTHERN STREAM AXIS
MEANDERS ACROSS CENTRAL/NORTHERN ARGENTINA/WESTERN ATLANTIC. AT
LOW LEVELS...THIS SUSTAINS A BROAD POLAR TROUGH OVER THE
BELLINGSHAUSEN SEA/ANTARCTIC PENINSULA AND THE SOUTHERN CONE. THIS
WILL MEANDER EAST INTO THE WESTERN ATLANTIC WHILE DRIVING A FRONT
NORTH ACROSS SOUTHERN TO CENTRAL ARGENTINA LATER TODAY...WITH THE
FRONT MOVING NORTH ACROSS RIO DE LA PLATA BASIN TO
URUGUAY/NORTHERN ARGENTINA LATER ON THURSDAY...AND MOVING TO
SOUTHERN BRASIL-NORTHERN ARGENTINA/PARAGUAY LATER IN THE WEEK.
OVER SOUTHERN CHILE THE BROAD TROUGH WILL SUSTAIN MODERATE
RAINFALL AMOUNTS WITH MAXIMA OF 20-40MM...WHILE OVER ARGENTINA
ACTIVITY GRADUALLY INTENSIFIES ON WEDNESDAY-THURSDAY...WITH MAXIMA
INCREASING FROM 15-30MM TO 35-70MM AS IT BUILDS NORTH. UNDER
FAVORABLE JET DYNAMICS THERE IS A HIGH RISK OF LARGE HAIL
PRODUCING SEVERE THUNDERSTORMS AHEAD OF THIS BOUNDARY.

SUCCESSIVE MID/UPPER LEVEL PERTURBATIONS ARE TO FOLLOW...WITH
MODELS FAVORING A DEEPER/HIGHER AMPLITUDE TROUGHS TO AMPLIFY
ACROSS THE SOUTHEAST PACIFIC TOWARDS THE END OF THE WEEK. THE
DETERMINISTIC GLOBAL MODELS AND ENSEMBLE MEMBERS ARE SLOWLY
REACHING A CONSENSUS ABOUT THIS EVOLUTION...WITH HIGHER CONFIDENCE
IN THE FORECAST THAN BEFORE. REGARDLESS...THE AMPLIFYING TROUGH
WILL SUSTAIN A LONG FETCH SUBTROPICAL CONNECTION. THIS WILL HELP
SUSTAIN HEAVY RAINS...TO FIRST AFFECT CHILE BETWEEN
CONCEPCION-ISLA DE CHILOE ON THURSDAY WITH MAXIMA OF 25-50MM.
THROUGH SATURDAY/SUNDAY THIS INCREASES TO 30-60MM WITH MOST
INTENSE BETWEEN PUERTO MONTT AND PUNTA ARENAS/TIERRA DEL FUEGO.

DAVISON...WPC (USA)
$$

280 
FXSA20 KWBC 181654
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1254 PM EDT MON APR 18 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 18/17 UTC: NORTH OVER THE
CONTINENT...AT 250 HPA...CELL OF THE SUBTROPICAL RIDGE CONFINES TO
AREA NORTH OF 20S WHILE CENTERING ON A CLOSED HIGH OVER NORTHERN
BOLIVIA. AS THE RIDGE HOLDS ACROSS BRASIL-PERU...IT IS TO STEER A
NORTHERN STREAM MID/UPPER LEVEL SHORT WAVE TROUGH ACROSS THE
SOUTHERN STATES OF BRASIL/URUGUAY LATER TODAY. THIS IS TO CONTINUE
EAST ACROSS 40W EARLY ON WEDNESDAY MORNING...SLOWING TO A CRAWL AS
IT NEAR 30W LATER ON THURSDAY. A SUBTROPICAL JET MAXIMA IS TO
ACCOMPANY THIS PERTURBATION AS IT STREAMS ACROSS MID SECTIONS OF
SOUTH AMERICA TO THE WESTERN ATLANTIC. THE UPPER PERTURBATION AND
JET MAXIMA WILL INTERACT WITH A MEANDERING FRONT OFF THE COAST OF
BRASIL...SUSTAINING THE LOW LEVEL BAROCLINIC BOUNDARY WHILE
TRIGGERING A PREFRONTAL SHEAR LINE ACROSS EASTERN BAHIA. THE SHEAR
LINE WILL REMAIN WELL DEFINED DURING THE NEXT THREE DAYS...WHILE
THE FRONT IS TO NEARLY DISSIPATE LATER IN THE WEEK.
MEANWHILE...CONVECTIVE CELLS BUILDING ALONG THE SHEAR LINE WILL
TRAIN ACROSS EASTERN BAHIA...FAVORING ADDITIONAL RAINFALL AMOUNTS
OF 40-80MM THROUGH TUESDAY MORNING...WHILE ON TUESDAY TO WEDNESDAY
EXPECTING ACCUMULATION OF 35-70MM. THROUGH THURSDAY MORNING THIS
WILL THEN RAPIDLY WEAKEN TO 15-30MM.

FURTHERMORE...THE PERSISTENT UPPER LEVEL RIDGE WILL VENT
CONVECTION ACROSS THE NORTHERN STATES OF BRASIL/EQUATORIAL SOUTH
AMERICA. ACROSS NORTHERN BRASIL...UNDER THE INFLUENCE OF A
DIVERGENT PULSE OF THE MJO...THE ENVIRONMENTAL CONDITIONS ARE
FAVORABLE FOR HEAVY RAINFALL PRODUCING MCS TO DEVELOP...WITH
RAINFALL MAXIMA OF 40-80MM/DAY IN ORGANIZED DEEP CONVECTION. THIS
WILL PERSIST DURING THE NEXT FOUR DAYS...WITH ACTIVITY WEAKENING
LATER IN THE WEEK. THIS IS TO ALSO ENHANCE DEVELOPMENT ACROSS THE
NORTHERN JUNGLE OF PERU INTO EASTERN ECUADOR...TO RESULT IN MAXIMA
OF 50-100MM DURING THE DAY TODAY...WITH AN ADDITIONAL 30-60MM ON
TUESDAY. THE MJO PULSE IS TO FAVOR A DEEP LAYER ONSHORE WESTERLY
FLOW ACROSS THE EASTERN PACIFIC THAT WILL ENHANCE MOISTURE
TRANSPORT ACROSS THE EASTERN PACIFIC TO SOUTHWEST
COLOMBIA/ECUADOR. THIS WILL LEAD TO SEVERAL DAYS OF HEAVY RAINFALL
AMOUNTS BETWEEN THE COAST/SIERRA...WITH DAILY MAXIMA OF 40-80MM.
THIS...HOWEVER...WEAKENS TO 20-40MM/DAY ON WEDNESDAY...WITH LESSER
AMOUNTS LATER IN THE WEEK.

UPSTREAM OVER THE EASTERN SOUTH PACIFIC...A HIGH AMPLITUDE LONG
WAVE TROUGH ENTERS THE SOUTHERN REGIONS OF CHILE LATER THIS
EVENING/EARLY ON TUESDAY MORNING. THROUGH WEDNESDAY MORNING THIS
IS TO MOVE FARTHER EAST ACROSS PATAGONIA IN ARGENTINA/CENTRAL
REGIONS OF CHILE...WITH AXIS SPLITTING AS IT PRESSES AGAINST A
RIDGE TO THE EAST. AT LOW LEVELS THIS WILL SUSTAIN A BROAD POLAR
TROUGH BETWEEN THE BELLINGSHAUSEN SEA-SOUTH COAST OF CHILE LATER
THIS AFTERNOON...WITH THE HIGH AMPLITUDE TROUGH FOCUSING PACIFIC
MOISTURE ACROSS CHILE TO THE SOUTH OF PUERTO MONTT. ON TUESDAY THE
FRONT PUSHES EAST ACROSS PATAGONIA IN ARGENTINA WHILE TRAILING
ACROSS LA PAMPA TO CENTRAL CHILE...WHILE ON WEDNESDAY IT IS TO
ADVANCE ACROSS CENTRAL ARGENTINA. OVER SOUTHERN CHILE THIS WILL
SUSTAIN MODERATE CONVECTION OVER THE NEXT TWO DAYS...WITH DAILY
MAXIMA PEAKING AT 20-40MM. OVER CENTRAL CHILE THIS WEAKENS TO
15-30MM IN ISOLATED TO SCATTERED CONVECTION ON TUESDAY...WHILE
OVER CENTRAL ARGENTINA ALSO EXPECTING MAXIMA OF 15-30MM ON
WEDNESDAY. THIS INCREASES TO 25-50MM ON THE NORTHERN PROVINCES
INTO SOUTHERN BRASIL IN POTENTIALLY SEVERE CONVECTION ON THURSDAY.

SUCCESSIVE MID/UPPER LEVEL PERTURBATIONS ARE TO FOLLOW...WITH
MODELS FAVORING DEEPER/HIGHER AMPLITUDE TROUGHS TO MAKE LANDFALL
TOWARDS THE END OF THE WEEK. DURING THE LATER
PERIODS...HOWEVER...THE ENSEMBLE MODEL MEMBERS DISAGREE ON THE
TIMING AND AMPLITUDE OF THESE PERTURBATIONS...WITH THE UKMET
STRONGLY DISAGREEING ON PATTERN EVOLUTION WELL INTO THE MEDIUM
RANGE PERIOD. HOWEVER...MOIST INFLOW IS LIKELY TO PERSIST...AND AS
A RESULT EXPECTING MODERATE TO HEAVY RAINS TO CONTINUE AFFECTING
AREA OVER CHILE TO THE SOUTH OF 40S.

DAVISON...WPC (USA)
$$

381 
FXSA20 KWBC 151624
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1223 PM EDT FRI APR 15 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON MONDAY APR 18.

FORECAST DISCUSSION FROM APR 15/17 UTC: AT MID/UPPER LEVELS...A
MEANDERING SHORT WAVE TROUGH IS INITIALIZED OVER THE WESTERN
ATLANTIC BETWEEN 55W-35W AND TO THE SOUTH OF 20S...WITH AXIS
CENTERING ON A CLOSED LOW NEAR 35S 40W. THROUGH SATURDAY MORNING
THE LOW IS TO SLOWLY PULL ACROSS 35S 35W...WHILE BASE OF THE MID
LEVEL TROUGH TRAILS TO SAO PAULO/RIO DE JANEIRO. EARLY ON SUNDAY
IT WILL WEAKEN TO AN OPEN TROUGH WHILE MERGING WITH A DEEPENING
TROUGH TO THE SOUTH. THE LATTER WILL THEN BECOME THE DOMINANT
FEATURE ACROSS THE CENTRAL/EASTERN ATLANTIC WHILE AMPLIFYING ALONG
20W TO 30S EARLY NEXT WEEK.

AT LOW LEVELS...THE UPPER PERTURBATION SUSTAIN AN OCCLUDING
FRONTAL TROUGH OVER THE WESTERN ATLANTIC...AND A POLAR FRONT
TRAILING ACROSS ESPIRITO SANTO-MINAS GERAIS TO ACRE/SOUTHERN
AMAZONAS IN WESTERN BRASIL. PORTION OF THE FRONT OVER THE
CONTINENT IS TO FRONTOLIZE THROUGH SUNDAY...WHILE TRAILING PORTION
OVER THE ATLANTIC PERSISTS THROUGH THE MIDDLE OF NEXT WEEK. UNDER
THE INFLUENCE OF THIS FRONT AND A BROAD RIDGE TO THE SOUTH...A
PREFRONTAL SHEAR LINE FORMS ACROSS SOUTHEAST BAHIA EARLY ON
SATURDAY. THE SHEAR LINE WILL THEN PERSIST THROUGH EARLY NEXT
WEEK. THE SHEAR LINE WILL BE THE FOCUS OF LOW LEVEL MOISTURE
CONVERGENCE...AND IN A COOL ADVECTIVE PATTERN IT WOULD LIKELY
FAVOR CONVECTIVE CELL REGENERATION ALONG THIS BOUNDARY. THIS WOULD
LEAD TO ECHO TRAINING CONDITIONS BETWEEN EARLY SATURDAY MORNING
THROUGH TUESDAY EVENING. THIS WILL RESULT IN HEAVY RAINFALL
AMOUNTS BETWEEN NORTHERN ESPIRITO SANTO AND EASTERN BAHIA THROUGH
MONDAY...WITH STORM TOTAL AMOUNTS OF 300-500MM. THE MODELS
CONSISTENTLY SHOW THE MOST INTENSE ON SUNDAY TO MONDAY...WITH
MAXIMA IN THIS AREA PEAKING AT 125-250MM. OTHER CONVECTION IS
EXPECTED TO THE WEST AS THE FRONT TRAILS ACROSS CENTRAL TO WESTERN
BRASIL...WITH RAINFALL AMOUNTS OF 20-45MM IN SCATTERED DEEP
CONVECTION. THROUGH SUNDAY THIS WILL WEAKEN TO 20-35MM/DAY WHILE
FOCUS OF THE ORGANIZED CONVECTION GRADUALLY SHIFTS NORTH ACROSS
AMAZONAS IN WESTERN BRASIL TO NORTHERN JUNGLE OF PERU/SOUTHERN
COLOMBIA. FURTHERMORE...UNDER THE INFLUENCE OF A DIVERGENT PULSE
OF THE MJO...A LONG FETCH WESTERLY FLOW IS TO ESTABLISH ACROSS THE
EASTERN TROPICAL PACIFIC TO COLOMBIA-ECUADOR. THIS WILL ENHANCE
MOISTURE TRANSPORT AND CONVERGENCE ALONG THE WESTERN SLOPES OF THE
ECUADORIAN ANDES. ACTIVITY IN THIS AREA IS LIKELY TO INTENSIFY
OVER THE NEXT FEW DAYS WITH AN ENHANCED RISK OF HEAVY RAINFALL
AMOUNTS EARLY NEXT WEEK.

PATTERN TO THE SOUTH...MEANWHILE...REMAINS UNDER THE INFLUENCE OF
PROGRESSIVE SHORT WAVE PERTURBATIONS STREAMING ACROSS THE SOUTHERN
CONE...WITH ONE MAKING LANDFALL EARLY IN THE CYCLE AS ANOTHER
REACHES SOUTHERN CHILE EARLY ON SUNDAY MORNING. THIS PAVES THE WAY
FOR A DEEPER TROUGH TO AMPLIFY ACROSS THE EASTERN PACIFIC TO THE
SOUTHERN/CENTRAL REGIONS OF CHILE EARLY ON MONDAY MORNING. THE
LATTER IS TO SLOWLY PULL ACROSS THE SOUTHERN CONE WHILE PRESSING
AGAINST A BROAD RIDGE TO THE EAST. AT LOW LEVELS...A SLOW TO
EVOLVE FRONT ENTERS SOUTHERN CHILE LATER ON SATURDAY...WITH A
BROAD/DEEP FRONTAL TROUGH LIFTING ACROSS THE SOUTHEAST PACIFIC
LATER ON MONDAY. OVER THE NEXT FEW DAYS THESE ARE TO FAVOR
MODERATE RAINFALL AMOUNTS WITH ACCUMULATION OF 15-25MM/DAY BETWEEN
TIERRA DEL FUEGO AND ISLA DE CHILOE IN SOUTHERN CHILE. ON MONDAY
TO TUESDAY THIS INCREASES TO 20-35MM WHILE BUILDING NORTH BETWEEN
PUERTO MONTT AND ISLA DE CHILOE...INCREASING TO 20-45MM ON TUESDAY
AS ENHANCED BY THE OCCLUDED FRONTAL LOW.

DAVISON...WPC (USA)
$$

023 
FXSA20 KWBC 141656
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1254 PM EDT THU APR 14 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 14/17 UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECAST...A MID/UPPER LEVEL HIGHLY AMPLIFIED
SINUSOIDAL WAVE PATTERN PREVAILS OVER THE SOUTH AMERICAN
DOMAIN...WITH AN UPPER LEVEL HIGH OFF THE CENTRAL COAST OF CHILE
ANCHORING A RIDGE OVER THE FAR EASTERN PACIFIC AND SOUTHERN CONE
OF SOUTH AMERICA. LONG WAVE TROUGH TO THE EAST EXTENDS FROM THE
WEDDELL SEA/SOUTH GEORGIA ISLANDS...ALONG 45S 50W TO NORTHERN
ARGENTINA/MID SECTIONS OF SOUTH AMERICA. THROUGH THIS EVENING THE
RIDGE RELOCATES ACROSS CHILE TO ARGENTINA...MOVING OFF THE COAST
TO THE WESTERN ATLANTIC ON FRIDAY...WHERE IT IS TO HOLD THROUGH
THE WEEKEND TO EARLY NEXT WEEK. AS THE RIDGE PRESSES AGAINST THE
LONG WAVE TROUGH TO THE EAST...IT WILL UNDERCUT THIS AXIS...WITH
THE TROUGH SPLITTING IN TWO EARLY ON FRIDAY. IT SOUTHERN HALF WILL
THEN ACCELERATE ACROSS THE CENTRAL TO EASTERN SOUTH
ATLANTIC...WHILE THE REMAINING NORTHERN STREAM VORTEX ORGANIZES
INTO A CLOSED MID LEVEL LOW NEAR 33S 40W. THE DEEP LOW WILL
MEANDER EAST TO 35S 35W EARLY ON SATURDAY MORNING...THEN WEAKEN TO
AN OPEN TROUGH WHILE MERGING WITH A DEEPENING TROUGH TO THE SOUTH
ON SUNDAY.

AT LOW LEVELS...A BROAD RIDGE DOMINATES THE FLOW ACROSS
ARGENTINA/THE SOUTHERN CONE...WHILE A DEEPENING FRONTAL TROUGH TO
THE EAST EXTENDS OVER THE WESTERN ATLANTIC. THROUGH FRIDAY THIS IS
EXPECTED TO RAPIDLY OCCLUDE...THEN PULL TO THE EAST-SOUTHEAST
LATER DURING THE WEEKEND. AS THE TROUGH DEEPENS AND THE RIDGE
HOLDS TO THE WEST...IT WILL SUSTAIN A SOUTHERLY LOW LEVEL JET
ACROSS PARAGUAY TO BOLIVIA...THIS IN-TURN DRIVES THE ASSOCIATED
FRONT NORTH ACROSS SOUTHEAST-CENTRAL BRASIL TO ACRE/RONDONIA LATER
TODAY. ON FRIDAY THE FRONT MOVES FARTHER NORTH ACROSS ESPIRITO
SANTO/MINAS GERAIS WHILE TRAILING ACROSS MATO GROSSO TO
RONDONIA/SOUTHERN AMAZONAS. TRAILING END OVER THE CONTINENT IS TO
THEN NEARLY DISSIPATE DURING THE WEEKEND...WHILE PORTION OVER THE
ATLANTIC EVOLVES INTO A PREFRONTAL SHEAR LINE ACROSS BAHIA. THE
SHEAR LINE WILL BECOME THE FOCUS OF LOW LEVEL MOISTURE CONVERGENCE
AND IN A COOL ADVECTIVE PATTERN IT WOULD LIKELY FAVOR A PERSISTENT
ECHO TRAINING EVENT. HEAVY RAINFALL AMOUNTS ARE EXPECTED BETWEEN
NORTHERN ESPIRITO SANTO AND EASTERN BAHIA ON FRIDAY THROUGH
MONDAY...WITH STORM TOTAL AMOUNTS OF 300-500MM...WITH MOST INTENSE
ON SUNDAY WHEN IT WOULD LIKELY FAVOR RAINFALL AMOUNTS OF 125-250MM.

OTHER CONVECTION IS EXPECTED TO THE WEST AS THE FRONT SURGES
ACROSS BRASIL. INITIALLY MOST INTENSE IS EXPECTED BETWEEN CENTRAL
BOLIVIA AND THE SOUTHERN JUNGLE OF PERU AS ENHANCED BY THE
SOUTHERLY LOW LEVEL JET...WITH MAXIMA OF 40-80MM. ON FRIDAY THIS
DECREASES TO 30-60MM WHILE SPREADING NORTH ACROSS ACRE TO AMAZONAS
IN BRASIL TO THE CENTRAL JUNGLE OF PERU...AND DURING THE WEEKEND
IT EVOLVES INTO A BROAD AREA OF MODERATE TO HEAVY RAINFALL AMOUNTS
ACROSS AMAZONAS TO THE NORTHERN JUNGLE OF PERU...WITH DAILY MAXIMA
OF 30-60MM IN SCATTERED DEEP CONVECTION. OTHER CONVECTION IS
EXPECTED ACROSS ECUADOR TO SOUTHWEST COLOMBIA...WHERE A DEEPENING
SURFACE TROUGH IS TO SUSTAIN A MOIST LONG FETCH NORTHWESTERLY
FLOW...RESULTING IN SEVERAL DAYS OF HEAVY RAINS.

THROUGH EARLY NEXT WEEK A DEEP/BROAD MID/UPPER LEVEL TROUGH WILL
ROLL ACROSS THE EASTERN PACIFIC TOWARDS THE SOUTHERN CONE OF SOUTH
AMERICA. MEANWHILE...PROGRESSIVE SHORT WAVE PERTURBATIONS WILL
PRECEDE THIS AXIS. AT LOW LEVELS THESE ARE TO INITIALLY FAVOR AN
ELONGATED FRONT ACROSS EXTREME SOUTHERN PORTIONS OF PATAGONIA IN
ARGENTINA TO TIERRA DEL FUEGO IN SOUTHERN CHILE. A DEEPER/HIGHER
AMPLITUDE FRONTAL TROUGH WILL FOLLOW EARLY DURING THE
WEEKEND...THAT SLOWLY LIFTS ACROSS THE SOUTHERN CONE TO THE
WESTERN ATLANTIC EARLY NEXT WEEK. THESE WILL FAVOR A TIGHT
GRADIENT AND STRONG BOUNDARY LAYER WINDS...ENHANCING ADIABATIC
LIFTING/SATURATION WHILE FAVORING PERIODS OF MODERATE TO HEAVY
RAINFALL AMOUNTS...WITH MOST INTENSE BETWEEN PUNTA ARENAS CHILE
AND ISLA DE CHILOE TO THE NORTH.

DAVISON...WPC (USA)
$$

204 
FXSA20 KWBC 131714
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
113 PM EDT WED APR 13 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 13/17 UTC: A HIGHLY AMPLIFIED
SINUSOIDAL WAVE PATTERN IS INITIALIZED OVER THE SOUTH AMERICAN
DOMAIN...WITH A CLOSED HIGH NEAR 43S 90W ANCHORING ALONG WAVE
RIDGE OVER THE SOUTHEAST PACIFIC. A LONG WAVE TROUGH TO THE EAST
EXTENDS NORTH ALONG 60W TO MID SECTIONS OF SOUTH AMERICA. THROUGH
THURSDAY EVENING THE RIDGE RELOCATES ACROSS CHILE TO
ARGENTINA...AND EARLY ON FRIDAY MORNING IT ROLLS OFF THE COAST
INTO THE WESTERN ATLANTIC. AS IT PRESSES AGAINST THE LONG WAVE
TROUGH TO THE EAST...THE LATTER WILL SPLIT IN TWO...WITH THE
SOUTHERN HALF OF THE TROUGH MEANDERING EAST ACROSS THE CENTRAL
SOUTH ATLANTIC...WHILE THE REMAINING NORTHERN STREAM VORTEX
ORGANIZES INTO A CLOSED MID LEVEL LOW NEAR 33S 40W. IN THIS CYCLE
THE GFS FAVORS A DEEPER LOW THAN WHAT IT PREVIOUSLY
SUGGESTED...WITH A STRONG LOW LEVEL REFLECTION.

AT LOW LEVELS...DRIVEN BY A POLAR RIDGE OVER ARGENTINA AND A
SOUTHERLY LOW LEVEL JET...A SURFACE FRONT SURGES ACROSS SOUTHERN
BRASIL-PARAGUAY TO CENTRAL BOLIVIA LATER THIS EVENING. THROUGH
THURSDAY AFTERNOON THE FRONT MOVES FARTHER EAST AND NORTH ACROSS
BRASIL...MEANWHILE INDUCING A PREFRONTAL SHEAR LINE ACROSS
SOUTHERN PARA TO AMAZONAS. ON THURSDAY TO FRIDAY A DEEPENING
FRONTAL LOW WILL BECOME THE DOMINANT NORTHERN STREAM FEATURE OVER
THE WESTERN SOUTH ATLANTIC...WITH THE OCCLUDING LOW TO SUSTAIN A
WELL ORGANIZED BAROCLINIC BOUNDARY ACROSS ESPIRITO SANTO-MINAS
GERAIS TO RONDONIA/SOUTHERN AMAZONAS IN WESTERN BRASIL. PORTION
OVER BRASIL FRONTOLIZES EARLY NEXT WEEK...WHILE REMNANTS OVER THE
SUBTROPICAL/TROPICAL ATLANTIC PERSIST THROUGH THE MIDDLE OF THE
WEEK. AS THE FRONT SURGES ACROSS SOUTHERN TO SOUTHEASTERN
BRASIL...HEAVY RAINS ARE EXPECTED OVER MATO GROSSO DO SUL TO
RESULT IN RAINFALL AMOUNTS OF 30-60MM...WHILE OVER CENTRAL BOLIVIA
THIS INCREASES TO 40-80MM. THIS SPREADS ACROSS SOUTHERN TO THE
CENTRAL JUNGLE OF PERU ON THURSDAY...WITH MAXIMA OF
40-80MM...WHILE ACROSS AMAZONAS EXPECTING MAXIMA OF 35-70MM.
ACTIVITY OVER NORTHWEST SOUTH AMERICA THEN WAXES AND WANES OVER
THE NEXT SEVERAL DAYS...WITH MAXIMA PEAKING AT 30-60MM/DAY...WHILE
OVER CENTRAL BRASIL EXPECTING MAXIMA OF 20-35MM. HEAVY RAINS ARE
ALSO EXPECTED OVER ESPIRITO SANTO/SOUTHERN BAHIA AS THE MEANDERING
FRONT STRADDLES THE NORTHEAST STATES OF BRASIL...WITH COASTAL
CONVECTION INCREASING FROM 35-70MM ON FRIDAY TO 75-125MM ON SUNDAY
THROUGH MONDAY.

OTHER SHORT WAVE PERTURBATIONS ARE TO FOLLOW...STREAMING ACROSS
THE EASTERN PACIFIC WHILE CONFINING TO THE DRAKE PASSAGE/SOUTHERN
PORTIONS OF SOUTH AMERICA DURING THE NEXT SEVERAL DAYS. AT LOW
LEVELS...THIS WILL HELP SUSTAIN AN ELONGATED FRONT OVER TIERRA DEL
FUEGO/EXTREME SOUTHERN CHILE DURING THE NEXT THREE DAYS...WITH
OTHERS TO FOLLOW LATER DURING THE WEEKEND/EARLY NEXT WEEK. THESE
WILL FAVOR A TIGHT GRADIENT AND STRONG BOUNDARY LAYER
WINDS...ENHANCING ADIABATIC LIFTING/SATURATION WHILE FAVORING
PERIODS OF MODERATE TO HEAVY RAINFALL AMOUNTS.

DAVISON...WPC (USA)
$$

879 
FXSA20 KWBC 111821
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
220 PM EDT MON APR 11 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 11/20 UTC: DISCUSSION NOT ISSUED

DAVISON...WPC (USA)
$$

313 
FXSA20 KWBC 071659
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1259 PM EDT THU APR 07 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 07/17 UTC: IN A HIGH AMPLITUDE
SINUSOIDAL PATTERN...A LONG WAVE RIDGE OVER THE SOUTHEAST PACIFIC
SEPARATES TWO TROUGHS...WITH THE WESTERNMOST EXTENDING ALONG 105W
TO 38S WHILE THE ONE TO THE EAST DOMINATES THE FLOW BETWEEN
60W-30W AND TO THE SOUTH OF 40S. ON FRIDAY THE ENTIRE PATTERN
SHIFT EASTWARD...WITH THE RIDGE RELOCATING ACROSS THE SOUTHERN
CONE/ANTARCTIC PENINSULA TO THE WESTERN ATLANTIC/WEDDELL SEA. THIS
DISPLACES THE ATLANTIC TROUGH FARTHER TO THE EAST...WHILE THE ONE
OVER THE EASTERN PACIFIC PUSHES EASTWARD INTO THE BELLINGSHAUSEN
SEA TO SOUTHERN/CENTRAL CHILE LATER IN THE DAY. SHEARING UNDER THE
RIDGE TO THE EAST...THE TROUGH SPLITS IN TWO...WITH ITS SOUTHERN
HALF ACCELERATING ACROSS THE DRAKE PASSAGE/ANTARCTIC PENINSULA...
WHILE THE REMAINING NORTHERN STREAM VORTEX EVOLVES INTO A NORTHERN
STREAM LOW OVER ACROSS SOUTHERN CHILE/PATAGONIA IN ARGENTINA LATER
ON FRIDAY. THROUGH THE WEEKEND THIS IS TO THEN SHEAR EASTWARD
ACROSS THE SOUTHERN CHILE TO PATAGONIA IN ARGENTINA AS A SIMILARLY
STRONG PERTURBATION MAKES LANDFALL OVER THE SOUTHERN CONE EARLY
NEXT WEEK.  

AT LOW LEVELS...THE ATLANTIC TROUGH SUSTAINS A BROAD FRONTAL
TROUGH AND AN ELONGATED FRONT STRETCHING FROM THE CENTRAL ATLANTIC
TO LA PAMPA/NORTHERN PATAGONIA IN ARGENTINA. OVER THE NEXT TWO
DAYS THE MEANDERING FRONT WILL ENHANCE LOW LEVEL MOISTURE
CONVERGENCE TO FAVOR SCATTERED CONVECTION...WITH RAINFALL MAXIMA
PEAKING AT 15-30MM EARLY IN THE CYCLE. ON FRIDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 15-20MM. NOTE THAT UNDER FAVORABLE
JET DYNAMICS THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS
ACROSS LA PAMPA DURING THE DAY TODAY.

NEXT FRONT LIFTS ACROSS THE SOUTHEAST PACIFIC TO THE SOUTHERN
REGIONS OF CHILE LATER ON FRIDAY. THE FRONTAL LOW DEEPENS AS IT
MEANDERS EAST ACROSS PATAGONIA IN ARGENTINA ON SATURDAY...DRIVING
THE ASSOCIATED FRONT NORTH TO LA PAMPA/CENTRAL ARGENTINA. AS THE
FRONT SURGES NORTH ACROSS CENTRAL ARGENTINA CONDITIONS APPEAR
FAVORABLE FOR A PREFRONTAL SQUALL LINE TO DEVELOP NORTH OF THIS
BOUNDARY ON SUNDAY. OVER SOUTHERN CHILE THE LOW WILL SUSTAIN
MODERATE RAINFALL AMOUNTS AS IT MAKES LANDFALL ON FRIDAY...WITH
RAINFALL AMOUNTS OF 15-20MM. OVER LA PAMPA/CENTRAL ARGENTINA THIS
INCREASES TO 20-45MM ON SATURDAY IN POTENTIALLY SEVERE CONVECTION
LATER ON SATURDAY. ON SUNDAY ACTIVITY TO THE NORTH ORGANIZES INTO
AN MCS/SQUALL LINE WHILE LIFTING ACROSS CENTRAL ARGENTINA/RIO DE
LA PLATA BASIN TO NORTHERN ARGENTINA...WITH THE CONSENSUS OF THE
GLOBAL AND ENSEMBLE MODEL GUIDANCE SHOWING AN ENHANCED RISK OF
HEAVY RAINFALL AMOUNTS DURING THE LATER PERIODS. UNDER THE
INFLUENCE OF COUPLED JETS THIS WILL SUSTAIN RAINFALL AMOUNTS OF
75-150MM...WHILE ON SUNDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS
OF 40-80MM AS IT SPREADS NORTH ACROSS SOUTHERN BRASIL TO PARAGUAY.

MEANWHILE...OVER TROPICAL SOUTH AMERICA...DOMINANT FEATURE IS A
250 HPA RIDGE ENVELOPING AREA TO THE NORTH OF 20S. AS THE RIDGE
HOLDS TO THE NORTH...A SUBTROPICAL JET IS TO MEANDER EAST ALONG
THE SOUTHERN  FRINGES OF THE RIDGE...TRAVERSING NORTHERN
CHILE/ARGENTINA AND THE SOUTHERN STATES OF BRASIL. EARLY IN THE
CYCLE THIS WILL VENT DEEP CONVECTION CLUSTERING ALONG A SURFACE
FRONT OVER SOUTHERN BRASIL-NORTHERN ARGENTINA. THIS WILL FAVOR A
NORTHERLY LOW LEVEL JET THAT ENHANCES MOISTURE TRANSPORT FROM THE
NORTH...AND LOW LEVEL CONVERGENCE ALONG THE SURFACE FRONT.
THIS...IN-TURN...WILL BE CONDUCIVE TO HEAVY RAINFALL
AMOUNTS...WITH MAXIMA OF 75-150MM EXPECTED BETWEEN CORRIENTES IN
ARGENTINA/SOUTHEAST PARAGUAY AND THE SOUTHERN STATES OF BRASIL. ON
FRIDAY TO SATURDAY JET PATTERN ALOFT WEAKENS...AND THE DAILY
MAXIMA DECREASES TO 15-20MM.

OTHER CONVECTION IS EXPECTED ACROSS NORTHERN BRASIL AND EQUATORIAL
SOUTH AMERICA...WITH A DUAL ITCZ PATTERN OVER THE WESTERN ATLANTIC
TO ENHANCE DEVELOPMENT ACROSS NORTHERN BRASIL AND WESTERN INTERIOR
PORTIONS OF SOUTH AMERICA. MOST ACTIVE IS EXPECTED BETWEEN PARA
AND NORTHERN AMAZONAS IN BRASIL...WITH HEAVY CONVECTION MOST
LIKELY THE NEXT COUPLE OF DAYS. TENDENCY IS FOR THE ACTIVITY TO
WEAKEN AS IT SPREADS FARTHER WESTWARD ACROSS BRASIL LATER DURING
THE WEEK...WHILE ALONG THE NORTHEAST COAST MOST ACTIVE IS EXPECTED
TODAY.

DAVISON...WPC (USA)
$$

919 
FXSA20 KWBC 061725
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
124 PM EDT WED APR 06 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 06/17 UTC: A BROAD MID/UPPER LEVEL
TROUGH IS INITIALIZED OVER THE SOUTHWEST ATLANTIC...SPANNING
BETWEEN THE WEDDELL SEA AND PATAGONIA IN SOUTHERN ARGENTINA.
THROUGH THURSDAY EVENING THE TROUGH IS TO SLOWLY MOVE ACROSS 38W
WHILE GRADUALLY AMPLIFYING ACROSS THE SOUTH GEORGIA ISLANDS TO
30S. THROUGH SATURDAY MORNING IT IS TO MEANDER FARTHER EASTWARD
ACROSS THE SOUTH ATLANTIC. AT LOW LEVELS...THIS SUSTAINS A BROAD
FRONTAL TROUGH OVER THE SOUTHWEST ATLANTIC THAT ORIGINATES ON A
DEEP/OCCLUDED LOW OVER THE WEDDELL SEA...WITH AN ELONGATED FRONT
STRETCHING ACROSS NORTHERN PATAGONIA IN ARGENTINA TO A LOW OFF THE
SOUTH COAST OF CHILE. THROUGH THURSDAY EVENING THE FRONTAL LOW
LIFTS ACROSS THE SOUTHERN ANDES TO NORTHERN PATAGONIA/LA
PAMPA...THEN GRADUALLY WEAKEN AS IT MEANDERS OFFSHORE INTO THE
WESTERN ATLANTIC LATER IN THE WEEK. OVER SOUTHERN CHILE THE
FRONTAL LOW WILL FAVOR MODERATE RAINFALL AMOUNTS WITH ACCUMULATION
OF 20-45MM EARLY IN THE CYCLE...WHILE OVER LA PAMPA/NORTHERN
PATAGONIA THIS WILL SUSTAIN ACCUMULATION OF 15-30MM ON THURSDAY.
IN THIS AREA...UNDER THE INFLUENCE OF A POLAR JET MAXIMA...THERE
IS A MODERATE RISK OF SEVERE CONVECTION ON THURSDAY AND FRIDAY.

IN A HIGHLY AMPLIFIED SINUSOIDAL WAVE PATTERN...A LONG WAVE TROUGH
IS TO FOLLOW...WITH MID LEVEL AXIS TO EXTEND NORTH ALONG 90W TO
37S EARLY ON FRIDAY MORNING. AS IT PRESSES AGAINST A RIDGE TO THE
EAST...THE TROUGH IS TO THEN SPLIT IN TWO AS IT REACHES THE
SOUTHERN CONE EARLY ON FRIDAY MORNING. THE SOUTHERN HALF OF THE
TROUGH WILL QUICKLY WEAKEN WHILE SHEARING ACROSS THE DRAKE
PASSAGE/ANTARCTIC PENINSULA...WHILE THE REMAINING NORTHERN STREAM
VORTEX EVOLVES INTO A CLOSED LOW OFF THE SOUTH COAST OF CHILE. IN
THIS CYCLE THE MODELS CORRECTED IN FAVOR OF A DEEPER/BETTER
ORGANIZED LOW THAN WHAT THEY PREVIOUSLY SUGGESTED. THROUGH
SATURDAY EVENING THE LOW/SHORT WAVE TROUGH IS TO SPILL ACROSS THE
SOUTHERN ANDES INTO NORTHERN PATAGONIA/LA PAMPA. DURING THE
WEEKEND THIS IS TO THEN ACCELERATE ACROSS THE WESTERN SOUTH
ATLANTIC WHILE PHASING WITH A SHORT WAVE TROUGH TO THE SOUTH. AT
LOW LEVELS THIS WILL SUSTAIN AN OCCLUDING FRONTAL LOW OVER
SOUTHERN CHILE LATER ON FRIDAY...DEEPENING AS IT MEANDERS EAST
ACROSS CENTRAL PATAGONIA ON SATURDAY. THIS WILL THEN DRIVE THE
ASSOCIATED FRONT NORTH ACROSS LA PAMPA TO CENTRAL ARGENTINA DURING
THE WEEKEND. OVER SOUTHERN CHILE THE LANDFALLING LOW WILL SUSTAIN
MODERATE RAINFALL AMOUNTS WITH ACCUMULATION OF 15-20MM ON FRIDAY.
OVER LA PAMPA/CENTRAL ARGENTINA THIS INCREASES TO 20-45MM ON
SATURDAY IN POTENTIALLY SEVERE CONVECTION. ON SUNDAY ACTIVITY
ORGANIZES INTO AN MCS/SQUALL LINE WHILE LIFTING ACROSS CENTRAL
ARGENTINA/RIO DE LA PLATA BASIN...WITH THE CONSENSUS OF THE GLOBAL
AND ENSEMBLE MODEL GUIDANCE SHOWING AN ENHANCED RISK OF HEAVY
RAINFALL AMOUNTS DURING THE LATER PERIODS.

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE IS EXPECTED TO PREVAIL DURING THE NEXT SEVERAL
DAYS. AS THE RIDGE HOLDS...A SUBTROPICAL JET MAXIMA WILL INITIALLY
EXTEND ALONG THE SOUTHERN FRINGES OF THIS RIDGE...STRADDLING
NORTHERN CHILE/ARGENTINA AND THE SOUTHERN STATES OF BRASIL. THIS
IS TO WEAKEN WHILE STREAMING ACROSS NORTHERN ARGENTINA/SOUTHERN
BRASIL ON THURSDAY. AT LOW LEVELS...AN OLD/ELONGATED FRONT WILL
EXTEND ACROSS THE CENTRAL ATLANTIC TO SOUTHERN BRASIL/NORTHERN
ARGENTINA LATER TODAY. THROUGH THE END OF THE WEEK THE FRONTAL
BOUNDARY IS FORECAST TO FRONTOLIZE. MEANWHILE...THIS WILL BE THE
FOCUS OF LOW LEVEL MOISTURE CONVERGENCE. EARLY IN THE CYCLE
CONDITIONS APPEAR FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO
FORM OVER NORTHERN ARGENTINA...FAVORING MAXIMA OF 50-100MM IN
POTENTIALLY SEVERE CONVECTION. ON THURSDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 35-70MM WHILE BUILDING EAST ACROSS RIO GRANDE
DO SUL IN SOUTHERN BRASIL...WHILE LATER IN THE WEEK EXPECTING AN
ADDITIONAL 20-30MM/DAY ALONG THE WANING SURFACE FRONT.

OTHER CONVECTION IS EXPECTED ACROSS NORTHERN BRASIL AND EQUATORIAL
SOUTH AMERICA...WITH A DUAL ITCZ PATTERN OVER THE WESTERN ATLANTIC
TO ENHANCE DEVELOPMENT BETWEEN NORTHERN BRASIL AND WESTERN
INTERIOR PORTIONS OF SOUTH AMERICA. MOST ACTIVE IS EXPECTED
BETWEEN PARA AND NORTHERN AMAZONAS IN BRASIL...WITH HEAVY
CONVECTION MOST LIKELY THE NEXT COUPLE OF DAYS. TENDENCY IS FOR
THE ACTIVITY TO WEAKEN AS IT SPREADS FARTHER WESTWARD ACROSS
BRASIL LATER DURING THE WEEK.

DAVISON...WPC (USA)
$$

865 
FXSA20 KWBC 051711
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
110 PM EDT TUE APR 05 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 05/17 UTC: A BROAD MID/UPPER LEVEL
TROUGH REMAINS THE DOMINANT MESO-SYNOPTIC FEATURE BETWEEN THE
ANTARCTIC PENINSULA AND THE SOUTHERN CONE...WITH AXIS ANCHORING AT
MID LEVELS ON A CLOSED LOW LIFTING ACROSS THE DRAKE PASSAGE. UNDER
THE INFLUENCE OF A RIDGE BUILDING TO THE WEST...THE TROUGH IS TO
SLOWLY RELOCATE TO THE SOUTHWEST ATLANTIC THROUGH WEDNESDAY
MORNING. MEANWHILE...THIS WILL SUSTAIN A LONG FETCH SOUTHERLY FLOW
BETWEEN THE BELLINGSHAUSEN SEA/ANTARCTIC PENINSULA AND TIERRA DEL
FUEGO TO SOUTHERN PATAGONIA...ADVECTING COLD ANTARCTIC AIR
NORTHWARD ACROSS THE BELLINGSHAUSEN SEA TO PATAGONIA IN SOUTHERN
ARGENTINA. AT LOW LEVELS...THIS WILL SUSTAIN A BROAD FRONTAL
TROUGH BETWEEN THE WEDDELL SEA/ANTARCTIC PENINSULA AND THE
MALVINAS/FALKLAND ISLANDS LATER TODAY...WITH A MEANDERING FRONT TO
THE NORTH STRETCHING ACROSS PATAGONIA/SOUTHERN CHILE TO THE
EASTERN PACIFIC. LATER ON THURSDAY THE FRONT MEANDERS NORTH ACROSS
PATAGONIA TO LA PAMPA IN ARGENTINA...WHERE IT IS EXPECTED TO
STALL. ACROSS SANTA CRUZ IN SOUTHERN PATAGONIA THIS WILL RESULT IN
HEAVY SNOWFALL AMOUNTS WITH ACCUMULATION OF 15-20CM. ACROSS
SOUTHERN CHILE...THE BROAD FRONTAL TROUGH IS FOCUSING A PLUME OF
DEEP SUBTROPICAL MOISTURE BETWEEN PUERTO MONTT AND ISLA DE CHILOE.
THIS IS FEEDING ORGANIZED CONVECTION AND THROUGH WEDNESDAY MORNING
IT WILL RESULT IN RAINFALL AMOUNTS OF 50-100MM...WITH AN
ADDITIONAL 20-45MM ON WEDNESDAY TO THURSDAY.

THROUGH THE MEDIUM RANGE PERIOD THE MID/UPPER LEVEL PATTERN TO THE
SOUTH WILL BECOME MORE AMPLIFIED AS A HIGH AMPLITUDE TROUGH
PROPAGATES ACROSS THE SOUTHEAST PACIFIC ON THURSDAY. THROUGH
FRIDAY THE MID LEVEL TROUGH WILL MOVE ACROSS 80W WHILE FOCUSING
ITS SHORT WAVE ENERGY ACROSS THE SOUTHERN REGIONS OF CHILE. LATER
ON SATURDAY IT WILL SLOWLY PULL ACROSS CHILE TO PATAGONIA/CENTRAL
ARGENTINA...CLEARING THE COAST LATER IN THE DAY. AS THE UPPER
TROUGH MAKES LANDFALL OVER THE SOUTHERN CONE...IT WILL INTERACT
WITH THE AFOREMENTIONED FRONT. UNDER THE INFLUENCE OF COUPLED JETS
THIS WILL FAVOR MODERATE RAINFALL AMOUNTS ON THURSDAY TO
FRIDAY...WITH MAXIMA OF 15-30MM IN POTENTIALLY SEVERE CONVECTION.
ANOTHER FRONT WILL THEN APPROACH FROM THE SOUTH...LIFTING ACROSS
SOUTHERN CHILE ON FRIDAY. DURING THE WEEKEND THE FRONT WILL THEN
SURGE ACROSS PATAGONIA TO CENTRAL ARGENTINA...WHERE IT IS LIKELY
TO FAVOR HEAVY RAINS AND POTENTIALLY SEVERE CONVECTION.

AN UPPER LEVEL CELL OF THE SUBTROPICAL RIDGE TO THE NORTH ENVELOPS
CONTINENTAL AREA BETWEEN THE EQUATOR AND NORTHERN ARGENTINA. THE
BROAD UPPER LEVEL RIDGE WILL HOLD THROUGH THE END OF THE WEEK.
EARLY IN THE CYCLE A SUBTROPICAL JET MAXIMA IS TO STREAM ALONG THE
SOUTHERN FRINGES OF THIS RIDGE...WITH AXIS DRAWING A SHORT WAVE
TROUGH EASTWARD ACROSS NORTHERN CHILE INTO CENTRAL/NORTHERN
ARGENTINA ON WEDNESDAY TO THURSDAY...WITH AXIS FORECAST TO THEN
WEAKEN AS IT STREAMS ACROSS THE SOUTHERN STATES OF BRASIL LATER IN
THE WEEK. AT LOW LEVELS...A MEANDERING FRONT EXTENDS ACROSS
SOUTHERN BRASIL TO NORTHERN ARGENTINA. THE FRONT IS FORECAST TO
REMAIN NEARLY STATIONARY DURING THE NEXT FEW DAYS...WITH DEEP
SUBTROPICAL MOISTURE CONVERGING ALONG THIS BOUNDARY. UNDER
FAVORABLE JET DYNAMICS CONVECTION ALONG THIS BOUNDARY WILL
GRADUALLY INTENSIFY THROUGH THURSDAY MORNING. INITIALLY EXPECTING
RAINFALL AMOUNTS OF 20-35MM...WITH A HEAVY RAINFALL PRODUCING MCS
EARLY ON THURSDAY MORNING TO SUSTAIN RAINFALL AMOUNTS OF 50-100MM.
THROUGH SATURDAY MORNING THIS IS TO GRADUALLY WEAKEN WHILE
BUILDING NORTH ACROSS SOUTHERN BRASIL TO CORRIENTES/RESISTENCIA IN
ARGENTINA TO SOUTHEAST PARAGUAY.

OTHER CONVECTION IS EXPECTED NORTH OF THIS RIDGE OVER EQUATORIAL
SOUTH AMERICA. EARLY IN THE CYCLE MOST ACTIVE IS TO AFFECT AMAPA
IN BRASIL/FRENCH GUIANA WITH MAXIMA OF 50-100MM. THROUGH THURSDAY
MORNING ACTIVITY SPREADS WESTWARD ACROSS PARA/RORAIMA IN NORTHERN
BRASIL TO AMAZONAS...WITH MAXIMA OF 35-70MM. MODERATE RAINFALL
AMOUNTS ARE TO THEN PERSIST THROUGH THE END OF THE WEEK...WITH
DAILY MAXIMA OF 25-50MM. FURTHERMORE...AS DEEP TROPICAL MOISTURE
SPREADS WESTWARD ACROSS EQUATORIAL SOUTH AMERICA TO SOUTHERN
COLOMBIA AND NORTHERN PERU/EASTERN ECUADOR...CONVECTION IN THIS
AREA IS ALSO EXPECTED TO SURGE AS THE WEEK WEARS ON. AN UPPER
LEVEL WIND MAXIMA STREAMING ACROSS EQUATORIAL SOUTH AMERICA WILL
PROVIDE THE UPPER LEVEL OUTFLOW THAT WILL VENT CONVECTION IN THIS
AREA. OVER WESTERN ECUADOR TO THE CAUCA IN SOUTHWEST COLOMBIA THIS
SURGES TO 35-70MM/DAY ON WEDNESDAY TO THURSDAY...WHILE ON THE
JUNGLE TO THE EAST IT WILL RESULT IN RAINFALL AMOUNTS OF 20-40MM.

DAVISON...WPC (USA)
$$

694 
FXSA20 KWBC 041703
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
101 PM EDT MON APR 04 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM APR 04/16 UTC: IN THE SOUTHERN STREAM...A
DEEPENING/DEEP LAYER POLAR TROUGH DOMINATES THE FLOW BETWEEN THE
BELLINGSHAUSEN-WEDDELL SEAS AND SOUTHERN PORTIONS OF
PATAGONIA...WHILE A CLOSED LOW LIFTS ACROSS THE DRAKE PASSAGE.
UNDER THE INFLUENCE OF A RIDGE TO THE WEST...THE TROUGH IS TO
SLOWLY RELOCATE TO THE SOUTHWEST ATLANTIC ON TUESDAY...MEANWHILE
FAVORING A LONG FETCH SOUTHERLY FLOW BETWEEN THE BELLINGSHAUSEN
SEA/ANTARCTIC PENINSULA AND TIERRA DEL FUEGO.
THIS...IN-TURN...WILL SUSTAIN A COLD ADVECTIVE PATTERN AND
ENVIRONMENTAL CONDITIONS HIGHLY FAVORABLE FOR A HEAVY SNOWFALL
EVENT. INITIALLY THE MOST INTENSE IS EXPECTED ACROSS TIERRA DEL
FUEGO WITH ACCUMULATION OF 15-30CM. ON TUESDAY THIS WILL RESULT IN
AN ADDITIONAL 05-10CM...WHILE OVER SANTA CRUZ IN SOUTHERN
PATAGONIA THIS WILL RESULT IN SNOWFALL AMOUNTS OF 15-20CM.
SIMULTANEOUSLY...THE SLOW TO EVOLVE FRONTAL TROUGH WILL HELP
SUSTAIN A TIGHT BELT OF MID LATITUDE WESTERLIES BETWEEN 40S-50S
INTO THE SOUTHERN REGIONS OF CHILE. THIS FLOW WILL THEN ADVECT A
PLUME OF HIGHER THAN NORMAL SUBTROPICAL MOISTURE EASTWARD ACROSS
THE SOUTHERN CONE...FOCUSING MOISTURE/SHORT WAVE ENERGY BETWEEN
TEMUCO AND ISLA DE CHILOE. INITIALLY EXPECTING RAINFALL AMOUNTS OF
35-70MM...SURGING TO 40-80MM ON TUESDAY. ON WEDNESDAY IT WILL
RAPIDLY WEAKEN WITH AN ADDITIONAL 20-45MM. IN THIS AREA EXPECTING
STORM TOTAL AMOUNTS OF 100-200MM DURING THE NEXT THREE DAYS.

AN UPPER LEVEL CELL OF THE SUBTROPICAL RIDGE TO THE NORTH CONFINES
TO CONTINENTAL AREA BETWEEN 10S-25S. A SUBTROPICAL JET MAXIMA
BOUNDS THE SOUTHERN FRINGES OF THIS RIDGE AS IT EXTENDS ACROSS
NORTHERN CHILE/ARGENTINA TO THE SOUTHERN STATES OF BRASIL/URUGUAY.
OVER THE NEXT 60-72 HRS THE JET WILL DRAW A NORTHERN STREAM
PERTURBATION ACROSS NORTHERN CHILE INTO NORTHWEST ARGENTINA...WITH
AXIS FORECAST TO THEN WEAKEN AS IT STREAMS ACROSS THE SOUTHERN
STATES OF BRASIL LATER IN THE WEEK. AT LOW LEVELS...A MEANDERING
FRONT EXTENDS ACROSS SOUTHERN BRASIL TO NORTHERN ARGENTINA LATER
TODAY...WHERE IT IS TO REMAIN NEARLY STATIONARY DURING THE NEXT
FEW DAYS. DEEP SUBTROPICAL MOISTURE WILL CONVERGE ALONG THE
MEANDERING FRONT. UNDER FAVORABLE JET DYNAMICS CONVECTION ALONG
THIS BOUNDARY WILL GRADUALLY INTENSIFY...TO INITIALLY FAVOR
RAINFALL AMOUNTS OF 20-35MM. ON WEDNESDAY TO THURSDAY THE
ENVIRONMENTAL CONDITIONS IN THIS AREA BECOME FAVORABLE FOR A HEAVY
RAINFALL PRODUCING MCS TO DEVELOP ALONG THIS BOUNDARY OVER
NORTHERN ARGENTINA...FAVORING RAINFALL AMOUNTS OF 75-125MM IN
POTENTIALLY SEVERE CONVECTION. LATER IN THE WEEK EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 20-45MM/DAY WHILE SPREADING
EASTWARD ACROSS SOUTHERN BRASIL.

OTHER CONVECTION IS EXPECTED TO THE NORTH ALONG THE NEAR
EQUATORIAL TROUGH AS IT MEANDERS ACROSS NORTHERN BRASIL. INITIALLY
THE MOST INTENSE IS EXPECTED ACROSS PARA IN BRASIL WHERE UNDER THE
INFLUENCE OF AN EASTERLY WAVE EXPECTING ACCUMULATION OF 80-120MM.
ON TUESDAY TO WEDNESDAY FOCUS OF THE CONVECTION SHIFTS ACROSS
RORAIMA TO AMAZONAS TO THE WEST...WITH MAXIMA INCREASING FROM
35-70MM ON TUESDAY TO 50-100MM ON WEDNESDAY...WITH MODERATE TO
HEAVY CONVECTION TO THEN PERSIST BETWEEN PARA AND AMAZONAS THROUGH
THE END OF THE WEEK. AS MOISTURE SPREADS WESTWARD ACROSS
EQUATORIAL SOUTH AMERICA TO SOUTHERN COLOMBIA AND NORTHERN
PERU/EASTERN ECUADOR...CONVECTION IN THIS AREA IS ALSO EXPECTED TO
SURGE AS THE WEEK WEARS ON. AN UPPER LEVEL WIND MAXIMA STREAMING
ACROSS EQUATORIAL SOUTH AMERICA WILL PROVIDE THE UPPER LEVEL
OUTFLOW THAT WILL VENT CONVECTION IN THIS AREA. OVER WESTERN
ECUADOR TO THE CAUCA IN SOUTHWEST COLOMBIA THIS SURGES TO
35-70MM/DAY ON WEDNESDAY TO THURSDAY...WHILE ON THE JUNGLE TO THE
EAST IT WILL RESULT IN RAINFALL AMOUNTS OF 20-40MM.

DAVISON...WPC (USA)
$$

901 
FXSA20 KWBC 221638
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1237 PM EDT TUE MAR 22 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 22/16 UTC: A POTENT TROUGH IN THE
SOUTHERN STREAM EXTENDS ACROSS THE EASTERN BELLINGSHAUSEN SEA INTO
THE EASTERN PACIFIC JUST TO THE WEST OF ISLA CHILOE IN CHILE.
UNDER THE INFLUENCE OF STRONG SOUTHERLY FLOW ALONG ITS REAR
FLANK...THIS TROUGH IS FORECAST TO AMPLIFY NORTH TO EXTEND ACROSS
THE MALVINAS...PATAGONIA INTO LA SERENA/LA RIOJA BY WEDNESDAY
EVENING. THE TROUGH IS INTERACTING WITH A SHORT WAVE TROUGH THAT
IS PROPAGATING INTO LA SERENA/SAN JUAN REGIONS ON TUESDAY. AS THE
SHORT WAVE TROUGH CROSSES INTO URUGUAY THROUGH THURSDAY
MORNING...IT WILL INDUCE SEVERAL ROUNDS OF SEVERE CONVECTION AND
HEAVY PRECIPITATION IN CENTRAL...NORTHEAST
ARGENTINA...URUGUAY...SOUTHERN BRASIL AND CENTRAL AND SOUTHERN
PARAGUAY.

ON TUESDAY...EXPECT CONVECTION IN ENTRE RIOS AND URUGUAY TO FAVOR
MAXIMA OF 20-35MM. IN FORMOSA...CORRIENTES AND SOUTHERN PARAGUAY
EXPECT MAXIMA OF 40-80MM WITH A RISK FOR MCS FORMATION. AS THE
MAIN SOUTHERN STREAM TROUGH APPROACHES ON WEDNESDAY...IT WILL
SUSTAIN CYCLOGENESIS IN LA PAMPA AND NORTHERN PATAGONIA. THE
SURFACE FRONT AND UPPER DYNAMICS WILL DEVELOP STRONG CONVECTION IN
THE BUENOS AIRES PROVINCE AND SOUTHWEST URUGUAY WHERE EXPECT
40-80MM AND A RISK FOR SEVERITY. IN INTERIOR PORTIONS OF CENTRAL
ARGENTINA EXPECT MAXIMA OF 15-20MM. AS UPPER JET DYNAMICS INTERACT
WITH A MOIST POOL IN NORTHEAST ARGENTINA...AND A LOW-LEVEL
JET...EXPECT STRONG THUNDERSTORMS TO DEVELOP BETWEEN
CORRIENTES/SOUTHEAST PARAGUAY AND NORTHERN URUGUAY/RIO GRANDE DO
SUL WHERE EXPECT MAXIMA OF 100-150MM AND AN ENHANCED RISK FOR MCS
FORMATION AND SEVERE WEATHER. ON THURSDAY...AS THE CYCLOGENETIC
PROCESS CONTINUES IN THE BUENOS AIRES PROVINCE...ONSHORE FLOW WILL
FAVOR LOCALLY HEAVY RAINFALL TO SUSTAIN MAXIMA OF 40-80MM. INLAND
ACROSS THE REST OF THE BUENOS AIRES PROVINCE EXPECT MAXIMA OF
20-40MM. HEAVY CONVECTION IS ALSO EXPECTED IN FORMOSA AND
PARAGUAY/WESTERN PARANA/MISIONES...WHERE EXPECT MAXIMA OF 75-125MM
AND AN ENHANCED RISK FOR MCS FORMATION. IN NORTHERN PARAGUAY AND
SOUTHEAST BOLIVIA EXPECT MAXIMA OF 20-35MM. ALONG THE ANDES OF
CENTRAL BOLIVIA EXPECT MAXIMA OF 40-80MM AND ENHANCED RISK FOR MCS
FORMATION. ON FRIDAY...THE STRONGEST CONVECTION AND HEAVY
PRECIPITATION ARE EXPECTED TO CLUSTER IN NORTHERN BOLIVIA AND
SOUTHERN PERU...TO PRODUCE MAXIMA OF 40-80MM/DAY. IN
PARANA/EASTERN PARAGUAY...CONVECTION NEAR/DOWNSTREAM FROM A
FRONTAL LOW WILL FAVOR MAXIMA OF 25-50MM. IN WESTERN MATO GROSSO
DO SUL THROUGH RONDONIA EXPECT MAXIMA OF 20-35MM.

IN TROPICAL PORTIONS OF SOUTH AMERICA...THE BOLIVIAN HIGH IS
FORECAST TO REMAIN PRESENT BUT WEAK THROUGH THE FORECAST
CYCLE...WHILE ITS AXIS EXTENDS FROM SOUTHERN PERU INTO MATO
GROSSO. THIS...HOWEVER WILL STILL ALLOW FOR EASTERLY DIVERGENT
UPPER FLOW OVER EQUATORIAL SOUTH AMERICA...WHICH WILL PROVIDE SOME
VENTILATION FOR DEEP CONVECTION IN ECUADOR...PERU...COLOMBIA AND
NORTHERN BRASIL. ENHANCED UPPED DIVERGENCE WILL BE PRESENT IN THE
GUIANAS AIDED BY AN UPPER TROUGH PRESSING FROM THE SUBTROPICAL
NORTH ATLANTIC. IN THE GUIANAS AND AMAPA...ENHANCED ITCZ
CONVERGENCE WILL FAVOR MAXIMA OF 35-70MM ON TUESDAY...GRADUALLY
DECREASING TO MAXIMA OF 15-30MM THROUGH THURSDAY. IN ECUADOR AND
EXTREME NORTHERN PERU...ACTIVE CONVECTION IS EXPECTED AIDED BY
ABOVE-AVERAGE SEA SURFACE TEMPERATURES. ON TUESDAY EXPECT MAXIMA
OF 20-45MM...INCREASING TO MAXIMA OF 30-60MM ON WEDNESDAY. ON
THURSDAY EXPECT MAXIMA OF 25-50MM. THIS INCREASES TO MAXIMA OF
35-70MM ON THURSDAY. CONVECTION WILL ALSO GRADUALLY ACTIVATE
ACROSS THE PERUVIAN SELVA...ECUADOR'S ORIENTE AND WESTERN
BRASIL/SOUTHERN COLOMBIA. SCATTERED DIURNAL CONVECTION WILL FAVOR
MAXIMA OF 20-35MM ON TUESDAY AND WEDNESDAY. ON THURSDAY THIS
INCREASES TO MAXIMA OF 35-70MM IN CENTRAL AND SOUTHERN PERU. IN
THE NORTHERN PERUVIAN ANDES AND SELVA ALTA THIS INCREASES TO
MAXIMA OF 25-50MM. ON FRIDAY EXPECT MAXIMA OF 25-50MM FROM THE
NORTHERN ANDES OF PERU INTO SOUTHERN COLOMBIA AND WESTERN BRASIL.
IN THE CENTRAL SELVA OF PERU EXPECT MAXIMA OF 40-80MM.

TO THE EAST...A BROAD UPPER TROUGH EXTENDS FROM THE SOUTH ATLANTIC
INTO NORTHEAST BRASIL. THIS WILL REORGANIZE INTO A NARROWER
TUTT...FORECAST TO FORM ON WEDNESDAY AND MEANDER IN
BAHIA/TOCANTINS/SOUTHERN MARANHAO ON THURSDAY AND FRIDAY. THE
TROUGH WILL INITIALLY INTERACT WITH AN ACTIVE SOUTHERN BRANCH OF
THE ITCZ TO FAVOR MAXIMA OF 20-40MM IN NORTHEAST BRASIL WEST INTO
THE AMAZON DELTA. ON WEDNESDAY...EXPECT MAXIMA OF 15-20MM FROM
BAHIA TO NATAL...AND MAXIMA OF 20-35MM IN AREAS TO THE WEST. ON
THURSDAY EXPECT A DECREASE TO MAXIMA OF 10-15MM. MODERATE
CONVECTION IS ALSO EXPECTED IN ASSOCIATION WITH A SURFACE FRONT
MEANDERING ACROSS ESPIRITO SANTO. THIS WILL SUSTAIN MAXIMA OF
20-45MM IN ESPIRITO SANTO AND SOUTHERN BAHIA ON TUESDAY AND
WEDNESDAY. THIS DECREASES TO MAXIMA OF 20-35MM ON
THURSDAY...FURTHER DECREASING AFTER...AS THE FRONT DISORGANIZES ON
FRIDAY.


GALVEZ...WPC (USA)
$$

609 
FXSA20 KWBC 211713
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
111 PM EDT MON MAR 21 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 21/16 UTC: IN THE SOUTHERN STREAM...
A TROUGH EXTENDS NEAR 100W AND IS FORECAST TO ARRIVE IN SOUTHERN
CHILE LATE ON MONDAY EVENING. THE SURFACE FRONT IS FORECAST TO
ADVANCE NORTHWARD RAPIDLY...TO REACH BIO BIO BY WEDNESDAY MORNING.
THE SYSTEM ARRIVES ACCOMPANIED BY A SUBTROPICAL MOIST PLUME OF
25-27MM...AND THE DIVERGENCE ENTRANCE OF AN UPPER JET...WHICH WILL
DEVELOP PRECIPITATION IN AYSEN AND NORTHERN MAGALLANES ON TUESDAY
TO SUSTAIN MAXIMA OF 20-35MM.  AS THE FRONT MOVES NORTHWARD ON
TUESDAY...EXPECT MAXIMA OF 10-15MM FROM ARAUCANIA SOUTH INTO LOS
LAGOS. ON TUESDAY...EXPECT MAXIMA OF 20-45MM IN AYSEN...MAXIMA OF
05-10MM/DAY BETWEEN LOS LAGOS AND ARAUCANIA. IN MAGALLANES EXPECT
MAXIMA OF 05-10MM/DAY WITH A RISK FOR RAIN MIXED WITH SNOW. LATE
ON WEDNESDAY INTO EARLY THURSDAY...ANOTHER FRONT ARRIVES INTO
SOUTHERN CHILE TO FAVOR MAXIMA OF 05-10MM/DAY IN SOUTHERN AYSEN
AND MAGALLANES. ANOTHER SYSTEM APPROACHES ON FRIDAY...BUT THE BULK
OF PRECIPITATION IS EXPECTED ONCE THE COLD FRONT ENTERS ON
SATURDAY.

IN THE NORTHERN STREAM...A TROUGH EXTENDS FROM SOUTHERN PATAGONIA
INTO CUYO ON MONDAY. THE TROUGH IS FORECAST TO MOVE INTO THE SOUTH
ATLANTIC THROUGH LATE TUESDAY...TO CROSS THE BUENOS AIRES PROVINCE
AND RIO DE LA PLATA REGION DURING THE DAY ON TUESDAY.
INITIALLY...UPPER JET DYNAMICS NORTH OF THE TROUGH ARE FORECAST TO
INTERACT WITH A MOIST POOL IN NORTHEAST ARGENTINA ON MONDAY
EVENING/EARLY TUESDAY. THIS WILL DEVELOP SCATTERED THUNDERSTORMS
WITH FORECAST MAXIMA OF 35-70MM FROM CHACO AND FORMOSA INTO ENTRE
RIOS AND WESTERN UGUGUAY THROUGH EARLY TUESDAY. ON
TUESDAY...EXPECT CONVECTION IN ENTRE RIOS AND URUGUAY TO FAVOR
MAXIMA OF 20-35MM. IN FORMOSA...CORRIENTES AND SOUTHERN PARAGUAY
EXPECT MAXIMA OF 40-80MM WITH A RISK FOR MCS FORMATION. ANOTHER
MID-UPPER TROUGH ENTERS THE REGION ON WEDNESDAY. THIS WILL SUSTAIN
CYCLOGENESIS IN LA PAMPA AND NORTHERN PATAGONIA. THE SURFACE FRONT
AND UPPER DYNAMICS WILL DEVELOP STRONG CONVECTION IN THE BUENOS
AIRES PROVINCE AND SOUTHWEST URUGUAY WHERE EXPECT 40-80MM AND A
RISK FOR SEVERITY. IN INTERIOR PORTIONS OF CENTRAL ARGENTINA
EXPECT MAXIMA OF 15-20MM. AS UPPER JET DYNAMICS INTERACT WITH A
MOIST POOL IN NORTHEAST ARGENTINA...AND A LOW-LEVEL JET...EXPECT
STRONG THUNDERSTORMS TO DEVELOP BETWEEN CORRIENTES/SOUTHEAST
PARAGUAY AND NORTHERN URUGUAY/RIO GRANDE DO SUL WHERE EXPECT
MAXIMA OF 100-150MM AND AN ENHANCED RISK FOR MCS FORMATION AND
SEVERE WEATHER. ON THURSDAY...AS THE CYCLOGENETIC PROCESS
CONTINUES IN CENTRAL PORTIONS OF ARGENTINA...ONSHORE FLOW IN THE
BUENOS AIRES PROVINCE WILL FAVOR LOCALLY HEAVY RAINFALL TO SUSTAIN
MAXIMA OF 40-80MM. INLAND ACROSS THE REST OF THE BUENOS AIRES
PROVINCE EXPECT MAXIMA OF 25-50MM. HEAVY CONVECTION IS ALSO
EXPECTED IN FORMOSA AND PARAGUAY/WESTERN PARANA/MISIONES...WHERE
EXPECT MAXIMA OF 75-125MM AND AN ENHANCED RISK FOR MCS FORMATION.
IN NORTHERN PARAGUAY AND SOUTHEAST BOLIVIA EXPECT MAXIMA OF
20-35MM. ALONG THE ANDES OF NORTHERN BOLIVIA AND SOUTHERN PERU
EXPECT MAXIMA OF 35-70MM.

IN TROPICAL PORTIONS OF SOUTH AMERICA...THE BOLIVIAN HIGH STARTS
CENTERING OVER SOUTHERN PERU ON MONDAY...SUSTAINING ENHANCED
DIVERGENT EASTERLY FLOW OVER NORTHERN PERU...ECUADOR AND COLOMBIA.
SIMULTANEOUSLY...A TUTT EXTENDS FROM THE SOUTH ATLANTIC INTO
EXTREME NORTHEAST BRASIL...TO PROVIDE VENTILATION IN NORTHEASTERN
PORTIONS OF BRASIL. MODELS SHOW BOTH SYSTEMS BECOMING LESS
ORGANIZED THROUGH THE WEEK...WHICH WILL DECREASE THE VENTILATION
FOR DEEP CONVECTION THROUGH THE WEEK. HOWEVER...A TROUGH
APPROACHING FROM THE NORTH ATLANTIC WILL MAINTAIN ENHANCED
VENTILATION IN THE AMAZON DELTA REGION AND THE GUIANAS THROUGH THE
CYCLE. REGIONS WHERE HEAVY RAIN IS EXPECTED CLUSTER IN COASTAL
ECUADOR AND IN THE AMAZON DELTA/GUIANAS. ANOTHER REGION OF
INTEREST THROUGH THE CYCLE IS ESPIRITO SANTO/SOUTHERN
BAHIA...WHERE A SURFACE FRONT IS FORECAST TO BECOME STATIONARY ON
TUESDAY...TO ENHANCE CONVECTION ON A DAILY BASIS. ON
MONDAY...EXPECT MAXIMA OF 30-60MM IN THE AMAZON DELTA...GUIANAS
AND MARANHAO. IN NORTHEAST BRASIL EXPECT MAXIMA OF 20-35MM. IN THE
WESTERN AMAZON AND SOUTHERN ECUADOR EXPECT MAXIMA OF 20-35MM. IN
COASTAL ECUADOR EXPECT 15-20MM. ON TUESDAY...EXPECT MAXIMA OF
35-70MM IN AMAPA/GUIANAS AND NORTHERN PARA. IN ECUADOR...EXPECT
MAXIMA OF 20-45MM. IN NORTHEAST BRASIL EXPECT MAXIMA OF 20-40MM.
ON WEDNESDAY...EXPECT MAXIMA OF 30-60MM IN AMAPA/GUIANAS. IN
ECUADOR EXPECT SIMILAR AMOUNTS. ON NORTHEAST BRASIL AND MOST OF
PARA/AMAZONAS EXPECT MAXIMA OF 20-35MM. IN THE SELVA OF PERU AND
THE NORTHERN ANDES EXPECT MAXIMA OF 20-35MM. ON THURSDAY...EXPECT
MAXIMA OF 20-45MM IN THE AMAZON DELTA/PARA. ALONG THE ANDES OF
SOUTHERN PERU AND NORTHERN BOLIVIA EXPECT MAXIMA OF 35-70MM. IN
NORTHERN PERU AND THE PACIFIC BASIN OF ECUADOR EXPECT MAXIMA OF
25-50MM. REGARDING THE FRONT...EXPECT MAXIMA OF 20-45MM IN
ESPIRITO SANTO/SOUTHERN BAHIA ON MONDAY AND TUESDAY. THIS
DECREASES TO 15-20MM ON WEDNESDAY AND TO MAXIMA OF 15MM ON
THURSDAY. 

GALVEZ...WPC (USA)
$$

068 
FXSA20 KWBC 171610
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1210 PM EDT THU MAR 17 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 17/16 UTC: ON THURSDAY...THE ROBUST
UPPER TROUGH IS FORECAST TO EXIT INTO THE SOUTH ATLANTIC. THIS
WILL SUSTAIN CYCLOGENESIS AND SPEED UP THE NORTHWARD MOVEMENT OF A
SURFACE FRONT FORMING IN ARGENTINA. SIMULTANEOUSLY...THE ROBUST
POLAR HIGH ENTERING SOUTHERN CHILE WILL START TO SPILL INTO
PATAGONIA TO STRENGTHEN THE PRESSURE GRADIENT AND DEVELOP A
PAMPERO JET. BY THURSDAY EVENING...THE SPEEDING FRONT IS FORECAST
ACROSS THE RIO DE LA PLATA INTO CENTRAL ARGENTINA. EXPECT THE
DEVELOPMENT OF A SHORT-LIVED PREFRONTAL SQUALL LINE FROM SOUTHERN
ENTRE RIOS INTO NORTHERN CORDOBA. THIS WILL FAVOR MAXIMA OF
20-35MM WITH THE RISK OF SEVERE CONVECTION FROM SANTA FE INTO
REGIONS TO THE WEST. IN THE RIO DE LA PLATA...EXPECT MAXIMA OF
10-15MM/DAY WITH A RISK FOR SEVERE CONVECTION. ON FRIDAY...THE
FRONT IS FORECAST TO EXTEND ACROSS RIO GRANDE DO SUL...CENTRAL
PARAGUAY...SOUTHERN BOLIVIA. MODELS AGREE THAT THE LARGEST
RAINFALL AMOUNTS ARE LIKELY TO DEVELOP IN PARAGUAY/PARANA...WHERE
FRONTAL CONVECTION WILL INTERACT WITH THE DIVERGENT ENTRANCE OF AN
UPPER JET. THIS WILL FAVOR MAXIMA OF 50-100MM. IN RIO GRANDE DO
SUL AND SANTA CATARINA...EXPECT MAXIMA OF 30-60MM WITH A RISK FOR
SEVERITY. IN SANTA FE AND ENTRE RIOS...DYNAMIC FORCING BY THE
UPPER TROUGH WILL TRIGGER POST FRONTAL CONVECTION...TO FAVOR
MAXIMA OF 15-20MM. IN SOUTHERN BOLIVIA...THE SOUTHERLY LOW-LEVEL
JET WILL TRIGGER MAXIMA OF 20-40MM. ON SATURDAY...THE FRONT IS
EXPECTED TO EXTEND ACROSS SAO PAULO...NORTHERN PARANA...THE
BRAZIL/BOLIVIA BORDER IN MATO GROSSO DO SUL...INTO EXTREME
SOUTHERN PERU. THE SOUTHERLY LOW-LEVEL JET WILL TRIGGER HEAVY
RAINFALL IN NORTHERN BOLIVIA AND SOUTHERN PERU WHERE EXPECT MAXIMA
OF 40-80MM AND A RISK FOR MCS FORMATION. MODERATE PRECIPITATION IS
ALSO EXPECTED IN THE SERRA DO MAR OF SAO PAULO...WHERE EXPECT
MAXIMA OF 25-50MM. IN INTERIOR PORTIONS OF SAO PAULO INTO RONDONIA
AND MATO GROSSO...EXPECT MAXIMA OF 20-35MM. ALSO ON SATURDAY...A
SHEAR LINE IS FORECAST TO FORM ACROSS MATO GROSSO INTO
AMAZONAS-BRASIL. THIS WILL ENHANCE MOISTURE CONVERGENCE IN
AMAZONAS AND NORTHERN PERU/ORIENTE ECUATORIANO WHERE EXPECT MAXIMA
OF 25-50MM. ON SUNDAY...AS THE FRONT MOVES INTO THE RIO DE JANEIRO
AREA...IT WILL ARRIVE ACCOMPANIED BY 20-35KT WINDS AND ENHANCED
AVAILABLE MOISTURE. THIS WILL INTERACT WITH THE SERRA DO MAR TO
TRIGGER EXCESSIVE PRECIPITATION. EXPECT ACCUMULATION IN THE ORDER
OF 100-200MM. THIS IS A POTENTIALLY DANGEROUS SITUATION. HEAVY
RAINS ARE TO CONTINUE ON MONDAY...BUT LESSER AMOUNTS ARE EXPECTED
AS THE FRONT MOVES INTO ESPIRITO SANTO AND CONVECTION IS PRIMARILY
DRIVEN BY ONSHORE FLOW ASSOCIATED WITH THE ROBUST 1033 HIGH IN THE
SOUTH ATLANTIC. ON MONDAY...EXPECT LINGERING CONVECTION IN RIO DE
JANEIRO AND SOUTHERN ESPIRITO SANTO TO SUSTAIN AN ADDITIONAL
35-70MM OF RAIN...GIVEN THAT OROGRAPHIC ENHANCEMENT IS FORECAST TO
CONTINUE FOR A LAST DAY...AS SOUTHEASTERLY LOW-LEVEL WINDS
INTERACT WITH THE SERRA DO MAR.

GALVEZ...WPC (USA)
$$

595 
FXSA20 KWBC 161624
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1223 PM EDT WED MAR 16 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 16/16 UTC: A ROBUST MID-UPPER TROUGH
IS ENTERING THE SOUTHERN CONE ON WEDNESDAY...WHILE EXTENDING FROM
TIERRA DEL FUEGO NORTHWEST INTO THE ARCHIPELAGO JUAN FERNANDEZ OFF
THE COAST OF CENTRAL CHILE. INITIALLY...THE ASSOCIATED SURFACE
FRONT WILL PROPAGATE RAPIDLY ACROSS SOUTHERN CHILE. UNDER THE
INFLUENCE OF A ROBUST RIDGE TO THE WEST...EXPECT
SOUTH-SOUTHWESTERLY FLOW TO ENHANCE CONVECTIVE INSTABILITY. THIS
WILL FAVOR MAXIMA OF 20-45MM IN MAGALLANES AND AYSEN...AND MAXIMA
OF 15-20MM IN LOS LAGOS. ON THURSDAY...CONTINUED COLD AIR
ADVECTION WILL FAVOR SNOWFALL IN MAGALLANES TO SUSTAIN 05-10CM OF
SNOW IN SOUTHERN SLOPES OF THE CORDILLERA.

ALSO ON THURSDAY...THE ROBUST UPPER TROUGH IS FORECAST TO EXIT
INTO THE SOUTH ATLANTIC. THIS WILL SUSTAIN CYCLOGENESIS AND SPEED
UP THE NORTHWARD MOVEMENT OF THE FRONT. SIMULTANEOUSLY...THE
ROBUST POLAR HIGH ENTERING SOUTHERN CHILE WILL START TO SPILL INTO
PATAGONIA TO STRENGTHEN THE PRESSURE GRADIENT AND DEVELOP A
PAMPERO JET. BY TUESDAY EVENING...THE SPEEDING FRONT IS FORECAST
ACROSS THE RIO DE LA PLATA INTO CENTRAL ARGENTINA. EXPECT THE
DEVELOPMENT OF A PREFRONTAL SQUALL LINE FROM SOUTHERN ENTRE RIOS
INTO NORTHERN CORDOBA. THIS WILL FAVOR MAXIMA OF 20-35MM WITH THE
RISK OF SEVERE CONVECTION FROM SANTA FE TO REGIONS TO THE WEST. IN
THE RIO DE LA PLATA...EXPECT MAXIMA OF 10-15MM/DAY WITH A RISK FOR
SEVERE CONVECTION. ON FRIDAY...THE FRONT IS FORECAST TO EXTEND
ACROSS RIO GRANDE DO SUL...CENTRAL PARAGUAY...SOUTHERN BOLIVIA.
MODELS AGREE THAT THE LARGEST RAINFALL AMOUNTS ARE LIKELY TO
DEVELOP IN PARAGUAY/PARANA...WHERE FRONTAL CONVECTION WILL
INTERACT WITH THE DIVERGENT ENTRANCE OF AN UPPER JET. THIS WILL
FAVOR MAXIMA OF 50-100MM. IN RIO GRANDE DO SUL AND SANTA
CATARINA...EXPECT MAXIMA OF 30-60MM WITH A RISK FOR SEVERITY. IN
SANTA FE AND ENTRE RIOS...DYNAMIC FORCING BY THE UPPER TROUGH WILL
TRIGGER POST FRONTAL CONVECTION...TO FAVOR MAXIMA OF 15-20MM. IN
SOUTHERN BOLIVIA...THE SOUTHERLY LOW-LEVEL JET WILL TRIGGER MAXIMA
OF 20-40MM. ON SATURDAY...THE FRONT IS EXPECTED TO EXTEND ACROSS
SAO PAULO...NORTHERN PARANA...THE BRAZIL/BOLIVIA BORDER IN MARO
GROSSO DO SIL...INTO EXTREME SOUTHERN PERU. THE SOUTHERLY
LOW-LEVEL JET WILL TRIGGER HEAVY RAINFALL IN NORTHERN BOLIVIA AND
SOUTHERN PERU WHERE EXPECT MAXIMA OF 40-80MM AND A RISK FOR MCS
FORMATION. MODERATE PRECIPITATION IS ALSO EXPECTED IN THE SERRA DO
MAR OF SAO PAULO...WHERE EXECT MAXIMA OF 25-50MM. IN INTERIOR
PORTIONS OF SAO PAULO INTO RONDONIA AND MATO GROSSO...EXECT MAXIMA
OF 20-35MM. ALSO ON SATURDAY...A SHEAR LINE IS FORECAST TO FORM
ACROSS MATO GROSSO INTO AMAZONAS-BRASIL. THIS WILL ENHANCE
MOISTURE CONVERGENCE IN AMAZONAS AND NORTHERN PERU/ORIENTE
ECUATORIANO WHERE EXPECT MAXIMA OF 25-50MM.

ON SUNDAY...AS THE FRONT MOVES INTO THE RIO DE JANEIRO AREA...IT
WILL ARRIVE ACCOMPANIED BY 20-35KT WINDS AND ENHANCED AVAILABLE
MOISTURE. THIS WILL INTERACT WITH THE SERRA DO MAR TO TRIGGER
EXCESSIVE PRECIPITATION. EXPECT ACCUMULATION IN THE ORDER OF
100-200MM. THIS IS A POTENTIALLY DANGEROUS SITUATION. HEAVY RAINS
ARE TO CONTINUE ON MONDAY...BUT LESSER AMOUNTS ARE EXPECTED AS THE
FRONT MOVES INTO ESPIRITO SANTO AND CONVECTION IS PRIMARILY DRIVEN
BY ONSHORE FLOW ASSOCIATED WITH THE ROBUST 1033 HIGH IN THE SOUTH
ATLANTIC.

GALVEZ...WPC (USA)
$$

524 
FXSA20 KWBC 151525
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1124 AM EDT TUE MAR 15 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 15/15 UTC: A BROAD MID/UPPER LEVEL
RIDGE IS INITIALIZED OVER THE EASTERN PACIFIC TO THE SOUTHERN CONE
OF SOUTH AMERICA...WITH AXIS DOMINATING AREA TO THE NORTH OF 60S
AND WEST OF 60W. BROAD TROUGH TO THE EAST EXTENDS BETWEEN 50W-30W
TO THE SOUTH OF 30S...WITH AXIS PROVIDING SUPPORT TO A FRONTAL
TROUGH OVER THE CENTRAL SOUTH ATLANTIC. THIS TROUGH EXTENDS A
FRONT TO THE WEST-NORTHWEST TO THE SOUTHERN STATES OF BRASIL. THE
MEANDERING FRONT IS TO PERSIST THROUGH WEDNESDAY EVENING...THEN
RAPIDLY WEAKEN AS THE TROUGH ALOFT GRADUALLY PULLS AWAY.
MEANWHILE...THIS WILL ENHANCE MOISTURE CONVERGENCE ACROSS SOUTHERN
BRASIL TO FAVOR MODERATE RAINFALL AMOUNTS WITH MAXIMA OF
15-25MM/DAY.

SIMULTANEOUSLY...THE MID/UPPER LEVEL RIDGE OVER THE EASTERN
PACIFIC/SOUTHERN CONE IS FORECAST TO GRADUALLY FLATTEN UNDER
PRESSURE FROM POLAR PERTURBATIONS STREAMING TO THE SOUTH. AS THE
RIDGE WEAKENS...THIS WILL SET THE STAGE FOR A ROBUST MID LEVEL
TROUGH TO LIFT ACROSS THE SOUTHERN REGIONS OF CHILE TO PATAGONIA
IN ARGENTINA ON WEDNESDAY. AS IT ENTERS THE SOUTHERN CONE THIS
WILL THEN PHASE WITH A SOUTHERN STREAM PERTURBATION LIFTING ACROSS
THE BELLINGSHAUSEN SEA TO THE SOUTHEAST PACIFIC. THROUGH THURSDAY
THESE WILL THEN COMBINE INTO A LONG WAVE TROUGH THAT AMPLIFIES
ACROSS THE WESTERN ATLANTIC INTO MIDSECTIONS OF SOUTH AMERICA
EARLY ON FRIDAY MORNING. AT 250 HPA A SUBTROPICAL AND A NORTHERN
POLAR JETS ARE TO ACCOMPANY THIS TROUGH AS IT STREAMS ACROSS CHILE
TO ARGENTINA. LATER ON THURSDAY/EARLY ON FRIDAY MORNING THE JETS
ARE TO COUPLE ON THEIR DIVERGENT ENTRANCE/EXIT REGIONS OVER
CENTRAL ARGENTINA/RIO DE LA PLATA BASIN. THIS WILL THEN VENT
ORGANIZED DEEP CONVECTION IN THIS AREA...WITH STRONG
MESO/DYNAMICAL FORCING LIKELY TO RESULT IN SEVERE CONVECTION.

AT LOW LEVELS...DEEPENING FRONTAL TROUGH ENTERS THE SOUTHERN CONE
LATER TODAY. ON WEDNESDAY...UNDER THE INFLUENCE OF A BUILDING
RIDGE TO THE WEST...THE TROUGH DEEPENS ACROSS THE SOUTHERN
CONE/WESTERN ATLANTIC SOUTH ATLANTIC. THE BUILDING RIDGE WILL
SUSTAIN A COLD ADVECTIVE PATTERN ACROSS TIERRA DEL FUEGO AND
EXTREME SOUTHERN PORTIONS OF CHILE. INITIALLY THIS WILL SUSTAIN
MODERATE RAINFALL AMOUNTS ACROSS TIERRA DEL FUEGO WITH MAXIMA OF
15-25MM...WHILE OVER SOUTHERN CHILE IT PEAKS AT 30-60MM ON
WEDNESDAY. ON THURSDAY THE AIR MASS COOLS ENOUGH TO SUSTAIN A
PHASE TRANSITION...WITH SOLID PRECIPITATION IN THE FORM OF SNOW
SHOWERS TO CLUSTER OVER THE ANDES TO THE SOUTH OF 58S. BUILDING
POLAR RIDGE AND ENSUING PAMPERO LOW LEVEL JET WILL THEN DRIVE THE
FRONT NORTH ACROSS RIO DE LA PLATA/CENTRAL ARGENTINA ON THURSDAY
AFTERNOON...WITH THE SURGING FRONT TRIGGERING A PREFRONTAL SQUALL
LINE OVER CENTRAL ARGENTINA. IN THIS AREA MOST INTENSE CONVECTION
IS EXPECTED BETWEEN CORDOBA AND MENDOZA WITH MAXIMA OF 20-35MM. ON
FRIDAY THIS INCREASES TO 75-125MM WHILE BUILDING NORTH ACROSS
PARAGUAY-MISIONES IN ARGENTINA TO SOUTHERN BRASIL. ON FRIDAY THIS
WEAKENS WHILE BUILDING NORTH AND WEST ACROSS SOUTHEAST TO CENTRAL
BRASIL...WITH MAXIMA OF 20-35MM...WHILE SIMULTANEOUSLY THE
CONVECTION EXPLODES ACROSS NORTHERN BOLIVIA INTO THE SOUTHERN
JUNGLE OF PERU...WITH MAXIMA OF 50-100MM. LATER ON SUNDAY...AS THE
POLAR RIDGE ROLLS ACROSS THE SOUTHERN CONE TO THE WESTERN
ATLANTIC...IT WILL SUSTAIN A COOL SOUTHEASTERLY FLOW. THE COOLER
ADVECTION OVER WARMER THAN NORMAL WATERS OFF THE SOUTHEAST COAST
OF BRASIL WILL ENHANCE CONVECTIVE INSTABILITY...AND IN COMBINATION
WITH STRONG TOPOGRAPHICAL FORCING BETWEEN RIO DE JANEIRO AND SAO
PAULO IT IS VERY LIKELY TO RESULT IN HEAVY RAINFALL AMOUNTS ALONG
THE COAST. THIS IS WELL SUPPORTED BY THE CONSENSUS OF THE GLOBAL
MODEL GUIDANCE...WITH MAXIMA OF 125-200MM.

THE EVOLVING PATTERN TO THE SOUTH WILL BE ACCOMPANIED BY CHANGES
ACROSS TROPICAL SOUTH AMERICA...WITH A 250 HPA CELL OF THE
SUBTROPICAL RIDGE EXPECTED TO BUILD BETWEEN SOUTHERN/SOUTHEAST
BRASIL AND PERU DURING THE NEXT COUPLE OF DAYS. AS THE RIDGE
BUILDS...IT IS TO STEER A MEANDERING SHORT WAVE TROUGH ON THE
NORTHERN STREAM/ILL ORGANIZED LOW ACROSS NORTHERN CHILE TO
NORTHWEST ARGENTINA EARLY ON WEDNESDAY MORNING. MEANWHILE...THIS
WILL TRIGGER SCATTERED SNOW SHOWERS ALONG THE ANDES BETWEEN LAKE
TITICACA AND EXTREME NORTHERN PORTIONS OF CHILE...WITH
ACCUMULATION OF 15-20CM EXPECTED EARLY IN THE CYCLE. ON WEDNESDAY
EXPECTING ADDITIONAL SNOWFALL AMOUNTS OF 10-15CM. ALSO...AS THE
SUBTROPICAL RIDGE INTENSIFIES ACROSS BRASIL...IT WILL INDUCE THE
NORTHWARD AMPLIFICATION OF AN UPPER LEVEL TROUGH ACROSS NORTHEAST
BRASIL TO THE AMAZON RIVER BASIN TO THE NORTH. THE DEEPENING UPPER
LEVEL TROUGH WILL INTERACT WITH THE ATLANTIC ITCZ TO TRIGGER HEAVY
RAINS ACROSS NORTHERN BRASIL...WITH MOST INTENSE EXPECTED BETWEEN
AMAPA/PARA AND CEARA WITH MAXIMA OF 75-150MM. THROUGH THURSDAY
THIS IS FORECAST TO WEAKEN TO 15-25MM/DAY...WHILE SIMULTANEOUSLY
BECOMING MORE ACTIVE AS IT BUILDS WEST ACROSS PARA TO AMAZONAS IN
NORTHERN BRASIL LATER IN THE WEEK. THIS IS TO ALSO FAVOR AN
INCREASE IN CONVECTION ACROSS ECUADOR...PARTICULARLY GUAYAQUIL
AREA AS ENHANCE BY AN ONSHORE WEST-NORTHWEST FLOW.

DAVISON...WPC (USA)
$$

396 
FXSA20 KWBC 101602
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1102 AM EST THU MAR 10 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT TBD.

FORECAST DISCUSSION FROM MAR 10/16 UTC: IN A HIGHLY AMPLIFIED
SINUSOIDAL WAVE PATTERN...A LONG WAVE RIDGE OVER THE EASTERN
PACIFIC DOMINATES THE FLOW BETWEEN THE COAST OF CHILE AND THE
BELLINGSHAUSEN SEAN. A DEEP EXTRATROPICAL CYCLONE LIES TO THE
EAST...WITH A CLOSED LOW TO THE NORTHEAST OF THE MALVINAS/FALKLAND
ISLANDS EXTENDING A TROUGH TO THE NORTH-NORTHWEST INTO NORTHERN
ARGENTINA. THROUGH THE END OF THE WEEK THE RIDGE TO THE WEST IS TO
FLATTEN TO THE SOUTH OF 50S...WHILE THE TROUGH MEANDERS EAST WHILE
TRAILING TO THE MIDSECTIONS OF SOUTH AMERICA. LATTER DURING THE
WEEKEND THE TROUGH GAINS MOMENTUM AND ACCELERATES ACROSS THE
CENTRAL TO THE EASTERN SOUTH ATLANTIC...MEANWHILE SHEARING A SHORT
WAVE TROUGH OVER NORTHERN CHILE/EASTERN PACIFIC. AT LOW
LEVELS...THIS REFLECTS AS DEEP/OCCLUDED 988 HPA LOW THAT MOVES TO
50S 50W LATER THIS EVENING. THIS...IN COMBINATION WITH A POLAR
RIDGE OVER THE SOUTHERN CONE...WILL FAVOR A SOUTHERLY LOW LEVEL
JET ACROSS CENTRAL TO NORTHERN ARGENTINA. THIS...IN-TURN...DRIVES
THE ASSOCIATED FORNT NORTH ACROSS URUGUAY-CORDOBA IN ARGENTINA TO
SOUTHERN BRASIL-NORTHERN ARGENTINA LATER TODAY.  ON FRIDAY TO
SATURDAY...DRIVEN BY THE SOUTHERLY LOW LEVEL JET...THE FRONT WILL
CONTINUE FARTHER NORTH ACROSS PARAGUAY TO MATO GROSSO DO SUL IN
BRASIL WHILE TRAILING ACROSS NORTHERN BOLIVIA TO THE SOUTHERN
JUNGLE OF PERU. LATER DURING THE WEEKEND THE FRONT IS FORECAST TO
FRONTOLIZE.

AS THE FRONT RACES ACROSS MIDSECTION OF SOUTH AMERICA AND CLASHES
WITH MOIST/WARM SUBTROPICAL AIR MASS TO THE NORTH...CONDITIONS
WILL BE HIGHLY FAVORABLE FOR HEAVY RAINFALL PRODUCING MESO SCALE
CONVECTIVE SYSTEMS TO DEVELOP. ACROSS RIO GRANDE DO SUL IN BRASIL
TO CORRIENTES ARGENTINA/SOUTHEAST ARGENTINA THIS WILL FAVOR
RAINFALL AMOUNTS OF 40-80MM...WHILE ACROSS JUJUY/NORTHERN SALTA TO
SOUTHERN BOLIVIA STRONG TOPOGRAPHICAL FORCING WILL FAVOR RAINFALL
AMOUNTS OF 75-125MM. ON FRIDAY TO SATURDAY...AS THE CONVECTION
SPREADS NORTH ACROSS PARAGUAY INTO SOUTHERN/SOUTHEAST
BRASIL...THIS WILL THEN TRIGGER MAXIMA OF 30-60MM...WHILE OVER
CENTRAL BOLIVIA TO THE SOUTHERN JUNGLE OF PERU THIS INCREASES TO
150-250MM AS ENHANCED BY THE SOUTHERLY LOW LEVEL JET. ON SATURDAY
TO SUNDAY THE CONVECTION WILL CONTINUE ITS NORTHWARD PROGRESSION
ACROSS ACRE IN BRASIL TO THE CENTRAL JUNGLE OF PERU...WITH MAXIMA
IN THIS AREA OF 40-80MM. LATER DURING THE WEEKEND/EARLY NEXT WEEK
THIS WILL THEN COMBINE INTO AN MCS OVER NORTHERN BRASIL...WITH
MAXIMA INCREASING FROM 35-70MM ON SUNDAY TO 75-125MM ON MONDAY.

OTHER MID/UPPER LEVEL PERTURBATIONS ARE TO FOLLOW. HOWEVER...UNDER
THE BLOCKING INFLUENCE OF THE LONG WAVE RIDGE TO THE WEST THESE
ARE TO INITIALLY CONFINE TO THE DRAKE PASSAGE/ANTARCTIC PENINSULA.
LATER IN THE PERIOD...AS THE RIDGE FLATTENS TO THE SOUTH OF
50S...CONDITIONS WILL BECOME MORE FAVORABLE FOR SHORT WAVE
PERTURBATIONS STREAMING TO THE SOUTH TO DEEPEN. LATER ON
MONDAY/EARLY ON TUESDAY MORNING...SOME OF THE MODELS ARE
ENTERTAINING THE POSSIBILITY OF A ROBUST SOUTHERN STREAM TROUGH TO
AMPLIFY AS IT ENTERS THE DRAKE PASSAGE/TIERRA DEL FUEGO. THIS HAS
THE POTENTIAL OF BECOMING A HEAVY RAINFALL PRODUCER FOR EXTREME
SOUTHERN PORTIONS OF CHILE...AND WOULD CARRY THE RISK OF SCATTERED
SNOW SHOWERS AS IT ENTERS TIERRA DEL FUEGO ON MONDAY.

AT 250 HPA...CELL OF THE SUBTROPICAL RIDGE BRANCHING FROM THE
EASTERN TROPICAL PACIFIC TO PERU/BOLIVIA WILL VENT THE
AFOREMENTIONED CONVECTION AS IT BUILDS NORTH ACROSS BOLIVIA TO
PERU/WESTERN BRASIL. THE RIDGE ALOFT WILL PERSIST WHILE SLOWLY
BUILDING EASTWARD ACROSS MATO GROSSO/MATO GROSSO DO SUL TO THE
SOUTHEAST STATES OF BRASIL DURING THE WEEKEND. MEANWHILE...A TUTT
LOW/CAVADO DO NORDESTE TO THE EAST OF RIO DE JANEIRO/ESPIRITO
SANTO WILL EXTEND A SHORT WAVE TROUGH TO MINAS GERAIS. AS THE
SUBTROPICAL RIDGE BUILDS ACROSS BRASIL...AND PRESSES AGAINST THE
TUTT LOW...THE LATTER IS TO GRADUALLY WEAKEN TO A SHEAR AXIS ALONG
THE NORTHEAST COAST OF BRASIL. MEANWHILE...THE UPPER LEVEL LOW
WILL ENHANCE TRADE WIND CONVERGENCE ACROSS SOUTHERN ESPIRITO SANTO
AND RIO DE JANEIRO...TO SUSTAIN RAINFALL MAXIMA OF 10-15MM IN
POTENTIALLY SEVERE DEEP CONVECTION. THROUGH THE WEEKEND THIS WILL
GRADUALLY WEAKEN TO 05-10MM.

HIGHER AMOUNTS ARE EXPECTED TO THE NORTH ALONG THE ITCZ AS IT
MAKES LANDFALL OVER EQUATORIAL SOUTH AMERICA. IN THIS AREA...AS
ENHANCED BY THE DIVERGENT/WET PHASE OF THE MJO...HEAVY/ORGANIZED
DEEP CONVECTION IS FORECAST TO AFFECT THE STATES OF PARA AND
AMAPA. MOST INTENSE IS EXPECTED DURING THE NEXT DAY OR SO...THEN
SHIFTS WESTWARD ACROSS EQUATORIAL SOUTH AMERICA TO NORTHERN
AMAZONAS/RORAIMA TO SOUTHERN VENEZUELA/SOUTHEAST COLOMBIA ON
SUNDAY TO MONDAY. AS ENHANCED BY THE SUBTROPICAL RIDGE TO THE
SOUTH...THIS WILL SUSTAIN HEAVY RAINFALL AMOUNTS...WITH TENDENCY
FOR THE ACTIVITY TO BECOME BETTER ORGANIZED AND MORE WIDESPREAD.

DAVISON...WPC (USA)
$$

061 
FXSA20 KWBC 091634
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1133 AM EST WED MAR 09 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 09/17 UTC: CONSISTENT WITH PREVIOUS
FORECASTS...BUILDING MID/UPPER LEVEL RIDGE IS TO RAPIDLY BECOME
THE DOMINANT FEATURE OVER THE FAR EASTERN PACIFIC DURING THE DAY
TODAY. AS THE RIDGE BUILDS TO THE WEST...IT WILL SUSTAIN THE
INTENSIFICATION OF A MID LATITUDE EXTRATROPICAL CYCLONE OFF THE
COAST OF PATAGONIA/NORTH OF THE FALKLAND ISLANDS LATER THIS
EVENING. AS THE LOW DEEPENS...IT WILL EXTEND A TROUGH NORTH ACROSS
THE BUENOS AIRES PROVINCE TO NORTHERN ARGENTINA/MID SECTIONS OF
SOUTH AMERICA. BOTH ARE EXPECTED TO REACH MAXIMUM INTENSITY EARLY
ON THURSDAY MORNING...WITH THE TROUGH TO THEN RAPIDLY WEAKEN ON
FRIDAY AS THE RIDGE TO THE WEST FLATTENS. AT LOW LEVELS...THIS
SUSTAINS A BROAD TROUGH CENTERING ON A DEEP 972 HPA LOW JUST NORTH
OF THE FALKLAND ISLANDS. UNDER THE INFLUENCE OF THIS LOW...AND A
BUILDING POLAR RIDGE OVER THE SOUTHERN CONE...THE SURFACE FRONT
SURGES ACROSS THE RIO DE LA PLATA BASIN/CENTRAL ARGENTINA LATER
TODAY...RACING TO SOUTHERN BRASIL-NORTHERN ARGENTINA ON THURSDAY
EVENING. ON FRIDAY TO SATURDAY...DRIVEN BY A 30-35KT SOUTHERLY LOW
LEVEL JET...THE FRONT WILL CONTINUE NORTH ACROSS PARAGUAY TO MATO
GROSSO DO SUL IN BRASIL AND INTO NORTHERN BOLIVIA/SOUTHERN JUNGLE
OF PERU.

AS IT RACES ACROSS MID SECTIONS OF SOUTH AMERICA...THE FRONT WILL
TRIGGER ORGANIZED DEEP CONVECTION/SQUALLY WEATHER. THROUGH THE DAY
MOST INTENSE IS EXPECTED ACROSS ENTRE RIOS IN ARGENTINA/URUGUAY
WITH MAXIMA OF 50-100MM...WHILE ON THURSDAY EXPECTING AN
ADDITIONAL 40-80MM WHILE BUILDING NORTH ACROSS RIO GRANDE DO SUL
TO CORRIENTES IN ARGENTINA/SOUTHEAST PARAGUAY. OVER NORTHWEST
ARGENTINA THIS WILL INCREASE FROM 35-70MM LATER TODAY TO 75-125MM
WHILE LIFTING ACROSS JUJUY/SALTA TO SOUTHERN BOLIVIA. ON FRIDAY
ECHO TRAINING CONDITIONS ARE EXPECTED AS THE FRONT SURGES ACROSS
CENTRAL BOLIVIA TO THE SOUTHERN JUNGLE OF PERU...WITH MAXIMA IN
THIS AREA OF 150-250MM HIGHLY LIKELY...WHILE ACROSS PARAGUAY TO
SOUTHERN BRASIL EXPECTING ADDITIONAL 30-60MM ON FRIDAY TO
SATURDAY. DURING THE WEEKEND CONVECTION OVER CENTRAL BRASIL WILL
WEAKEN TO MAXIMA OF 20-35MM...WHILE CONVECTION ALONG THE LEE OF
THE PERUVIAN ANDES RAPIDLY SURGES TO 40-80MM ON SATURDAY TO SUNDAY.

AT 250 HPA...CELL OF THE SUBTROPICAL RIDGE BRANCHING BETWEEN
BOLIVIA/PERU TO THE EASTERN PACIFIC...WILL VENT THE AFOREMENTIONED
CONVECTION AS IT BUILDS NORTH ACROSS NORTHWESTERN SOUTH AMERICA.
THE RIDGE ALOFT WILL PERSIST WHILE SLOWLY BUILDING EASTWARD ACROSS
MATO GROSSO/MATO GROSSO DO SUL TO THE SOUTHEAST STATES OF BRASIL
LATER DURING THE WEEKEND. MEANWHILE...A TUTT LOW TO THE EAST
CENTERS OVER THE TROPICAL ATLANTIC OFF THE COAST OF ESPIRITO SANTO
IN BRASIL. THE UPPER LEVEL LOW IS TO BRIEFLY MEANDER INLAND ACROSS
ESPIRITO SANTO TO MINAS GERAIS LATER ON THURSDAY...BUT AS THE
UPPER LEVEL RIDGE BUILDS TO THE WEST...IT IS TO THEN RELOCATE ONCE
AGAIN TO THE TROPICAL ATLANTIC DURING THE WEEKEND.
MEANWHILE...THIS WILL ENHANCE TRADE WIND CONVERGENCE ACROSS
SOUTHERN ESPIRITO SANTO AND RIO DE JANEIRO...TO SUSTAIN RAINFALL
MAXIMA OF 10-15MM IN POTENTIALLY SEVERE DEEP CONVECTION. THROUGH
THE WEEKEND THIS WILL GRADUALLY WEAKEN TO 05-10MM.

HIGHER AMOUNTS ARE EXPECTED TO THE NORTH ALONG THE ITCZ AS IT
MAKES LANDFALL OVER EQUATORIAL SOUTH AMERICA. IN THIS AREA...AS
ENHANCED BY THE DIVERGENT/WET PHASE OF THE MJO...HEAVY/ORGANIZED
DEEP CONVECTION IS FORECAST TO AFFECT THE STATES OF PARA AND
AMAPA. MOST INTENSE IS EXPECTED DURING THE NEXT TWO DAYS...WITH
DAILY MAXIMA OF 75-150MM. THROUGH FRIDAY THIS WILL THEN DECREASE
TO 35-70MM. BUT AS THE MJO PULSE MOVES AWAY DURING THE
WEEKEND...THIS IS FORECAST TO WEAKEN TO 20-45MM/DAY...WITH MOST
INTENSE BETWEEN AMAPA AND NORTHERN PARA.

DAVISON/GALVEZ...WPC (USA)
$$

542 
FXSA20 KWBC 081650
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1149 AM EST TUE MAR 08 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 07/17 UTC: FORECAST DISCUSSION FROM
MAR 08/17 UTC: AN ELONGATED UPPER TROUGH EXTENDS FROM THE
BELLINGSHAUSEN SEA INTO ISLA CHILOE ON TUESDAY. THIS POTENT TROUGH
IS ACCOMPANIED BY THE DIVERGENT EXIT OF AN UPPER JET AND IS
SUSTAINING MODERATE PRECIPITATION IN SOUTHERN CHILE. ON
TUESDAY...THIS WILL FAVOR MAXIMA OF 20-35MM IN LOS LAGOS AND AYSEN
WITH A RISK OF EMBEDDED THUNDERSTORMS. CYCLOGENESIS IS EXPECTED
OFF THE COAST OF SOUTHERN PATAGONIA. THIS WILL TRIGGER MAXIMA OF
15-20MM IN THE REGION. ON WEDNESDAY...A POTENT CYCLONE IS EXPECTED
NEAR THE FALKLANDS/MALVINAS...BUT PRECIPITATION WITH THIS SYSTEM
WILL REMAIN MOSTLY OFFSHORE. TRAILING BEHIND...A SHORT WAVE TROUGH
IS FORECAST TO ENTER SOUTHERN CHILE ON WEDNESDAY TO FAVOR MAXIMA
OF 15-20MM IN AYSEN. TRAILING BEHIND...A SHORT WAVE TROUGH IS
FORECAST TO RAPIDLY PROPAGATE ACROSS THE SOUTHERN CONE ON
FRIDAY...WHILE A ROBUST RIDGE BUILDS BEHIND OVER THE SOUTHEAST
PACIFIC. INITIALLY...A TIGHT PRESSURE GRADIENT ON THURSDAY WILL
FAVOR MAXIMA OF 15-25MM IN NORTHWEST SLOPES OF MAGALLANES. BUT
ONCE THE TROUGH MOVES THROUGH...MOST OF THE PRECIPITATING SYSTEMS
WILL LIMIT TO THE DRAKE PASSAGE AS A RIDGE BUILDS INTO SOUTHERN
CHILE...TO SUSTAIN FAIR WEATHER CONDITIONS ON FRIDAY. A FRONT
MOVES IN ON SATURDAY...TO SUSTAIN MAXIMA OF 15-20MM.

IN MID-SECTIONS OF THE CONTINENT AND TO THE EAST OF THE
ANDES...ACTIVE CONVECTION AND MODERATE PRECIPITATION IS EXPECTED
TO GRADUALLY MIGRATE FROM NORTH-CENTRAL ARGENTINA INTO
BOLIVIA/SOUTHERN PERU AND SOUTHERN BRASIL THROUGH THE CYCLE...AS A
PERSISTENT UPPER TROUGH PATTERN INTERACTS WITH A BUILDING MOIST
POOL...AND LATER IN THE CYCLE WITH A PROGRESSIVE SURFACE FRONT. ON
TUESDAY...EXPECT CONVECTION TO FLARE UP ALONG AND TO THE NORTH OF
A STATIONARY FRONT FORECAST TO EXTEND ACROSS RIO GRANDE DO
SUL...CORRIENTES...SANTIAGO DEL ESTERO. IN SOUTHERN BRASIL THIS
WILL TRIGGER MAXIMA OF 20-35MM WHILE IN NORTHERN IRIGIAY AND
NORTHERN ARGENTINA EXPECT MAXIMA OF 35-70MM WITH A RISK FOR
SEVERITY. ON WEDNESDAY...THE OLF FRONT WILL RETURN SOUTH AS A WARM
FRONT INTO NORTHERN URUGUAY AND ENTRE RIOS. UNDER THE INFLUENCE OF
THE DIVERGENT ENTRANCE OF AN UPPER JET AND DEEPENING UPPER TROUGH
TO THE WEST...THIS WILL TRIGGER MAXIMA OF 50-100MM/DAY WITH A RISK
OF MCS FORMATION FROM SANTA FE INTO THE RIO DE LA PLATA. IN AREAS
TO THE WEST EXPECT MAXIMA OF 35-70MM WITH THE RISK OF MCS
FORMATION AND SEVERE CONVECTION. ON THURSDAY...AN INCREASE IN
SOUTHERLY WINDS WILL PUSH THE OLF FRONT NORTHWARD. THIS WILL
TRIGGER HEAVY RAIN FROM SOUTHERN BOLIVIA INTO FORMOSA/CHACO IN
ARGENTINA TO DEVELOP MAXIMA OF 75-125MM AND A RISK FOR MCS
FORMATION. FROM CORRIENTES EAST INTO RIO GRANDE DO SUL EXPECT
MAXIMA OF 35-70MM. ON FRIDAY...THE DIVERGENT ENTRANCE OF AN UPPER
JET WILL TRIGGER MAXIMA OF 30-60MM FROM SOUTHEAST BOLIVIA INTO
OARAGUAY AND PARANA/SANTA CATARINA...ALONG AND AHEAD OF THE
SURFACE FRONT. AS A SOUTHERLY LOW-LEVEL JET DEVELOPS INTO CENTRAL
BOLIVIA...EXPECT EXTREME MOISTURE CONVERGENCE TO DEVELOPS ALONG
THE ANDES. THIS WILL TRIGGER MAXIMA OVER 100MM/DAY...AND ISOLATED
AMOUNTS IN THE 150-250MM RANGE ARE POSSIBLE IN REGION WHERE ECHO
TRAINING DEVELOPS IN INTERACTION WITH THE MOUNTAINS. THE FRONT IS
FORECAST TO REACH PARANA...WESTERN MATO GROSSO...SOUTHERN PERU ON
SATURDAY. THIS WILL TRIGGER MAXIMA OF 40-80MM IN SOUTHERN
PERU...WHILE ALONG WESTERN BRASIL/NORTHERN BOLIVIA EXPECT MAXIMA
OF 15-25MM. ONSHORE FLOW IN SANTA CATARINA/NORTHERN RIO GRANDE DO
SUL WILL INTERACT WITH THE SIERRA GAUCHA TO TRIGGER MAXIMA OF
30-60MM.

IN TROPICAL SOUTH AMERICA...THE MOST ACTIVE CONVECTION IS FORECAST
TO PERSIST IN NORTHERN BRASIL...FROM CEARA WEST ACROSS THE AMAZON
DELTA INTO NORTHENR PARA. IN THE UPPER LEVELS...THE SUBEQUATORIAL
RIDGE IS FORECAST TO REMAIN ENHANCED TO PROVIDE A FORMIDABLE
VENTILATION PATTERN. THIS...IN COMBINATION WITH HIGH PRECIPITABLE
WATER VALUES AND AN ACTIVE ATLANTIC ITCZ WILL TRIGGER MAXIMUM
AMOUNTS OF 35-70MM FROM TOCANTINS INTO EASTERN AMAZONAS...WHILE
ALONG THE NORTH COAST OF BRASIL EXPECT MAXIMA OF 20-35MM. ON
WEDNESDAY...EXPECT A FLARE UP OF CONVECTION FROM CEARA INTO ALL OF
PARA TO SUSTAIN MAXIMA OF 25-50MM. ON THURSDAY...EXPECT SIMILAR
AMOUNTS. ON FRIDAY...EXPECT MAXIMA OF 35-70MM ALONG THE NORTH
COAST OF BRASIL WHILE IN NORTHERN PARA/AMAZONAS EXPECT MAXIMA OF
20-35MM. ON SATURDAY...EXPECT MAXIMA OF 30-60MM FROM MARANHAO INTO
AMAPA. ALSO OF RELEVANCE...A TUTT IS FORECAST TO LINGER OVER
EASTERN BRASIL THROUGH THE CYCLE. THIS WILL INTERACT WITH ONSHORE
TRADES TO SUSTAIN DAILY CONVECTION FROM BAHIA INTO
PERNAMBUCO...WITH FORECAST AMOUNTS OF 10-15MM THROUGH FRIDAY. IN
ESPIRITO SANTO...THE TUTT DYNAMICS AND ENHANCED INSTABILITY WILL
BECOME FAVORABLE FOR SEVERE CONVECTION ON THURSDAY...WHEN RAINFALL
AMOUNTS ARE FORECAST TO REMAIN IN THE 10-15MM/DAY RANGE. A
CONTINUED RISK FOR SEVERE CONVECTION IS EXPECTED ON FRIDAY...WHEN
MAXIMA IS FORECAST IN THE 05-10MM/DAY RANGE.

IN WESTERN PORTIONS OF THE CONTINENT...SEASONAL CONVECTION IS
EXPECTED TO PRODUCE AMOUNTS WITHIN THE CLIMATOLOGICAL
RANGE...UNDER THE VENTILATING INFLUENCE OF THE BOLIVIAN
HIGH...FORECAST TO LINGER FROM SOUTHERN BOLIVIA INTO THE EASTERN
PACIFIC TO THE WEST OF NORTHERN CHILE. IN THE LOW-LEVELS...THE
FLOW IS FORECAST TO REMAIN UNFAVORABLE FOR HEAVY RAINFALL IN
ECUADOR AND WESTERN SLOPES OF PERU. THIS WILL FAVOR MAXIMA
GENERALLY IN THE 10-15M/DAY RANGE THROUGH THE THE CYCLE IN
COASTAL/WESTERN ECUADOR AND ALONG THE PERUVIAN ANDES. HIGHER
AMOUNTS ARE EXPECTED EAST OF THE ANDES...ESPECIALLY ALONG THE
ANDES. THIS WILL TRIGGER MAXIMA OF 20-35MM ON TUESDAY IN SOUTHERN
PERU/CENTRAL BOLIVIA. ON WEDNESDAY...EXPECT MAXIMA OF 15-25MM. ON
THURSDAY...THIS INCREASES TO MAXIMA OF 20-35MM. HIGHER AMOUNTS ARE
EXPECTED AFTER AS THE AFOREMENTIONED SURFACE FRONT AND SOUTHERLY
LOW-LEVEL JET ARRIVE FROM THE SOUTH.

DAVISON/GALVEZ...WPC (USA)
$$

063 
FXSA20 KWBC 071659
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1158 AM EST MON MAR 07 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 07/17 UTC:  A SLOW-TO-EVOLVE
AMPLIFIED WAVE PATTERN CONTINUES IN THE SOUTHERN CONE. ON
MONDAY...A LONG WAVE TROUGH IS APPROACHING SOUTHERN CHILE...AND IT
IS FORECAST TO ENTER THE CONTINENT ON TUESDAY. THE SURFACE FRONTS
WILL START TRIGGERING PRECIPITATION IN SOUTHERN CHILE LATE ON
MONDAY EVENING...TO SUSTAIN MAXIMA OF 25-50MM/DAY. AMOUNTS ARE
FORECAST TO RAPIDLY INCREASE ON TUESDAY MORNING...AS THE DIVERGENT
EXIT OF THE UPPER JET ENTERS AYSEN IN SOUTHERN CHILE. IN
COMBINATION WITH THE SURFACE FRONT AND TRAILING COOL CONVECTIVELY
UNSTABLE AIR MASS...THIS WILL TRIGGER MAXIMA OF 20-35MM IN AYSEN
AND LOS LAGOS...INCLUDING A RISK FOR ISOLATED THUNDERSTORMS. THE
FRONT RAPIDLY MOVES NORTHWARD ON TUESDAY TO SUSTAIN MAXIMA VERY
LIGHT AMOUNTS FROM LOS RIOS INTO BIO BIO. EAST OF THE ANDES...THE
OCCLUDED LOW WILL FAVOR MAXIMA OF 05-10MM/DAY IN PATAGONIA AND
TIERRA DEL FUEGO. THE SYSTEM THEN EXITS INTO THE SOUTH ATLANTIC.
THE NEXT SYSTEM OF INTEREST IS A RAPIDLY MOVING SHORT WAVE TROUGH
FORECAST TO ENTER SOUTHERN CHILE LATE ON WEDNESDAY. THIS WILL
FAVOR ISOLATED MAXIMA OF 15-20MM. A LONGER TROUGH CROSSES THE
DRAKE PASSAGE LATER IN THE WEEK. THIS SYSTEM WILL ALSO SUSTAIN
LIGHT PRECIPITATION IN EXTREME SOUTHERN CHILE ON THURSDAY AND
FRIDAY...TO TRIGGER ISOLATED MAXIMA OF 15-25MM IN MAGALLANES ON
THURSDAY.

EAST OF THE ANDES...AND AT UPPER LEVELS...A SHORT WAVE TROUGH IS
PROGRESSING SLOWLY INTO NORTHEAST ARGENTINA ON MONDAY. AS THIS
INTERACTS WITH THE SLOW-TO EVOLVE LONG WAVE TROUGH CROSSING THE
SOUTHERN CONE ON TUESDAY/WEDNESDAY...EXPECT ENHANCED DYNAMICAL
ASCENT TO INCREASE...WHICH WILL SUSTAIN SEVERAL DAYS WITH MODERATE
AND LOCALLY HEAVY PRECIPITATION AMOUNTS. IN TERMS OF AVAILABLE
MOISTURE...AMOUNTS IN THE ORDER OF 35-50MM ARE CLUSTERING IN AREAS
LOCATED TO THE NORTH OF NORTHERN CORDOBA...SANTA FE AND THE RIO DE
LA PLATA...ALONG AND TO THE NORTH OF A SURFACE FRONT. ON
MONDAY...THE SHORT WAVE TROUGH WILL CROSS THE ANDES OF NORTHERN
ARGENTINA TO TRIGGER MAXIMA OF 30-60MM/DAY. IN URUGUAY AND RIO
GRANDE DO SUL EXPECT MAXIMA OF 15-20MM. ON TUESDAY...REMNANT
CONVECTION ALONG THE FRONT WILL TRIGGER MAXIMA OF 20-35MM IN RIO
GRANDE DO SUL AND SANTA CATARINA. LATE ON TUESDAY...EXPECT THE
DEVELOPMENT OF NOCTURNAL CONVECTION WITH FORECAST MAXIMA OF
35-70MM FROM CORDOBA INTO URUGUAY...INCLUDING A RISK OF SEVERITY.
THIS IS FORECAST TO CONTINUE INTO WEDNESDAY...WHEN EXPECT MAXIMA
OF 40-80MM FROM SANTA FE INTO ALL OF URUGUAY AND A RISK FOR SEVERE
AND MCS FORMATION. IN CORDOBA/TUCUMAN AND SANTIAGO DEL ESTERO
EXPECT MAXIMA OF 30-60MM AND RISK FOR SEVERE CONVECTION. ON
THURSDAY...EXPECT MAXIMA OF 40-80MM/DAY AND A RISK FOR MCS
FORMATION IN NORTHWEST ARGENTINA. IN CORRIENTES AND RIO GRANDE DO
SUL EXPECT MAXIMA OF 15-25MM. ON FRIDAY...ACTIVITY IS FORECAST TO
CLUSTER ALONG AND NORTH OF THE SURFACE FRONT...TO EXTEND ACROSS
PARANA/SANTA CATARINA INTO CENTRAL PARAGUAY...TO SUSTAIN MAXIMA IN
THE ORDER OF 20-45MM.

IN TROPICAL PORTIONS OF THE CONTINENT...THE MOST ACTIVE CONVECTION
WILL PERSIST IN NORTHERN BRASIL/AMAZON DELTA...PARTLY IN RESPONSE
TO THE UPPER DIVERGENT PULSE OF THE MJO MOVING FROM SOUTH AMERICA
INTO THE SOUTHERN ATLANTIC. THIS WILL FAVOR AN ACTIVE
SUBEQUATORIAL RIDGE OVER THE GUIANAS/TROPICAL ATLANTIC THAT WILL
SUSTAIN AN ENHANCED PATTERN OF VENTILATION IN THE REGION. IN THE
LOW-LEVELS...THE SOUTH ATLANTIC ITCZ IS VERY ACTIVE. DEEP
CONVECTION CONTINUES ADDING MOISTURE INTO THE MID/UPPER
TROPOSPHERE...WHICH WILL RESULT IN HIGH PRECIPITABLE WATER
AMOUNTS...FAVORABLE FOR HEAVY RAINFALL. ON MONDAY...EXPECT MAXIMA
OF 25-50MM FROM NORTHERN CEARA INTO THE AMAZON DELTA/EASTERN PARA.
ON TUESDAY...EXPECT MAXIMA OF 35-70MM FROM TOCANTINS INTO EASTERN
AMAZONAS...WHILE ALONG THE NORTH COAST OF BRASIL EXPECT MAXIMA OF
20-35MM. ON WEDNESDAY...EXPECT A FLARE UP OF CONVECTION FROM CEARA
INTO ALL OF PARA TO SUSTAIN MAXIMA OF 25-50MM. ON
THURSDAY...EXPECT SIMILAR AMOUNTS. ON FRIDAY...EXPECT MAXIMA OF
20-45MM ALONG THE NORTH COAST OF BRASIL WHILE IN NORTHERN
PARA/AMAZONAS EXPECT MAXIMA OF 20-35MM. ALSO OF RELEVANCE TO THE
REGION...A TUTT IS FORECAST TO LINGER OVER EASTERN BRASIL THROUGH
THE CYCLE. THIS WILL INTERACT WITH ONSHORE TRADES TO SUSTAIN DAILY
CONVECTION FROM BAHIA INTO PERNAMBUCO...WITH FORECAST AMOUNTS OF
10-15MM. IN ESPIRITO SANTO...THE TUTT DYNAMICS WILL BECOME
FAVORABLE FOR SEVERE CONVECTION ON THURSDAY...WHEN RAINFALL
AMOUNTS ARE FORECAST TO REMAIN IN THE 10-15MM/DAY RANGE.

IN WESTERN PORTIONS OF THE CONTINENT...SEASONAL CONVECTION IS
EXPECTED TO PRODUCE AMOUNTS WITHIN THE CLIMATOLOGICAL RANGE. IN
THE UPPER TROPOSPHERE...THE BOLIVIAN HIGH IS FORECAST TO LINGER
FROM SOUTHERN BOLIVIA INTO THE EASTERN PACIFIC TO THE WEST OF
NORTHERN CHILE. THIS WILL SUSTAIN VENTILATION ESPECIALLY IN
WESTERN BRASIL/ECUADOR/PERU AND BOLIVIA. IN THE LOW-LEVELS...THE
FLOW IS FORECAST TO REMAIN UNFAVORABLE FOR HEAVY RAINFALL IN
ECUADOR AND WESTERN SLOPES OF PERU. THIS WILL FAVOR MAXIMA
GENERALLY IN THE 10-15M/DAY RANGE THROUGH THE THE CYCLE IN
COASTAL/WESTERN ECUADOR AND ALONG THE PERUVIAN ANDES. HIGHER
AMOUNTS ARE EXPECTED EAST OF THE ANDES. ON MONDAY...EXPECT MAXIMA
OF 35-70MM IN EASTERN PERU/WESTERN BRASIL. IN CENTRAL
BOLIVIA/SOUTHERN AMAZON OF PERU EXPECT MAXIMA OF 20-45MM. ON
TUESDAY EXPECT A DECREASE TO MAXIMA OF 20-35MM IN BOTH LOCATIONS.
A DECREASE IS EXPECTED ON WEDNESDAY AND THURSDAY. ON
FRIDAY...EXPECT CONVECTION TO FLARE UP FROM CENTRAL BOLIVIA INTO
SOUTHERN PERY ALONG A SURFACE TROUGH...TO DEVELOP MAXIMA OF
35-70MM WITH A RISK FOR MCS FORMATION.

DAVISON/GALVEZ...WPC (USA)
$$

685 
FXSA20 KWBC 041714
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1213 PM EST FRI MAR 04 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON MONDAY MAR 07

FORECAST DISCUSSION FROM MAR 04/17 UTC: A SLOW-TO-EVOLVE BROAD
MID-UPPER TROUGH IS CROSSING THE SOUTHERN CONE ON FRIDAY. THIS
SUSTAINS AN EXTRATROPICAL CYCLONE FORECAST TO CENTER OVER PUERTO
WILLIAMS/USHUAIA ON FRIDAY...SOUTH OF THE MALVINAS/FALKLANDS ON
SATURDAY TO THEN EXIT. THIS WILL CONTINUE TO MAINTAIN ONSHORE FLOW
INTO THE SOUTHERN ANDES AND DARWIN CORDILLERA TO FAVOR MODERATE
ACCUMULATIONS. ON FRIDAY...EXPECT MAXIMA OF 20-35MM. ON
SATURDAY...EXPECT MAXIMA OF 15-20MM IN REMNANT CONVECTION IN THE
DARWIN CORDILLERA. THE NEXT SYSTEM OF INTEREST IS ANOTHER
EXTRATROPICAL CYCLONE FORECAST TO APPROACH AYSEN ON SATURDAY. THE
SYSTEM ARRIVES ACCOMPANIED BY THE DIVERGENT EXIT OF AN UPPER JET.
THIS WILL ENHANCE LIFT TO FAVOR MAXIMA OF 20-45MM. ON SUNDAY...THE
OCCLUDED LOW IS FORECAST TO WEAKEN OVER LOS LAGOS TO TRIGGER
MAXIMA OF 15-30MM. THE NEXT SYSTEM TO AFFECT THE SOUTHERN CONE IS
A LARGE MID-UPPER TROUGH FORECAST TO EXTEND FROM THE SOUTHERN
BELLINGSHAUSEN SEA INTO 43S 82W LATE ON MONDAY. THIS TROUGH WILL
ALSO ARRIVE WITH THE DIVERGENT EXIT OF AN UPPER JET...AND A TIGHT
PRESSURE GRADIENT IN THE LOWER TROPOSPHERE. THIS WILL TRIGGER
MAXIMA OF 25-50MM IN EXTREME SOUTHERN CHILE ON MONDAY THROUGH
EARLY TUESDAY. ON TUESDAY...LINGERING ONSHORE FLOW WILL TRIGGER
MAXIMA OF 20-35MM IN LOS LAGOS AND AYSEN...AND MAXIMA OF 10-15MM
IN THE DARWIN CORDILLERA.

EAST OF THE ANDES...THE UPPER TROUGH IS ENHANCING CONVECTION IN
CENTRAL ARGENTINA ON FRIDAY. THIS WILL TRIGGER MAXIMA OF 35-70MM
WITH A RISK OF MCS FORMATION FROM CORDOBA INTO ENTRE RIOS AND
SOUTHWEST URUGUAY. TO THE SOUTH...FROM CUYO INTO THE CENTRAL
BUENOS AIRES PROVINCE...EXPECT MAXIMA OF 15-25MM. ON
SATURDAY...EXPECT MAXIMA OF 50-100MM/DAY IN NORTHEAST ARGENTINA
AND ALL OF URUGUAY...WITH A RISK FOR MCS FORMATION. IN NORTHWEST
ARGENTINA EXPECT MAXIMA OF 30-60MM. ON SUNDAY...A SHORT WAVE
MID-UPPER TROUGH MOVES IN FROM THE WEST. THIS WILL ACTIVATE
CONVECTION ALONG A STATIONARY FRONT THAT IS MEANDERING IN THE RIO
DE LA PLATA BASIN AND CENTRAL ARGENTINA...TO FAVOR MAXIMA OF
30-60MM/DAY WITH A RISK FOR SEVERE CONVECTION IN SAN LUIS/SOUTHERN
CORDOBA/WESTERN BUENOS AIRES. IN THE RIO DE LA PLATA REGION EXPECT
MAXIMA OF 40-80MM WITH A RISK FOR MCS FORMATION. ON MONDAY...THE
SURFACE FRONT ADVANCES INTO RIO GRANDE DO SUL AND SANTIAGO DEL
ESTERO/NORTHERN SANTA FE. THE LARGEST ACCUMULATIONS ARE EXPECTED
IN NORTHWEST ARGENTINA AIDED BY THE CHACO LOW AND A LOW-LEVEL JET.
THIS WILL TRIGGER MAXIMA OF 30-60MM. IN NORTHEAST ARGENTINA AND
RIO GRANDE DO SUL EXPECT MAXIMA OF 15-20MM. ON TUESDAY...SCATTERED
DEEP CONVECTION IS EXPECTED ALONG THE WEAKENING STATIONARY
FRONT...FROM SANTIAGO DEL ESTERO/TUCUMAN INTO RIO GRANDE DO SUL
AND SANTA CATARINA...WHERE EXPECT MAXIMA OF 15-30MM.

NORTH IN TROPICAL SOUTH AMERICA...THE BOLIVIAN HIGH STARTS AS A
ROBUST ANTICYCLONE CENTERING OVER NORTHERN CHILE. ALSO ON
FRIDAY...A TUTT CENTERS OVER GOIAS. MODELS DO AGREE IN ELONGATING
BOTH SYSTEMS ZONALLY. THIS WILL LEAD TO AN ELONGATED RIDGE FROM
SANTA CATARINA INTO NORTHERN CHILE AND INTO 15N 85W BY
MONDAY/TUESDAY...WHILE THE TUTT IS FORECAST TO EXTEND FROM
SOUTHERN ESPIRITO SANTO INTO SOUTHERN MARO GROSSO. A FEATURE OF
INTEREST IS THE SUBEQUATORIAL RIDGE IN THE NORTH
HEMISPHERE...WHICH IS FORECAST TO DEVELOP A ROBUST ZONALLY
ORIENTED AXIS FROM THE EQUATORIAL NORTH ATLANTIC INTO CENTRAL
COLOMBIA. THIS WILL PROVIDE VENTILATION TO SUSTAIN ACTIVE
CONVECTION IN THE NORTHERN AMAZON BASIN INCLUDING THE GUIANAS.
ANOTHER REGION IN WHICH MODERATE VENTILATION WILL PERSIST THROUGH
THE CYCLE IS PERU AND ECUADOR...AS EASTERLY FLOW IN THE NORTHERN
PERIPHERY OF THE BOLIVIAN HIGH REMAINS ACCELERATED TO THE WEST OF
THE ANDES THROUGH THE ENTIRE FORECAST CYCLE. CONVECTION AND
PRECIPITATION WILL BE FURTHER REINFORCED BY THE INFLUENCE OF AN
UPPER DIVERGENT PULSE OF THE MJO.

AREAS WITH ENHANCED PRECIPITATION WILL CLUSTER IN THREE
REGIONS...EASTERN AND NORTHEASTERN BRASIL...THE AMAZON
BASIN/NORTHERN BRASIL...AND PERU/ECUADOR. IN EASTERN BRASIL...FROM
BAHIA INTO COASTAL PERNAMBUCO...ENHANCED ONSHORE FLOW IN THE
LOW-LEVELS WILL TRIGGER AMOUNTS OF 20-45MM ON FRIDAY. THIS
DECREASES TO MAXIMA OF 20-35MM ON SATURDAY...AND TO MAXIMA OF
10-15MM/DAY BY MONDAY. IN THE AMAZON BASIN/NORTHERN
BRASIL...EXPECT MAXIMA OF 50-100MM FROM MATO GROSSO TO
AMAZONAS-BRASIL ON FRIDAY...WHILE FROM CEARA INTO EASTERN PARA
EXPECT MAXIMA OF 30-60MM. ON SATURDAY...EXPECT MAXIMA OF 75-150MM
FROM WESTERN PARA INTO NORTHERN AMAZONAS. FROM CENTRAL PARA INTO
CEARA EXPECT MAXIMA OF 20-35MM. ITCZ CONVERGENCE IN AMAPA WILL
TRIGGER MAXIMA OF 20-45MM. ON SUNDAY...EXPECT MAXIMA OF 75-125MM
FROM PIAUI/TOCANTINS INTO PARA. IN AMAZONAS EXPECT MAXIMA OF
20-35MM. ITCZ CONVERGENCE ALONG THE NORTH COAST OF BRASIL FROM
CEARA TO AMAPA WILL TRIGGER MAXIMA OF 20-45MM. ON MONDAY...EXPECT
MAXIMA OF 25-50MM FROM CEARA INTO THE MAZON DELTA...STIMULATED
ALSO BY A TROUGH IN THE TRADES. IN RONDONIA/ACRE INTO THE PERUVIAN
AMAZON EXPECT MAXIMA OF 30-60MM. TO THE WEST...IN ECUADOR...EXPECT
MAXIMA OF 25-50MM ON FRIDAY. THIS DECREASES TO A RANGE OF MAXIMA
OF 15-30MM THROUGH SUNDAY. ON MONDAY AND TUESDAY...MODELS HAVE
SHIFTED TO SOUTH WESTERLY FLOW IN THE LOWER LEVELS...WHICH
DECREASES THE CHANCES FOR EXTREME RAINFALL. IN PERU...MOST ACTIVE
WILL CLUSTER ALONG THE EASTERN SLOPES OF THE ANDES...ALTHOUGH
DIURNAL CONVECTION WILL ALSO REMAIN ACTIVE IN THE WESTERN
CORDILLERA OF PERU. EAST OF THE ANDES EXPECT MAXIMA OF 35-70MM IN
SOUTHERN PERU AND CENTRAL BOLIVIA ON FRIDAY...ON SATURDAY EXPECT
SIMILAR AMOUNTS FROM SOUTHERN ECUADOR INTO CENTRAL PERU...WHILE IN
SOUTHERN PERU EXPECT MAXIMA OF 20-35MM. THIS DECREASES ON SUNDAY
WHILE ON MONDAY ACTIVITY FLARES UP TO SUSTAIN MAXIMA OF 20-40MM.
ON TUESDAY EXPECT MAXIMA OF 20-35MM. IN THE ANDEAN REGION EXPECT
MAXIMA IN THE 10-20MM/DAY RANGE DURING THE WEEKEND...DECREASING TO
MAXIMA IN THE 05-15MM/DAY RANGE THEREAFTER.

DAVISON/GALVEZ...WPC (USA)
$$

219 
FXSA20 KWBC 031725
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1224 PM EST THU MAR 03 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 03/17 UTC:  IN SOUTHERN SOUTH
AMERICA...A SLOW-TO-EVOLVE BROAD MID-UPPER TROUGH IS CROSSING THE
SOUTHERN CONE ON THURSDAY. AS IT MOVES SLOWLY...SHORTER
PERTURBATIONS ARE EXPECTED TO PROPAGATE FROM THE WEST-SOUTHWEST
INTO SOUTHERN CHILE AND ARGENTINA. INITIALLY...A ROBUST
EXTRATROPICAL CYCLONE WILL APPROACH TIERRA DEL FUEGO FROM THE WEST
ON THURSDAY...TO POSITION EAST OF PUERTO WILLIAMS ON FRIDAY WHILE
WEAKENING...TO THEN SPLIT INTO TWO LOWS ON SATURDAY. THE
WESTERNMOST LOW IS FORECAST TO MEANDER TO THE SOUTH OF THE
FALKLANDS ON SATURDAY...SUSTAINING CONTINUED ONSHORE FLOW INTO THE
DARWIN CORDILLERA. ON THURSDAY...FAST CONVECTIVELY UNSTABLE
WESTERLIES WILL TRIGGER MAXIMA OF 20-45MM IN WESTERN MAGALLANES
AND AYSEN. ON FRIDAY...EXPECT MAXIMA OF 20-35MM IN MAGALLANES AND
MAXIMA OF 15-25MM IN AYSEN. ON SATURDAY...EXPECT MAXIMA OF 15-20MM
IN THE DARWIN CORDILLERA. THE NEXT SYSTEM OF INTEREST IS ANOTHER
EXTRATROPICAL CYCLONE FORECAST TO APPROACH AYSEN ON SATURDAY. THE
WARM FRONT WILL FAVOR MAXIMA OF 20-35MM. ON SUNDAY...THE OCCLUDED
LOW IS FORECAST TO WEAKEN OVER LOS LAGOS TO TRIGGER MAXIMA OF
15-30MM. ANOTHER SYSTEM ENTERS AYSEN AND WESTERN MAGALLANES ON
MONDAY...WHERE EXPECT MAXIMA OF 25-50MM.

TO THE EAST OF THE ANDES...THE UPPER TROUGH PATTERN IN THE
SOUTHERN CONE WILL CONTINUE TO LOWER THE PRESSURES IN
ARGENTINA...TO TRIGGER SEVERAL ROUNDS OF CONVECTION. ON
THURSDAY...EXPECT SEVERE THUNDERSTORMS TO DEVELOP FROM CUYO INTO
NORTHEAST PATAGONIA...TO FAVOR MAXIMA OF 15-25MM. ON FRIDAY...THIS
INCREASES TO MAXIMA OF 35-70MM FROM CORDOBA INTO SOUTHWEST
URUGUAY. TO THE SOUTH...FROM CUYO INTO THE CENTRAL BUENOS AIRES
PROVINCE...EXPECT MAXIMA OF 15-25MM. ON SATURDAY...EXPECT MAXIMA
OF 50-100MM/DAY IN NORTHEAST ARGENTINA AND ALL OF URUGUAY...WITH A
RISK FOR MCS FORMATION. IN NORTHWEST ARGENTINA EXPECT MAXIMA OF
30-60MM. ON SUNDAY...A SHORT WAVE MID-UPPER TROUGH MOVES IN FROM
THE WEST. THIS WILL ACTIVATE CONVECTION ALONG A STATIONARY FROM
MEANDERING IN THE RIO DE LA PLATA BASIN AND CENTRAL ARGENTINA.
EXPECT MAXIMA OF 30-60MM/DAY WITH  RISK FOR SEVERE CONVECTION IN
SAN LUIS/SOUTHERN CORDOBA/WESTERN BUENOS AIRES. IN THE RIO DE LA
PLATA REGION EXPECT MAXIMA OF 40-80MM WITH A RISK FOR MCS
FORMATION. ON MONDAY...THE SURFACE FRONT ADVANCES INTO RIO GRANDE
DO SUL AND SANTIAGO DEL ESTERO/NORTHERN SANTA FE. THE LARGEST
ACCUMULATIONS ARE EXPECTED IN NORTHWEST ARGENTINA AIDED BY THE
CHACO LOW AND A LOW-LEVEL JET. THIS WILL TRIGGER MAXIMA OF
30-60MM. IN NORTHEAST ARGENTINA AND RIO GRANDE DO SUL EXPECT
MAXIMA OF 15-20MM.

IN TROPICAL SOUTH AMERICA...THE UPPER PATTERN IS GRADUALLY
BECOMING MORE FAVORABLE FOR STRONG CONVECTION...AS THE BOLIVIAN
HIGH/SUBTROPICAL UPPER RIDGE INTENSIFIES UNDER THE INFLUENCE OF AN
ARRIVING UPPER DIVERGENT PULSE OF THE MJO. ON THURSDAY...THE HIGH
IS FORECAST TO CENTER OVER BOLIVIA AND SOUTHERN PERU. THIS
GRADUALLY MEANDERS TO THE SOUTHEAST PACIFIC NEAR 20S 74W BY
MONDAY. TO THE EAST...A TUTT CENTERS OVER GOIAS INITIALLY...AND IS
FORECAST TO MEANDER SOUTHWESTWARD VERY SLOWLY...TO EXTEND ACROSS
SOUTHERN ESPIRITO SANTO...MINAS GERAIS...EASTERN MATO GROSSO BY
SUNDAY AND MONDAY. THE TUTT IS ACCOMPANIED BY UPPER JETS...WHICH
WILL ENHANCE CONVECTION. HOWEVER...LIMITED AMOUNTS OF AVAILABLE
MOISTURE IN SOUTHEAST BRASIL WILL LIMIT POTENTIAL ACCUMULATIONS
WITH SUCH A STRONG SYSTEM. ON THURSDAY...EXPECT MAXIMA OF 35-70MM
FROM GOIAS INTO SOUTHERN PARA/NORTHERN MATO GROSSO. SIMILAR
AMOUNTS ARE EXPECTED IN CENTRAL BAHIA...WHERE ENHANCED ONSHORE
FLOW WILL FAVOR WET CONDITIONS. ON FRIDAY...EXPECT MAXIMA OF
35-70MM FROM MATO GROSSO/RONDONIA INTO AMAZONAS. FROM CENTRAL
BAHIA INTO PERNAMBUCO EXPECT MAXIMA OF 20-45MM. IN THE
NORDESTE...FROM CEARA WEST INTO EASTERN PARA...EXPECT MAXIMA OF
30-60MM. ON SATURDAY...THE IMPROVING UPPER DIVERGENT PATTERN IN
EQUATORIAL SOUTH AMERICA WILL FAVOR MAXIMA OF 75-150MM IN
AMAZONAS-BRASIL AND WESTERN PARA. IN THE REST OF PARA AND
MARANHAO/PIAUI/CEARA EXPECT MAXIMA OF 20-35MM. FROM BAHIA INTO
COASTAL PERNAMBUCO EXPECT ALSO MAXIMA OF 20-35MM. ON
SUNDAY...EXPECT MAXIMA OF 75-125MM IN PARA AND TOCANTINS/MARANHAO.
IN AMAZONAS EXPECT MAXIMA OF 20-35MM.

TO THE WEST...ALSO IN ASSOCIATION WITH AN ENHANCED UPPER DIVERGENT
PATTERN...EXPECT SEASONALLY ACTIVE CONVECTION TO CONTINUE ACROSS
ECUADOR AND THE PERUVIAN ANDES/PERUVIAN AMAZON. IN THE
ANDES...EXPECT GENERALLY MAXIMA OF 10-20MM. IN ECUADOR...EXPECT
LARGER AMOUNTS IN ASSOCIATION WITH A LOCALIZED SST WARMING AND
ENHANCED ONSHORE FLOW. THIS WILL TRIGGER MAXIMA OF 40-80MM/DAY ON
THURSDAY...DECREASING TO 15-20MM ON FRIDAY. ON SATURDAY...EXPECT
MAXIMA OF 35-70MM IN SOUTHERN ECUADOR...AND MAXIMA OF 15-25MM IN
NORTHERN ECUADOR. ON SUNDAY...EXPECT MAXIMA OF 15-30MM. ON
MONDAY...THE LOW-LEVEL FLOW BECOMES NORTHWESTERLY TO ENHANCE
CONVECTION IN NORTHERN PERU/SOUTHERN ECUADOR. EXPECT MAXIMA OF
20-40MM.

DAVISON/GALVEZ...WPC (USA)
$$

297 
FXSA20 KWBC 021651
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1151 AM EST WED MAR 02 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 02/17 UTC: OVER SOUTHERN SOUTH
AMERICA...THE MID/UPPER LEVEL FLOW REMAINS UNDER THE INFLUENCE OF
A SLOW-TO-EVOLVE HIGHLY AMPLIFIED SINUSOIDAL PATTERN. IN THIS
PATTERN...A LONG WAVE TROUGH IS TO EXTEND ALONG 90-95W EARLY IN
THE CYCLE...WHILE A RIDGE TO THE EAST EXTENDS ALONG THE ANDES AND
PATAGONIA TO THE BELLINGSHAUSEN SEA/ANTARCTIC PENINSULA. THROUGH
THURSDAY THE RIDGE WILL RELOCATE ACROSS THE SOUTHERN CONE TO THE
WESTERN ATLANTIC WHILE YIELDING TO THE POLAR TROUGH. AS THE TROUGH
APPROACHES CHILE...IT WILL INTERACT WITH A SUBTROPICAL MOIST PLUME
TO ENHANCE PRECIPITATION IN EXTREME SOUTHERN PORTIONS ON
WEDNESDAY...WHERE WE EXPECT MAXIMA OF 30-60MM IN MAGALLANES AND
15-20MM IN AYSEN. THE ASSOCIATED EXTRATROPICAL CYCLONE WILL THEN
SUSTAIN A 40-50KT ONSHORE FLOW ON THURSDAY. THIS...IN COMBINATION
WITH ENHANCED CONVECTIVE INSTABILITY...WILL FAVOR ADDITIONAL
RAINFALL AMOUNTS OF 20-35MM. THE MODERATE AMOUNTS ARE TO PERSIST
ACROSS THE MAGALLANES REGION ON FRIDAY...WHILE ACROSS AYSEN
EXPECTING 15-20MM.

EAST OF THE ANDES OVER CENTRAL ARGENTINA...THE DEEP UPPER LEVEL
TROUGH WILL START TO STIMULATE CONVECTION ON THURSDAY...WITH
RAINFALL MAXIMA OF 15-25MM/DAY IN POTENTIALLY SEVERE CONVECTION
BETWEEN CUYO AND NORTHEAST PATAGONIA. ON FRIDAY...AS THE FRONT
STALLS OVER CENTRAL ARGENTINA...UNDER THE INFLUENCE OF A
WARM/MOIST NORTHERLY LOW LEVEL JET AND AN UPPER LEVEL SUBTROPICAL
JET MAXIMA...THE ENVIRONMENTAL CONDITIONS ALONG AND NORTH OF THIS
FRONT WILL BECOME FAVORABLE FOR MCS FORMATION WITH EMBEDDED SEVERE
THUNDERSTORMS...WITH RAINFALL MAXIMA OF 35-70MM. CONTINUED
STRONG/ORGANIZED DEEP CONVECTION ON SATURDAY WILL FOCUS BETWEEN
CORDOBA IN ARGENTINA AND THE RIO DE LA PLATA BASIN...WHILE THE
MAXIMA INCREASING TO 50-100MM IN A CONTINUED RISK FOR MCS
FORMATION. UNDER FAVORABLE UPPER LEVEL JET DYNAMICS...EXPECT STORM
TOTAL AMOUNTS TO APPROACH/EXCEED 200MM IN ISOLATED LOCATIONS.

NORTH ACROSS THE CONTINENT...AN ILL-DEFINED CELL OF THE
SUBTROPICAL RIDGE/BOLIVIAN HIGH CENTERS OVER BOLIVIA...WHILE A
ROBUST TUTT CENTERS OVER GOIAS IN EASTERN BRASIL. DURING THE NEXT
TWO DAYS...UNDER THE INFLUENCE OF AN EASTWARD PROPAGATING UPPER
DIVERGENT KELVIN WAVE AND THE UPPER DIVERGENT PHASE OF AN MJO
PULSE...EXPECT THE RIDGE TO BECOME BETTER ORGANIZED.
MEANWHILE...THE TUTT TO THE EAST IS FORECAST TO REMAIN ORGANIZED
WHILE MEANDERING ACROSS EASTERN AND NORTH EAST BRASIL
INITIALLY...TO EVOLVE INTO A TROUGH EXTENDING ACROSS MINAS GERAIS
INTO MATO GROSSO BY THE WEEKEND. THIS IS TO GRADUALLY ENHANCE
VENTILATION IN TROPICAL PORTIONS OF SOUTH AMERICA TO FAVOR AN
INCREASE IN THE COVERAGE AND INTENSITY OF CONVECTION. ON
WEDNESDAY...CONVECTION BETWEEN PARA AND TOCANTINS/GOIAS IS
EXPECTED TO PRODUCE MAXIMA OF 35-70MM WHILE AMAZONAS AND NORTHERN
PERU/SOUTHEAST COLOMBIA SHOULD EXPECT MAXIMA OF 25-50MM. ON
THURSDAY AND FRIDAY...EXPECT MAXIMA OF 35-70MM FROM MATO GROSSO
INTO WESTERN PARAN/NORTHERN AMAZONAS AND ALONG THE NET IN NORTHERN
PERU. ON SATURDAY...ENHANCED VENTILATION WILL FAVOR MAXIMA OF
50-100MM/DAY AND THE RISK FOR MCS FORMATION FROM NORTHERN MATO
GROSSO INTO AMAZONAS-BRASIL AND NORTHEAST PERU/SOUTHEAST COLOMBIA.

UNDER THE INFLUENCE OF ENHANCED VENTILATION...SEASONALLY WET
CONDITIONS ARE ALSO EXPECTED ALONG THE ANDES OF PERU AND
ECUADOR...AND IN THE ECUADORIAN COAST...GIVEN A LOCAL WARMING OF
SEA SURFACE TEMPERATURES THAT LIMITS TO LATITUDES NORTH OF 05S.
THIS WILL FAVOR MAXIMA IN THE 10-20MM/DAY RANGE IN THE PERUVIAN
ANDES ON A DAILY BASIS. EAST OF THE PERUVIAN ANDES EXPECT MAXIMA
OF 20-45MM ON THURSDAY...AND MAXIMA OF 20-35MM ON FRIDAY AND
SATURDAY. IN THE ECUADORIAN COAST...EXPECT MAXIMA OF 30-60MM ON
WEDNESDAY...DECREASING TO MAXIMA OF 20-35MM ON THURSDAY...AND TO
MAXIMA OF 10-15MM ON FRIDAY. ON SATURDAY...EXPECT MAXIMA OF
15-20MM IN THE NORTHERN COAST OF ECUADOR AS SOUTHWESTERLY FLOW
LIMITS ACCUMULATIONS. BUT ON SUNDAY...THE NORTHWESTERLY/ONSHORE
COMPONENT OF THE LOW-LEVEL FLOW INCREASES...TO FAVOR MAXIMA OF
20-35MM IN MOST OF THE COAST OF ECUADOR AND NORTHERN PORTIONS OF
PERU.

DAVISON/GALVEZ...WPC (USA)
$$

804 
FXSA20 KWBC 011858
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 PM EST TUE MAR 01 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 01/17 UTC: MID/UPPER LEVEL FLOW OVER
THE EASTERN SOUTH PACIFIC AND WESTERN SOUTH ATLANTIC REMAIN UNDER
THE DOMINANT INFLUENCE OF SLOW TO EVOLVE HIGHLY AMPLIFIED
SINUSOIDAL WAVE PATTERN...WITH A LONG WAVE RIDGE OVER THE
SOUTHEAST PACIFIC BOOKENDED BY TWO LONG WAVE TROUGHS. THE
EASTERNMOST EXTENDS OVER THE WESTERN ATLANTIC WITH AXIS BOTTOMING
OUT OVER MID SECTIONS OF SOUTH AMERICA...WHILE THE WESTERNMOST
EXTENDS OVER THE PACIFIC ALONG 100W/110W TO 35S. DURING THE NEXT
TWO DAYS THE PATTERN WILL SHIFT EASTWARD...WITH THE TROUGH OVER
THE ATLANTIC PULLING AWAY AS THE RIDGE RELOCATES TO THE SOUTHERN
CONE. THIS...IN-TURN...ALLOWS THE OTHER TROUGH TO PUSH FARTHER
EASTWARD ACROSS THE EASTERN PACIFIC TO THE SOUTHERN REGIONS OF
CHILE. IN THIS PROCESS THIS IS TO ESTABLISH A SUBTROPICAL
CONNECTION...SUSTAINING A MOIST ADVECTIVE PATTERN THAT WILL HELP
FEED SEVERAL DAYS OF ORGANIZED CONVECTION. LATER IN THE WEEK THE
TROUGH IS TO ALSO MEANDER EAST ACROSS THE SOUTHERN CONE/DRAKE
PASSAGE-ANTARCTIC PENINSULA TO THE WESTERN ATLANTIC.

AT LOW LEVELS THIS WILL SUSTAIN A DEEPENING FRONTAL TROUGH OVER
THE SOUTHEAST PACIFIC LATER TODAY...WITH OCCLUDING LOW TO
INTENSIFY AS IT NEARS THE DRAKE PASSAGE/TIERRA DEL FUEGO LATER ON
WEDNESDAY EVENING. STRONG BOUNDARY LAYER WINDS OF 35-50KT ARE TO
ACCOMPANY THIS SYSTEM AS IT MAKES LANDFALL OVER THE SOUTHERN
CONE...WITH THE STRONG WESTERLY WINDS TO PERSIST THROUGH SATURDAY
MORNING. THIS COMBINES WITH THE STEEP TERRAIN OVER SOUTHERN CHILE
TO FAVOR MOIST ADIABATIC LIFTING/CONVERGENCE ACROSS THE SOUTHERN
ANDES. THROUGH WEDNESDAY CONVECTION IN THIS AREA WILL INCREASE
FROM 20-35MM TO 30-60MM...WHILE ON THURSDAY AND FRIDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 20-35MM. OVER ARGENTINA...AS THE
SURFACE FRONT SURGES ACROSS PATAGONIA TO LA PAMPA ON THURSDAY THIS
WILL SUSTAIN A ROUND OF MODERATE/POTENTIALLY SEVERE CONVECTION.
UNDER FAVORABLE UPPER LEVEL JET DYNAMICS...THIS IS THEN EXPECTED
TO TRIGGER HEAVY RAINFALL PRODUCING MCS ACROSS CENTRAL
ARGENTINA-RIO DE LA PLATA BASIN ON BOTH FRIDAY AND SATURDAY...WITH
STORM TOTAL AMOUNTS IN THIS AREA LIKELY TO EXCEED 200MM. 

FARTHER NORTH OVER THE CONTINENT...THE UPPER LEVEL FLOW SPLITS
BETWEEN AN ILL ORGANIZED CELL OF THE SUBTROPICAL RIDGE EXTENDING
WESTWARD ACROSS SOUTHERN BRASIL/PARAGUAY-NORTHERN
ARGENTINA/BOLIVIA TO THE EASTERN PACIFIC...AND A TUTT EXTENDING
ALONG A CLOSED LOW OVER BAHIA IN BRASIL TO SOUTHERN AMAZONAS/ACRE.
DURING THE NEXT TWO DAYS...UNDER THE INFLUENCE OF AN EASTWARD
PROPAGATING ATMOSPHERIC KELVIN WAVE AND THE DIVERGENT PHASE OF AN
MJO PULSE ENTERING THE CONTINENT...THE RIDGE ALOFT IS TO BECOME
BETTER ORGANIZED WHILE BUILDING NORTH ACROSS WESTERN BRASIL TO
PERU. THE TUTT TO THE EAST...MEANWHILE...BECOMES BETTER ORGANIZED
WHILE AMPLIFYING INTO NORTHWEST BRASIL. AS THE RIDGE INTENSIFIES
AND THE TROUGH DEEPENS THIS WILL FAVOR A COLD ADVECTIVE PATTERN
ACROSS THE CENTRAL STATES OF BRASIL TO NORTHWEST SOUTH AMERICA.
THIS...IN-TURN...WILL LEAD TO DEEPER CONVECTIVE INSTABILITY AND
HIGHER PROBABILITY OF ORGANIZED HEAVY RAINFALL AMOUNTS. THROUGH
WEDNESDAY CONVECTION BETWEEN PARA AND TOCANTINS/GOIAS IN EASTERN
BRASIL IS EXPECTED TO INTENSIFY...WITH MAXIMA OF 35-70MM IN
ORGANIZED DEEP CONVECTION. THIS PERSIST WHILE BUILDING WESTWARD
ACROSS AMAZONAS IN BRASIL TO SOUTHERN COLOMBIA/NORTHERN PERU ON
THURSDAY TO FRIDAY. THROUGH THE WEEKEND CONDITIONS WILL GROW
HIGHLY FAVORABLE FOR CONVECTION TO ORGANIZED ACROSS WESTERN BRASIL
INTO A HEAVY RAINFALL PRODUCING MCS...WITH STORM TOTAL AMOUNTS IN
THIS AREA OF 200-300MM HIGHLY LIKELY.

DAVISON/GALVEZ...WPC (USA)
$$

708 
FXSA20 KWBC 011855
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
155 PM EST TUE MAR 01 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 04/17UTC: A LONG WAVE TROUGH IS
INITIALIZED OVER THE SOUTHERN CONE...WITH MID/UPPER LEVEL AXIS
EXTENDING TO THE NORTH-NORTHWEST FROM THE ANTARCTIC
PENINSULA...ACROSS TIERRA DEL FUEGO/PATAGONIA TO 27S 87W. UNDER
THE INFLUENCE OF A BROAD RIDGE TO THE WEST...THE TROUGH AMPLIFIES
ACROSS CENTRAL ARGENTINA/CHILE LATER TODAY. ON FRIDAY...WHILE
PRESSING AGAINST A RIDGE TO THE EAST...THE TROUGH WILL SPLIT IN
TWO. THE SOUTHERN HALF OF THE TROUGH IS TO RAPIDLY DAMPEN WHILE
SHEARING UNDER THE RIDGE...WHILE ITS NORTHERN SEGMENT EVOLVES INTO
A DEEP/CLOSED LOW TO THE EAST-SOUTHEAST OF URUGUAY. THIS IS TO
THEN MEANDER NEAR 37S 30W THROUGH THE WEEKEND TO EARLY NEXT WEEK.
AT LOW LEVELS...UNDER THE INFLUENCE OF A BUILDING POLAR RIDGE TO
THE SOUTH AND WEST...A 35-50KT SOUTHERLY PAMPERO LOW LEVEL JET
WILL DRIVE THE ASSOCIATED FRONT NORTH ACROSS CENTRAL TO NORTHERN
ARGENTINA LATER TODAY. THE FRONT CONTINUES FARTHER NORTH ACROSS
SOUTHERN BRASIL-PARAGUAY TO SOUTHEAST BOLIVIA ON FRIDAY...INTO
MATO GROSSO-ACRE/RONDONIA TO SOUTHERN PERU ON SATURDAY. LOSING
UPPER LEVEL SUPPORT...THE FRONT IS TO THEN FRONTOLIZE EARLY NEXT
WEEK.

AS IT SURGES ACROSS CENTRAL TO NORTHERN ARGENTINA THE FRONT WILL
TRIGGER ORGANIZED DEEP CONVECTION...WITH MAXIMA OF 35-70MM BETWEEN
CORDOBA AND ENTRE RIOS...WHILE TO THE NORTH THIS SURGES TO
75-150MM IN POTENTIALLY SEVERE CONVECTION. AS IT BUILDS ACROSS
PARAGUAY TO MATO GROSSO DO SUL ON FRIDAY THIS DECREASES TO
25-50MM. OVER CENTRAL BOLIVIA...AS ENHANCED BY THE LOW LEVEL
JET...CONDITIONS APPEAR FAVORABLE FOR AN ECHO TRAINING PATTERN TO
DEVELOP ALONG AND AHEAD OF THE SURFACE FRONT...WITH MAXIMA OF
75-150MM ON FRIDAY TO SATURDAY. ON SATURDAY FRONTAL CONVECTION
ACROSS CENTRAL BRASIL WEAKENS TO 2O-35MM...WHILE OVER SOUTHEAST
PARAGUAY/MISIONES IN ARGENTINA TO PARANA/SANTA CATARINA IN
SOUTHERN BRASIL THIS IS TO SUSTAIN MAXIMA OF 20-45MM. HIGHER
AMOUNTS ARE EXPECTED OVER SOUTHERN PERU WHERE THE LEADING
CONVECTION IS TO RESULT IN RAINFALL AMOUNTS OF 40-80MM ON SATURDAY
TO SUNDAY. ON SUNDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-35MM WHILE BUILDING NORTH ACROSS CENTRAL PERU AND AMAZONAS IN
BRASIL.

NORTH OVER THE CONTINENT...AT 250 HPA...A BROAD CELL OF THE
SUBTROPICAL RIDGE REMAINS WELL ENTRENCHED ACROSS PERU AND BRASIL.
AS THE RIDGE HOLDS OVER NORTHERN SOUTH AMERICA...SHORT WAVE
PERTURBATIONS ARE TO REVOLVE AROUND THIS AXIS...FIRST STREAMING
ACROSS NORTHERN CHILE/ARGENTINA...THEN LIFTING ACROSS THE WESTERN
ATLANTIC. UNDER THE INFLUENCE OF THESE VORTICES...ORGANIZED DEEP
CONVECTION IS FORECAST TO BUILD ACROSS BAHAIA-ESPIRITO SANTO IN
BRASIL...WITH MAXIMA IN THIS AREA INCREASING FROM 35-70MM EARLY IN
THE CYCLE TO 40-80MM ON FRIDAY. ON SATURDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 30-60MM. LATER DURING THE WEEKEND THE FOCUS OF
THE ORGANIZED CONVECTION SHIFTS TO TOCANTINS/GOIAS-PARA TO
AMAZONAS/ACRE IN WESTERN BRASIL...WITH RAINFALL AMOUNTS OF 20-35MM
AND MAXIMA OF 30-60MM. EARLY NEXT WEEK EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 25-50MM/DAY BETWEEN MATO GROSSO AND AMAZONAS
IN BRASIL.

DAVISON...WPC (USA)
$$

927 
FXSA20 KWBC 011648
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1147 AM EST TUE MAR 01 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM MAR 01/17 UTC: MID/UPPER LEVEL FLOW OVER
THE EASTERN SOUTH PACIFIC AND WESTERN SOUTH ATLANTIC REMAIN UNDER
THE DOMINANT INFLUENCE OF SLOW TO EVOLVE HIGHLY AMPLIFIED
SINUSOIDAL WAVE PATTERN...WITH A LONG WAVE RIDGE OVER THE
SOUTHEAST PACIFIC BOOKENDED BY TWO LONG WAVE TROUGHS. THE
EASTERNMOST EXTENDS OVER THE WESTERN ATLANTIC WITH AXIS BOTTOMING
OUT OVER MID SECTIONS OF SOUTH AMERICA...WHILE THE WESTERNMOST
EXTENDS OVER THE PACIFIC ALONG 100W/110W TO 35S. DURING THE NEXT
TWO DAYS THE PATTERN WILL SHIFT EASTWARD...WITH THE TROUGH OVER
THE ATLANTIC PULLING AWAY AS THE RIDGE RELOCATES TO THE SOUTHERN
CONE. THIS...IN-TURN...ALLOWS THE OTHER TROUGH TO PUSH FARTHER
EASTWARD ACROSS THE EASTERN PACIFIC TO THE SOUTHERN REGIONS OF
CHILE. IN THIS PROCESS THIS IS TO ESTABLISH A SUBTROPICAL
CONNECTION...SUSTAINING A MOIST ADVECTIVE PATTERN THAT WILL HELP
FEED SEVERAL DAYS OF ORGANIZED CONVECTION. LATER IN THE WEEK THE
TROUGH IS TO ALSO MEANDER EAST ACROSS THE SOUTHERN CONE/DRAKE
PASSAGE-ANTARCTIC PENINSULA TO THE WESTERN ATLANTIC.

AT LOW LEVELS THIS WILL SUSTAIN A DEEPENING FRONTAL TROUGH OVER
THE SOUTHEAST PACIFIC LATER TODAY...WITH OCCLUDING LOW TO
INTENSIFY AS IT NEARS THE DRAKE PASSAGE/TIERRA DEL FUEGO LATER ON
WEDNESDAY EVENING. STRONG BOUNDARY LAYER WINDS OF 35-50KT ARE TO
ACCOMPANY THIS SYSTEM AS IT MAKES LANDFALL OVER THE SOUTHERN
CONE...WITH THE STRONG WESTERLY WINDS TO PERSIST THROUGH SATURDAY
MORNING. THIS COMBINES WITH THE STEEP TERRAIN OVER SOUTHERN CHILE
TO FAVOR MOIST ADIABATIC LIFTING/CONVERGENCE ACROSS THE SOUTHERN
ANDES. THROUGH WEDNESDAY CONVECTION IN THIS AREA WILL INCREASE
FROM 20-35MM TO 30-60MM...WHILE ON THURSDAY AND FRIDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 20-35MM. OVER ARGENTINA...AS THE
SURFACE FRONT SURGES ACROSS PATAGONIA TO LA PAMPA ON THURSDAY THIS
WILL SUSTAIN A ROUND OF MODERATE/POTENTIALLY SEVERE CONVECTION.
UNDER FAVORABLE UPPER LEVEL JET DYNAMICS...THIS IS THEN EXPECTED
TO TRIGGER HEAVY RAINFALL PRODUCING MCS ACROSS CENTRAL
ARGENTINA-RIO DE LA PLATA BASIN ON BOTH FRIDAY AND SATURDAY...WITH
STORM TOTAL AMOUNTS IN THIS AREA LIKELY TO EXCEED 200MM. 

FARTHER NORTH OVER THE CONTINENT...THE UPPER LEVEL FLOW SPLITS
BETWEEN AN ILL ORGANIZED CELL OF THE SUBTROPICAL RIDGE EXTENDING
WESTWARD ACROSS SOUTHERN BRASIL/PARAGUAY-NORTHERN
ARGENTINA/BOLIVIA TO THE EASTERN PACIFIC...AND A TUTT EXTENDING
ALONG A CLOSED LOW OVER BAHIA IN BRASIL TO SOUTHERN AMAZONAS/ACRE.
DURING THE NEXT TWO DAYS...UNDER THE INFLUENCE OF AN EASTWARD
PROPAGATING ATMOSPHERIC KELVIN WAVE AND THE DIVERGENT PHASE OF AN
MJO PULSE ENTERING THE CONTINENT...THE RIDGE ALOFT IS TO BECOME
BETTER ORGANIZED WHILE BUILDING NORTH ACROSS WESTERN BRASIL TO
PERU. THE TUTT TO THE EAST...MEANWHILE...BECOMES BETTER ORGANIZED
WHILE AMPLIFYING INTO NORTHWEST BRASIL. AS THE RIDGE INTENSIFIES
AND THE TROUGH DEEPENS THIS WILL FAVOR A COLD ADVECTIVE PATTERN
ACROSS THE CENTRAL STATES OF BRASIL TO NORTHWEST SOUTH AMERICA.
THIS...IN-TURN...WILL LEAD TO DEEPER CONVECTIVE INSTABILITY AND
HIGHER PROBABILITY OF ORGANIZED HEAVY RAINFALL AMOUNTS. THROUGH
WEDNESDAY CONVECTION BETWEEN PARA AND TOCANTINS/GOIAS IN EASTERN
BRASIL IS EXPECTED TO INTENSIFY...WITH MAXIMA OF 35-70MM IN
ORGANIZED DEEP CONVECTION. THIS PERSIST WHILE BUILDING WESTWARD
ACROSS AMAZONAS IN BRASIL TO SOUTHERN COLOMBIA/NORTHERN PERU ON
THURSDAY TO FRIDAY. THROUGH THE WEEKEND CONDITIONS WILL GROW
HIGHLY FAVORABLE FOR CONVECTION TO ORGANIZED ACROSS WESTERN BRASIL
INTO A HEAVY RAINFALL PRODUCING MCS...WITH STORM TOTAL AMOUNTS IN
THIS AREA OF 200-300MM HIGHLY LIKELY.

DAVISON/GALVEZ...WPC (USA)
$$

319 
FXSA20 KWBC 281651
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1150 AM EST MON FEB 28 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 28/17 UTC: THE LARGE SCALE PATTERN
ANALYSIS SHOWS THE UPPER DIVERGENT (WET PHASE) OF THE MJO
APPROACHING THE AMERICAS. THIS IS FORECAST TO ENTER THE CONTINENT
BY MID-WEEK...TO PEAK BETWEEN MARCH 09 AND 19. AHEAD OF THE
PULSE...AN UPPER DIVERGENT KELVIN WAVE IS FORECAST TO ENTER SOUTH
AMERICA ON WEDNESDAY AND EXIT DURING THE WEEKEND...TO PROVIDE
ENHANCEMENT TO THE BOLIVIAN HIGH/SUBTROPICAL UPPER RIDGE. THIS
WILL FAVOR AN INCREASE IN THE COVERAGE AND INTENSITY OF AREAS OF
DEEP CONVECTION IN TROPICAL SOUTH AMERICA BY THE END OF THE
WORKWEEK.

IN THE SOUTHERN STREAM...A SHORT WAVE TROUGH IN THE WESTERLIES IS
ENTERING THE SOUTHERN CONE ON MONDAY. THIS IS ACCOMPANIED BY A
TRAIN OF FRONTS THAT WILL SUSTAIN MODERATE PRECIPITATION IN
SOUTHERN CHILE ON MONDAY EVENING THROUGH EARLY TUESDAY...AS THE
FRONTS MAKES LANDFALL IT WILL BE ACCOMPANIED BY A SUBTROPICAL
MOIST PLUME OF 30-35MM OF PRECIPITABLE WATER...AND AS IT COINCIDES
WITH THE DIVERGENT EXIT OF AN UPPER JET THE MAXIMA WILL INCREASE
TO 20-45MM NEAR AYSEN CHILE WHILE ON WESTERN PORTIONS OF
MAGALLANES THE MAXIMA PEAKS AT 20-30MMS THROUGH TUESDAY MORNING.
ON WEDNESDAY...A LONGER AMPLITUDE TROUGH ENTERS THE SOUTHERN CONE
ACCOMPANIED BY A ROBUST EXTRATROPICAL CYCLONE. THIS WILL ONCE
AGAIN ENHANCE MOISTURE CONVERGENCE ACROSS MAGALLANES TO FAVOR
MAXIMA OF 25-50MM ON THE WINDWARD SIDE OF THE SOUTHERN ANDES WHILE
NEAR AYSEN THE MAXIMA PEAKS AT 15-20MM. AS THE FRONT PROGRESSES
NORTHWARD ON THURSDAY...IT WILL SUSTAIN LESSER AMOUNTS IN LOS
LAGOS/ISLA CHILOE. IN AYSEN AND MAGALLANES...HOWEVER...COLD AIR
CUMULUS CONVECTION WILL CONTINUE TO SUSTAIN SCATTERED
PRECIPITATION.

IN CENTRAL PORTIONS OF THE CONTINENT...A SURFACE FRONT STALLS
ACROSS RIO GRANDE DO SUL INTO NORTHWEST ARGENTINA. THIS BOUNDARY
WILL BE THE FOCUS FOR  ENHANCED MOISTURE CONVERGENCE DURING THE
NEXT 72-84 HRS...AND WILL FAVOR MODERATE TO LOCALLY HEAVY
PRECIPITATION AS IT INTERACTS WITH THE DIVERGENT ENTRANCE OF AN
UPPER JET ON MONDAY AND TUESDAY. THROUGH EARLY TUESDAY...EXPECT
MAXIMA OF 40-80MM WITH A RISK FOR MCS FORMATION. ON TUESDAY
THROUGH WEDNESDAY...EXPECT MAXIMA OF 30-60MM IN
ARGENTINA...SOUTHEAST PARAGUAY AND WESTERN RIO GRANDE DO SUL. IN
SANTA CATARINA EXPECT MAXIMA OF 20-35MM. ON WEDNESDAY...EXPECT
MAXIMA OF 20-35MM IN SANTA CATARINA AND PARANA. IN PARAGUAY AND
NORTHERN ARGENTINA EXPECT MAXIMA OF 15-20MM.

IN TROPICAL PORTIONS OF THE CONTINENT AND AT UPPER LEVELS...THE
BOLIVIAN HIGH/SUBTROPICAL UPPER RIDGE CENTERS OVER
PARAGUAY/SOUTHERN BOLIVIA. ALTHOUGH THE RIDGE IS NOT AS INTENSE AS
IT SHOULD BE FOR THE TIME OF THE YEAR...THE ACCELERATION OF THE
EASTERLIES OVER NORTHWEST PERU AND ECUADOR WILL SUSTAIN ENHANCED
UPPER DIVERGENCE IN THE REGION...FORECAST TO INCREASE THROUGH THE
WORKWEEK. ON MONDAY...EXPECT THE HEAVIEST CONVECTION IN WESTERN
BRASIL/SOUTHERN COLOMBIA TO SUSTAIN MAXIMA OF 35-70MM...STIMULATED
BY A SURFACE TROUGH. ON TUESDAY...EXPECT MAXIMA OF 30-60MM IN
NORTHWEST BRASIL AND MAXIMA OF 20-35MM IN RONDONIA/MATO GROSSO. ON
WEDNESDAY...EXPECT MAXIMA OF 20-45MM IN NORTHERN PERU AND
NORTHWEST BRASIL. ALSO IN ASSOCIATION WITH THE BOLIVIAN
HIGH...EXPECT DIURNAL CONVECTION ON A DAILY BASIS ALONG THE ANDES
OF PERU AND BOLIVIA. THIS WILL FAVOR MAXIMA IN THE 10-20MM/DAY
RANGE ON A DAILY BASIS IN THE FORM OF AFTERNOON CONVECTION ON THE
CORDILLERA...AND NOCTURNAL CONVECTION ALONG THE EASTERN SLOPES OF
THE ANDES. HEAVY EVENING/NOCTURNAL CONVECTION IS ALSO EXPECTED IN
ECUADOR ON A DAILY BASIS...FROM MONDAY THROUGH EARLY THURSDAY.
THIS IS IN ASSOCIATION WITH ENHANCED ONSHORE FLOW AND A PEAK IN
SEA SURFACE TEMPERATURES. ON MONDAY...EXPECT MAXIMA OF
50-100MM/DAY IN THE GUAYAQUIL REGION...AND MAXIMA OF 30-60MM IN
NORTHERN ECUADOR. ON TUESDAY EXPECT MAXIMA OF 35-70MM ALONG THE
ENTIRE PACIFIC BASIN OF ECUADOR. ON WEDNESDAY...EXPECT MAXIMA OF
30-60MM. AMOUNTS DECREASE THEREAFTER.

TO THE EAST...A POTENT TROUGH EXTENDS ACROSS SOUTHERN BAHIA INTO
GOIAS ON MONDAY. THIS TROUGH IS ACCOMPANIED BY UPPER JETS ALONG
ITS PERIPHERY...AND WILL BE SUFFICIENTLY STRONG TO SUSTAIN A
DYNAMICAL ENHANCEMENT OF CONVECTION. HOWEVER...LIMITED AMOUNTS OF
AVAILABLE MOISTURE WILL DOMINATE...TO LIMIT RAINFALL
ACCUMULATIONS. ON MONDAY...EXPECT MAXIMA OF 15-25MM IN ESPIRITO
SANTO AND MINAS GERAIS...AND MAXIMA OF 20-35MM IN MARANHAO AND
PARA IN BRASIL. ON TUESDAY...EXPECT MAXIMA OF 15-20MM IN MINAS
GERAIS WITH A SIRK FOR SEVERE CONVECTION. IN PIAUI/MARANHAO INTO
THE AMAZON DELTA EXPECT MAXIMA OF 20-35MM. ON WEDNESDAY...EXPECT
AN MAXIMA OF 20-45MM IN GOIAS/TOCANTINS INTO SOUTHERN PARA.

DAVISON/GALVEZ...WPC (USA)
$$

361 
FXSA20 KWBC 241624
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1124 AM EST THU FEB 24 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON MONDAY FEB 28

FORECAST DISCUSSION FROM FEB 24/17 UTC: AT MID/UPPER LEVELS...A
SHORT WAVE TROUGH ON THE NORTHERN STREAM IS INITIALIZED OVER THE
FAR EASTERN PACIFIC OFF THE SOUTH-CENTRAL COAST OF CHILE. DRAWN BY
A SUBTROPICAL JET MAXIMA TO THE NORTH THIS WILL SPILL ACROSS THE
CENTRAL ANDES INTO ARGENTINA EARLY IN THE CYCLE. AS IT EMERGES
ACROSS LA PAMPA/BUENOS AIRES PROVINCE ON FRIDAY MORNING THE TROUGH
IS FORECAST TO BRIEFLY DEEPEN WHILE CENTERING ON A CLOSED LOW TO
THE SOUTH. THIS...HOWEVER...WILL BE SHORT LIVED...TO ONCE AGAIN
WEAKEN TO AN OPEN TROUGH AS IT MIGRATES FARTHER EAST ACROSS THE
WESTERN SOUTH ATLANTIC. AT LOW LEVELS...UNDER FAVORABLE JET
DYNAMICS...THE MID LEVEL TROUGH WILL SUSTAIN AN OCCLUDING LOW JUST
SOUTH OF THE SIERRA DE LA VENTANA/TANDIL. THE DEEPENING LOW WILL
THEN DRIVE THE ASSOCIATED FRONT NORTH ACROSS THE BUENOS AIRES
PROVINCE-CORDOBA IN ARGENTINA...WITH A SEVERE WEATHER INDUCING
PREFRONTAL SQUALL LINE FORMING ACROSS URUGUAY TO NORTHERN
ARGENTINA. THIS IS TO ALSO TRIGGER MODERATE TO HEAVY RAINFALL
AMOUNTS...WITH MAXIMA OF 25-50MM. ON FRIDAY...AS THE FRONT STALLS
TO THE NORTH...EXPECTING AN ADDITIONAL 20-35MM ACROSS SOUTHERN
BRASIL-CORRIENTES/ENTRE RIOS IN ARGENTINA AND NORTHERN URUGUAY.

FARTHER UPSTREAM OVER THE PACIFIC...THE GLOBAL MODELS CONTINUE TO
FORECAST A LONG WAVE RIDGE TO GRADUALLY BUILD SOUTH ALONG
120W/130W TO THE POLAR ICECAP. THIS REACHES MAXIMUM AMPLITUDE
LATER ON FRIDAY. AS THE RIDGE BUILDS...IT IS TO INDUCE THE
NORTHWARD AMPLIFICATION OF OF SHORT WAVE PERTURBATIONS STREAMING
ACROSS THE SOUTHEAST PACIFIC. THROUGH SATURDAY THIS WILL THEN
EVOLVE INTO A HIGH AMPLITUDE LONG WAVE TROUGH THAT IS TO EXTEND
FROM THE BELLINGSHAUSEN SEA NORTHWARD TO THE SOUTHERN/CENTRAL
COAST OF CHILE. THE LONG WAVE TROUGH IS TO THEN MEANDER EAST
ACROSS THE SOUTHERN CONE INTO CENTRAL ARGENTINA ON SUNDAY. AS IT
MOVES ACROSS THE SOUTHERN CONE...THE LONG WAVE TROUGH WILL THEN
PRESS AGAINST A BROAD CELL OF THE SUBTROPICAL RIDGE TO THE
NORTH...TIGHTENING THE UPPER GRADIENT AND FAVORING THE
INTENSIFICATION OF THE SUBTROPICAL JET ON SUNDAY. THE STRONG FLOW
ACROSS THE CENTRAL ANDES WILL LEAD TO A HIGHER INCIDENCE OF LEE
SIDE PERTURBATIONS ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA
BASIN...WHILE ALSO FAVORING AN UPPER DIVERGENT PATTERN THAT WILL
VENT ORGANIZED DEEP CONVECTION.

AT LOW LEVELS THE DEEPENING POLAR TROUGH WILL SUSTAIN A BROAD
POLAR TROUGH ACROSS THE SOUTHEAST PACIFIC LATER ON FRIDAY. THIS
WILL BE ACCOMPANIED BY STRONG BOUNDARY LAYER WINDS OVER
CHILE/ARGENTINA TO THE SOUTH OF 40S. THE STRONGER WINDS WILL
ENHANCE MOISTURE TRANSPORT/MOIST ADIABATIC LIFTING ON THE WINDWARD
SIDE OF THE SOUTHERN ANDES...RESULTING IN SEVERAL DAYS OF MODERATE
TO HEAVY RAINFALL AMOUNTS. ON FRIDAY AND SATURDAY THIS WILL
SUSTAIN RAINFALL MAXIMA OF AROUND 25-50MM/DAY. ON SUNDAY...AS A
DEEP OCCLUDED LOW LIFTS ACROSS THE SOUTHERN CONE...THIS CHANGES TO
SOLID PRECIPITATION ACROSS THE SOUTHERN ANDES...WITH SNOWFALL
AMOUNTS OF 10-15CM VERY LIKELY. ACROSS ARGENTINA...THE EVOLVING
FRONTAL TROUGH WILL DRIVE A PROGRESSIVE FRONT ACROSS PATAGONIA TO
LA PAMPA ON SATURDAY...WHILE A SECONDARY BOUNDARY IS TO CLOSELY
FOLLOW ON SUNDAY. AHEAD OF THIS SYSTEM...IN RESPONSE TO THE
INTENSIFYING SUBTROPICAL JET...THE THERMAL TROUGH TO THE NORTHWEST
IS FORECAST TO DEEPEN. THIS IN TURN WILL SUSTAIN A NORTHERLY LOW
LEVEL JET ACROSS PARAGUAY TO NORTHERN ARGENTINA. THE ENHANCED
VERTICAL WIND SHEAR AND ENSUING HELICITY WILL LIKELY RESULT IN
PERIODS OF ORGANIZED HEAVY DEEP CONVECTION IN THE FORM OF MESO
SCALE CONVECTIVE SYSTEMS ACROSS THE RIO DE LA PLATA BASIN TO
CENTRAL ARGENTINA...WITH STORM TOTAL AMOUNTS ON SATURDAY TO SUNDAY
OF 125-200MM. ON SUNDAY THERE IS ALSO AN EHANCED RISK OF SEVERE
THUNDERSTORMS.

AS PREVIOUSLY MENTIONED...BROAD CELL OF THE SUBTROPICAL RIDGE LIES
TO THE NORTH...WITH AXIS SPANNING BETWEEN NORTHERN
ARGENTINA/SOUTHERN BRASIL AND BOLIVIA/PERU TO THE CENTRAL STATES
OF BRASIL. THIS WILL PERSIST DURING THE NEXT FEW DAYS...MEANWHILE
CENTERING ON A 250 HPA HIGH THAT MEANDERS BETWEEN BOLIVIA AND
NORTHWEST ARGENTINA. AS THE RIDGE HOLDS...AN UPPER TROUGH
AMPLIFIES ALONG THE EASTERN TO NORTHERN FRINGES OF THIS
RIDGE...WITH AXIS TO TRAVERSE THE BRAZILIAN STATES OF MINAS
GERAIS/BAHIA TO AMAZONAS TO THE NORTHWEST. THE COLD CORE TROUGH
ALOFT WILL ENHANCE CONVECTIVE INSTABILITY ACROSS TROPICAL SOUTH
AMERICA AS DEPICTED BY THE GFS AND ECMWF GDI FORECAST FOR THE
SHORT THROUGH MEDIUM RANGE PERIODS. INITIALLY THE MOST ACTIVE IS
EXPECTED ACROSS CENTRAL BRASIL. THROUGH SATURDAY THIS WILL SHIFT
TO THE NORTH-NORTHWEST ACROSS AMAZONAS TO NORTHERN PERU/EASTERN
ECUADOR-SOUTHERN COLOMBIA...WITH ENVIRONMENTAL CONDITIONS IN THIS
AREA TO RAPIDLY BECOME FAVORABLE FOR A HEAVY RAINFALL PRODUCING
MESO SCALE CONVECTIVE SYSTEM. THE CONDITIONS WILL REMAIN HIGHLY
FAVORABLE THROUGH SUNDAY MORNING...THEN A MORE SEASONAL PATTERN IS
LIKELY ACROSS TROPICAL SOUTH AMERICA.

DAVISON...WPC (USA)
$$

728 
FXSA20 KWBC 231707
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1207 PM EST WED FEB 23 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 22/17 UTC: A SPLIT FLOW PATTERN
PERSISTS OVER THE SOUTHERN CONE OF SOUTH AMERICA...WITH THE FLOW
DIVIDING BETWEEN A RIDGE ON THE SOUTHERN STREAM AND A SHORT WAVE
TROUGH TO THE NORTH. THE RIDGE ORIGINATES OVER PATAGONIA IN
ARGENTINA/SOUTHERN REGIONS OF CHILE...WITH AXIS SOUTH ALONG 75W TO
THE BELLINGSHAUSEN SEA. THE SHORT WAVE TROUGH TO THE
NORTH...MEANWHILE...EXTENDS OFF THE CENTRAL/NORTHERN COAST OF
CHILE WHILE CENTERING ON A CLOSED MID LEVEL LOW JUST WEST OF
CONCEPCION CHILE. THROUGH THE DAY...UNDER PRESSURE FROM A DIGGING
TROUGH TO THE WEST...THE RIDGE WILL RELOCATE ACROSS THE SOUTHERN
CONE TO THE WESTERN SOUTH ATLANTIC...WHERE IT WILL REMAIN THROUGH
THE WEEKEND TO EARLY NEXT WEEK. THE LOW TO THE NORTH WILL WEAKEN
TO AN OPEN TROUGH LATER THIS EVENING...TO THEN STREAM ACROSS
NORTHERN PATAGONIA/LA PAMPA TO CENTRAL ARGENTINA EARLY ON THURSDAY
MORNING. THE SHORT WAVE TROUGH BRIEFLY STRENGTHENS OFF THE COAST
OF BUENOS AIRES LATER ON THURSDAY...BUT THEN WEAKENS TO AN OPEN
TROUGH WHILE SLOWLY PULLING TO THE EAST-SOUTHEAST.

AT LOW LEVELS...AS THE MID LEVEL TROUGH SPILLS ACROSS THE CENTRAL
ANDES INTO ARGENTINA...IT WILL INTERACT WITH A MEANDERING FRONT.
LATER TODAY THIS WILL SUSTAIN CYCLOGENESIS OVER THE BUENOS AIRES
PROVINCE/LA PAMPA. ON THURSDAY THE LOW WILL DEEPEN AS IT MOVES
SOUTH OF THE BUENOS AIRES PROVINCE TO THE WESTERN ATLANTIC. AS IT
DEEPENS...THIS WILL DRIVE THE SURFACE FRONT NORTH ACROSS CENTRAL
ARGENTINA...TO POTENTIALLY TRIGGER A PREFRONTAL SQUALL LINE ACROSS
URUGUAY-ENTRE RIOS TO CORRIENTES IN NORTHERN ARGENTINA. THE FRONT
THEN STALLS OVER SOUTHERN BRASIL-NORTHERN ARGENTINA LATER IN THE
WEEK. MEANWHILE...UNDER FAVORABLE JET DYNAMICS...THERE IS AN
ENHANCED RISK OF SEVERE THUNDERSTORMS OVER CENTRAL ARGENTINA EARLY
IN THE CYCLE...AND ENTRE RIOS/CORDOBA ON THURSDAY...WITH RAINFALL
MAXIMA DURING THIS PERIOD PEAKING AT 25-50MM. LATER IN THE
WEEK...AS THE FRONT STALLS OVER SOUTHERN BRASIL-CORRIENTES/ENTRE
RIOS...THE DAILY MAXIMA DROPS TO 20-35MM.

UPSTREAM OVER THE PACIFIC...A LONG WAVE RIDGE IS EXPECTED TO
GRADUALLY BUILD SOUTH ALONG 110W/120W TO THE POLAR ICECAP...WITH
AXIS REACHING MAXIMUM AMPLITUDE LATER ON FRIDAY. AS THE RIDGE
BUILDS TO THE WEST...SHORT WAVE TROUGHS ARE TO LIFT ACROSS THE
SOUTHEAST PACIFIC. INFLOW OF SHORT WAVE ENERGY WILL HELP SUSTAIN
THE NORTHWARD AMPLIFICATION OF A LONG WAVE TROUGH ACROSS THE
EASTERN PACIFIC THROUGH THE END OF THE WEEK. DISPLACED BY THE
BUILDING RIDGE TO THE WEST...THE TROUGH WILL RELOCATE ACROSS THE
SOUTHERN CONE TO THE WESTERN ATLANTIC DURING THE WEEKEND...AND
EARLY NEXT WEEK IT WILL EVOLVE INTO A BROAD AS IT MEANDERS OFF THE
COAST OF ARGENTINA.  AT LOW LEVELS...THIS WILL SUSTAIN A BROAD
OVER THE SOUTHEAST PACIFIC LATER TODAY. THIS TENDS TO DEEPEN WHILE
MEANDERING EAST ACROSS THE ANTARCTIC PENINSULA TO THE SOUTHERN
REGIONS OF CHILE/PATAGONIA-LA PAMPA IN ARGENTINA DURING THE
WEEKEND. AS THE TROUGH DEEPENS...POLAR FRONTS ARE TO REVOLVE
AROUND THIS AXIS...FOCUSING MOISTURE ACROSS SOUTHERN CHILE AS THEY
STREAM ACROSS THE SOUTHERN CONE. INITIALLY THESE CONFINE TO
PATAGONIA IN ARGENTINA...BUT LATER DURING THE WEEKEND THE MODELS
AGREE ON FRONTAL SYSTEM SURGING ACROSS CENTRAL ARGENTINA/RIO DE LA
PLATA AS A RIDGE BUILDS TO THE WEST. IN RESPONSE...ACTIVITY ACROSS
SOUTHERN CHILE WILL GRADUALLY BECOME MORE ACTIVE AS A DEEPER PLUME
OF SUBTROPICAL MOISTURE LIFTS ACROSS THE SOUTHEAST PACIFIC ON
FRIDAY. THIS WILL FAVOR MODERATE RAINFALL AMOUNTS WITH
ACCUMULATION OF 25-50MM/DAY THROUGH THE WEEKEND. OVER
ARGENTINA...UNDER THE DEEPENING INFLUENCE OF A THERMAL TROUGH TO
THE NORTH...A NORTHERLY LOW LEVEL JET IS EXPECTED ACROSS EASTERN
BOLIVIA/CHACO PARAGUAYO LATER ON FRIDAY/EARLY ON SATURDAY. THIS
WILL ENHANCE MOISTURE TRANSPORT/CONVERGENCE ACROSS CENTRAL
ARGENTINA. IN THIS AREA EXPECTING RAINFALL MAXIMA OF 25-50MM ON
FRIDAY...WHILE ON SATURDAY THE ENVIRONMENTAL CONDITIONS BECOME
FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO DEVELOP ALONG THIS
BOUNDARY.

AT 250 HPA...NORTH OVER THE CONTINENT...THE SUBTROPICAL RIDGE
SPANS FROM SOUTHERN BRASIL/PARAGUAY TO NORTHERN BOLIVIA/SOUTHERN
PERU. THE RIDGE PERSISTS OVER THE NEXT FEW DAYS...MEANWHILE
FAVORING THE WESTWARD AMPLIFICATION OF AN UPPER LEVEL TROUGH
ACROSS NORTHEAST TO WESTERN BRASIL. AS THE TROUGH AMPLIFIES ACROSS
TROPICAL SOUTH AMERICA...WHILE PRESSING AGAINST THE RIDGE TO THE
SOUTH...THE UPPER LEVEL WINDS INTENSIFY FROM 25-35KT EARLY IN THE
CYCLE TO 40-45KT.THIS WILL FAVOR AN UPPER DIVERGENT PATTERN THAT
WILL VENT DEEP/ORGANIZED CONVECTION ACROSS BRASIL. IN RESPONSE TO
THE UPPER LEVEL EVOLUTION ACROSS BRASIL...CONVECTION ACROSS
CENTRAL AND WESTERN BRASIL IS TO GRADUALLY INTENSIFY. INITIALLY
MOST ACTIVE IS EXPECTED ACROSS EQUATORIAL SOUTH
AMERICA/PARA-AMAZONAS IN BRASIL...WITH MAXIMA INCREASING TO
75-125MM THROUGH THE DAY INTO THURSDAY MORNING...THEN WEAKEN TO
20-35MM ON FRIDAY. AS ACTIVITY TO THE NORTH WEAKENS...CONVECTION
ACROSS CENTRAL BRASIL WILL SURGE...WITH MAXIMA OF 30-50MM ON
THURSDAY TO FRIDAY. THROUGH THE END OF THE WEEK THE FOCUS OF THE
HEAVIEST CONVECTION SHIFTS TO NORTHERN PERU-EASTERN ECUADOR AND
SOUTHERN COLOMBIA. ON FRIDAY EXPECTING ACCUMULATION OF
35-70MM...INCREASING TO 100-175MM ON SATURDAY.

DAVISON...WPC (USA)
$$

158 
FXSA20 KWBC 221640
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1140 AM EST TUE FEB 22 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 22/17 UTC: IN A SPLIT FLOW
PATTERN...THE POLAR FLOW OVER THE CONTINENT DIVIDES BETWEEN A
RIDGE ON THE SOUTHERN STREAM OVER SOUTHERN CHILE/PATAGONIA IN
ARGENTINA AND A SHORT WAVE TROUGH TO THE NORTH. THE LATTER CENTERS
ON A CLOSED LOW JUST WEST OF CONCEPCION IN CENTRAL CHILE. THIS
PATTERN IS TO PERSIST THROUGH WEDNESDAY MORNING...THEN RAPIDLY
EVOLVE AS AS ANOTHER TROUGH AMPLIFIES ACROSS THE SOUTHEAST
PACIFIC. UNDER PRESSURE...THE RIDGE IS TO NEARLY COLLAPSE WHILE
RELOCATING ACROSS THE SOUTHERN CONE TO THE WESTERN ATLANTIC EARLY
ON THURSDAY MORNING...WHILE THE SHORT WAVE TROUGH/CLOSED LOW TO
THE NORTH SPILLS ACROSS THE CENTRAL ANDES OF CHILE INTO CENTRAL
PROVINCES IN ARGENTINA. ALTHOUGH INITIALLY IT TENDS TO
WEAKEN...THE SHORT WAVE VORTEX THEN STRENGTHENS AS IT MOVES JUST
NORTH OF THE MALVINAS/FALKLAND ISLANDS ON FRIDAY.

AT LOW LEVELS...IN THE DIVERGENT RIGHT EXIT REGION OF AN UPPER
LEVEL JET MAXIMA....A DEEPENING FRONTAL LOW FORMS OVER LA PAMPA IN
ARGENTINA ON WEDNESDAY. THROUGH THURSDAY THE LOW DEEPENS/RAPIDLY
OCCLUDE...IN THIS PROCESS FAVORING A SOUTHERLY LOW LEVEL JET THAT
DRIVES THE FRONT NORTH ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA
BASIN. THE SURGING BOUNDARY IS LIKELY TO TRIGGER A PREFRONTAL
SQUALL LINE THAT PROPAGATES ACROSS URUGUAY TO NORTHERN ARGENTINA
LATER ON THURSDAY. ON FRIDAY THE FRONT IS TO BRIEFLY STALL OVER
SOUTHERN BRASIL-NORTHERN ARGENTINA WHILE ALIGNING ALONG 30S. BUT
EARLY ON SATURDAY...DRIVEN BY A NORTHERLY LOW LEVEL JET...IT
RETROGRESSES AS A WARM FRONT. THE INFLOW OF MID LEVEL ENERGY WILL
LIKELY FAVOR SCATTERED DEEP CONVECTION ALONG THE LEE OF THE
CENTRAL ANDES OVER ARGENTINA...WITH MAXIMA OF 20-45MM. ON
WEDNESDAY...AS THE CONVECTION SPREADS EAST AND NORTH ACROSS
CENTRAL ARGENTINA...THIS IS LIKELY TO TRIGGER SEVERE
THUNDERSTORMS. ON THURSDAY THE ACTIVITY SURGES ACROSS
URUGUAY-CORDOBA TO NORTHERN PROVINCES IN ARGENTINA...WHERE IT IS
TO ALSO TRIGGER MODERATE TO HEAVY RAINFALL AMOUNTS.

AT 250 HPA...NORTH OVER THE CONTINENT...THE SUBTROPICAL RIDGE
STRETCHES BETWEEN SOUTHERN BRASIL/PARAGUAY AND PERU...WHILE ILL
ORGANIZED TUTT CONFINE TO SOUTHEAST AND NORTHEASTERN BRASIL. AS
THE AFOREMENTIONED SHORT WAVE TROUGH STREAMS ACROSS ARGENTINA...IT
IS TO PRESS AGAINST THE RIDGE TO THE NORTH. THE GRADIENT TIGHTENS
TO THE NORTH...FAVORING A 35-45KT WIND MAXIMA ACROSS SAO PAULO/RIO
DE JANEIRO TO MATO GROSSO EARLY ON THURSDAY MORNING. THROUGH THE
END OF THE WEEK THE JET MAXIMA INTENSIFIES ACROSS BRASIL TO
AMAZONAS/ACRE AND THE CENTRAL/NORTHERN JUNGLE OF PERU.
MEANWHILE...THIS WILL FAVOR COLD AIR ADVECTION ACROSS CENTRAL
BRASIL THAT IN COMBINATION WITH RADIATIONAL HEATING IT WILL
ENHANCE  CONVECTIVE INSTABILITY ACROSS THE CENTRAL AND WESTERN
STATES OF BRASIL AND PERU. IN RESPONSE TO UPPER LEVEL
EVOLUTION...CONVECTION ACROSS CENTRAL AND WESTERN BRASIL IS TO
GRADUALLY INTENSIFY. INITIALLY MOST ACTIVE IS EXPECTED ACROSS
EQUATORIAL SOUTH AMERICA/PARA-AMAZONAS IN BRASIL...WITH MAXIMA OF
35-70MM IN SCATTERED DEEP CONVECTION. ON WEDNESDAY TO THURSDAY
ACTIVITY INTENSIFIES AND BECOMES BETTER ORGANIZED AS AN MCS FORMS
TO THE NORTH...WITH THE MAXIMA INCREASING TO 75-125MM. ON THURSDAY
THIS WILL RAPIDLY WEAKEN AS CONVECTION ACROSS CENTRAL
BRASIL-NORTHERN BOLIVIA DEEPENS...WITH MAXIMA IN THIS AREA PEAKING
AT 35-70MM. DRIVEN BY THE UPPER JET MAXIMA...THE FOCUS OF THE
ORGANIZED DEEP CONVECTION THEN SHIFTS TO CENTRAL/NORTHERN
PERU-EASTERN ECUADOR LATER ON FRIDAY.

DAVISON...WPC (USA)
$$

386 
FXSA20 KWBC 181714
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1213 PM EST FRI FEB 18 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON 22 FEB.

FORECAST DISCUSSION FROM FEB 18/17 UTC: AT MID/UPPER LEVELS...A
LONG WAVE RIDGE IS TO BUILD SOUTH ACROSS THE EASTERN PACIFIC TO
THE BELLINGSHAUSEN SEA EARLY IN THE CYCLE. AS THE RIDGE BUILDS...A
SHORT WAVE TROUGH ON THE NORTHERN STREAM IS FORECAST TO DEEPEN AS
IT NEARS THE SOUTHERN REGIONS OF CHILE EARLY ON SATURDAY MORNING.
THROUGH EARLY NEXT WEEK THE RIDGE WILL THEN BUILD EAST ACROSS
SOUTHERN CHILE/PATAGONIA...IN THIS PROCESS UNDERCUTTING THE
TROUGH/LOW TO THE NORTH WHILE FAVORING A SPLIT FLOW PATTERN...WITH
THE LOW/SHORT WAVE TROUGH STALLING OFF THE CENTRAL COAST OF CHILE
WHILE THE RIDGE SETTLES TO THE SOUTH. AT 250 HPA...A SUBTROPICAL
JET MAXIMA WILL ROUND THE BASE OF THE UPPER LEVEL TROUGH...TO
EXTEND INLAND ALONG 30S WHILE EXITING OVER CORDOBA IN ARGENTINA.
DIVERGENCE ON ITS RIGHT EXIT REGION WILL VENT DEEP CONVECTION
ACROSS CENTRAL ARGENTINA AND WILL LIKELY FAVOR SEVERE CONVECTION.

AT LOW LEVELS...THIS WILL SUSTAIN A BUILDING RIDGE TO THE WEST AND
A FRONTAL TROUGH ACROSS THE DRAKE PASSAGE TO THE SOUTHERN CONE.
THE TROUGH WILL FOCUS DEEP SUBTROPICAL MOISTURE ACROSS EXTREME
SOUTHERN PORTIONS OF CHILE EARLY IN THE CYCLE...RESULTING IN AREAS
OF MODERATE TO HEAVY RAINFALL AMOUNTS BETWEEN ISLA DE CHILOE AND
PUNTA ARENAS TO THE SOUTH...WITH MAXIMA OF 30-60MM. ON
SATURDAY...AS THE LOW LEVEL RIDGE BUILDS ACROSS TIERRA DEL FUEGO
AND THE FRONTAL LOW MEANDERS NORTH OVER PATAGONIA...IT WILL THEN
SUSTAIN A MOIST SOUTHEASTERLY FLOW THAT DRIVES THE ASSOCIATED
FRONT FARTHER NORTH ACROSS SOUTHERN ARGENTINA TO CENTRAL CHILE.
THROUGH SUNDAY THE RIDGE EXPANDS ACROSS PATAGONIA...DISPLACING THE
FRONT FARTHER NORTH ACROSS LA PAMPA TO THE BUENOS AIRES
PROVINCE/CENTRAL ARGENTINA. AS IT PUSHES NORTH AND THE RIDGE
BUILDS TO THE SOUTH THE FOCUS OF THE LOW LEVEL MOISTURE
CONVERGENCE SHIFTS NORTH ALONG THE LEE OF THE CENTRAL ANDES
BETWEEN MENDOZA AND NEUQUEN/RIO NEGRO. ACROSS PATAGONIA THIS WILL
SUSTAIN MODERATE CONVECTION ON SATURDAY WITH MAXIMA OF 20-35MM. ON
SUNDAY-MONDAY THIS INCREASES TO 25-50MM WHILE BUILDING NORTH
ACROSS CUYO IN ARGENTINA...WHILE OVER THE BUENOS AIRES PROVINCE
EXPECTING MAXIMA OF 20-35MM IN POTENTIALLY SEVERE CONVECTION.

AT 250 HPA...CELL OF THE SUBTROPICAL RIDGE TO THE NORTH SPANS
BETWEEN NORTHERN CHILE-BOLIVIA/NORTHWEST ARGENTINA AND CENTRAL
PERU...WHILE CENTERING ON A CLOSED HIGH WEST OF ANTOFAGASTA IN
NORTHERN CHILE. AS THE RIDGE HOLDS...IT FAVORS THE NORTHWARD
AMPLIFICATION OF A MID/UPPER LEVEL TROUGH OVER THE WESTERN
ATLANTIC TO THE SOUTHERN/SOUTHEAST STATES OF BRASIL. THROUGH THE
DAY THIS EVOLVES INTO A CLOSED LOW OFF THE COAST OF URUGUAY/RIO
GRANDE DO SUL WHILE THE SHORT WAVE TROUGH AMPLIFIES ACROSS MATO
GROSSO DO SUL TO THE CENTRAL STATES OF BRASIL. THROUGH SUNDAY
MORNING THE LOW WEAKENS TO AN OPEN TROUGH WHILE SHEARING SHORT
WAVE ENERGY TO THE EAST-SOUTHEAST. THIS WILL THEN GRADUALLY
WEAKEN/FILL THROUGH EARLY NEXT WEEK. MEANWHILE...THE TROUGH ALOFT
WILL ENHANCE CONVECTIVE INSTABILITY ACROSS SOUTHEAST BRASIL WHILE
ALSO FAVORING AN UPPER DIVERGENT PATTERN. AT LOW LEVELS...MOISTURE
CONVERGES ALONG THE SOUTH AMERICA CONVERGENCE ZONE AS IT EXTENDS
TO THE NORTHWEST ACROSS RIO DE JANEIRO/MINAS GERAIS TO MATO
GROSSO/NORTHERN BOLIVIA. UNDER THE DYNAMICAL SUPPORT OF THE UPPER
LEVEL TROUGH AND FAVORABLE JET DYNAMICS HEAVY RAINS WILL CONTINUE
TO AFFECT SOUTHEAST BRASIL DURING THE NEXT COUPLE OF DAYS...WITH
MOST INTENSE CLUSTERING BETWEEN RIO DE JANEIRO/NORTHERN SAO PAULO
AND TOCANTINS/GOIAS. IN THIS AREA EXPECTING MAXIMA OF 75-150MM/DAY
WITH POTENTIAL FOR LOCALLY HIGHER AMOUNTS DUE TO TOPOGRAPHICAL
FORCING. AS THE UPPER TROUGH WEAKENS ON SUNDAY...FOCUS OF THE
CONVECTION SHIFTS WEST ACROSS NORTHERN BOLIVIA TO ACRE IN WESTERN
BRASIL AND THE SOUTHERN JUNGLE OF PERU...WITH A HEAVY RAINFALL
PRODUCING MCS LIKELY TO DEVELOP LATER ON SUNDAY/EARLY ON MONDAY
MORNING.

DAVISON...WPC (USA)
$$

595 
FXSA20 KWBC 171705
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1205 PM EST THU FEB 17 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 17/17 UTC: A BROAD MID/UPPER LEVEL
RIDGE IS INITIALIZED OVER THE EASTERN PACIFIC OFF THE COAST OF
CHILE TO THE BELLINGSHAUSEN SEA. UPSTREAM FROM THIS AXIS...A LONG
WAVE TROUGH EXTENDS NORTH ALONG 110W/120W TO 35S. AS IT PRESSES
AGAINST THE RIDGE TO THE EAST... THE TROUGH IS FORECAST TO SPLIT
IN TWO. IN A TIGHTER GRADIENT AND STRONGER FLOW TO THE SOUTH...THE
SOUTHERN HALF OF THE TROUGH THEN ACCELERATES ACROSS THE DRAKE
PASSAGE/ANTARCTIC PENINSULA LATER TODAY...WHILE THE REMAINING
NORTHERN STREAM VORTEX IS FORECAST TO MEANDERS EAST TOWARDS THE
SOUTHERN CONE. THIS REACHES SOUTHERN CHILE EARLY ON SATURDAY
MORNING. AS IT MAKES LANDFALL...UNDER THE INFLUENCE OF A BUILDING
RIDGE TO THE WEST...THE SHORT WAVE TROUGH DEEPENS INTO A CLOSED
LOW JUST WEST OF TEMUCO/PUERTO MONTT. IN THIS CYCLE THE MODELS
CORRECTED IN FAVOR OF A DEEPER LOW THAN WHAT THEY PREVIOUSLY
SUGGESTED. BLOCKED BY THE HIGHER ELEVATION OF THE CENTRAL ANDES OF
CHILE...THE DEEP LOW IS NOW FORECAST TO STALL OFF THE CENTRAL
COAST...WITH THE CLOSED LOW MEANDERING JUST WEST OF CONCEPCION.
SIMULTANEOUSLY...THE MID/UPPER LEVEL RIDGE BRANCHES ACROSS
SOUTHERN CHILE/PATAGONIA IN ARGENTINA TOWARDS THE DRAKE
PASSAGE...UNDERCUTTING THE LOW TO THE NORTH WHILE FAVORING A SPLIT
FLOW PATTERN. THIS PATTERN IS TO THEN HOLD THROUGH THE MEDIUM
RANGE PERIOD.

AT LOW LEVELS...THE TROUGH ALOFT SUSTAINS A OCCLUDED LOW THAT
STREAMS ACROSS THE DRAKE PASSAGE TO THE SOUTH GEORGIA ISLANDS
EARLY IN THE CYCLE...WHILE SUSTAINING AN ELONGATED FRONT ACROSS
TIERRA DEL FUEGO/SOUTHERN PATAGONIA IN ARGENTINA. IN A TIGHT
GRADIENT...STRONG WESTERLY WINDS ARE TO ACCOMPANY THIS
BOUNDARY...ENHANCING MOISTURE TRANSPORT/CONVERGENCE BETWEEN ISLA
DE CHILOE AND PUNTA ARENAS. THE INFLOW OF DEEP SUBTROPICAL
MOISTURE WILL LIKELY FAVOR AN ECHO TRAINING PATTERN AND HEAVY
RAINFALL AMOUNTS. THROUGH TODAY EXPECTING MAXIMA OF
35-70MM...WHILE ON FRIDAY THE MAXIMA IN THIS AREA PEAKS AT
30-60MM. DURING THE WEEKEND...THE MEANDERING MID LEVEL TROUGH/LOW
OFF THE CENTRAL COAST OF CHILE WILL THEN INTERACT WITH THIS
BOUNDARY...PROVIDING THE DYNAMICAL SUPPORT AND VENTILATION ALOFT.
THIS COMBINES WITH A BROAD RIDGE TO THE SOUTH TO SUSTAIN A MOIST
EAST-SOUTHEASTERLY FLOW ACROSS PATAGONIA/LA PAMPA TO CUYO IN
ARGENTINA...WITH THE MOISTURE CONVERGING/LIFTING ALONG THE LEE OF
THE CENTRAL ANDES. THROUGH THE WEEKEND/EARLY NEXT WEEK CONVECTION
IN THIS AREA IS FORECAT TO INTENSIFY...INCREASING FROM MAXIMA OF
25-50MM ON SUNDAY TO 35-70MM ON MONDAY TO TUESDAY.

UPPER LEVEL PATTERN TO THE NORTH REMAINS UNDER THE STEERING
INFLUENCE OF A BROAD CELL OF THE SUBTROPICAL RIDGE...WITH AXIS
ENVELOPING NORTHERN CHILE/NORTHWEST ARGENTINA-BOLIVIA-PERU...WHILE
CENTERING ON A CLOSED HIGH OVER NORTHERN CHILE. UNDER THE
INFLUENCE OF WARMER THAN NORMAL WATERS OFF THE NORTH COAST OF
CHILE THE HIGH MOVES OFF THE COAST INTO THE TROPICAL EASTERN
PACIFIC EARLY ON FRIDAY. MEANWHILE...A TROUGH STREAMING TO THE
SOUTH AMPLIFIES ALONG THE FRINGES OF THIS RIDGE TO THE THE
SOUTHERN/SOUTHEAST STATES OF BRASIL. ON FRIDAY A LOW CLOSES ALONG
THIS AXIS JUST EAST OF RIO GRANDE DO SUL...WHILE THE SHORT WAVE
TROUGH AMPLIFIES TO MATO GROSSO. THROUGH THE WEEKEND THE TROUGH IS
TO GRADUALLY WEAKEN...AND EARLY NEXT WEEK IT IS TO NEARLY FILL.
MEANWHILE...THIS WILL FAVOR AN UPPER DIVERGENT PATTERN WHILE
ENHANCING CONVECTIVE INSTABILITY. AT LOW LEVELS...UNDER THE
INFLUENCE OF THE UPPER LEVEL TROUGH AND AN ATMOSPHERIC KELVIN
WAVE...THE SOUTH AMERICA CONVERGENCE DEVELOPS BETWEEN NORTHERN SAO
PAULO/RIO DE JANEIRO AND MATO GROSSO. ACROSS RIO DE
JANEIRO-SOUTHERN MINAS GERAIS THIS IS TO SUSTAIN SEVERAL DAYS OF
ORGANIZED DEEP CONVECTION...WITH POTENTIAL FOR EXTREME RAINFALL
AMOUNTS FROM EARLY ON FRIDAY MORNING THROUGH SATURDAY. BUT AS THE
UPPER TROUGH WEAKENS ON SUNDAY...THE LOW LEVEL BOUNDARY WEAKENS TO
AN OPEN TROUGH AND RAINFALL AMOUNTS ARE TO DECREASE.

DAVISON...WPC (USA)
$$

688 
FXSA20 KWBC 161703
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1203 PM EST WED FEB 16 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 16/17 UTC: A PROGRESSIVE MID/UPPER
LEVEL TROUGH ON THE SOUTHERN STREAM LIFTS ACROSS THE
BELLINGSHAUSEN SEA TO THE DRAKE PASSAGE EARLY IN THE CYCLE. THIS
WILL BE FOLLOWED BY A CONSIDERABLY SLOWER PERTURBATION ON THE
NORTHERN STREAM...WITH THE LATTER REACHING THE SOUTHERN REGIONS OF
CHILE EARLY ON SATURDAY MORNING. A BUILDING LONG WAVE RIDGE TRAILS
THIS PERTURBATION...WITH AXIS FORECAST TO BUILD TO THE
SOUTH-SOUTHEAST ACROSS THE EASTERN PACIFIC TO THE BELLINGSHAUSEN
SEA DURING THE WEEKEND. AS THE MID/UPPER LEVEL RIDGE BUILDS...IT
WILL UNDERCUT THE SHORT WAVE TROUGH TO THE NORTH. BY THE END OF
THE CYCLE/EARLY NEXT WEEK THIS WILL THEN EVOLVE INTO A SPLIT FLOW
PATTERN...WITH THE RIDGE SETTLING BETWEEN EXTREME SOUTHERN
PORTIONS OF CHILE/PATAGONIA AND THE ANTARCTIC PENINSULA...WHILE
THE SHORT WAVE TROUGH TO THE NORTH EVOLVES INTO A CLOSED/CUTOFF
LOW OVER CENTRAL CHILE/ARGENTINA. THIS IS A VERY UNUSUAL/ANOMALOUS
PATTERN THAT MIGHT BE INDICATIVE OF ONSET TRANSITION TO WARM ENSO
CONDITIONS.

AT LOW LEVELS...A DEEP OCCLUDED LOW IS TO STREAM ACROSS THE DRAKE
PASSAGE/ANTARCTIC PENINSULA TO THE SOUTH GEORGIA ISLANDS ON
THURSDAY...WHILE THE ASSOCIATED FRONT MEANDERS NORTH ACROSS TIERRA
DEL FUEGO TO EXTREME SOUTHERN CHILE. THE FRONT WILL THEN REMAIN
NEARLY STATIONARY THROUGH FRIDAY MORNING...WITH THE ENSUING
GRADIENT FAVORING STRONG BOUNDARY LAYER WINDS ACROSS THE SOUTHERN
REGIONS OF CHILE. THIS WILL ENHANCE MOISTURE CONVERGENCE/TRANSPORT
ACROSS THE SOUTHEAST PACIFIC...AND WOULD LIKELY LEAD TO A HEAVY
RAINFALL PRODUCING ECHO TRAINING PATTERN THROUGH FRIDAY
EVENING...WITH STORM TOTAL AMOUNTS OF 125-200MM.

THE NORTHERN STREAM VORTEX...AS IT ENTERS SOUTHERN CHILE ON
FRIDAY...WILL THEN INDUCE A FRONTAL LOW. THIS IS FORECAST TO
DEEPEN AS IT MEANDERS EAST ACROSS SOUTHERN CHILE TO PATAGONIA ON
SATURDAY. BUILDING RIDGE TO THE SOUTH AND EAST WILL THEN COMBINE
WITH THIS FEATURE TO SUSTAIN MOIST EAST-SOUTHEASTERLY FLOW ACROSS
CENTRAL/NORTHERN PATAGONIA TO LA PAMPA IN ARGENTINA DURING THE
WEEKEND. THE STRONG ONSHORE FLOW IS LIKELY TO TRIGGER HEAVY
RAINFALL AMOUNTS ACROSS NORTHERN PATAGONIA/LA PAMPA IN
ARGENTINA...WITH MODELS CURRENTLY AGREEING ON POTENTIAL FOR
INTENSE RAINFALL AMOUNTS IN EXCESS OF 100MM/DAY. THERE IS A STRONG
CONSENSUS AMONG THE DETERMINISTIC AND ENSEMBLE MODEL
GUIDANCE...LEADING TO A HIGHER THAN NORMAL CONFIDENCE IN THE
FORECAST AS WE ENTER THE MEDIUM/LONG RANGE PERIOD.

AT 250 HPA...BROAD CELL OF THE SUBTROPICAL RIDGE ENVELOPS
CONTINENTAL AREA BETWEEN NORTHERN CHILE/NORTHWEST ARGENTINA AND
PERU...WHILE CENTERING ON A CLOSED HIGH OVER SOUTHWEST BOLIVIA. A
TROUGH STREAMING TO THE SOUTH IS FORECAST TO THEN AMPLIFY ALONG
THE EASTERN FRINGES OF THIS RIDGE TO THE SOUTHERN STATES OF BRASIL
EARLY ON FRIDAY MORNING. THROUGH FRIDAY THIS EVOLVES INTO A
CLOSED/CUTOFF LOW OFF THE SOUTH COAST OF BRASIL...WHILE THE TROUGH
AMPLIFIES TO THE NORTH/NORTHWEST ACROSS PARANA/SAO PAULO TO MATO
GROSSO DURING THE WEEKEND. BUT WHILE REMAINING CUTOFF FROM THE
FLOW...IT IS TO THEN EXHAUST ITS AVAILABLE ENERGY AND GRADUALLY
WEAKEN. MEANWHILE...UNDER THE INFLUENCE OF THE UPPER LEVEL TROUGH
AND AN ATMOSPHERIC KELVIN WAVE THE SOUTH AMERICA CONVERGENCE ZONE
IS TO BECOME BETTER ORGANIZE OVER SOUTHEAST BRASIL. INITIALLY THE
MOST INTENSE CONVECTION IS EXPECTED ACROSS RIO DE JANEIRO/SOUTHERN
MINAS GERAIS. BUT AS THE SACZ STRENGTHENS ON THURSDAY-FRIDAY...THE
CONVECTION IS TO THEN FARTHER INLAND ALONG THE CONVERGENCE ZONE.
THROUGH SATURDAY THE ACTIVITY SURGES...THEN RAPIDLY WEAKENS WHILE
SHIFTING WESTWARD ACROSS CENTRAL TO SOUTHWESTERN BRASIL EARLY NEXT
WEEK.

DAVISON...WPC (USA)
$$

475 
FXSA20 KWBC 151657
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1157 AM EST TUE FEB 15 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 15/17 UTC: CONSISTENT WITH PREVIOUS
FORECAST...A MID/UPPER LEVEL TROUGH LIFTS ACROSS THE
BELLINGSHAUSEN SEA TO THE SOUTHEAST PACIFIC EARLY IN THE CYCLE. AS
IT NEARS THE SOUTH COAST OF CHILE...UNDER THE INFLUENCE OF A
BUILDING RIDGE TO THE WEST...THE TROUGH RAPIDLY AMPLIFIES. THROUGH
MID MORNING ON WEDNESDAY THE TROUGH IS TO THEN LIFT ACROSS
PATAGONIA IN ARGENTINA TO THE MALVINAS/FALKLAND ISLANDS. A LOWER
AMPLITUDE TROUGH IS TO CLOSELY FOLLOW. BLOCKED BY A RIDGE TO THE
NORTH...THE SHORT WAVE TROUGH IS TO RAPIDLY STREAM ACROSS THE
ANTARCTIC PENINSULA/DRAKE PASSAGE WHILE BOTTOMING OUT OVER TIERRA
DEL FUEGO LATER ON THURSDAY. AT LOW LEVELS...THE MID LEVEL VORTEX
WILL SUSTAIN A DEEP OCCLUDED LOW OVER THE SOUTHEAST PACIFIC LATER
TODAY. AS IT MEANDERS EAST ACROSS THE DRAKE PASSAGE TO THE
SOUTHWEST ATLANTIC...THIS WILL DRAW AN ELONGATED FRONT NORTH
ACROSS TIERRA DEL FUEGO TO EXTREME SOUTHERN CHILE/PATAGONIA ON
WEDNESDAY. THE FRONT WILL THEN REMAIN NEARLY STATIONARY THROUGH
FRIDAY. IN A MOIST ADVECTIVE PATTERN...CONVECTIVE CELLS BUILDING
ALONG THE MEANDERING FRONT ARE TO THEN TRAIN BETWEEN ISLA DE
CHILOE AND PUNTA ARENAS IN SOUTHERN CHILE. THIS WILL SUSTAIN
PERIODS OF VERY HEAVY/INTENSE RAINFALL AMOUNTS ON
WEDNESDAY-FRIDAY...WITH STORM TOTAL AMOUNTS IN THIS OF 125-200MM.

LATER IN THE WEEK...A SLOWER TO EVOLVE MID/UPPER LEVEL SHORT WAVE
TROUGH WILL PROPAGATE ACROSS THE SOUTHEAST PACIFIC...TO EVOLVE
INTO A CLOSED LOW AS IT NEARS SOUTHERN CHILE EARLY ON SATURDAY
MORNING. THE CLOSED LOW WILL THEN LIFT ALONG THE COAST TO CENTRAL
CHILE LATER DURING THE WEEKEND/EARLY NEXT WEEK. MEANWHILE...THIS
WILL INTERACT WITH THE MEANDERING FRONT OVER THE SOUTHERN
CONE...SUSTAINING A FRONTAL LOW THAT OCCLUDES ALONG THE SOUTH
COAST. FOCUS OF THE CONVECTION WILL THEN SHIFT NORTH BETWEEN ISLA
DE CHILOE AND TEMUCO/PUERTO MONTT...TO TRIGGER MODERATE RAINFALL
AMOUNTS ALONG THE SOUTH COAST OF CHILE DURING THE WEEKEND. THIS
WILL ALSO TRIGGER SCATTERED CONVECTION ON THE ARGENTINEAN SIDE OF
PATAGONIA...WITH THE SLOW TO EVOLVE PERTURBATION TO LIKELY TRIGGER
MODERATE/LOCALLY HEAVY RAINFALL AMOUNTS.

NORTH OVER THE CONTINENT...AT 200 HPA...A CELL OF THE SUBTROPICAL
RIDGE DOMINATES THE UPPER FLOW TO THE NORTH OF 33S AND WEST OF
50W...WHILE CENTERING ON A CLOSED HIGH OVER THE ALTIPLANO OF
BOLIVIA. THROUGH THE END OF THE WEEK THE RIDGE IS FORECAST TO
INTENSIFY WHILE SIMULTANEOUSLY ROLLING ACROSS BOLIVIA TO THE
EASTERN PACIFIC...AND DURING THE WEEKEND IT IS TO THEN CENTER ON A
CLOSED HIGH OVER THE EASTERN PACIFIC OFF THE SOUTH COAST OF PERU.
AS THE PATTERN TO THE NORTH EVOLVES...A CLOSED MID/UPPER LEVEL LOW
OFF THE COAST OF URUGUAY IS TO GRADUALLY WEAKEN TO AN OPEN TROUGH
WHILE SLOWLY SHEARING TO THE EAST-SOUTHEAST. BUT AS THE UPPER
LEVEL RIDGE SETTLES TO THE WEST...IT IS TO SIMULTANEOUSLY FAVOR
THE NORTHWARD AMPLIFICATION OF A TROUGH ACROSS THE WESTERN
ATLANTIC TO THE SOUTHERN STATES OF BRASIL. THIS THEN MERGES WITH
THE REMNANTS OF THE FORMER TO SUSTAIN A DEEPER TROUGH THAT
AMPLIFIES ACROSS SOUTHEAST BRASIL TO MATO GROSSO DURING THE
WEEKEND. THE EVOLVING UPPER LEVEL PATTERN WILL THEN INTERACT WITH
A MEANDERING LOW LEVEL TROUGH STRETCHING FROM SOUTHEAST TO CENTRAL
BRASIL TO SUSTAIN THE SOUTH AMERICA CONVERGENCE ZONE (SACZ). THIS
IS TO STRENGTHEN/BECOME BETTER ORGANIZED ON THURSDAY TO
FRIDAY...WITH AXIS TO LIKELY PERSIST THROUGH THE WEEKEND. AS THE
CONVERGENCE ZONE GRADUALLY BECOMES BETTER ORGANIZED...CONVECTION
ACROSS RIO DE JANEIRO/ESPIRITO SANTO IS FORECAST TO GRADUALLY
INTENSIFY WHILE BUILDING NORTHWESTWARD ACROSS MINAS GERAIS TO
TOCANTINS/GOIAS. MOST INTENSE CONVECTION IS EXPECTED LATER DURING
THE WEEK WHEN THE ENVIRONMENTAL CONDITIONS BECOME MORE FAVORABLE
FOR MCS FORMATION. OTHER CONVECTION IS TO CLUSTER TO THE NORTH
ALONG THE NEAR EQUATORIAL TROUGH BETWEEN PARA-AMAZONAS IN NORTHERN
BRASIL. ACTIVITY ALONG THE NET...HOWEVER...IS EXPECTED TO
GRADUALLY WEAKEN AS CONVECTION ALONG THE SACZ TO THE SOUTH
INTENSIFIES LATER IN THE WEEK.

OTHER CONVECTION IS EXPECTED ACROSS ECUADOR AS ENHANCED BY A
MEANDERING LOW LEVEL TROUGH. THE TROUGH WILL SUSTAIN A LONG FETCH
NORTHWESTERLY FLOW OVER WARMER THAN NORMAL WATERS OFF THE COAST OF
COLOMBIA. MOST INTENSE CONVECTION IS EXPECTED TODAY...THEN
GRADUALLY WEAKEN THROUGH THE END OF THE WEEK AS THE UPPER LEVEL
RIDGE SETTLES FARTHER TO THE SOUTH AND WEST OFF THE COAST OF PERU.

DAVISON...WPC (USA)
$$

373 
FXSA20 KWBC 141643
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1142 AM EST MON FEB 14 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 14/17 UTC: A MID LATITUDE RIDGE THAT
BRANCHES EAST ACROSS THE EASTERN PACIFIC TO THE CENTRAL REGIONS OF
CHILE IS STEERING SHORT WAVE PERTURBATIONS ON THE SOUTHERN STREAM
ACROSS THE SOUTHEAST PACIFIC INTO THE SOUTHERN REGIONS OF
CHILE/PATAGONIA IN ARGENTINA. THE ENSUING GRADIENT FAVORS A FAIRLY
INTENSE UPPER LEVEL JET ACROSS EXTREME SOUTHERN PORTIONS OF CHILE
AND A PROGRESSIVE MID LEVEL PATTERN ACROSS THE SOUTHERN CONE. AT
LOW LEVELS THIS WILL LEAD TO A RAPID TRANSITION ACROSS THE
SOUTHERN CONE ON TUESDAY TO WEDNESDAY...WITH A BUILDING POLAR
RIDGE TO THE SOUTH TO SUSTAIN A SOUTHERLY PAMPERO LOW LEVEL JET
THAT DRIVES A FRONT NORTH ACROSS PATAGONIA/LA PAMPA TO CENTRAL
ARGENTINA LATER ON WEDNESDAY. AS IT RACES ACROSS ARGENTINA...AS
ENHANCED BY THE DIVERGENT RIGHT EXIT REGION OF A SUBTROPICAL JET
MAXIMA...CONDITIONS APPEAR FAVORABLE FOR SEVERE THUNDERSTORMS TO
DEVELOP ACROSS PORTIONS OF MENDOZA-SAN LUIS AND CORDOBA IN CENTRAL
ARGENTINA.

SIMULTANEOUSLY...THE UPSTREAM PATTERN OVER THE SOUTHEAST PACIFIC
IS TO GRADUALLY EVOLVE INTO A MORE AMPLIFIED SINUSOIDAL WAVE
PATTERN BY THE END OF THE  WEEK...WITH DEEPER/HIGHER AMPLITUDE
PERTURBATION TO MAKE LANDFALL ACROSS THE SOUTHERN CONE LATER ON
FRIDAY. THE SLOWER TO EVOLVE TROUGH IS TO THEN AMPLIFY ACROSS THE
SOUTHERN CONE AS AN UNSEASONABLY STRONG RIDGE BUILDS TO THE WEST.
THE SLOWER EVOLUTION ALLOWS THIS TROUGH TO ESTABLISH A SUBTROPICAL
CONNECTION AS IT REACHES THE SOUTHERN REGIONS OF CHILE EARLY ON
THURSDAY MORNING...WITH DEEP MOISTURE TO LINGER THROUGH SATURDAY
MORNING. AT LOW LEVELS THIS WILL BE PRECEDED BY A DEEP OCCLUDED
LOW THAT LIFTS ACROSS THE BELLINGSHAUSEN SEA TO THE DRAKE
PASSAGE...WHILE AN ELONGATED FRONT MEANDERS OVER THE SOUTHERN CONE
ALONG 50S. THE FRONT WILL THEN REMAIN NEARLY STATIONARY OVER
SOUTHERN CHILE AS THE DEEP OCCLUSION MEANDERS EAST ACROSS THE
DRAKE PASSAGE/ANTARCTIC PENINSULA TO THE WEDDELL SEA ON THURSDAY
TO FRIDAY. CONVECTIVE CELLS BUILDING ALONG THE MEANDERING FRONT
ARE TO THEN TRAIN BETWEEN ISLA DE CHILOE AND PUNTA ARENAS...TO
SUSTAIN PERIODS OF HEAVY INTENSE RAINFALL AMOUNTS. STORM TOTAL
AMOUNTS IN THIS ARE ARE EXPECTED TO PEAK AT 125-200MM.

NORTH OVER THE CONTINENT...AT 200 HPA...A CLOSED HIGH OVER THE
ALTIPLANO DE BOLIVIA ANCHORS A RIDGE OVER NORTHERN SOUTH AMERICA.
THROUGH THE END OF THE WORKWEEK THE HIGH/RIDGE ROLLS ACROSS
NORTHERN CHILE TO SETTLE OFF THE COAST LATER ON THURSDAY/EARLY
FRIDAY MORNING. AS THE PATTERN TO THE NORTH EVOLVES...A CLOSED
MID/UPPER LEVEL LOW OFF THE COAST OF URUGUAY IS TO GRADUALLY
WEAKEN TO AN OPEN TROUGH WHILE SLOWLY SHEARING TO THE
EAST-SOUTHEAST. BUT AS THE UPPER LEVEL RIDGE SETTLES TO THE
WEST..A SECONDARY PERTURBATION IS TO THEN AMPLIFY ACROSS THE
WESTERN ATLANTIC TO THE SOUTHERN STATES OF BRASIL ON
THURSDAY-FRIDAY. THIS THEN MERGES WITH THE REMNANTS OF THE FORMER
TO SUSTAIN A DEEPER TROUGH THAT AMPLIFIES ACROSS SOUTHEAST BRASIL
TO MATO GROSSO DURING THE WEEKEND. THE EVOLVING UPPER LEVEL
PATTERN WILL THEN INTERACT WITH A MEANDERING LOW LEVEL TROUGH
STRETCHING FROM SOUTHEAST TO CENTRAL BRASIL TO SUSTAIN THE SOUTH
AMERICA CONVERGENCE ZONE (SACZ). THIS IS TO STRENGTHEN/BECOME
BETTER ORGANIZED ON FRIDAY-SATURDAY. AS THE CONVERGENCE ZONE
GRADUALLY BECOMES BETTER ORGANIZED...CONVECTION ACROSS RIO DE
JANEIRO/ESPIRITO SANTO IS FORECAST TO GRADUALLY INTENSIFY WHILE
BUILDING NORTHWESTWARD ACROSS MINAS GERAIS TO TOCANTINS/GOIAS.
MOST INTENSE CONVECTION IS EXPECTED LATER DURING THE WEEK. OTHER
CONVECTION IS TO CLUSTER TO THE NORTH ALONG THE NEAR EQUATORIAL
TROUGH BETWEEN PARA-AMAZONAS IN NORTHERN BRASIL. ACTIVITY IN THIS
AREA SURGES THIS EVENING...BUT THEN GRADUALLY WEAKENS AS
CONVECTION ALONG THE SACZ TO THE SOUTH INTENSIFIES LATER IN THE
WEEK.

DAVISON...WPC (USA)
$$

425 
FXSA20 KWBC 111714
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1214 PM EST FRI FEB 11 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON MONDAY FEBRUARY 14

FORECAST DISCUSSION FROM FEB 11/17 UTC: AT MID/UPPER LEVELS...THE
GLOBAL MODELS INITIALIZE A BROAD/LOW AMPLITUDE RIDGE OVER THE
EASTERN SOUTH PACIFIC...WITH AXIS TO DOMINATE THE FLOW DURING THE
NEXT SEVERAL DAYS. IRREGULARLY SPACED SHORT WAVE PERTURBATIONS ARE
STREAMING TO THE SOUTH OF THIS RIDGE. REACHING THE SOUTHEAST
PACIFIC...THESE THEN PRESS AGAINST THE RIDGE TO THE NORTH. THE
ENSUING GRADIENT SUSTAINS A TIGHT BELT OF MID/UPPER LEVEL
WESTERLIES ACROSS SOUTHERN CHILE/PATAGONIA IN ARGENTINA.
THIS...IN-TURN...ALLOWS THE SHORT WAVE TROUGHS TO ACCELERATE AS
THEY ENTER THE SOUTHERN CONE. CONSENSUS AMONG THE MODELS ON THIS
PATTERN AND ENSUING EVOLUTION IS STRONG. BUT THIS ONLY LASTS
THROUGH EARLY NEXT WEEK WHEN THE MODELS DEVELOP TIMING/AMPLITUDE
DIFFERENCES. MEANWHILE...THESE ARE TO FAVOR PROGRESSIVE FRONTAL
LOWS THAT ARE TO STREAM ACROSS THE DRAKE PASSAGE/TIERRA DEL FUEGO
FROM TIME-TO-TIME...WHERE THESE ARE TO TRIGGER STRONG BOUNDARY
LAYER WINDS AND MODERATE TO HEAVY RAINFALL AMOUNTS. THE GENERAL
TENDENCY IF FOR THE CONVECTION TO GRADUALLY INTENSIFY EARLY NEXT
WEEK...WITH MODELS AGREEING ON AN ENHANCED RISK OF MODERATE
AMOUNTS ON MONDAY THROUGH WEDNESDAY MORNING.

SIMULTANEOUSLY...UNDER THE INFLUENCE OF THE MID/UPPER LEVEL RIDGE
TO THE WEST...A LONG TROUGH AMPLIFIES ACROSS THE WESTERN
ATLANTIC-MID SECTIONS OF CHILE/ARGENTINA TO THE ARCHIPELAGO DE
JUAN FERNANDEZ OVER THE EASTERN PACIFIC. THE TROUGH REACHES
MAXIMUM AMPLITUDE LATER TODAY. A SUBTROPICAL AND A NORTHERN POLAR
JET MAXIMA ACCOMPANY THE DEEPENING TROUGH. THE MODELS FORECAST
COUPLING OF THESE JETS ON THEIR RESPECTIVE EXIT/ENTRANCE REGIONS
AS THEY STREAM ACROSS CHILE TO ARGENTINA...FAVORING A BROAD AREA
OF UPPER DIVERGENCE ACROSS THE BUENOS AIRES PROVINCE/CENTRAL
ARGENTINA. THIS WILL VENT ORGANIZED/POTENTIALLY SEVERE CONVECTION
DURING THE DAY. THROUGH THE WEEKEND...UNDER THE STRETCHING
INFLUENCE OF THE POLAR JET MAXIMA...THE LONG WAVE AXIS WILL
RAPIDLY SPLIT IN TWO. DRAWN BY THE JET...THE SOUTHERN HALF OF THE
TROUGH ACCELERATES ACROSS THE SOUTH GEORGIA ISLANDS TO THE CENTRAL
SOUTH ATLANTIC. THE REMAINING NORTHERN STREAM
PORTION...MEANWHILE...EVOLVES INTO TWO DISTINCT CLOSED LOWS...WITH
ONE OVER THE EASTERN PACIFIC CENTERING JUST WEST OF JUAN FERNANDEZ
WHILE THE OTHER OVER THE WESTERN ATLANTIC MEANDERS OFF THE COAST
OF URUGUAY. THE LATTER IS A SYSTEM OF CONCERN...AS IT MEANDERS
OVER WARMER THAN NORMAL WATERS OFF THE COAST OF URUGUAY IT HAS THE
POTENTIAL OF INDUCING A SUBTROPICAL CYCLONE EARLY NEXT WEEK. AT
LOW LEVELS THE DEEPENING UPPER LEVEL TROUGH SUSTAIN A PROGRESSIVE
FRONT THAT RACES ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA BASIN
DURING THE DAY TODAY...INTO SOUTHERN BRASIL-PARAGUAY ON SATURDAY.
EARLY ON SATURDAY MORNING...UNDER THE DYNAMICAL INFLUENCE OF THE
COUPLED UPPER LEVEL JETS...A DEEPENING FRONTAL LOW DEVELOPS OVER
URUGUAY/RIO DE LA PLATA. THE ENSUING CYCLOGENESIS WILL RESULT IN
ORGANIZED HEAVY DEEP CONVECTION THAT IS LIKELY TO BECOME SEVERE AS
IT SPREADS ACROSS THE BUENOS AIRES PROVINCE TO URUGUAY. LATER
FRIDAY/EARLY ON SATURDAY MORNING...AS IT RACES ACROSS NORTHERN
ARGENTINA AND CLASHES AGAINST THE SOUTHERN SLOPES OF THE BOLIVIAN
ANDES CONDITIONS APPEAR FAVORABLE FOR A HEAVY RAINFALL PRODUCING
MESO SCALE CONVECTIVE SYSTEM TO FORM AHEAD OF THIS SYSTEM. THROUGH
SATURDAY ACTIVITY SPREADS NORTH AND WEST ACROSS CENTRAL BOLIVIA TO
SOUTHERN PERU/ACRE IN BRASIL...TO RESULT IN STORM TOTAL AMOUNTS OF
100-200MM.

AS CONVECTION ACROSS BOLIVIA AND SOUTHERN PERU INTENSIFIES AHEAD
OF THIS FRONT...THE RELEASE OF LATENT HEAT WILL THEN SUSTAIN THE
GRADUAL INTENSIFICATION OF THE SUBTROPICAL RIDGE OVER NORTHERN
SOUTH AMERICA DURING THE WEEKEND...WITH AXIS TO ANCHOR ON A
MEANDERING 250 HPA HIGH OVER BOLIVIA/SOUTHERN PERU.
THIS...IN-TURN...WILL INDUCE THE AMPLIFICATION OF AN UPPER LEVEL
TROUGH/CAVADO DO NORDESTE ACROSS NORTHEAST BRASIL. AT LOW LEVELS
THE RIDGE ALOFT IS VENTING DEEP CONVECTION ALONG THE SOUTH AMERICA
CONVERGENCE ZONE (SACZ)...AS IT STRETCHES ACROSS NORTHERN SAO
PAULO/RIO DE JANEIRO TO RONDONIA/NORTHERN BOLIVIA. INITIALLY MOST
ACTIVE CONVECTION IS TO CLUSTER ON THE SOUTHEAST STATES OF BRASIL.
BUT AS THE AFOREMENTIONED PREFRONTAL CONVECTION SURGES ACROSS
CENTRAL BOLIVIA ON FRIDAY-TO-SATURDAY...THE FOCUS OF THE
CONVECTION ALONG THE SACZ IS TO SHIFT WEST ACROSS MATO GROSSO IN
CENTRAL BRASIL TO RONDONIA/NORTHERN BOLIVIA DURING THE WEEKEND.
THE CONVERGENCE ZONE IS EXPECTED TO WEAKEN EARLY NEXT WEEK.
INITIALLY MOST INTENSE CONVECTION IS EXPECTED BETWEEN SOUTHERN
MINAS GERAIS/NORTHERN SAO PAULO AND RIO DE JANEIRO. THROUGH THE
WEEKEND...AS THE UPPER RIDGE INTENSIFIES...FOCUS OF THE ORGANIZED
DEEP CONVECTION SHIFTS NORTHWESTWARD ACROSS CENTRAL TO NORTHWEST
BRASIL/SOUTHERN COLOMBIA. THIS IS TO ALSO FAVOR AN INCREASE IN
CONVECTION ACROSS ECUADOR TO SOUTHWEST COLOMBIA...WITH PEAK IN
CONVECTION EXPECTED ON SATURDAY THROUGH MONDAY MORNING.

DAVISON/GALVEZ...WPC (USA)
$$

212 
FXSA20 KWBC 101740
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1240 PM EST THU FEB 10 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM FEB 10/18 UTC: THE GLOBAL MODELS
CONSISTENTLY FORECAST A DEEPENING MID/UPPER LEVEL TROUGH TO BECOME
THE DOMINANT SYNOPTIC FEATURE OVER THE SOUTHERN CONE...WITH AXIS
TO AMPLIFY ACROSS PATAGONIA/SOUTHERN CHILE DURING THE DAY TODAY.
THROUGH FRIDAY EVENING THE POSITIVELY TILTED LONG WAVE TROUGH
REACHES MAXIMUM AMPLITUDE...WHEN IT IS TO STRETCH FROM THE SOUTH
GEORGIA ISLANDS...ACROSS THE CENTRAL PROVINCES IN ARGENTINA/CHILE
TO THE ARCHIPELAGO OF JUAN FERNANDEZ. A SUBTROPICAL AND A NORTHERN
POLAR JET MAXIMA ARE TO ACCOMPANY THIS TROUGH AS IT DEEPENS ACROSS
ARGENTINA/CHILE. IN A COUPLED JET CONFIGURATION...THE RIGHT EXIT
REGION OF THE SUBTROPICAL JET WILL PHASE WITH THE LEFT ENTRANCE
REGION OF THE NORTHERN POLAR OVER CENTRAL ARGENTINA/BUENOS AIRES
PROVINCE ON FRIDAY...FAVORING A BROAD AREA OF UPPER LEVEL
DIVERGENCE THAT WILL VENT ORGANIZED DEEP CONVECTION. THEN DURING
THE WEEKEND...UNDER THE STRETCHING INFLUENCE OF THE POLAR JET
MAXIMA...THE LONG WAVE AXIS SPLITS IN TWO. DRAWN BY THE JET MAXIMA
ITS SOUTHERN HALF ACCELERATES ACROSS THE SOUTH ATLANTIC.
MEANWHILE...THE REMAINING NORTHERN STREAM PORTION EVOLVES INTO TWO
DISTINCT CLOSED LOWS...WITH ONE OVER THE EASTERN PACIFIC CENTERING
JUST WEST OF JUAN FERNANDEZ WHILE THE OTHER OVER THE WESTERN
ATLANTIC MEANDERS OFF THE COAST OF URUGUAY. THE LATTER IS A SYSTEM
OF CONCERN...AS IT HAS THE POTENTIAL OF INDUCING A SUBTROPICAL
CYCLONE EARLY NEXT WEEK.

AT LOW LEVELS THE DEEPENING UPPER LEVEL TROUGH WILL COMBINE WITH A
BUILDING RIDGE TO THE WEST TO SUSTAIN A PROGRESSIVE FRONT THAT
RACES ACROSS PATAGONIA TO CENTRAL ARGENTINA LATER TODAY. DRIVEN BY
A PAMPERO LOW LEVEL JET...THE FRONT THEN RACES ACROSS NORTHERN
ARGENTINA TO SOUTHERN BRASIL/PARAGUAY ON FRIDAY TO SATURDAY. THE
SURGING FRONT WILL INITIALLY TRIGGER SCATTERED CONVECTION ACROSS
THE BUENOS AIRES PROVINCE-CENTRAL ARGENTINA. LATER ON FRIDAY/EARLY
ON SATURDAY MORNING...UNDER THE DYNAMICAL INFLUENCE OF THE COUPLED
UPPER LEVEL JETS...A DEEPENING FRONTAL LOW DEVELOPS OVER
URUGUAY/RIO DE LA PLATA. THE ENSUING CYCLOGENESIS WILL RESULT IN
ORGANIZED HEAVY DEEP CONVECTION THAT IS LIKELY TO BECOME SEVERE AS
IT SPREADS ACROSS THE BUENOS AIRES PROVINCE TO URUGUAY. LATER
FRIDAY/EARLY ON SATURDAY MORNING...AS IT RACES ACROSS NORTHERN
ARGENTINA AND CLASHES AGAINST THE SOUTHERN SLOPES OF THE BOLIVIAN
ANDES CONDITIONS APPEAR FAVORABLE FOR A HEAVY RAINFALL PRODUCING
MESO SCALE CONVECTIVE SYSTEM TO FORM AHEAD OF THIS SYSTEM. THROUGH
SATURDAY ACTIVITY SPREADS NORTH AND WEST ACROSS CENTRAL BOLIVIA TO
SOUTHERN PERU/ACRE IN BRASIL...TO RESULT IN STORM TOTAL AMOUNTS OF
100-200MM.

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE DOMINATES THE FLOW TO THE NORTH OF OF
20S...WHILE AN UPPER TROUGH TO THE EAST-NORTHEAST CENTERS ON A
CLOSED LOW OVER NORTHEAST BRASIL. AT LOW LEVELS THE RIDGE ALOFT IS
VENTING DEEP CONVECTION ALONG THE SOUTH AMERICA CONVERGENCE
ZONE...AS IT STRETCHES ACROSS NORTHERN SAO PAULO/RIO DE JANEIRO TO
RONDONIA/NORTHERN BOLIVIA. INITIALLY MOST ACTIVE CONVECTION IS TO
CLUSTER ON THE SOUTHEAST STATES OF BRASIL. BUT AS THE
AFOREMENTIONED PREFRONTAL CONVECTION SURGES ACROSS CENTRAL BOLIVIA
ON FRIDAY-TO-SATURDAY...THE FOCUS OF THE CONVECTION ALONG THE SACZ
IS TO SHIFT WEST ACROSS MATO GROSSO IN CENTRAL BRASIL TO
RONDONIA/NORTHERN BOLIVIA LATER DURING THE WEEKEND.
MEANWHILE...HEAVY RAINS WILL CONTINUE TO BATTER  SOUTHERN MINAS
GERAIS/NORTHERN SAO PAULO AND RIO DE JANEIRO...WITH STORM TOTAL
AMOUNTS IN EXCESS OF 250MM HIGHLY LIKELY.

AS CONVECTION ALONG THE SACZ WEAKENS AND ACTIVITY ACROSS
BOLIVIA/NORTHWESTERN SOUTH AMERICA BECOMES BETTER ORGANIZED...THE
UPPER LEVEL CELL OF THE SUBTROPICAL RIDGE IS FORECAST TO RELOCATE
ACROSS THE CONTINENT...SHIFTING WESTWARD TO BOLIVIA/PERU AND
WESTERN BRASIL DURING THE WEEKEND. THE RELEASE OF LATENT HEAT
DURING THE DEEP CONVECTION WILL THEN FAVOR THE GRADUAL
INTENSIFICATION OF THIS RIDGE EARLY NEXT WEEK.
THIS...IN-TURN...WILL THEN FAVOR AN UPPER DIVERGENT PATTERN THAT
IS TO VENT DEEP CONVECTION ALONG THE NEAR EQUATORIAL TROUGH. AS
THE PATTERN ALOFT EVOLVES...EXPECTING MODERATE TO HEAVY CONVECTION
ALONG THE NEAR EQUATORIAL TROUGH TO THEN SHIFT ACROSS PARA TO
AMAZONAS/RORAIMA IN BRASIL TO NORTHERN PERU/SOUTHERN COLOMBIA
WHILE ALSO HELPING SUSTAIN IN INCREASE IN ACTIVITY ACROSS ECUADOR.

DAVISON/GALVEZ...WPC (USA)
$$

624 
FXSA20 KWBC 251638
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1138 AM EST TUE JAN 25 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 25/16UTC: THE GLOBAL MODELS MAINTAIN
FAIRLY GOOD CONTINUITY WITH THE PREVIOUS FORECAST THROUGH THE
MEDIUM RANGE PERIOD...WITH PATTERN GRADUALLY TRANSITIONING TO A
MORE AMPLIFIED SINUSOIDAL WAVE PATTERN THROUGH EARLY DURING THE
MEDIUM RANGE PERIOD. CONSISTENT WITH PREVIOUS FORECASTS...A LONG
WAVE RIDGE IS TO BUILD ACROSS SOUTH AMERICA TO THE BELLINGSHAUSEN
SEA/ANTARCTIC PENINSULA EARLY ON FRIDAY MORNING. THIS WILL BE
FLANKED BY TWO HIGHLY AMPLIFIED LONG WAVE TROUGHS...WITH ONE OVER
THE EASTERN PACIFIC AND THE OTHER SPANNING BETWEEN THE
CENTRAL-WESTERN ATLANTIC. THE LATTER WILL BE THE SYSTEM OF CONCERN
DURING THE NEXT SEVERAL DAYS...EVOLVING FROM A BROAD TROUGH OVER
THE SOUTHWEST ATLANTIC EARLY IN THE CYCLE TO A HIGH AMPLITUDE
TROUGH EXTENDING INTO THE SOUTHEAST STATES OF BRASIL. AT LOW
LEVELS...THIS WILL COMBINE WITH A RIDGE BUILDING FROM THE SOUTH
ACROSS PATAGONIA IN ARGENTINA TO DRIVE A FRONT NORTH ACROSS
CENTRAL ARGENTINA LATER THIS EVENING/EARLY ON WEDNESDAY
MORNING...WHERE IT WILL MERGE WITH/REINFORCE AN OLD BOUNDARY TO
THE NORTH. A SOUTHERLY (PAMPERO) LOW LEVEL JET WILL THEN DRIVE THE
FRONT FARTHER NORTH WHILE FAVORING A RAPID CHANGE IN AIR MASS
ACROSS CENTRAL-NORTHERN ARGENTINA. THIS WOULD LIKELY FAVOR SQUALLY
SEVERE CONVECTION WHILE TRIGGERING HEAVY RAINFALL AMOUNTS.  WOULD
LIKELY RESULT IN SEVERE CONVECTION AS IT LIFTS ACROSS THE RIO DE
LA PLATA BASIN/CENTRAL ARGENTINA. INITIALLY THE MOST INTENSE IS
EXPECTED OVER URUGUAY-ENTRE RIOS/CENTRAL ARGENTINA. ON TUESDAY THE
ENVIRONMENTAL CONDITIONS BECOME HIGHLY FAVORABLE FOR A HEAVY
RAINFALL PRODUCING MCS TO DEVELOP BETWEEN NORTHWEST PROVINCES IN
ARGENTINA AND SOUTHERN BOLIVIA. THE FRONT IS TO THEN STALL ACROSS
SOUTHERN BRASIL-PARAGUAY/NORTHERN ARGENTINA ON THURSDAY...WITH THE
DEEPENING UPPER LEVEL TROUGH INDUCING THE FORMATION OF THE SOUTH
AMERICA CONVERGENCE ZONE (SACZ) TO THE NORTH OVER BRASIL. THIS
WILL LEAD TO SEVERAL DAYS OF EXTREME RAINFALL AMOUNTS ACROSS
PORTIONS OF PARANA/SANTA CATARINA AND SOUTHERN SAO PAULO...AS WELL
AS ACROSS CENTRAL/NORTHERN BOLIVIA TO THE SOUTHERN JUNGLE OF PERU.
ACTIVITY WILL THEN GRADUALLY WEAKEN BEGINNING ON SUNDAY AS THE
UPPER TROUGH BEGINS TO PULL TO THE EAST-SOUTHEAST.

UPSTREAM FROM THIS AXIS...THE MID/UPPER LEVEL RIDGE WILL HOLD ITS
GROUND OVER CHILE/ARGENTINA TO THE ANTARCTIC PENINSULA THROUGH AT
LEAST SATURDAY MORNING. THROUGH SUNDAY MORNING...UNDER PRESSURE
FROM THE LONG WAVE TROUGH TO THE WEST...THE RIDGE WILL THEN
RELOCATE ACROSS THE SOUTHERN CONE TO THE WESTERN ATLANTIC/WEDDELL
SEA. AS IT YIELDS...THE LONG WAVE TROUGH WILL THEN MOVE INLAND
ACROSS SOUTHERN CHILE TO PATAGONIA IN ARGENTINA...WHERE IT IS
EXPECTED TO DEEPEN. HOWEVER...DURING THIS PERIOD THE GLOBAL MODELS
START TO DIVERGE ON THE INTENSITY OF THIS TROUGH...WITH THE GFS
OVER CORRECTING IN FAVOR OF A DEEPER TROUGH THAN WHAT THE EUROPEAN
MODELS SUGGEST. VARIABILITY AMONG THE ENSEMBLE MEMBERS SUGGEST
THAT FURTHER CORRECTIONS ARE LIKELY DURING THE NEXT RUNS OF THE
GLOBAL MODELS...SO MEDIUM/LONG RANGE PATTERN CONFIDENCE IS LOWER
THAN NORMAL FOR SUCH A HIGHLY AMPLIFIED LONG WAVE FEATURE. OVER
THE SOUTHERN CONE MOST INTENSE CONVECTION WITH THIS SYSTEM IS
EXPECTED OVER SOUTHERN CHILE BETWEEN PUERTO MONTT AND ISLA DE
CHILOE...TRIGGERING MODERATE TO HEAVY RAINFALL AMOUNTS DURING THE
WEEKEND. ALTHOUGH LESSER AMOUNTS ARE EXPECTED ACROSS PATAGONIA TO
CENTRAL ARGENTINA...THERE IS A SLIGHT RISK OF SEVERE CONVECTION.
BUT THIS WILL BE HIGHLY DEPENDENT ON THE INTENSITY OF THE
MID/UPPER LEVEL TROUGH.

THE LONG WAVE PATTERN TRANSITION ACROSS THE SOUTHERN CONE IS TO
ALSO FAVOR UPPER FLOW PATTERN CHANGES ACROSS TROPICAL/SUBTROPICAL
SOUTH AMERICA. AT 250 HPA...CELL OF THE SUBTROPICAL INITIALIZED
OVER SOUTHERN/SOUTHEASTERN BRASIL AND THE WESTERN ATLANTIC IS
FORECAST TO GRADUALLY RELOCATE ACROSS MID SECTIONS OF SOUTH
AMERICA. THIS IS EXPECTED TO SLOWLY ROLL ACROSS PARAGUAY/NORTHERN
ARGENTINA AND BOLIVIA INTO THE EASTERN PACIFIC JUST SOUTH OF PERU
DURING THE WEEKEND. THIS...IN-TURN...ALLOWS A TUTT LOW OFF THE
NORTHEAST COAST OF BRASIL TO RETROGRESS INLAND AS THE RIDGE
SETTLES TO THE WEST. AS THE UPPER FLOW SPLITS BETWEEN THE RIDGE
AND THE RETROGRESSING UPPER LEVEL LOW/TROUGH THIS WILL FAVOR AN
UPPER DIVERGENT PATTERN THAT WILL VENT THE AFOREMENTIONED
CONVECTION ALONG THE SACZ OVER BRASIL-BOLIVIA. INITIALLY...THE
RIDGE IS TO ALSO ENHANCE CONVECTION ALONG THE SIERRA OF
PERU...RESULTING IN AREAS OF LOCALLY MODERATE/HEAVY RAINFALL
AMOUNTS. BUT AS THE UPPER FLOW EVOLVES...THE MODELS AGREE ON
CONVECTION SURGING BETWEEN GUAYAQUIL IN SOUTHWEST ECUADOR AND
NORTHERN PERU...WITH AN ENHANCED RISK OF HEAVY RAINFALL AMOUNTS ON
WEDNESDAY AND ONWARD. THE OPPOSITE IS EXPECTED TO THE EAST OF THE
ANDES...WHERE A NORTHERLY WIND SURGE ACROSS COLOMBIA TO EASTERN
ECUADOR/NORTHERN JUNGLE OF PERU WILL FAVOR A DRYING TREND DUE TO
ADIABATIC COMPRESSION...WHILE OVER THE CENTRAL/SOUTHERN JUNGLE OF
PERU ACTIVITY IS TO INTENSIFY AS ENHANCED BY THE LOW/MID LEVEL
NORTHERLY FLOW CONVERGING ALONG THE EASTERN SLOPES OF THE SIERRA.

DAVISON/GALVEZ...WPC (USA)
$$

123 
FXSA20 KWBC 241910
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
209 PM EST MON JAN 24 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 24/19UTC: AT MID/UPPER LEVELS THE
GLOBAL MODELS AGREE ON A GRADUAL PATTERN TRANSITION THROUGH THE
MEDIUM RANGE PERIOD. THIS WILL EVOLVE FROM A LOW AMPLITUDE/BROAD
MID LEVEL TROUGH SPANNING BETWEEN THE SOUTHERN CONE OF SOUTH
AMERICA AND THE WESTERN ATLANTIC EARLY IN THE FORECAST CYCLE...TO
A HIGHLY AMPLIFIED SINUSOIDAL LONG WAVE PATTERN TOWARDS THE END OF
THE WORKWEEK. SPEARHEADING THE TRANSITION...A RIDGE IS FORECAST TO
BUILD SOUTH ACROSS CHILE/ARGENTINA TO THE ANTARCTIC PENINSULA
EARLY ON THURSDAY. TWO LONG WAVE TROUGHS ARE TO FLANK THE
CONTINENTAL RIDGE...WITH ONE OVER THE PACIFIC TO EXTEND NORTH
BETWEEN 80W/90W TO 30S EXPECTED TO SLOWLY WEAKEN AS IT PRESSES
AGAINST THE CONTINENTAL RIDGE LATER IN THE WEEK...WHILE A HIGHER
AMPLITUDE TROUGH DEEPENS OVER THE WESTERN ATLANTIC TO THE
SOUTHERN/SOUTHEASTERN STATES OF BRASIL.

ACROSS CHILE AND ARGENTINA THE BUILDING MID LEVEL RIDGE IS TO
SUSTAIN A GRADUAL DRYING TREND...WITH A LOW LEVEL POLAR RIDGE TO
BUILD ACROSS THE SOUTHERN CONE ON TUESDAY THROUGH THURSDAY. THIS
WILL SUSTAIN A SOUTHERLY/PAMPERO LOW LEVEL JET THAT WILL THEN
DRIVE A SURFACE FRONT NORTH ACROSS ARGENTINA. THE BOUNDARY WILL
RACE ACROSS THE RIO DE LA PLATA BASIN/CENTRAL ARGENTINA LATER ON
TUESDAY...REACHING THE SOUTHERN STATES OF BRASIL-NORTHERN
ARGENTINA ON WEDNESDAY EVENING. MEANWHILE...ORGANIZED DEEP
CONVECTION IS TO CLUSTER ACROSS URUGUAY/RIO DE LA PLATA TO MENDOZA
IN ARGENTINA...WITH MODELS SHOWING A HEAVY RAINFALL PRODUCING MCS
LIKELY TO DEVELOP LATER THIS EVENING. THROUGH WEDNESDAY FOCUS OF
THE CONVECTION SHIFTS NORTH ACROSS SOUTHERN BRASIL-NORTHERN
ARGENTINA/SOUTHERN BOLIVIA...WITH MOST INTENSE CONVECTION
AFFECTING JUJUY/SALTA TO THE NORTHWEST OF ARGENTINA-SOUTHERN
BOLIVIA LATER ON WEDNESDAY/EARLY ON THURSDAY. THE FRONT IS TO THEN
STALL ACROSS RIO GRANDE DO SUL IN BRASIL-NORTHERN ARGENTINA LATER
IN THE WEEK...WHILE CONVECTION TO THE NORTH CLUSTERS ALONG A
TROUGH BETWEEN SOUTHEAST BRASIL...MATO GROSSO DO SUL AND NORTHERN
BOLIVIA. AS DEEP TROPICAL MOISTURE CLUSTERS ALONG THIS
BOUNDARY...IT IS FORECAST TO RAPIDLY INTENSIFY ON THURSDAY THROUGH
SATURDAY...EVOLVING INTO THE SOUTH AMERICA CONVERGENCE ZONE
(SACZ). ENVIRONMENTAL CONDITIONS WILL THEN BECOME HIGHLY FAVORABLE
FOR THE REGENERATION OF VERY INTENSE CONVECTIVE CLUSTERS AND
LIKELY TO RESULT IN SEVERAL DAYS OF HEAVY RAINFALL PRODUCING MESO
SCALE CONVECTIVE COMPLEXES.

AS THE MESO-SYNOPTIC PATTERN CHANGES TO THE SOUTH...UPPER LEVEL
FLOW PATTERN OVER THE CONTINENT IS TO ALSO CHANGE...WITH CELL OF
THE SUBTROPICAL RIDGE EXTENDING BETWEEN SOUTHERN/SOUTHEASTERN
BRASIL AND THE WESTERN ATLANTIC TO GRADUALLY RELOCATE ACROSS MID
SECTIONS OF SOUTH AMERICA TO THE NORTH COAST OF CHILE/OFF THE
SOUTH COAST OF PERU LATER IN THE WEEK. THIS...IN-TURN...ALLOWS A
TUTT LOW OFF THE NORTHEAST COAST OF BRASIL TO MOVE INLAND AS THE
RIDGE SETTLES TO THE WEST. AS THE UPPER FLOW SPLITS BETWEEN THE
RIDGE AND THE RETROGRESSING UPPER LEVEL LOW/TROUGH THIS WILL FAVOR
AN UPPER DIVERGENT PATTERN THAT WILL VENT THE AFOREMENTIONED
CONVECTION ALONG THE SACZ OVER BRASIL-BOLIVIA. INITIALLY...THE
RIDGE IS TO ALSO ENHANCE CONVECTION ALONG THE SIERRA OF
PERU...RESULTING IN AREAS OF LOCALLY MODERATE/HEAVY RAINFALL
AMOUNTS. BUT AS THE UPPER FLOW EVOLVES...THE MODELS AGREE ON
CONVECTION SURGING BETWEEN GUAYAQUIL IN SOUTHWEST ECUADOR AND
NORTHERN PERU...WITH AN ENHANCED RISK OF HEAVY RAINFALL AMOUNTS ON
WEDNESDAY-THURSDAY. THE OPPOSITE IS EXPECTED TO THE EAST OF THE
ANDES...WHERE A NORTHERLY WIND SURGE ACROSS COLOMBIA TO EASTERN
ECUADOR/NORTHERN JUNGLE OF PERU ARE MORE LIKELY TO SUSTAIN A
DRYING TREND DUE TO ADIABATIC COMPRESSION. SO TRENDING BACK TO A
SIMILAR UPPER PATTERN AS WE PREVIOUSLY EXPERIENCED DURING THE
MONTH OF DECEMBER.

DAVISON/GALVEZ...WPC (USA)
$$

290 
FXSA20 KWBC 211754
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1253 PM EST FRI JAN 21 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 21/18UTC: A MID/UPPER LEVEL RIDGE
OVER THE SOUTH PACIFIC...BUILDS SOUTH ALONG 130W TO 70S/80S EARLY
IN THE CYCLE. IN A SINUSOIDAL PATTERN...AS THE RIDGE BUILDS TO THE
WEST...IT IS INDUCING THE NORTHWARD AMPLIFICATION OF A LONG WAVE
TROUGH ACROSS THE SOUTHEAST PACIFIC. THE TROUGH REACHES MAXIMUM
AMPLITUDE EARLY ON SATURDAY MORNING...WHEN IT IS TO EXTEND NORTH
ALONG 83W TO 20S. AS IT DEEPENS...THE LONG WAVE TROUGH WILL STEER
A SHORT WAVE PERTURBATION ACROSS SOUTHERN/CENTRAL CHILE TO
PATAGONIA/LA PAMPA IN ARGENTINA EARLY IN THE CYCLE. AT 250 HPA...A
SUBTROPICAL JET MAXIMA IS TO ACCOMPANY THE SHORT WAVE TROUGH AS IT
STREAMS ACROSS THE SOUTHERN CONE...WITH DIVERGENCE ON ITS LEFT
ENTRANCE REGION TO VENT CONVECTIVE DEVELOPMENT ACROSS CENTRAL
ARGENTINA. AT LOW LEVELS...A NORTHERLY JET ACROSS EASTERN
BOLIVIA/PARAGUAY WILL FAVOR A WARM/MOIST ADVECTIVE PATTERN...WITH
DEEP MOISTURE CONVERGING ALONG A MEANDERING FRONT TO THE SOUTH.
THE INFLOW OF MID LEVEL SHORT WAVE ENERGY AND FAVORABLE UPPER
LEVEL JET DYNAMICS WILL HELP SUSTAIN A ROUND OF ORGANIZED DEEP
CONVECTION ACROSS CENTRAL ARGENTINA...WITH OUR SEVERE WEATHER
INDICATORS SHOWING A HIGH RISK OF LARGE HAIL PRODUCING SEVERE
THUNDERSTORMS DURING THE NEXT COUPLE OF DAYS. MOST INTENSE IS
EXPECTED TODAY WITH MAXIMA OF 75-125MM IN A LARGE AREA BETWEEN THE
BUENOS AIRES PROVINCE AND MENDOZA IN ARGENTINA. ON SATURDAY
EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 40-80MM.

THROUGH THE WEEKEND THE TROUGH WILL SLOWLY MOVE EAST ACROSS THE
SOUTHERN/CENTRAL REGIONS OF CHILE TO ARGENTINA...WITH AXIS TO THEN
DAMPEN AS IT PRESSES AGAINST A BROAD CELL OF THE SUBTROPICAL RIDGE
TO THE EAST. SECONDARY VORTICES ARE TO FOLLOW...WITH SHORT WAVE
PERTURBATIONS LIFTING ACROSS THE DRAKE PASSAGE TO THE SOUTHERN
REGIONS OF CHILE. AT LOW LEVELS...THE LONG WAVE AXIS WILL SUSTAIN
A BROAD TROUGH OVER THE SOUTHEAST PACIFIC EARLY ON SATURDAY. AS IT
MEANDERS ACROSS THE SOUTHERN CONE...SHORT WAVE POLAR PERTURBATIONS
ARE TO THEN LIFT ACROSS THE SOUTHEAST PACIFIC TO THE SOUTHERN
REGIONS OF CHILE DURING THE NEXT FEW DAYS...WITH A STRONG VORTEX
ENTERING THE DRAKE PASSAGE/SOUTHERN REGIONS OF CHILE EARLY ON
TUESDAY. OVER THE ATLANTIC...THE CONSENSUS AMONG THE GLOBAL MODEL
GUIDANCE IS THAT THIS SYSTEM WILL INTENSIFY BETWEEN THE
MALVINAS/FALKLAND ISLANDS AND THE SOUTH GEORGIA ISLANDS THROUGH
THE MIDDLE OF NEXT WEEK. AS THE POLAR MID/UPPER LEVEL TROUGH
RELOCATES ACROSS THE SOUTHERN CONE...A BRANCH OF THE NORTHERN
POLAR IS TO ACCOMPANY THIS AXIS AS IT TRAVERSES THE CONTINENT.
THIS WILL CONTRIBUTE TO AN UPPER LEVEL ENVIRONMENT FAVORABLE AND
CONDUCIVE TO ANOTHER ROUND OF ORGANIZED DEEP CONVECTION.

AT LOW LEVELS...THE UPPER LEVEL AXIS WILL SUSTAIN A BROAD TROUGH
ACROSS THE SOUTHEAST PACIFIC/BELLINGSHAUSEN SEA LATER THIS
AFTERNOON...WITH AXIS TO THEN SLOWLY PULL ACROSS THE SOUTHERN CONE
TO THE SOUTHWEST ATLANTIC LATER ON SUNDAY. BUILDING POLAR RIDGE TO
THE SOUTH AND WEST ON TUESDAY IS TO THEN SUSTAIN THE AMPLIFICATION
OF THE LOW LEVEL POLAR TROUGH OVER THE SOUTH GEORGIA ISLANDS/SOUTH
ATLANTIC BY THE MIDDLE OF NEXT WEEK. AS IT MEANDERS ACROSS THE
SOUTHERN...POLAR FRONTS ARE TO REVOLVE AROUND THIS AXIS. INITIALLY
THESE ARE TO FOCUS DEEP SUBTROPICAL MOISTURE ACROSS THE SOUTHERN
REGIONS OF CHILE..TO SUSTAIN SEVERAL DAYS OF MODERATE TO HEAVY
RAINFALL AMOUNTS...WITH DAILY MAXIMA PEAKING AT 20-45MM/DAY
THROUGH SUNDAY MORNING...WITH AN ADDITIONAL 20-35MM/DAY ON SUNDAY
TO MONDAY. OVER CENTRAL ARGENTINA THIS WILL THEN HELP REINFORCE AN
OLD BOUNDARY TO THE NORTH...AS THE LATTER MEANDERS ACROSS THE
BUENOS AIRES PROVINCE/CENTRAL ARGENTINA. THE ENSUING GRADIENT IS
TO CONTINUE FAVORING SEVERAL DAYS OF MODERATE RAINFALL
AMOUNTS...WITH A SURGE IN ACTIVITY ON SUNDAY AS ENHANCED BY THE
UPPER LEVEL JET. THIS WILL THEN PERSIST THROUGH THE MIDDLE OF NEXT
WEEK WITH POTENTIAL FOR HIGHER AMOUNTS ON TUESDAY-WEDNESDAY AS A
SECONDARY FRONT SURGES ACROSS PATAGONIA TO CENTRAL ARGENTINA.

NORTH OVER THE CONTINENT...AT 250 HPA...CELL OF THE SUBTROPICAL
RIDGE CONFINES TO SOUTHERN BRASIL-PARAGUAY-NORTHERN ARGENTINA. AN
ELONGATED TUTT BOUNDS THE NORTHERN FRINGES OF THIS RIDGE...WITH
AXIS WEST ALONG 10S/12S TO CENTRAL BRASIL. SHORT WAVE VORTICES
REVOLVING AROUND THE RIDGE TO THE SOUTH WILL THEN FEED INTO THIS
AXIS. THROUGH EARLY NEXT WEEK THESE ARE TO THEN SUSTAIN THE
FORMATION OF A CLOSED TUTT LOW OVER THE WESTERN TROPICAL ATLANTIC
TO THE EAST OF VITORIA/RIO DE JANEIRO IN BRASIL. THIS REACHES
MAXIMUM INTENSITY ON MONDAY. UNDER THE STEERING INFLUENCE OF THE
RIDGE TO THE SOUTH THE CLOSED LOW WILL THEN MEANDER WESTWARD
ACROSS RIO DE JANEIRO/ESPIRITO SANTO TO MINAS GERAIS. THE UPPER
LEVEL COLD CORE TROUGH WILL ENHANCE CONVECTIVE INSTABILITY ALONG
THE NEAR EQUATORIAL TROUGH OVER NORTHERN BRASIL. THROUGH SUNDAY
ACTIVITY IS TO BECOME MORE WIDESPREAD AND BETTER ORGANIZED ACROSS
NORTHEAST BRASIL...WITH ACTIVITY TO THEN BUILD WESTWARD ACROSS
EQUATORIAL SOUTH AMERICA. FURTHERMORE...UNDER THE INFLUENCE OF THE
RETROGRESSING UPPER LEVEL LOW...CONVECTION IS TO ALSO INCREASE TO
THE SOUTH ACROSS BAHIA TO TOCANTINS/GOIAS THROUGH THE MIDDLE OF
THE WEEK.

DAVISON/GALVEZ...WPC (USA)
$$

993 
FXSA20 KWBC 201909
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
208 PM EST THU JAN 20 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 20/19UTC: UNDER THE INFLUENCE OF A
MID/UPPER LEVEL RIDGE TO THE WEST...THE GLOBAL MODELS CONSISTENTLY
FORECAST A LONG WAVE TROUGH TO AMPLIFY OVER THE SOUTHEAST PACIFIC
EARLY IN THE CYCLE...WITH THE LONG WAVE AXIS BOTTOMING OUT JUST
SOUTH OF 30S EARLY ON FRIDAY MORNING. THE DEEPENING LONG WAVE
TROUGH WILL INTERACT WITH A SHORT WAVE PERTURBATION OFF THE
CENTRAL COAST OF CHILE. THE SHORT WAVE TROUGH CENTERS ON A CLOSED
LOW JUST WEST OF CONCEPCION/TEMUCO IN CENTRAL CHILE. AS THE LONG
WAVE AXIS DEEPENS...IT WILL DISPLACE THE SHORT WAVE TROUGH EAST
ACROSS CENTRAL ARGENTINA/PATAGONIA. THROUGH THE WEEKEND THE TROUGH
IS TO THEN FOCUS ITS SHORT WAVE ENERGY ACROSS SOUTHERN CHILE INTO
ARGENTINA WHILE MEANDERING EAST ACROSS THE SOUTHERN CONE. AXIS IS
TO THEN EVOLVE INTO A BROAD TROUGH OVER THE SOUTHWEST ATLANTIC
EARLY NEXT WEEK. A SUBTROPICAL JET MAXIMA IS TO ACCOMPANY THE
SHORT WAVE TROUGH AS IT STREAMS ACROSS CHILE TO ARGENTINA...WITH A
FINGER OF THE NORTHERN POLAR TO ENTER THE SOUTHERN CONE AHEAD OF
THE LONG WAVE TROUGH DURING THE WEEKEND. THESE JETS ARE TO
GENERALLY FAVOR AN UPPER DIVERGENT PATTERN OVER CENTRAL
ARGENTINA/RIO DE LA PLATA BASIN...VENTING ORGANIZED DEEP
CONVECTION DURING THE NEXT FEW DAYS.

AT LOW LEVELS...A THERMAL TROUGH EXTENDS ALONG THE LEE OF THE
ANDES BETWEEN NORTHERN BOLIVIA AND NORTHWEST ARGENTINA. THIS
FAVORS A MOIST/WARM NORTHERLY FLOW ACROSS PARAGUAY TO NORTHERN
ARGENTINA...WITH MOISTURE CONVERGING ALONG A MEANDERING FRONT OVER
LA PAMPA/CENTRAL ARGENTINA. AS ENHANCED BY THE SHORT WAVE TROUGH
AND UPPER LEVEL JET MAXIMA...THE ENVIRONMENTAL CONDITIONS ARE
FAVORABLE FOR SEVERE WEATHER PRODUCING MCS TO FORM ACROSS CENTRAL
ARGENTINA DURING THE NEXT THREE DAYS...WITH MOST INTENSE TODAY TO
SUSTAIN MAXIMA OF 75-125MM. THROUGH SATURDAY THIS WEAKENS TO
40-80MM.

UNDER THE INFLUENCE OF THE DEEPENING LONG WAVE TROUGH TO THE
WEST...ANOTHER FRONT ENTERS SOUTHERN CHILE ON FRIDAY...SURGING
ACROSS PATAGONIA TO CENTRAL ARGENTINA DURING THE WEEKEND. THIS
WILL LEAD TO SEVERAL DAYS OF MODERATE RAINFALL AMOUNTS...WITH
MAXIMA OF 20-35MM/DAY EXPECTED THROUGH SUNDAY. OTHER CONVECTION
WITH THIS FEATURE IS EXPECTED OVER CENTRAL ARGENTINA...WHERE THE
SURGING BOUNDARY IS TO ALSO TRIGGER MODERATE RAINFALL AMOUNTS ON
SUNDAY...WITH MAXIMA OF 20-35MM. HIGHER AMOUNTS...HOWEVER...ARE
FORECAST ALONG THE LEE OF THE ANDES OVER NORTHWEST
ARGENTINA...WITH MAXIMA OF 35-70MM.

SIMULTANEOUSLY...THE LONG WAVE TROUGH...AS IT SETTLES OVER THE
EASTERN PACIFIC...IT WILL SUSTAIN A SURFACE FRONT OVER SOUTHERN
CHILE TO PATAGONIA IN ARGENTINA ON FRIDAY. THIS FRONT IS FORECAST
TO STALLS OVER PATAGONIA...WHILE MORE PROGRESSIVE FRONTAL
BOUNDARIES FOCUSING ACROSS THE SOUTHERN REGIONS OF CHILE/TIERRA
DEL FUEGO AS THEY LIFT ACROSS THE SOUTHEAST PACIFIC. IN RESPONSE
TO THE INFLOW OF SHORT WAVE ENERGY...SCATTERED CONVECTION IS TO
AFFECT SOUTHERN CHILE FROM FRIDAY THROUGH MONDAY...WITH DAILY
MAXIMA PEAKING AT 20-35MM. HOWEVER...DUE TO STRONG TOPOGRAPHICAL
FORCING...LOCALLY HIGHER AMOUNTS ARE HIGHLY PROBABLE ACROSS THE
SOUTHERN ANDES AND THE OFFSHORE ISLANDS SOUTH OF CHILE.

NORTH OF THE POLAR TROUGH...OVER NORTHERN SOUTH AMERICA...THE
UPPER LEVEL FLOW SPLITS BETWEEN A CELL OF THE SUBTROPICAL RIDGE
AND A TUTT TO THE NORTH. THE SUBTROPICAL RIDGE WILL CONFINE TO THE
SOUTHERN/SOUTHEAST STATES OF BRASIL WHILE CENTERING ON A CLOSED
HIGH OVER RIO GRANDE DO SUL. THE UPPER LEVEL
TROUGH/TUTT...MEANWHILE...WILL EXTEND WEST ALONG 10S TO MATO
GROSSO/RONDONIA IN BRASIL. THIS PATTERN WILL PERSIST NEARLY
UNCHANGED DURING THE NEXT FEW DAYS. THE RIDGE ALOFT WILL VENT
DIURNAL CONVECTION CLUSTERING ALONG THE SIERRA BETWEEN
PARANA/SANTA CATARINA IN BRASIL AND SAOPAULO...WITH RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM/DAY. MOST ACTIVE IN
THIS AREA IS EXPECTED OVER THE NEXT THREE DAYS. THE TUTT TO THE
NORTH...MEANWHILE...IS TO INTERACT WITH THE NEAR EQUATORIAL TROUGH
OVER NORTHERN BRASIL. INITIALLY MOST ACTIVE IS EXPECTED BETWEEN
AMAZONAS IN BRASIL AND THE NORTHERN JUNGLE OF PERU/SOUTHERN
COLOMBIA...WITH RAINFALL MAXIMA OF 20-45MM/DAY. THROUGH SATURDAY
THIS WEAKENS TO 20-35MM/DAY. MEANWHILE...ACTIVITY ACROSS NORTHEAST
BRASIL IS TO GRADUALLY BECOME MORE ACTIVE AND BETTER
ORGANIZED...WITH CONVECTION IN THIS AREA INCREASING FROM
15-20MM/DAY EARLY IN THE CYCLE TO MAXIMA OF 20-35MM/DAY ON
SATURDAY TO SUNDAY.

DAVISON/GALVEZ...WPC (USA)
$$

210 
FXSA20 KWBC 191820
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
120 PM EST WED JAN 19 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 19/18UTC: THE MID/UPPER LEVEL
ANALYSIS SHOWS A SHORT WAVE TROUGH ON THE NORTHERN STREAM
MEANDERING OFF THE CENTRAL COAST OF CHILE...WITH AXIS ANCHORING ON
A CLOSED LOW JUST WEST OF CONCEPCION/TEMUCO CHILE. THIS WILL
REMAIN NEARLY STATIONARY AND UNCHANGED THROUGH MID AFTERNOON ON
THURSDAY...THEN START TO WEAKEN WHILE SHEARING EAST AHEAD OF A
DEEPENING LONG WAVE TROUGH. THE LONG WAVE TROUGH WILL THEN BECOME
THE DOMINANT FEATURE OVER THE EASTERN PACIFIC LATER ON FRIDAY.
UNDER THE STEERING INFLUENCE OF A BUILDING RIDGE TO THE
WEST...PROGRESSIVE SHORT WAVE PERTURBATIONS ARE TO THEN LIFT
ACROSS THE SOUTHEAST PACIFIC INTO THE SOUTHERN CONE. AT 250 HPA
THESE ARE TO FOCUS A SUBTROPICAL JET ACROSS CENTRAL CHILE INTO LA
PAMPA/BUENOS AIRES PROVINCE IN ARGENTINA. AS THE UPPER LEVEL JET
PATTERN HOLDS...IT WILL SUSTAIN A DIVERGENT PATTERN ACROSS CENTRAL
ARGENTINA/RIO DE LA PLATA BASIN. AT LOW LEVELS...THE SHORT WAVE
TROUGH WILL INTERACT WITH A MEANDERING FRONT OVER CENTRAL
ARGENTINA...WITH INFLOW OF COLD AIR ALOFT ENHANCING DEEP LAYER
CONVECTIVE INSTABILITY BETWEEN NORTHERN PATAGONIA AND THE BUENOS
AIRES PROVINCE. THIS WILL LEAD TO SEVERAL DAYS OR ORGANIZED DEEP
CONVECTION...WITH CONVECTION SURGING TO 75-125MM IN POTENTIALLY
SEVERE WEATHER ON THURSDAY. HEAVY RAINS WILL THEN PERSIST THROUGH
SATURDAY WITH DAILY MAXIMA OF 40-80MM.

SIMULTANEOUSLY...THE LONG WAVE TROUGH...AS IT SETTLES OVER THE
EASTERN PACIFIC...IT WILL SUSTAIN A SURFACE FRONT OVER SOUTHERN
CHILE TO PATAGONIA IN ARGENTINA ON FRIDAY. THIS FRONT IS FORECAST
TO STALLS OVER PATAGONIA...WHILE MORE PROGRESSIVE FRONTAL
BOUNDARIES FOCUSING ACROSS THE SOUTHERN REGIONS OF CHILE/TIERRA
DEL FUEGO AS THEY LIFT ACROSS THE SOUTHEAST PACIFIC. IN RESPONSE
TO THE INFLOW OF SHORT WAVE ENERGY...SCATTERED CONVECTION IS TO
AFFECT SOUTHERN CHILE FROM FRIDAY THROUGH MONDAY...WITH DAILY
MAXIMA PEAKING AT 20-35MM. HOWEVER...DUE TO STRONG TOPOGRAPHICAL
FORCING...LOCALLY HIGHER AMOUNTS ARE HIGHLY PROBABLE ACROSS THE
SOUTHERN ANDES AND THE OFFSHORE ISLANDS SOUTH OF CHILE.

NORTH OVER THE CONTINENT...AT 250 HPA...THE UPPER FLOW SPLITS
BETWEEN A CELL OF THE SUBTROPICAL RIDGE THAT MEANDERS BETWEEN
SOUTHERN BRASIL/URUGUAY/ AND NORTHWEST ARGENTINA AND BOLIVIA...AND
A TUTT OVER NORTHEAST BRASIL. THE LATTER IS TO CENTER ON A CLOSED
LOW NEAR 12S 37W. THROUGH SATURDAY THE RIDGE STRENGTHEN ITS
FOOTHOLD ON THE SOUTHERN/SOUTHEAST STATES OF BRASIL...WHILE THE
TROUGH ALOFT AMPLIFIES TO CENTRAL BRASIL ALONG 10S/12S. THE RIDGE
ALOFT WILL VENT DEEP CONVECTION ACROSS CENTRAL BOLIVIA...THE
SOUTHERN JUNGLE OF PERU/ACRE IN BRASIL...WITH RAINFALL AMOUNTS OF
10-15MM/DAY AND DAILY MAXIMA OF 20-45MM. THE TROUGH ALOFT WILL
ENHANCE CONVECTION ACROSS EQUATORIAL SOUTH AMERICA...WITH FOCUS OF
THE MOST INTENSE BETWEEN PARA/AMAZONAS IN BRASIL AND THE NORTHERN
JUNGLE OF PERU/EASTERN ECUADOR. IN THIS AREA INITIALLY EXPECTING
MAXIMA OF 20-45MM/DAY...GRADUALLY WEAKENING TO 20-35MM/DAY LATER
IN THE WEEK.

DAVISON/GALVEZ...WPC (USA)
$$

013 
FXSA20 KWBC 181814
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
114 PM EST TUE JAN 18 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 18/18UTC: THE DETERMINISTIC AND THE
GLOBAL ENSEMBLE MEMBERS ARE IN EXCELLENT AGREEMENT IN THEIR
FORECAST OF A NORTHERN STREAM SHORT WAVE TROUGH THAT FORMS OFF THE
CENTRAL COAST OF CHILE EARLY IN THE CYCLE...WITH AXIS TO CENTER ON
A MEANDERING LOW NEAR TEMUCO. THIS IS TO REMAIN NEARLY STATIONARY
THROUGH THURSDAY MORNING...THEN RAPIDLY WEAKEN WHILE SHEARING EAST
AHEAD OF A DEEPENING LONG WAVE TROUGH TO THE WEST. AT 250
HPA...MEANWHILE...A SUBTROPICAL JET MAXIMA ROUNDING THE BASE OF
THE TROUGH IS TO EXTEND ACROSS CENTRAL CHILE INTO THE CENTRAL
PROVINCES IN ARGENTINA. AS THE MID/UPPER LEVEL VORTEX SHEARS
ACROSS THE CENTRAL ANDES INTO ARGENTINA...THIS WILL THEN DRAW THE
JET MAXIMA EASTWARD ACROSS THE SOUTHERN CONE LATER IN THE WEEK.
MEANWHILE...THE JET ALOFT IS TO FAVOR A DIVERGENT PATTERN BETWEEN
THE BUENOS AIRES PROVINCE AND THE CENTRAL PROVINCES IN ARGENTINA.

AT LOW LEVELS...A MEANDERING/QUASISTATIONARY FRONT WILL TRAIL
ACROSS THE WESTERN SOUTH ATLANTIC INTO THE RIO DE LA PLATA
BASIN/CENTRAL ARGENTINA. A NORTHERLY LOW LEVEL FLOW ACROSS
PARAGUAY WILL FAVOR A WARM/MOIST ADVECTIVE PATTERN THAT IS TO
CONVERGE ALONG THE MEANDERING FRONT TO THE SOUTH. THIS BOUNDARY
WILL BE THE FOCUS FOR ORGANIZED DEEP CONVECTION...WITH MOST ACTIVE
TO INITIALLY BUILD ACROSS URUGUAY-ENTRE RIOS ARGENTINA...WITH
RAINFALL MAXIMA OF 40-80MM IN POTENTIALLY SEVERE CONVECTION. ON
WEDNESDAY THIS DECREASES TO 20-45MM/DAY WHILE THE RISK OF SEVERE
CONVECTION PERSISTS...WITH A SECONDARY MAXIMA OF 20-35MM ACROSS LA
PAMPA TO NORTHERN PATAGONIA. ON THURSDAY...ACTIVITY SURGES ACROSS
THE SOUTHERN CONE AS THE MID LEVEL VORTEX SPILLS ACROSS THE
SOUTHERN ANDES...SUSTAINING A FRONTAL LOW OVER PATAGONIA. IN
RESPONSE...CONVECTION OVER PATAGONIA AND LA PAMPA INCREASES TO
20-45MM...WHILE OVER CENTRAL ARGENTINA/BUENOS AIRES PROVINCE IT
SURGES TO 40-80MM.

THROUGH FRIDAY A HIGHER AMPLITUDE/LONG WAVE TROUGH WILL THEN TAKE
ITS PLACE OVER THE EASTERN PACIFIC...WITH THE MID LEVEL TROUGH TO
AMPLIFY NORTH BETWEEN 100W-80W TO 30S EARLY ON FRIDAY MORNING.
THIS IS TO THEN SLOWLY MOVE EAST ALONG 80W EARLY ON
SATURDAY...FOCUSING ITS SHORT WAVE ENERGY ACROSS SOUTHERN/CENTRAL
CHILE INTO CENTRAL ARGENTINA. AT LOW LEVELS THIS WILL SUSTAIN
ANOTHER FRONT THAT ENTERS THE SOUTHERN REGIONS OF CHILE LATER ON
FRIDAY...AND ACROSS PATAGONIA TO LA PAMPA IN ARGENTINA LATER ON
SATURDAY/EARLY ON SUNDAY MORNING. OVER SOUTHERN CHILE THIS WILL
SUSTAIN MODERATE CONVECTION ON FRIDAY WITH MAXIMA OF 15-25MM. ON
SATURDAY THIS INCREASES TO 20-35MM AS THE LONG WAVE AXIS SUSTAINS
A MOIST SUBTROPICAL FLOW ACROSS THE EASTERN SOUTH PACIFIC. OVER
CENTRAL ARGENTINA THE ENVIRONMENTAL CONDITIONS ARE TO ONCE AGAIN
BECOME HIGHLY FAVORABLE FOR MCS FORMATION...WITH HEAVY RAINS
EXPECTED BETWEEN CORDOBA AND THE BUENOS AIRES PROVINCE ON SATURDAY
AND SUNDAY. RAINFALL MAXIMA ON BOTH DAYS IS TO PEAK AT
40-80MM...WITH SOME OF THE MODELS SHOWING LOCALLY HIGHER RAINFALL
AMOUNTS.

NORTH OVER THE CONTINENT...AT 250 HPA...THE UPPER FLOW SPLITS
BETWEEN A CELL OF THE SUBTROPICAL RIDGE THAT MEANDERS OVER
SOUTHERN BRASIL-URUGUAY/NORTHERN ARGENTINA AND BOLIVIA...AND A
TUTT OVER NORTHEAST BRASIL. THE LATTER IS TO CENTER ON A CLOSED
LOW NEAR 10S 40W. THE RIDGE ALOFT WILL VENT DEEP CONVECTION ACROSS
CENTRAL BOLIVIA...THE SOUTHERN JUNGLE OF PERU/ACRE IN
BRASIL...WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND DAILY MAXIMA OF
20-45MM. THE TROUGH ALOFT WILL ENHANCE CONVECTION ACROSS
EQUATORIAL SOUTH AMERICA...WITH FOCUS OF THE MOST INTENSE RAPIDLY
SHIFTING FROM PARA/AMAPA EARLY IN THE CYCLE TO AMAZONAS AND THE
NORTHERN JUNGLE OF PERU ON WEDNESDAY AND THURSDAY...WITH DAILY
MAXIMA OF 20-45MM. LATER IN THE WEEK THIS WEAKENS TO 20-35MM/DAY..

DAVISON/GALVEZ...WPC (USA)
$$

984 
FXSA20 KWBC 131659
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1158 AM EST THU JAN 13 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON TUESDAY JANUARY 18.

FORECAST DISCUSSION FROM JAN 13/17UTC: AT 1550 UTC...THE REMNANTS
OF A SUBTROPICAL STORM OVER THE EASTERN PACIFIC CENTERED NEAR 37S
82W. THROUGH THIS EVENING THIS WILL PHASE WITH A DEEPENING MID
LEVEL TROUGH OVER THE SOUTHEAST PACIFIC...WITH AXIS TO ACCELERATE
ACROSS THE SOUTHERN CONE TO THE WESTERN SOUTH ATLANTIC EARLY ON
FRIDAY MORNING. AT LOW LEVELS...THE MID LEVEL TROUGH WILL SUSTAIN
A SURFACE FRONT THAT SURGES ACROSS SOUTHERN PATAGONIA IN
ARGENTINA/SOUTHERN CHILE LATER TODAY. AS IT PHASES WITH THE
REMNANTS OF THE STORM...THE INFLOW OF SUBTROPICAL MOISTURE WILL
HELP SUSTAIN HEAVY RAINFALL AMOUNTS...WITH ACCUMULATION OF
75-125MM. THIS IS TO ALSO FAVOR STRONG BOUNDARY LAYER WINDS OF
35-45KT ACROSS THE SOUTHERN REGIONS OF CHILE INTO PATAGONIA IN
ARGENTINA.

A BUILDING MID/UPPER LEVEL RIDGE TO THE WEST THEN SETS THE STAGE
FOR A DEEPER TROUGH TO FOLLOW. UNDER THE INFLUENCE OF THE RIDGE
THE TROUGH AMPLIFIES TO THE NORTH-NORTHWEST ACROSS THE
BELLINGSHAUSEN SEA TO 40S 90W EARLY ON SATURDAY MORNING. THROUGH
SUNDAY THE INFLOW OF SHORT WAVE ENERGY AND COLD AIR WILL HELP
SUSTAIN THE FURTHER INTENSIFICATION OF THIS TROUGH AS IT MOVES
ACROSS THE SOUTHERN CONE. EARLY NEXT WEEK IT WILL SPLIT IN TWO
DISTINCT CLOSED CIRCULATIONS...WITH ONE NEAR THE SOUTH GEORGIA
ISLANDS AND THE OTHER NEAR TEMUCO/CONCEPCION CHILE. THE LATTER
WILL THEN ANCHOR A SHORT WAVE TROUGH OFF THE CENTRAL/NORTHERN
COAST OF CHILE THROUGH THE MIDDLE OF THE WEEK. A NORTHERN POLAR
JET MAXIMA IS TO ACCOMPANY THIS TROUGH AS IT AMPLIFIES ACROSS THE
SOUTHERN CONE...WITH DIVERGENCE ON ITS LEFT ENTRANCE REGION TO
VENT ORGANIZED DEEP CONVECTION DURING THE LATER PERIODS.

AT LOW LEVELS...THE CORRESPONDING SURFACE CYCLONE DEEPENS TO A
CLOSED 990 HPA LOW AS IT NEARS TIERRA DEL FUEGO/EXTREME SOUTHERN
REGION OF CHILE LATER ON FRIDAY EVENING...WITH LITTLE CHANGE IN
INTENSITY AS IT NEARS THE MALVINAS/FALKLAND ISLANDS LATER ON
SATURDAY. ON SUNDAY TO MONDAY THE LOW IS TO THEN EXPERIENCE AN
EXPLOSIVE RATE OF INTENSIFICATION AS IT MOVES ACROSS THE SOUTH
GEORGIA ISLANDS TO THE CENTRAL SOUTH ATLANTIC...DEEPENING FROM A
986 HPA LOW SUNDAY TO A 952 HPA LOW ON MONDAY. THE DEEPENING
FRONTAL LOW WILL COMBINE WITH A BUILDING POLAR RIDGE TO THE WEST
TO DRIVE THE ASSOCIATED FRONT NORTH ACROSS PATAGONIA TO LA PAMPA
IN ARGENTINA EARLY ON SUNDAY MORNING...WITH BOUNDARY TO BRIEFLY
STALL ACROSS THE RIO DE LA PLATA BASIN-MENDOZA IN ARGENTINA ON
MONDAY. BUT DRIVEN BY A SOUTHERLY WIND SURGE...THE FRONT RACES
ACROSS NORTHWEST ARGENTINA TO SOUTHERN BOLIVIA ON
TUESDAY-WEDNESDAY MORNING. AS IT RACES ACROSS NORTHERN ARGENTINA
THIS IS LIKELY TO TRIGGER A SEVERE WEATHER PRODUCING PREFRONTAL
SQUALL LINE. OVER SOUTHERN CHILE THIS WILL SUSTAIN MODERATE
TOHEAVY RAINFALL AMOUNTS ON FRIDAY AND SATURDAY...WITH MAXIMA OF
25-50MM IN MIXED PRECIPITATION OF RAIN AND SNOW SHOWERS. OVER
CENTRAL ARGENTINA/RIO DE LA PLATA BASIN THIS IS LIKELY TO TRIGGER
SEVERE THUNDERSTORMS...WITH RAINFALL MAXIMA INCREASING FROM
15-20MM ON SATURDAY TO 25-50MM ON SUNDAY. EARLY NEXT WEEK
CONVECTION BECOMES BETTER ORGANIZED WHILE BUILDING NORTH ACROSS
URUGUAY TO NORTHERN ARGENTINA...WITH RAINFALL MAXIMA OF 75-125MM.
ON TUESDAY THIS INCREASES TO 75-150MM WHILE BUILDING NORTH ACROSS
NORTHWEST ARGENTINA TO SOUTHERN BOLIVIA...WHILE OVER URUGUAY/ENTRE
RIOS THE MAXIMA PEAKS AT 35-70MM. 

AT 250 HPA...THE DEEPENING POLAR TROUGH TO THE SOUTH WILL PRESS
AGAINST A WANING CELL OF THE SUBTROPICAL RIDGE TO THE NORTH. THE
RIDGE SPANS BETWEEN CENTRAL ARGENTINA AND WESTERN BOLIVIA/SOUTHERN
SIERRA OF PERU. A RETROGRESSING UPPER LEVEL TROUGH BOUNDS THE
EASTERN FRINGES OF THIS RIDGE WHILE CENTERING ON A CLOSED LOW OVER
SANTA CRUZ IN EASTERN BOLIVIA. UNDER PRESSURE FROM THE POLAR
TROUGH THE RIDGE IS TO GRADUALLY WEAKEN...AND THE UPPER LEVEL
TROUGH IS TO FILL AS IT RETROGRESSES ACROSS BOLIVIA TO SOUTHERN
PERU. LATER DURING THE WEEKEND AN OPEN/LOW AMPLITUDE RIDGE WILL
REMAIN OVER MID SECTIONS OF SOUTH AMERICA. MEANWHILE...THE RIDGE
ALOFT WILL VENT DIURNAL CONVECTION ALONG THE NORTHERN ANDES OF
CHILE/ARGENTINA...WITH DAILY MAXIMA OF 10-15MM/DAY. THE
RETROGRESSING UPPER LEVEL TROUGH...AS IT WEAKENS...WILL INITIALLY
TRIGGER MODERATE RAINFALL AMOUNTS ACROSS SOUTHEAST BRASIL WITH
MAXIMA OF 20-35MM. OVER CENTRAL BOLIVIA AND SOUTHERN JUNGLE OF
PERU THIS INCREASES TO 20-45MM ON FRIDAY...THEN RAPIDLY WEAKEN ON
SATURDAY. SIMULTANEOUSLY...A WANING TUTT LOW IS TO ALSO RETROGRESS
ACROSS THE NORTHEAST STATES OF BRASIL. EARLY IN THE CYCLE THIS
WILL INTERACT WITH THE ATLANTIC ITCZ TO TRIGGER MODERATE
CONVECTION ACROSS NORTHEAST BRASIL...WITH ACTIVITY TO WEAKEN AS IT
SPREADS WEST ALONG THE NEAR EQUATORIAL TROUGH ACROSS PARA TO
AMAZONAS IN BRASIL DURING THE WEEKEND.

DAVISON/GALVEZ...WPC (USA)
$$

322 
FXSA20 KWBC 131658
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1157 AM EST THU JAN 13 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 13/17UTC: AT 1550 UTC...THE REMNANTS
OF A SUBTROPICAL STORM OVER THE EASTERN PACIFIC CENTERED NEAR 37S
82W. THROUGH THIS EVENING THIS WILL PHASE WITH A DEEPENING MID
LEVEL TROUGH OVER THE SOUTHEAST PACIFIC...WITH AXIS TO ACCELERATE
ACROSS THE SOUTHERN CONE TO THE WESTERN SOUTH ATLANTIC EARLY ON
FRIDAY MORNING. AT LOW LEVELS...THE MID LEVEL TROUGH WILL SUSTAIN
A SURFACE FRONT THAT SURGES ACROSS SOUTHERN PATAGONIA IN
ARGENTINA/SOUTHERN CHILE LATER TODAY. AS IT PHASES WITH THE
REMNANTS OF THE STORM...THE INFLOW OF SUBTROPICAL MOISTURE WILL
HELP SUSTAIN HEAVY RAINFALL AMOUNTS...WITH ACCUMULATION OF
75-125MM. THIS IS TO ALSO FAVOR STRONG BOUNDARY LAYER WINDS OF
35-45KT ACROSS THE SOUTHERN REGIONS OF CHILE INTO PATAGONIA IN
ARGENTINA.

A BUILDING MID/UPPER LEVEL RIDGE TO THE WEST THEN SETS THE STAGE
FOR A DEEPER TROUGH TO FOLLOW. UNDER THE INFLUENCE OF THE RIDGE
THE TROUGH AMPLIFIES TO THE NORTH-NORTHWEST ACROSS THE
BELLINGSHAUSEN SEA TO 40S 90W EARLY ON SATURDAY MORNING. THROUGH
SUNDAY THE INFLOW OF SHORT WAVE ENERGY AND COLD AIR WILL HELP
SUSTAIN THE FURTHER INTENSIFICATION OF THIS TROUGH AS IT MOVES
ACROSS THE SOUTHERN CONE. EARLY NEXT WEEK IT WILL SPLIT IN TWO
DISTINCT CLOSED CIRCULATIONS...WITH ONE NEAR THE SOUTH GEORGIA
ISLANDS AND THE OTHER NEAR TEMUCO/CONCEPCION CHILE. THE LATTER
WILL THEN ANCHOR A SHORT WAVE TROUGH OFF THE CENTRAL/NORTHERN
COAST OF CHILE THROUGH THE MIDDLE OF THE WEEK. A NORTHERN POLAR
JET MAXIMA IS TO ACCOMPANY THIS TROUGH AS IT AMPLIFIES ACROSS THE
SOUTHERN CONE...WITH DIVERGENCE ON ITS LEFT ENTRANCE REGION TO
VENT ORGANIZED DEEP CONVECTION DURING THE LATER PERIODS.

AT LOW LEVELS...THE CORRESPONDING SURFACE CYCLONE DEEPENS TO A
CLOSED 990 HPA LOW AS IT NEARS TIERRA DEL FUEGO/EXTREME SOUTHERN
REGION OF CHILE LATER ON FRIDAY EVENING...WITH LITTLE CHANGE IN
INTENSITY AS IT NEARS THE MALVINAS/FALKLAND ISLANDS LATER ON
SATURDAY. ON SUNDAY TO MONDAY THE LOW IS TO THEN EXPERIENCE AN
EXPLOSIVE RATE OF INTENSIFICATION AS IT MOVES ACROSS THE SOUTH
GEORGIA ISLANDS TO THE CENTRAL SOUTH ATLANTIC...DEEPENING FROM A
986 HPA LOW SUNDAY TO A 952 HPA LOW ON MONDAY. THE DEEPENING
FRONTAL LOW WILL COMBINE WITH A BUILDING POLAR RIDGE TO THE WEST
TO DRIVE THE ASSOCIATED FRONT NORTH ACROSS PATAGONIA TO LA PAMPA
IN ARGENTINA EARLY ON SUNDAY MORNING...WITH BOUNDARY TO BRIEFLY
STALL ACROSS THE RIO DE LA PLATA BASIN-MENDOZA IN ARGENTINA ON
MONDAY. BUT DRIVEN BY A SOUTHERLY WIND SURGE...THE FRONT RACES
ACROSS NORTHWEST ARGENTINA TO SOUTHERN BOLIVIA ON
TUESDAY-WEDNESDAY MORNING. AS IT RACES ACROSS NORTHERN ARGENTINA
THIS IS LIKELY TO TRIGGER A SEVERE WEATHER PRODUCING PREFRONTAL
SQUALL LINE. OVER SOUTHERN CHILE THIS WILL SUSTAIN MODERATE
TOHEAVY RAINFALL AMOUNTS ON FRIDAY AND SATURDAY...WITH MAXIMA OF
25-50MM IN MIXED PRECIPITATION OF RAIN AND SNOW SHOWERS. OVER
CENTRAL ARGENTINA/RIO DE LA PLATA BASIN THIS IS LIKELY TO TRIGGER
SEVERE THUNDERSTORMS...WITH RAINFALL MAXIMA INCREASING FROM
15-20MM ON SATURDAY TO 25-50MM ON SUNDAY. EARLY NEXT WEEK
CONVECTION BECOMES BETTER ORGANIZED WHILE BUILDING NORTH ACROSS
URUGUAY TO NORTHERN ARGENTINA...WITH RAINFALL MAXIMA OF 75-125MM.
ON TUESDAY THIS INCREASES TO 75-150MM WHILE BUILDING NORTH ACROSS
NORTHWEST ARGENTINA TO SOUTHERN BOLIVIA...WHILE OVER URUGUAY/ENTRE
RIOS THE MAXIMA PEAKS AT 35-70MM. 

AT 250 HPA...THE DEEPENING POLAR TROUGH TO THE SOUTH WILL PRESS
AGAINST A WANING CELL OF THE SUBTROPICAL RIDGE TO THE NORTH. THE
RIDGE SPANS BETWEEN CENTRAL ARGENTINA AND WESTERN BOLIVIA/SOUTHERN
SIERRA OF PERU. A RETROGRESSING UPPER LEVEL TROUGH BOUNDS THE
EASTERN FRINGES OF THIS RIDGE WHILE CENTERING ON A CLOSED LOW OVER
SANTA CRUZ IN EASTERN BOLIVIA. UNDER PRESSURE FROM THE POLAR
TROUGH THE RIDGE IS TO GRADUALLY WEAKEN...AND THE UPPER LEVEL
TROUGH IS TO FILL AS IT RETROGRESSES ACROSS BOLIVIA TO SOUTHERN
PERU. LATER DURING THE WEEKEND AN OPEN/LOW AMPLITUDE RIDGE WILL
REMAIN OVER MID SECTIONS OF SOUTH AMERICA. MEANWHILE...THE RIDGE
ALOFT WILL VENT DIURNAL CONVECTION ALONG THE NORTHERN ANDES OF
CHILE/ARGENTINA...WITH DAILY MAXIMA OF 10-15MM/DAY. THE
RETROGRESSING UPPER LEVEL TROUGH...AS IT WEAKENS...WILL INITIALLY
TRIGGER MODERATE RAINFALL AMOUNTS ACROSS SOUTHEAST BRASIL WITH
MAXIMA OF 20-35MM. OVER CENTRAL BOLIVIA AND SOUTHERN JUNGLE OF
PERU THIS INCREASES TO 20-45MM ON FRIDAY...THEN RAPIDLY WEAKEN ON
SATURDAY. SIMULTANEOUSLY...A WANING TUTT LOW IS TO ALSO RETROGRESS
ACROSS THE NORTHEAST STATES OF BRASIL. EARLY IN THE CYCLE THIS
WILL INTERACT WITH THE ATLANTIC ITCZ TO TRIGGER MODERATE
CONVECTION ACROSS NORTHEAST BRASIL...WITH ACTIVITY TO WEAKEN AS IT
SPREADS WEST ALONG THE NEAR EQUATORIAL TROUGH ACROSS PARA TO
AMAZONAS IN BRASIL DURING THE WEEKEND.

DAVISON/GALVEZ...WPC (USA)
$$

868 
FXSA20 KWBC 121850
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
150 PM EST WED JAN 12 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 12/19UTC: UNDER THE DYNAMICAL
INFLUENCE OF A WANING MID/UPPER LEVEL LOW...A SUBTROPICAL STORM
OVER THE EASTERN SOUTH PACIFIC  CENTERS NEAR 34S 89W...THIS IS
APPROXIMATELY 440 NAUTICAL MILES TO THE WEST-SOUTHWEST OF THE
ARCHIPELAGO OF JUAN FERNANDEZ. CONSISTENT WITH PREVIOUS MODEL
GUIDANCE...THIS IS EXPECTED TO TRANSITION TO AN EXTRA TROPICAL
STORM AS IT NEARS THE SOUTH COAST OF CHILE LATER ON THURSDAY.
HAZARDS TO SOUTHERN CHILE INCLUDES STRONG LOW LEVEL WINDS OF
35-45KT AND POTENTIAL FOR HEAVY RAINFALL AMOUNTS...WITH STORM
TOTAL AMOUNTS OF 75-150MM. PLEASE REFER TO THE DIRECCION
METEOROLOGICA DE CHILE AND THE SERVICIO METEOROLOGICO DE LA ARMADA
DE CHILE FOR OFFICIAL FORECAST GUIDANCE AND WARNINGS PERTAINING
THIS SYSTEM.

A BUILDING LONG WAVE RIDGE TO THE WEST...WITH MID LEVEL AXIS SOUTH
ALONG 115W/120W...WILL INDUCE THE NORTHWARD AMPLIFICATION OF A
SOUTHERN STREAM TROUGH ACROSS THE SOUTHEAST PACIFIC TO THE
SOUTHERN REGIONS OF CHILE LATER ON FRIDAY EVENING. THROUGH SUNDAY
THE INFLOW OF SHORT WAVE ENERGY AND COLD AIR WILL HELP SUSTAIN THE
INTENSIFICATION OF THIS TROUGH AS IT MOVES ACROSS THE SOUTHERN
CONE...AND EARLY NEXT WEEK IT WILL SPLIT IN TWO DISTINCT CLOSED
CIRCULATIONS...WITH ONE NEAR THE SOUTH GEORGIA ISLANDS AND THE
OTHER NEAR TEMUCO/PUERTO MONTT IN SOUTHERN CHILE. AT LOW
LEVELS...THE CORRESPONDING SURFACE CYCLONE DEEPENS TO A CLOSED 994
HPA LOW AS IT NEARS TIERRA DEL FUEGO/EXTREME SOUTHERN REGIONS OF
CHILE LATER ON FRIDAY...INTENSIFYING TO A 992 HPA LOW AS IT NEARS
THE MALVINAS/FALKLAND ISLANDS LATER ON SATURDAY. AS IT MAKES
LANDFALL OVER SOUTHERN CHILE...THE INTENSE SURFACE LOW WILL
SUSTAIN ANOTHER ROUND OF HEAVY RAINFALL AMOUNTS...WITH THE MAXIMA
INCREASING FROM 20-45MM ON FRIDAY TO 30-60MM ON SATURDAY IN A MIX
OF RAIN AND SNOW SHOWERS ACROSS THE SOUTHERN ANDES. A BUILDING
POLAR RIDGE TO THE WEST WILL THEN DRIVE THE ASSOCIATED SURFACE
FRONT NORTH ACROSS PATAGONIA TO LA PAMPA IN ARGENTINA LATER ON
SATURDAY...WITH THE FRONT SURGING ACROSS THE RIO DE LA PLATA
BASIN/CENTRAL ARGENTINA LATER ON SUNDAY. THE SURGING BOUNDARY WILL
THEN SUSTAIN MODERATE TO HEAVY RAINFALL AMOUNTS AS IT RACES ACROSS
URUGUAY TO NORTHERN ARGENTINA...WITH MAXIMA OF 25-50MM IN
POTENTIALLY SEVERE CONVECTION. ON MONDAY THIS INCREASES TO 35-70MM
AS ENVIRONMENTAL CONDITIONS BECOMES FAVORABLE FOR AN MCS TO
DEVELOP IN THIS AREA.

AS THE POLAR TROUGH DEEPENS ACROSS THE SOUTHERN CONE...IT WILL
PRESS AGAINST A MID/UPPER LEVEL RIDGE TO THE NORTH. EARLY IN THE
CYCLE THE RIDGE WILL SPAN BETWEEN BOLIVIA AND
CENTRAL/CHILE-ARGENTINA...WHILE CENTERING ON A 250 HPA HIGH OVER
NORTHERN CHILE. THROUGH THE END OF THE WEEK THE RIDGE IS TO NEARLY
COLLAPSE UNDER PRESSURE FROM THE POLAR TROUGH TO THE SOUTH.
MEANWHILE...A SHORT WAVE TROUGH WILL BOUND THE EASTERN FRINGES OF
THE MID/UPPER LEVEL RIDGE...WITH AXIS TO THE NORTHWEST ACROSS
SOUTHERN BRASIL TO MATO GROSSO/NORTHERN BOLIVIA. THE SHORT WAVE
TROUGH WILL REMAIN CUT OFF FROM THE UPPER FLOW...AND A SUCH IT IS
EXPECTED TO WEAKEN AS IT RETROGRESSES ACROSS MATO GROSSO DO SUL TO
PARAGUAY/BOLIVIA ON THURSDAY TO FRIDAY. THIS WILL SET THE STAGE
FOR A TUTT LOW TO THE NORTH TO ALSO RETROGRESS ACROSS NORTHEAST
BRASIL TO EQUATORIAL SOUTH AMERICA. AT LOW LEVELS...THE MID/UPPER
LEVEL TROUGH SUSTAINS THE SOUTH AMERICA CONVERGENCE ZONE (SACZ)
OVER BRASIL. THE CONVERGENCE ZONE EXTENDS TO THE NORTHWEST ACROSS
SAO PAULO-MATO GROSSO TO RONDONIA IN BRASIL. ON THURSDAY THE SACZ
WEAKENS TO A TROUGH OVER MATO GROSSO-RONDONIA IN BRASIL...AND ON
FRIDAY IT IS NOW EXPECTED TO DISSIPATE AS THE MID LEVEL TROUGH
FILLS. IN RESPONSE...CONVECTION OVER SOUTHEAST BRASIL WEAKENS TO
20-35MM/DAY EARLY IN THE CYCLE...WHILE OVER CENTRAL BRASIL IT
BRIEFLY SURGES TO 30-60MM. THROUGH FRIDAY THIS IS TO ALSO WEAKEN
TO 20-35MM/DAY WHILE BUILDING WEST ACROSS PARA TO AMAZONAS IN
BRASIL. THE FOCUS OF THE DIURNAL CONVECTION WILL THEN SHIFT TO
NORTHERN BRASIL/EQUATORIAL SOUTH AMERICA UNDER THE INFLUENCE OF
THE NEAR EQUATORIAL TROUGH AND RETROGRESSING UPPER LEVEL TUTT.

DAVISON/GALVEZ...WPC (USA)
$$

672 
FXSA20 KWBC 111855
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 PM EST TUE JAN 11 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 11/19UTC: CONSISTENT WITH PREVIOUS
FORECASTS...UNDER THE INFLUENCE OF A MID/UPPER LEVEL CLOSED
LOW...THE GLOBAL MODELS CONTINUE TO FORECAST A DEEPENING SURFACE
LOW NEAR 31S 90W...OR 530 NAUTICAL MILES WEST OF THE ARCHIPELAGO
OF JUAN FERNANDEZ...TO TRANSITION TO A SUBTROPICAL STORM EARLY IN
THE CYCLE. THIS IS FORECAST TO RETAIN ITS SUBTROPICAL CYCLONE
CHARACTERISTICS THROUGH WEDNESDAY EVENING...THEN TRANSITION TO
EXTRATROPICAL STORM AS IT NEARS SOUTHERN CHILE LATER ON THURSDAY.
HAZARDS TO SOUTHERN CHILE INCLUDES STRONG LOW LEVEL WINDS OF
35-45KT AND POTENTIAL FOR HEAVY RAINFALL AMOUNTS OF 75-150MM.
PLEASE REFER TO THE DIRECCION METEOROLOGICA DE CHILE AND THE
SERVICIO METEOROLOGICO DE LA ARMADA DE CHILE FOR OFFICIAL FORECAST
GUIDANCE AND WARNINGS PERTAINING THIS SYSTEM.

BUILDING MID/UPPER LEVEL RIDGE TO THE WEST IS TO THEN INDUCE THE
NORTHWARD AMPLIFICATION OF A SOUTHERN STREAM TROUGH ACROSS THE
SOUTHEAST PACIFIC TO THE SOUTHERN REGIONS OF CHILE LATER ON
FRIDAY. INFLOW OF COLD AIR WILL LEAD TO FURTHER INTENSIFICATION OF
THIS TROUGH AS IT MOVES ACROSS THE SOUTHERN CONE TO THE WESTERN
ATLANTIC DURING THE WEEKEND. AT LOW LEVELS...THE CORRESPONDING
SURFACE CYCLONE INTENSIFIES TO A CLOSED 998 HPA LOW AS IT NEARS
TIERRA DEL FUEGO/EXTREME SOUTHERN REGIONS OF CHILE LATER ON
FRIDAY...PUSHING EAST ACROSS PATAGONIA TO THE MALVINAS/FALKLAND
ISLANDS ON SATURDAY-SUNDAY. THIS IS TO SUSTAIN ANOTHER ROUND OF
HEAVY RAINS ACROSS SOUTHERN CHILE...WITH MAXIMA INCREASING FROM
20-45MM ON FRIDAY TO 30-60MM ON SATURDAY IN A MIX OF RAIN AND SNOW
SHOWERS OVER THE SOUTHERN ANDES. BUILDING POLAR RIDGE TO THE WEST
WILL THEN DRIVE THE ASSOCIATED FRONT NORTH ACROSS PATAGONIA TO LA
PAMPA IN ARGENTINA EARLY ON MONDAY...CROSSING INTO THE RIO DE LA
PLATA BASIN/CENTRAL ARGENTINA LATER IN THE DAY. THE SURGING
BOUNDARY WILL THEN SUSTAIN MODERATE TO HEAVY RAINFALL AMOUNTS AS
IT RACES ACROSS URUGUAY TO NORTHERN ARGENTINA...WITH MAXIMA OF
25-50MM IN POTENTIALLY SEVERE CONVECTION.

AT 250 HPA...THE UPPER FLOW PATTERN OVER NORTHERN SOUTH AMERICA
REMAINS UNDER THE STEERING INFLUENCE OF A 250 HPA CELL OF THE
SUBTROPICAL RIDGE THAT SPANS BETWEEN NORTHWEST ARGENTINA/CHILE AND
BOLIVIA. ALSO AT UPPER LEVELS...A SHORT WAVE TROUGH EXTENDS ALONG
THE EASTERN FRINGES OF THIS RIDGE...WITH AXIS TO THE
NORTH-NORTHWEST ACROSS THE SOUTHERN STATES OF BRASIL TO MATO
GROSSO/RONDONIA. AT LOW LEVELS...THE MID/UPPER LEVEL TROUGH
SUSTAINS THE SOUTH AMERICA CONVERGENCE ZONE (SACZ) OVER BRASIL.
THE CONVERGENCE ZONE EXTENDS TO THE NORTHWEST ACROSS SAO
PAULO-MATO GROSSO TO RONDONIA IN BRASIL. THROUGH SATURDAY THE
UPPER LEVEL TROUGH IS FORECAST TO GRADUALLY WEAKEN AS IT
RETROGRESSES ACROSS CENTRAL BRASIL TO BOLIVIA/PARAGUAY. AS THE
UPPER TROUGH WEAKENS...THE LOW LEVEL CONVERGENCE ZONE (SACZ) IS
THEN FORECAST TO DISSIPATE. INITIALLY...MOST ACTIVE CONVECTION
WILL FAN OUT BETWEEN NORTHERN SAO PAULO/RIO DE JANEIRO AND MATO
GROSSO/PARA IN BRASIL...WITH MAXIMA OF 35-70MM/DAY. ON WEDNESDAY
TO THURSDAY CONVECTION ACROSS SOUTHEAST BRASIL WEAKENS TO
20-35MM/DAY...WHILE OVER PARA-MATO GROSSO MAXIMA OF 30-60MM
PERSISTS. THIS WILL QUICKLY WEAKEN ON FRIDAY-SATURDAY AS THE
MID/UPPER LEVEL TROUGH FILLS AND THE SACZ DISSIPATES. FOCUS OF THE
DIURNAL CONVECTION WILL THEN SHIFT TO NORTHERN BRASIL/EQUATORIAL
SOUTH AMERICA UNDER THE INFLUENCE OF THE NEAR EQUATORIAL TROUGH.

DAVISON/GALVEZ...WPC (USA)
$$

635 
FXSA20 KWBC 101852
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 PM EST MON JAN 10 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 10/19UTC: UNDER THE DYNAMICAL
INFLUENCE OF A MEANDERING CUT OFF LOW CENTERING NEAR 32S 90W AND
ABOVE NORMAL OCEAN TEMPERATURES...THE MODELS CONSISTENTLY FORECAST
A SUBTROPICAL CYCLONE TO FORM LATER TODAY NEAR 31S 94W OR ABOUT
750 NAUTICAL MILES WEST OF THE ARCHIPELAGO OF JUAN FERNANDEZ.
OVERNIGHT...DECREASING UPPER LEVEL SHEAR WOULD MAKE IT FAVORABLE
FOR GRADUAL INTENSIFICATION...WITH MODELS PROJECTING SYSTEM TO
STRENGTHEN TO SUBTROPICAL STORM INTENSITY BY DAYBREAK ON TUESDAY.
THIS WILL LIKELY RETAIN ITS SUBTROPICAL CYCLONE CHARACTERISTICS
THROUGH WEDNESDAY EVENING...WITH THE FORECAST TRACK KEEPING THE
CYCLONE NO CLOSER THAN 300NM FROM JUAN FERNANDEZ AS IT TRACKS
TOWARDS THE SOUTHERN CONE. FOR OFFICIAL FORECAST AND WARNINGS
PLEASE VISIT LA DIRECCION METEOROLOGICA DE CHILE AT: METEOCHILE.CL

ON THE SOUTHERN STREAM...PROGRESSIVE MID/UPPER LEVEL SHORT WAVE
PERTURBATIONS ARE TO STREAM ACROSS THE DRAKE PASSAGE/SOUTHERN CONE
FROM TIME-TO-TIME...WITH A ROBUST SHORT WAVE TROUGH TO STREAM
ACROSS THE SOUTHERN CONE LATER TODAY. THIS WILL SUSTAIN A
BROAD/DEEP SURFACE TROUGH THAT IS TO SPAN BETWEEN THE ANTARCTIC
PENINSULA/TIERRA DEL FUEGO LATER THIS EVENING...FAVORING STRONG
BOUNDARY LAYER WINDS AND MODERATE RAINFALL AMOUNTS WITH MAXIMA OF
20-45MM. ANOTHER WELL ORGANIZED MID LEVEL TROUGH WILL FOLLOW THREE
DAYS LATER...REACHING THE SOUTHERN REGIONS OF CHILE LATER ON
THURSDAY. AS IT ENTERS THE SOUTHEAST PACIFIC...THE LATTER WILL
INTERACT WITH THE REMNANTS OF THE SUBTROPICAL CYCLONE TO THE
NORTH. AS THEY INTERACT...THE SURFACE CYCLONE IS TO ONCE AGAIN
STRENGTHEN WHILE EVOLVING INTO AN EXTRA TROPICAL STORM. HIGHER
THAN NORMAL MOISTURE CONTENT IS TO ACCOMPANY THIS FEATURE AS IT
MAKES LANDFALL OVER SOUTHERN CHILE ON THURSDAY
EVENING...TRIGGERING HEAVY RAINFALL AMOUNTS WITH MAXIMA OF
40-80MM. HEAVY RAINS WILL THEN PERSIST THROUGH THE END OF THE WEEK
AS A SECONDARY FRONTAL LOW DEEPENS OFF THE SOUTH COAST OF CHILE ON
FRIDAY EVENING...TO ALSO FAVOR STRONG BOUNDARY LAYER WINDS AS
PRESSURE GRADIENT RAPIDLY TIGHTENS ON FRIDAY.

UPPER FLOW PATTERN OVER NORTHERN SOUTH AMERICA REMAINS UNDER THE
STEERING INFLUENCE OF A 250 HPA CELL OF THE SUBTROPICAL RIDGE THAT
SPANS BETWEEN NORTHWEST ARGENTINA/CHILE AND BOLIVIA. AS THE RIDGE
HOLDS...IT ANCHORS A SHORT WAVE TROUGH ACROSS THE SOUTHERN TO THE
SOUTHEAST STATES OF BRASIL. AT LOW LEVELS THE LATTER HELPS SUSTAIN
THE SOUTH AMERICA CONVERGENCE ZONE (SACZ) ACROSS PORTIONS OF
BRASIL. THE CONVERGENCE ZONE WILL EXTEND TO THE NORTHWEST ACROSS
SAO PAULO-MATO GROSSO TO RONDONIA IN BRASIL...WHERE IT IS TO
REMAIN NEARLY STATIONARY DURING THE NEXT FOUR DAYS. LATER IN THE
WEEK THE UPPER TROUGH FILLS AND THE RIDGE BUILDS EAST ACROSS
SOUTHEAST BRASIL. LOSING UPPER SUPPORT...THE SACZ DISSIPATES ON
FRIDAY. MEANWHILE...CONTINUE TO EXPECT HEAVY RAINS BETWEEN SAO
PAULO/RIO DE JANEIRO-MINAS GERAIS AND MATO GROSSO/RONDONIA. ON
WEDNESDAY-THURSDAY ACTIVITY ACROSS SAO PAULO-MINAS GERAIS BEGINS
TO WEAKEN...WHILE OVER MATO GROSSO-RONDONIA TO SOUTHERN
PARA/AMAZONAS THE CONVECTION WILL BRIEFLY SURGE. THIS THEN WEAKENS
AS THE UPPER TROUGH DISSIPATES AND THE RIDGE BUILDS ACROSS MID AND
NORTHERN SECTIONS OF SOUTH AMERICA. AS THE RIDGE ALOFT HOLDS OVER
NORTHERN CHILE/NORTHWEST ARGENTINA...IT IS TO ALSO VENT DEEP
CONVECTION BUILDING ALONG THE CENTRAL AND NORTHERN ANDES. IN THIS
AREA MODELS PROJECT MODERATE RAINFALL AMOUNTS WITH DAILY MAXIMA OF
15-20MM POSSIBLE. THIS COULD LEAD TO FLASH FLOODING AND
LANDSLIDES.

DAVISON/GALVEZ...WPC (USA)
$$

028 
FXSA20 KWBC 071816
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
115 PM EST FRI JAN 07 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON JAN 10

FORECAST DISCUSSION FROM JAN 07/18UTC: NOTE TO ALL USERS...THE
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME MORE FAVORABLE AND
CONDUCIVE TO SUBTROPICAL CYCLOGENESIS TO THE WEST OF ARCHIPELAGO
DE JUAN FERNANDEZ ON TUESDAY-WEDNESDAY. TROPICAL STORM INTENSITY
WINDS COULD AFFECT THE ISLANDS DURING THIS PERIOD. IF
NECESSARY...LA DIRECCION METEOROLOGICA DE CHILE WILL ISSUE THE
OFFICIAL FORECAST.

UNDER THE BUILDING INFLUENCE OF A RIDGE TO THE WEST...A MID/UPPER
LEVEL TROUGH IS TO AMPLIFY ACROSS THE FAR EASTER PACIFIC LATER
TODAY...WITH LONG WAVE AXIS TO EXTEND TO THE NORTHWEST FROM THE
BELLINGSHAUSEN SEA TO 36S 103W. THE TROUGH MAINTAINS A POSITIVE
TILT AS IT MOVES EAST TOWARDS THE DRAKE PASSAGE/ANTARCTIC
PENINSULA SOUTHERN CHILE EARLY ON SATURDAY. UNDER THE SHEARING
INFLUENCE OF A RIDGE TO THE EAST...THE TROUGH IS TO THEN SPLIT IN
TWO...WITH ITS SOUTHERN HALF TO ACCELERATE ACROSS THE SOUTH
ATLANTIC WHILE ITS NORTHERN PORTION EVOLVES INTO A CLOSED LOW NEAR
34S 97W LATER ON SUNDAY. CUT OFF FROM THE FLOW...THIS IS TO THEN
MEANDER JUST WEST OF THE ARCHIPELAGO OF JUAN FERNANDEZ THROUGH THE
MIDDLE OF THE WEEK. UNDER THE INFLUENCE OF THE MEANDERING
MID/UPPER LEVEL LOW...MODELS FORESEE POSSIBLE WARM CORE
CYCLOGENESIS NEAR 32S 91W LATER ON TUESDAY. THE ENSUING
SUBTROPICAL CYCLONE MEANDERS TO 33S 87W LATER ON WEDNESDAY...WHERE
IT WILL BEGIN TO WEAKEN.

AT LOW LEVELS...RIDGE BUILDING ALONG 110W WILL SUSTAIN THE RAPID
INTENSIFICATION OF A POLAR TROUGH BETWEEN THE BELLINGSHAUSEN SEA
AND THE SOUTHERN REGIONS OF CHILE EARLY IN THE CYCLE. SHEARING
ACROSS THE DRAKE PASSAGE ON SATURDAY THE LOW/TROUGH WILL THEN
DRIVE A SURFACE FRONT NORTH ACROSS SOUTHERN CHILE TO PATAGONIA IN
ARGENTINA...WHERE THE BOUNDARY STALLS ON SUNDAY. THIS BOUNDARY IS
TO INITIALLY TRIGGER MODERATE RAINFALL AMOUNTS OVER SOUTHERN CHILE
BETWEEN ISLA DE CHILOE AND PUERTO MONTT...WITH MAXIMA OF 20-45MM.
ON SATURDAY THE FOCUS OF THE ACTIVITY SHIFTS TO TIERRA DEL
FUEGO/EXTREME SOUTHERN CHILE WITH RAINFALL MAXIMA OF 05-10MM. A
BROAD TROUGH WILL FOLLOW...LIFTING ACROSS THE SOUTHEAST PACIFIC TO
THE SOUTHERN REGIONS OF CHILE LATER ON SUNDAY. THIS WILL QUICKLY
MOVE ACROSS THE DRAKE PASSAGE TO THE SOUTHWEST ATLANTIC WHILE
GRADUALLY DEEPENING AS IT NEARS THE SOUTH GEORGIA ISLANDS ON
TUESDAY. OVER EXTREME SOUTHERN CHILE AND ACROSS TIERRA DEL FUEGO
THIS WILL THEN FAVOR ANOTHER ROUND OF MODERATE TO HEAVY RAINFALL
AMOUNTS...INCREASING FROM 15-25MM ON SUNDAY TO 20-45MM ON MONDAY.
IN THIS AREA EXPECTING STORM TOTAL AMOUNTS OF 50-100MM DURING THE
MEDIUM RANGE PERIOD.

NORTH OVER THE CONTINENT...AT 250 HPA...A CELL OF THE SUBTROPICAL
RIDGE IS TO BUILD SOUTH FROM BOLIVIA/SOUTHERN PERU TO THE NORTHERN
REGIONS OF CHILE AND NORTHWEST ARGENTINA. EARLY IN THE CYCLE THIS
WILL ANCHORS ON A CLOSED HIGH OVER THE ALTIPLANO OF BOLIVIA.
THROUGH MONDAY THE HIGH WILL MEANDER SOUTH ALONG THE NORTHERN
ANDES OF CHILE. AS THE RIDGE BUILDS...IT WILL STEER A SHORT WAVE
TROUGH ACROSS THE BUENOS AIRES PROVINCE/URUGUAY. ENTERING SOUTHERN
BRASIL...THE SHORT WAVE TROUGH IS TO THEN DEEPEN AS IT AMPLIFIES
ACROSS SOUTHERN BRASIL TO MATO GROSSO...REACHING MAXIMUM INTENSITY
EARLY NEXT WEEK. AT LOW LEVELS THE DEEPENING MID/UPPER LEVEL
TROUGH SUSTAINS A FRONTAL LOW OVER THE WESTERN ATLANTIC TO THE
EAST-SOUTHEAST OF SAO PAULO...AND THE SOUTH AMERICA CONVERGENCE
ZONE (SACZ) AS IT EXTENDS ACROSS NORTHERN SAO PAULO/RIO DE JANEIRO
TO RORAIMA/NORTHERN BOLIVIA. THIS WILL PERSIST DURING THE NEXT
96-120 HRS...WEAKENING TO AN OPEN TROUGH ON WEDNESDAY. THE DEEP
LAYER TROUGH WILL SUSTAIN HEAVY RAINFALL AMOUNTS ACROSS CENTRAL
AND SOUTHEAST BRASIL...WITH MOST INTENSE EXPECTED OVER EASTERN SAO
PAULO/RIO DE JANEIRO...WHERE THE DAILY MAXIMA IS TO PEAK AT
75-150MM/DAY DURING THE NEXT 72-84 HRS. OTHER CONVECTION IS
EXPECTED ALONG AND NORTH OF THE CONVERGENCE ZONE ON THE BRAZILIAN
STATES OF MINAS GERAIS-TOCANTIS AND GOIAS...WITH ACCUMULATION OF
35-70MM. THIS WAXES AND WANES DURING THE NEXT FEW DAYS...WITH A
MINIMA OF 20-35MM ON SUNDAY...WHILE ON MONDAY TO TUESDAY IT
BOUNCES BACK TO 35-70MM.

ALSO AT UPPER LEVELS...A MEANDERING TUTT LOW TO THE EAST OF RECIFE
IN NORTHEAST BRASIL...WILL ANCHOR A TROUGH OVER THE NORTHEAST
STATES OF BRASIL. THE UPPER LEVEL TROUGH WILL ENHANCE CONVECTIVE
INSTABILITY...AND IN INTERACTION WITH WARM SEA SURFACE
TEMPERATURES OVER THE TROPICAL ATLANTIC...IT WILL INDUCE A DUAL
ITCZ PATTERN. INITIALLY THE SINGLE ITCZ IS TO MAKE LANDFALL
BETWEEN ILHA DE MARAJO AND AMAPA IN BRASIL. BUT EARLY NEXT WEEK
THIS WILL SPLIT IN TWO BRANCHES AS INDUCED BY THE UPPER LEVEL
TROUGH...WITH THE SOUTHERN BRANCH TO MEANDER INLAND ACROSS RIO
GRANDE DO NORTE/PARAIBA. IN RESPONSE...CONVECTION ACROSS NORTHEAST
BRASIL GRADUALLY INTENSIFIES WHILE BUILDING WESTWARD BETWEEN
NORTHEAST BRASIL AND PARA. PER CFS GUIDANCE THIS WILL COINCIDE
WITH AN ATMOSPHERIC KELVIN WAVE TRAVERSING EQUATORIAL SOUTH
AMERICA EARLY NEXT WEEK...SO THERE IS AN ENHANCED RISK OF HEAVY
RAINFALL AMOUNTS FOR THIS AREA.

DAVISON/GALVEZ...WPC (USA)
$$

380 
FXSA20 KWBC 061857
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 PM EST THU JAN 06 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 06/19UTC: ON THE SOUTHERN STREAM
FLOW...AT 500 HPA...A BROAD TROUGH IS TO SLOWLY MOVE TO THE
SOUTHEAST PACIFIC/BELLINGSHAUSEN SEA WHILE PRESSING AGAINST A
RIDGE TO THE EAST. THROUGH SATURDAY MORNING THE SLOW TO EVOLVE
SYSTEM IS TO THEN AMPLIFY TO THE NORTH-NORTHWEST. LATER DURING THE
WEEKEND IT IS TO THEN SPLIT...WITH THE SOUTHERN HALF ACCELERATING
ACROSS THE DRAKE PASSAGE/ANTARCTIC PENINSULA WHILE THE NORTHERN
HALF EVOLVES INTO A CLOSED LOW TO THE SOUTH-SOUTHWEST OF THE
ARCHIPELAGO OF JUAN FERNANDEZ. THE DEEP MID LEVEL LOW WILL THEN
REMAIN NEARLY STATIONARY OVER THE EASTERN PACIFIC THROUGH THE
MEDIUM RANGE PERIOD. AT LOW LEVELS THIS WILL SUSTAIN A BROAD
TROUGH OVER THE SOUTHEAST PACIFIC LATER TODAY...WHERE IT IS TO
MEANDER WHILE MEANDERING EAST TOWARDS THE SOUTHERN REGIONS OF
CHILE LATER ON FRIDAY. LATER DURING THE WEEKEND IT WILL ACCELERATE
INTO THE SOUTH ATLANTIC WHILE LEAVING BEHIND A WANING FRONTAL LOW
NEAR JUAN FERNANDEZ. MEANWHILE...THIS WILL ENHANCE MOIST FLUX
CONVERGENCE ACROSS SOUTHERN CHILE...WITH RAINFALL MAXIMA
INCREASING FROM 15-30MM TODAY TO 20-45MM ON FRIDAY. LIGHT TO
MODERATE RAINFALL AMOUNTS ARE TO THEN PERSIST THROUGH THE
WEEKEND...WITH POTENTIAL FOR HIGHER AMOUNTS EARLY NEXT WEEK.

FARTHER NORTH...AT 250 HPA...A CELL OF THE SUBTROPICAL RIDGE IS TO
REMAIN WELL ENTRENCHED BETWEEN NORTHERN CHILE/NORTHWEST ARGENTINA
AND BOLIVIA/CENTRAL BRASIL. AS THE UPPER LEVEL RIDGE HOLDS...A
SHORT WAVE TROUGH WILL AMPLIFY ACROSS SOUTHERN BRASIL TO MATO
GROSSO DO SUL/MATO GROSSO. THIS IS TO GRADUALLY DEEPEN THROUGH THE
WEEKEND/EARLY NEXT WEEK. AT LOW LEVELS THE UPPER LEVEL
PERTURBATION SUSTAINS THE SOUTH AMERICA CONVERGENCE ZONE...WITH
AXIS TO THE NORTHWEST ACROSS NORTHERN SAO PAULO/RIO DE JANEIRO TO
MATO GROSSO/RONDONIA IN CENTRAL BRASIL. THE DEEP LAYER TROUGH WILL
SUSTAIN HEAVY RAINFALL AMOUNTS ACROSS CENTRAL AND SOUTHEAST
BRASIL...WITH MOST INTENSE EXPECTED OVER EASTERN SAO PAULO/RIO DE
JANEIRO...WHERE THE DAILY MAXIMA IS TO PEAK AT 75-150MM/DAY DURING
THE NEXT THREE DAYS. OTHER CONVECTION IS EXPECTED ON THE BRAZILIAN
STATES OF MINAS GERAIS-TOCANTIS AND GOIAS...WITH ACCUMULATION OF
40-80MM. THIS WAXES AND WANES DURING THE NEXT FEW DAYS.

ALSO AT UPPER LEVELS...A MEANDERING TUTT LOW TO THE EAST OF RECIFE
IS TO ANCHOR A TROUGH OVER THE NORTHEAST STATES OF BRASIL. THE
UPPER LEVEL TROUGH WILL ENHANCE CONVECTIVE INSTABILITY ALONG THE
ITCZ TO THE NORTH AND THE NEAR EQUATORIAL TROUGH OVER BRASIL.
INITIALLY THE MOST ACTIVE IS TO CLUSTER BETWEEN THE AMAZON RIVER
DELTA REGION/AMAPA...BUT THROUGH THE WEEKEND ACTIVITY IS TO
GRADUALLY BUILD WESTWARD ACROSS PARA AND SOUTHWARD ACROSS
BAHIA...WITH MAXIMA INCREASING FROM 20-35MM ON FRIDAY TO 30-60MM
ON SATURDAY. SCATTERED DEEP CONVECTION IS TO THEN PERSIST THROUGH
THE WEEKEND TO EARLY NEXT WEEK. OVER NORTHWEST SOUTH
AMERICA...UNDER THE INFLUENCE OF THE SUBEQUATORIAL JET...DRYER
THAN NORMAL CONDITIONS ARE EXPECTED BETWEEN COLOMBIA AND NORTHERN
JUNGLE OF PERU. THE JET ALOFT WILL SUSTAIN AN UPPER
CONVERGENT/SUBSIDENT PATTERN THAT IS TO CONTINUE INHIBITING
CONVECTIVE DEVELOPMENT DURING THE NEXT SEVERAL DAYS.

DAVISON/GALVEZ...WPC (USA)
$$

276 
FXSA20 KWBC 051820
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
120 PM EST WED JAN 05 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 05/18UTC: EAST OVER THE PACIFIC...AT
MID LEVELS...A BROAD/LOW AMPLITUDE RIDGE DOMINATES THE FLOW
BETWEEN 105W-70W AND TO THE NORTH OF 70S. OVER THE NEXT COUPLE OF
DAYS THE RIDGE IS FORECAST TO RELOCATE TO THE SOUTHERN CONE WHILE
YIELDING TO AN AMPLIFYING POLAR TROUGH. MEANWHILE...AS IT
HOLDS...THE RIDGE WILL INDUCE THE NORTHWARD AMPLIFICATION OF A
LONG WAVE TROUGH ALONG 50W/55W TO THE SOUTHERN STATES OF BRASIL.
THIS IS TO THEN SLOWLY PULL TO THE EAST/SOUTHEAST...IN THIS
PROCESS SHEARING A NORTHERN STREAM VORTEX OVER THE SOUTHEAST
STATES OF BRASIL. SUCCESSIVE SHORT WAVE VORTICES WILL THEN HELP
SUSTAIN THIS PERTURBATION THROUGH THE END OF THE WEEK...WITH AXIS
TO LIKELY EVOLVE INTO A CLOSED LOW OVER RIO GRANDE DO SUL/SANTA
CATARINA. AT LOW LEVELS...THIS WILL SUSTAIN AN ELONGATED FRONT
THAT IS TO EXTEND TO THE NORTHWEST ACROSS THE SOUTH ATLANTIC TO
SOUTHERN BRASIL/MID SECTIONS OF SOUTH AMERICA. IT WILL ALSO HELP
SUSTAIN THE SOUTH AMERICA CONVERGENCE ZONE OVER BRASIL...WITH
LOW-MID LEVEL CONVERGENCE ZONE TO MEANDER ACROSS NORTHERN SAO
PAULO/RIO DE JANEIRO TO MATO GROSSO/SANTA CRUZ IN EASTERN BOLIVIA
DURING THE NEXT 60-72 HRS. LATER IN THE WEEK IT MEANDERS NORTH
ACROSS SOUTHERN MINAS GERAIS TO RONDONIA/NORTHWESTERN BOLIVIA.
THIS WILL ENHANCE LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE BETWEEN
NORTHERN SAO PAULO AND RIO DE JANEIRO...WITH RAINFALL MAXIMA
INCREASING FROM 50-100MM DURING THE DAY TODAY TO 75-150MM ON
THURSDAY-FRIDAY. HEAVY RAINS WILL THEN PERSIST THROUGH THE END OF
THE WEEK. OVER MATO GROSSO/MATO GROSSO DO SUL THIS INCREASES FROM
20-30MM/DAY EARLY IN THE CYCLE TO 40-80MM ON THURSDAY. THIS
GRADUALLY WEAKENS TO 30-60MM WHILE BUILDING NORTH ACROSS MINAS
GERAIS AND THE CENTRAL STATES OF BRASIL.

UPSTREAM OVER THE EASTERN PACIFIC...IN A HIGHLY AMPLIFIED LONG
WAVE PATTERN...A MID/UPPER LEVEL TROUGH IS TO EXTEND FROM THE
BELLINGSHAUSEN SEA TO 35S 115W EARLY ON FRIDAY. AS IT PRESSES
AGAINST THE RIDGE TO THE EAST...THE TROUGH WILL SHEAR SHORT WAVE
ENERGY ACROSS THE SOUTHERN REGIONS OF CHILE/TIERRA DEL FUEGO TO
PATAGONIA IN ARGENTINA. THROUGH SATURDAY THE TROUGH WILL SPLIT IN
TWO...WITH ITS SOUTHERN HALF TO PROPAGATE ACROSS THE DRAKE PASSAGE
TO THE SOUTHWEST ATLANTIC...WHILE THE REMAINING NORTHERN STREAM
VORTEX EVOLVES INTO A CLOSED LOW TO THE SOUTH-SOUTHWEST OF THE
ARCHIPELAGO OF JUAN FERNANDEZ. THE NORTHERN STREAM VORTEX IS TO
BRIEFLY INTENSIFY ON SATURDAY AFTERNOON...THEN GRADUALLY WEAKEN AS
IT CUTS OFF FROM THE MEAN SYNOPTIC FLOW. AT LOW LEVELS...A BROAD
FRONTAL TROUGH WILL DOMINATE THE BELLINGSHAUSEN SEA/SOUTHEAST
PACIFIC DURING THE NEXT 72-84 HRS...WITH THE TROUGH TO SUSTAIN AN
ELONGATED/MEANDERING FRONT ACROSS SOUTHERN CHILE/PATAGONIA IN
ARGENTINA. THE FRONT WILL FOCUS DEEP SUBTROPICAL MOISTURE AND
SHORT WAVE ENERGY ACROSS THE SOUTHERN REGIONS OF CHILE/TIERRA DEL
FUEGO. AS ENHANCED BY THE STEEP TERRAIN TO THE SOUTH...THIS WILL
FAVOR HEAVY RAINFALL AMOUNTS TO THE SOUTH OF TEMUCO IN SOUTHERN
CHILE...WITH MAXIMA OF 35-70MM THROUGH THURSDAY MORNING. MODERATE
RAINFALL AMOUNTS WILL THEN PERSIST THROUGH FRIDAY MORNING...WHEN
THE DAILY MAXIMA INCREASES TO 20-45MM. THE ENSUING NORTHERN STREAM
MID LEVEL LOW WILL THEN INDUCE A FRONTAL LOW SOUTH OF JUAN
FERNANDEZ NEAR 40S 80W. THROUGH SUNDAY THE LOW IS TO INTENSIFY AS
IT REMAINS OFF THE COAST OF CHILE. WARMER THAN NORMAL OCEAN
SURFACE TEMPERATURES COULD THEN AID WITH TRANSITION OF THIS LOW
INTO A SUBTROPICAL CYCLONE EARLY NEXT WEEK.

UPPER FLOW PATTERN OVER NORTHERN SOUTH AMERICA REMAINS NEARLY
UNCHANGED...WITH A MEANDERING CELL OF THE SUBTROPICAL RIDGE TO
DOMINATE THE 250 HPA FLOW BETWEEN NORTHERN CHILE/NORTHWEST
ARGENTINA AND BOLIVIA. THIS RIDGE IS EXPECTED TO HOLD ITS GROUND
DURING THE NEXT FEW DAYS. AS IT HOLDS...IT WILL SEPARATE TWO TUTT
LOWS...WITH ONE OVER THE EASTERN TROPICAL PACIFIC CENTERING NEAR
18S 105W EARLY ON THURSDAY MORNING. THE OTHER TUTT
LOW...MEANWHILE...IS TO MEANDER OVER THE TROPICAL ATLANTIC OFF THE
NORTHEAST COAST OF BRASIL. AS THE ONE OVER THE EASTERN TROPICAL
PACIFIC HOLDS...IT WILL STEER A SUBEQUATORIAL JET MAXIMA ACROSS
THE GALAPAGOS ISLANDS INTO ECUADOR/COLOMBIA ON THURSDAY. SPEED
CONFLUENCE ALONG THE LEADING EDGE OF THIS JET MAXIMA WILL THEN
SUSTAIN A DEEP LAYER SUBSIDENT PATTERN THAT WILL EXACERBATE
DROUGHT CONDITIONS ALONG THE LEE OF THE ANDES BETWEEN SOUTHERN
COLOMBIA-PERUVIAN JUNGLE/NORTHWEST BRASIL. DIURNAL CONVECTIVE
DEVELOPMENT WILL LIMIT TO EQUATORIAL SOUTH AMERICA EAST OF
AMAZONAS IN BRASIL AND PORTIONS OF ECUADOR/SIERRA OF PERU. MOST
ACTIVE IS EXPECTED ALONG THE NEAR EQUATORIAL TROUGH (NET) AS IT
MEANDERS OVER NORTHERN BRASIL. AS ENHANCED BY THE TUTT LOW OVER
THE TROPICAL ATLANTIC. THIS WILL LEAD TO HEAVY RAINS BETWEEN PARA
AND AMAPA IN NORTHERN BRASIL...WITH POTENTIAL FOR HEAVY CONVECTION
AS CONVECTIVE CELLS TRAIN ALONG THE ITCZ ACROSS AMAPA.

DAVISON/GALVEZ...WPC (USA)
$$

898 
FXSA20 KWBC 041850
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
149 PM EST TUE JAN 04 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 04/19UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECASTS...A BROAD/LOW AMPLITUDE MID LEVEL TROUGH
REMAINS THE DOMINANT FEATURE ACROSS THE SOUTHEAST PACIFIC...WITH
MID LEVEL AXIS DOMINATING AREA BETWEEN 100W-70W. A DEEPENING
TROUGH LIES TO THE EAST...WITH AXIS NORTH FROM A CLOSED LOW AT 60S
55W TO THE CENTRAL PROVINCES IN ARGENTINA. THROUGH WEDNESDAY
MORNING THIS IS EXPECTED TO AMPLIFY WHILE SLOWLY MERGING WITH A
SHORT WAVE TROUGH OVER SOUTHERN BRASIL. AS THEY INTERACT...A LONG
WAVE TROUGH WILL THEN BECOME THE DOMINANT MESO-SYNOPTIC FEAURE
OVER THE WESTERN ATLANTIC DURING THE NEXT COUPLE OF DAYS. ON
THURSDAY...THE RIDGE MOVES TO THE SOUTHERN CONE...DISPLACING THE
TROUGH FARTHER EAST INTO THE CENTRAL SOUTH ATLANTIC. AT 250 HPA
THE RIDGE IS FOCUSING THE POLAR JET ACROSS EXTREME SOUTHERN
REGIONS OF CHILE...WHILE AN UNUSUALLY WEAK SUBTROPICAL JET
CONFINES TO CENTRAL CHILE/ARGENTINA-SOUTHERN STATES OF BRASIL

AT LOW LEVELS THIS SUSTAINS A DEEPENING LOW NEAR THE SOUTH GEORGIA
ISLANDS...AND A FRONT THAT MOVES NORTH ACROSS THE RIO DE LA PLATA
BASIN AS A POLAR RIDGE BUILDS TO THE SOUTH. THIS WILL DRIVE THE
FRONT FARTHER NORTH ACROSS SOUTHERN BRASIL TO MID SECTIONS OF
SOUTH AMERICA ON WEDNESDAY...WHERE IT IS EXPECTED TO STALL. THE
SURGING BOUNDARY WILL SUSTAIN SCATTERED/POTENTIALLY SEVERE
CONVECTION AS IT SURGES ACROSS URUGUAY/ENTRE RIOS IN ARGENTINA
LATER TODAY..WITH RAINFALL MAXIMA OF 15-25MM. UNDER INFLUENCE OF
POLAR RIDGE DRIVEN SOUTHERLY JET...CONVECTION THEN SURGES ACROSS
SOUTHERN BOLIVIA THIS EVENING...WITH MAXIMA OF 40-80MM. ON
WEDNESDAY THE FOCUS OF THE HEAVY CONVECTION SHIFTS TO CENTRAL
BOLIVIA WHERE IT IS TO SUSTAIN SIMILAR RAINFALL AMOUNTS.
SIMULTANEOUSLY...AS THE MID/UPPER LEVEL TROUGH DEEPENS ACROSS THE
WESTERN ATLANTIC TO SOUTHEAST BRASIL ON WEDNESDAY...IT IS TO THEN
PROVIDE THE SUPPORT TO THE SOUTH AMERICA CONVERGENCE ZONE (SACZ)
OVER BRASIL. THE CONVERGENCE ZONE IS TO EXTEND TO THE
WEST-NORTHWEST ACROSS SAO PAULO TO MATO GROSSO/SANTA CRUZ IN
SOUTHEAST BOLIVIA. THIS WILL FAVOR SEVERAL DAYS OF HEAVY RAINFALL
AMOUNTS ACROSS NORTHERN SAO PAULO/RIO DE JANEIRO AND SOUTHERN
MINAS GERAIS...WITH DAILY MAXIMA OF 50-100MM. TENDENCY IS TO
GRADUALLY INTENSIFY LATER IN THE WEEK...WHEN THE DAILY MAXIMA
INCREASES TO 75-150MM.

AS THE MID LEVEL RIDGE RELOCATES ACROSS THE EASTERN PACIFIC TO THE
SOUTHERN CONE OF SOUTH AMERICA...IT WILL THEN SET THE STAGE FOR A
DEEP/HIGH AMPLITUDE TROUGH TO GRADUALLY SETTLE ACROSS THE
BELLINGSHAUSEN SEA/SOUTHEAST PACIFIC. THE TROUGH REACHES MAXIMUM
AMPLITUDE ON FRIDAY-SATURDAY. IT THEN SPLITS IN TWO WITH THE
SOUTHERN HALF ACCELERATING ACROSS THE DRAKE PASSAGE TO THE SOUTH
GEORGIA ISLANDS WHILE ITS NORTHERN HALF EVOLVES INTO A CUT
OFF/CLOSED LOW OFF THE SOUTH COAST OF CHILE. AT LOW LEVELS THIS
WILL INITIALLY FAVOR AN ELONGATED FRONT THAT IS TO MEANDER ACROSS
SOUTHERN CHILE/PATAGONIA...FOCUSING MOISTURE AND SHORT WAVE ENERGY
ACROSS THE SOUTHERN REGIONS OF CHILE. AS A RESULT...CONVECTION
SOUTH OF TEMUCO CHILE IS EXPECTED TO GRADUALLY
INTENSIFY...INCREASING FROM 15-25MM EARLY IN THE CYCLE TO 35-70MM
ON WEDNESDAY TO THURSDAY. THIS IS CONSIDERABLY HIGHER THAN
PREVIOUSLY ANTICIPATED. DEEPENING/AMPLIFYING FRONTAL TROUGH ACROSS
THE SOUTHEAST PACIFIC ON FRIDAY WILL THEN TAKE OVER...EVOLVING
INTO A DEEP/CLOSED LOW OFF THE SOUTH COAST OF CHILE DURING THE
WEEKEND. ALTHOUGH THIS IS LIKELY TO SUSTAIN ANOTHER ROUND OF HEAVY
RAINS...UNCERTAINTY AMONG THE MODELS IS HIGH.

NORTH OVER THE CONTINENT...AT 250 HPA...A MEANDERING CELL OF THE
SUBTROPICAL RIDGE IS TO DOMINATE THE FLOW BETWEEN NORTHERN
CHILE/NORTHWEST ARGENTINA AND BOLIVIA. THE RIDGE ALOFT WILL THE
SEPARATE TWO TUTT LOWS...WITH ONE CLOSING OVER THE EASTERN
TROPICAL PACIFIC NEAR 18S 105W WHILE THE OTHER MEANDERS OVER THE
TROPICAL ATLANTIC OFF THE NORTHEAST COAST OF BRASIL. AS THE FORMER
DEEPENS...IT WILL STEER A SUBEQUATORIAL JET MAXIMA ACROSS THE
GALAPAGOS ISLANDS INTO ECUADOR/COLOMBIA. CONVERGENCE ALONG THE
LEADING EDGE OF THIS JET MAXIMA WILL THEN SUSTAIN A DEEP LAYER
SUBSIDENT PATTERN THAT WILL EXACERBATE DROUGHT CONDITIONS ALONG
THE LEE OF THE ANDES BETWEEN SOUTHERN COLOMBIA-PERUVIAN
JUNGLE/NORTHWEST BRASIL. DEVELOPMENT WILL LIMIT TO EQUATORIAL
SOUTH AMERICA EAST OF AMAZONAS IN BRASIL...WITH MOST ACTIVE ALONG
THE NEAR EQUATORIAL TROUGH AND THE ATLANTIC ITCZ AS ENHANCED BY
THE TUTT LOW OVER THE TROPICAL ATLANTIC. THIS WILL LEAD TO HEAVY
RAINS BETWEEN PARA AND AMAPA IN NORTHERN BRASIL...WITH POTENTIAL
FOR HEAVY CONVECTION AS CONVECTIVE CELLS TRAIN ALONG THE ITCZ
ACROSS AMAPA.

DAVISON/GALVEZ...WPC (USA)
$$

335 
FXSA20 KWBC 031725
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1224 PM EST MON JAN 03 2022

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM JAN 03/17UTC: A BROAD/LOW AMPLITUDE
MID-UPPER LEVEL RIDGE IS INITIALIZED OVER THE EASTERN SOUTH
PACIFIC...WITH AXIS SOUTH BETWEEN 115W-90W. A DEEP CLOSED LOW OVER
THE DRAKE PASSAGE ANCHORS A BROAD TROUGH TO THE EAST OF THIS
RIDGE...WHILE A ROBUST SHORT WAVE TROUGH ON THE SOUTHERN STREAM
LIFTS ACROSS THE SOUTHERN REGIONS OF CHILE TO PATAGONIA IN
ARGENTINA. UNDER THE INFLUENCE OF THE RIDGE TO THE WEST...THE
LATTER IS EXPECTED TO AMPLIFY AS IT EXITS THE CONTINENT AND ENTERS
THE WESTERN ATLANTIC LATER THIS EVENING. PHASING WITH THE BROAD
TROUGH TO THE SOUTH...THESE WILL THEN GRADUALLY EVOLVE INTO A
BROAD TROUGH OVER THE WESTERN ATLANTIC EARLY ON WEDNESDAY. AT LOW
LEVELS...THIS WILL SUSTAIN A DEEPENING OCCLUDED LOW NORTH OF THE
FALKLAND ISLANDS/MALVINAS LATER THIS EVENING. THROUGH TUESDAY
EVENING THIS WILL RAPIDLY INTENSIFY AS IT NEARS THE SOUTH GEORGIA
ISLANDS. INITIALLY...AS IT DEEPENS...THE LOW WILL SUSTAIN A
PROGRESSIVE FRONT THAT RACES ACROSS PATAGONIA TO LA PAMPA IN
ARGENTINA. THIS WILL TRIGGER ORGANIZED CONVECTION ALONG THE LEE OF
THE ANDES BETWEEN MENDOZA AND LA RIOJA IN NORTHWEST
ARGENTINA...WITH MAXIMA OF 20-45MM IN POTENTIALLY SEVERE
CONVECTION. A BUILDING POLAR RIDGE TO THE SOUTH WILL THEN DRIVE
THE FRONT FARTHER NORTH ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA
BASIN ON TUESDAY...WITH THE FRONT THEN MEANDERING NORTH ACROSS
SOUTHERN BRASIL TO NORTHERN ARGENTINA ON WEDNESDAY-THURSDAY.
ACTIVITY SURGES AHEAD OF THIS BOUNDARY...WITH A SECOND ROUND OF
HEAVY CONVECTION TO AFFECT NORTHWEST ARGENTINA ON TUESDAY. MOST
INTENSE...HOWEVER...IS EXPECTED BETWEEN SOUTHEAST BOLIVIA AND
CHACO PARAGUAYO...WITH CONDITIONS FAVORABLE FOR A HEAVY RAINFALL
PRODUCING MCS. IN THIS AREA EXPECTING MAXIMA OF 40-80MM THROUGH
WEDNESDAY MORNING.

THE HIGHLY AMPLIFIED MID/UPPER LEVEL TROUGH WILL THEN FAVOR THE
GENERATION OF THE SOUTH AMERICA CONVERGENCE ZONE (SACZ) ACROSS
BRASIL...WITH THE CONVERGENCE ZONE TO EXTEND TO THE NORTHWEST
ACROSS SAO PAULO-MATO GROSSO DO SUL TO SANTA CRUZ IN EASTERN
BOLIVIA. LATER IN THE WEEK IT IS TO GRADUALLY ALIGN ALONG 20S
BETWEEN SOUTHERN MINAS GERAIS/RIO DE JANEIRO AND SOUTHEAST
BOLIVIA. MOST ACTIVE CONVECTION IS EXPECTED ALONG AND NORTH OF THE
SACZ...WITH ACTIVITY FOCUSING OVER SOUTHEAST BRASIL. IN THIS AREA
EXPECTING MAXIMA INCREASES FROM 30-60MM ON WEDNESDAY TO 40-80MM ON
THURSDAY. UNDER THE INFLUENCE OF A COASTAL LOW...HIGHER AMOUNTS
ARE EXPECTED ACROSS RIO DE JANEIRO-NORTHERN SAO PAULO/SOUTHERN
MINAS GERAIS ON FRIDAY AND SATURDAY...WITH DAILY MAXIMA OF
75-125MM.

UPSTREAM...THE BROAD/LOW AMPLITUDE MID/UPPER LEVEL RIDGE OVER THE
EASTERN PACIFIC IS EXPECTED TO HOLD ITS GROUND THROUGH THURSDAY
MORNING...THEN RAPIDLY CRUMBLE AS A HIGHER AMPLITUDE TROUGH
REACHES THE SOUTH AMERICAN DOMAIN. MEANWHILE...IN A SLOW TO EVOLVE
PATTERN...PROGRESSIVE SHORT WAVE PERTURBATIONS ARE TO STREAM
ACROSS THE SOUTHERN REGIONS OF CHILE/PATAGONIA IN ARGENTINA...WITH
VORTICES FOCUSING SHORT WAVE ENERGY AND SUBTROPICAL MOISTURE OVER
THE CONTINENT TO THE SOUTH OF 45S. AT LOW LEVELS THIS WILL HELP
SUSTAIN A BROAD TROUGH OVER THE SOUTHEAST PACIFIC/BELLINGSHAUSEN
SEA...AND AN ELONGATED FRONT THAT IS TO MEANDER OVER SOUTHERN
CHILE-PATAGONIA IN ARGENTINA ON TUESDAY THROUGH THURSDAY. IN
RESPONSE...CONVECTION SOUTH OF TEMUCO CHILE IS EXPECTED TO
GRADUALLY INTENSIFY...INCREASING FROM 15-25MM ON TUESDAY TO
20-45MM/DAY ON WEDNESDAY TO THURSDAY. THIS IS TO ONCE AGAIN FLARE
UP DURING THE WEEKEND AS A DEEPER FRONTAL TROUGH MAKES LANDFALL
OVER THE SOUTHERN CONE.

AT 250 HPA...PATTERN TO THE NORTH WILL REMAIN UNDER INFLUENCE OF
AN ILL ORGANIZED CELL OF THE SUBTROPICAL RIDGE SPANNING BETWEEN
CENTRAL BRASIL AND THE EASTERN TROPICAL PACIFIC. WARMER THAN
NORMAL SST OFF THE NORTH COAST OF CHILE CONTINUE TO ANCHOR THIS
RIDGE WEST OF ITS NORMAL CLIMATOLOGICAL POSITION OVER THE
CONTINENT. THIS...IN-TURN...FAVORS A TUTT/TUTT LOW OVER THE
WESTERN TROPICAL ATLANTIC JUST EAST OF RECIFE IN NORTHEAST BRASIL.
THE TUTT/TUTT LOW CONTINUES TO INTERACT WITH THE ATLANTIC ITCZ IN
SUPPORT OF SCATTERED DEEP CONVECTION BETWEEN PARA/AMAPA AND
NORTHEAST BRASIL. IN THIS AREA INITIALLY EXPECTING MAXIMA OF
35-70MM...WEAKENING TO 20-35MM ON TUESDAY TO WEDNESDAY.
HOWEVER...IN AN ECHO TRAINING PATTERN...HIGHER AMOUNTS ARE
FORECAST FOR THE AMAZON RIVER DELTA REGION/ILHA DE MARANJO AND
AMAPA...WITH MAXIMA PEAKING AT 30-60MM LATER IN THE WEEK. ALTHOUGH
CONVECTION TO THE EAST REMAINS ACTIVE AND WELL
ORGANIZED...CONVECTION OVER THE PERUVIAN JUNGLE/EASTERN ECUADOR
AND NORTHWEST BRASIL IS FORECAST TO WEAKEN AS A FINGER OF THE
SUBEQUATORIAL RIDGE MOVES FROM THE EASTERN TROPICAL PACIFIC TO
EQUATORIAL SOUTH AMERICA. SUBSIDENCE ALONG THE LEADING EDGE OF
THIS UPPER LEVEL JET MAXIMA WILL LEAD TO THE GRADUAL
INTENSIFICATION OF THE TRADE WINDS INVERSION OVER NORTHWEST
BRASIL. IN RESPONSE...PWAT CONTENT PLUMMETS AND ACTIVITY IN THIS
AREA GRADUALLY BECOMES MORE SPARSE AND LESS INTENSE.

DAVISON/GALVEZ...WPC (USA)
$$

154 
FXSA20 KWBC 301628
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1128 AM EST THU DEC 30 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT ON JAN 03.

FORECAST DISCUSSION FROM DEC 30/16UTC: PERSISTENT MID/UPPER LEVEL
RIDGE REMAINS OVER THE SOUTH PACIFIC...WITH AXIS EXTENDING SOUTH
ALONG 120W/130W TO 60S/65S. DOWNSTREAM FROM THIS RIDGE...A
BROAD/LOW AMPLITUDE TROUGH EXTENDS BETWEEN 100W-50W TO THE
SOUTHERN CONE OF SOUTH AMERICA. THE RIDGE IS FORECAST TO HOLD
DURING THE NEXT 72-96 HRS...THEN FLATTEN UNDER PRESSURE FROM SHORT
WAVE PERTURBATIONS STREAMING TO THE SOUTH. MEANWHILE...UNDER THE
STEERING INFLUENCE OF THIS RIDGE...SUCCESSIVE SHORT WAVE
PERTURBATIONS ARE FORECAST TO LIFT ACROSS THE SOUTHEAST PACIFIC
INTO SOUTHERN REGIONS OF CHILE/PATAGONIA IN ARGENTINA. ALTHOUGH
INITIALLY WEAK...THESE ARE TO GRADUALLY INTENSIFY WHILE
SIMULTANEOUSLY SUSTAINING INTENSE CYCLOGENESIS OVER ACROSS THE
DRAKE PASSAGE EARLY ON SATURDAY MORNING. THE SLOW TO EVOLVE SYSTEM
WILL THEN MEANDER EASTWARD AS ADDITIONAL PERTURBATIONS LIFT ACROSS
THE SOUTHERN REGIONS OF CHILE. AT 250 HPA THE DEEPENING TROUGH IS
TO THEN FOCUS A VERY STRONG POLAR JET ACROSS THE SOUTHERN REGIONS
OF CHILE TO PATAGONIA IN ARGENTINA...WITH UPPER LEVEL WINDS OF
150-170KT. THE JET ALOFT WILL F
FAVOR AN UPPER DIVERGENT PATTERN THAT IS TO VENT CONVECTION ACROSS
THE SOUTHERN CONE.

AT LOW LEVELS THIS REFLECTS AS BROAD TROUGH SPANNING BETWEEN THE
BELLINGSHAUSEN SEA AND THE SOUTHERN REGIONS OF CHILE/PATAGONIA IN
ARGENTINA. UNDER FAVORABLE UPPER LEVEL JET DYNAMICS THIS IS TO
ALSO INTENSIFY...WITH DEEP OCCLUDED LOW REACHING THE SOUTHERN
REGIONS OF CHILE LATER ON FRIDAY. THE DEEP LOW LEVEL LOW IS TO
THEN MEANDER EASTWARD ACROSS THE DRAKE PASSAGE AS ANOTHER REACHES
THE SOUTHERN CONE ON SUNDAY. THESE PERTURBATIONS WILL HELP SUSTAIN
STRONG LOW LEVEL WINDS ACROSS THE CONTINENT TO THE SOUTH OF
50S...WITH LOW LEVEL WINDS PEAKING AT 40-55KT. THIS IS TO ALSO
FAVOR A MOIST ADVECTIVE PATTERN...WHICH IN COMBINATION WITH THE
STRONG LOW LEVEL WINDS AND FAVORABLE UPPER JET PATTERN ALOFT WILL
LEAD TO SEVERAL DAYS OF MODERATE TO HEAVY RAINFALL AMOUNTS. MOST
INTENSE ARE EXPECTED BETWEEN TEMUCO/PUERTO MONTT AND ISLA DE
CHILOE...WITH STORM TOTAL AMOUNTS DURING THE NEXT FIVE DAYS OF
200-300MM. ALTHOUGH LESSER AMOUNTS ARE EXPECTED ACROSS TIERRA DEL
FUEGO...THE DEEPENING/OCCLUDING FRONTAL LOW WILL ENHANCE COLD AIR
ADVECTION ACROSS THE REGION...AND A WINTRY MIX OF SNOW/RAIN
SHOWERS IS HIGHLY PROBABLE DURING THE WEEKEND.

OVER ARGENTINA THIS WILL HELP SUSTAIN A MEANDERING SURFACE
FRONT...WITH BOUNDARY TO EXTEND TO THE WEST-NORTHWEST ACROSS THE
SOUTH ATLANTIC TO THE BUENOS AIRES PROVINCE/MENDOZA. THE FRONT
WILL BE THE FOCUS OF LOW LEVEL MOISTURE CONVERGENCE...WHILE THE
AFOREMENTIONED PERTURBATIONS AND ASSOCIATED JET MAXIMA STREAMING
ACROSS CHILE ARE TO PROVIDE THE DYNAMICAL SUPPORT. IN THIS PATTERN
THE ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE FOR HAIL
PRODUCING SEVERE THUNDERSTORMS TO DEVELOP...WITH RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15MM. THROUGH SUNDAY THIS WILL
INCREASE TO MAXIMA OF 15-30MM WHILE BUILDING NORTH AND EAST ACROSS
ENTRE RIOS IN ARGENTINA TO THE BUENOS AIRES PROVINCE.

NORTH OVER THE CONTINENT...AT 250 HPA...A WEAKER THAN NORMAL CELL
OF THE SUBTROPICAL RIDGE CONFINES BETWEEN BOLIVIA-PERU AND THE
NORTH COAST OF CHILE. THE UNUSUAL POSITION OF THE SUBTROPICAL
RIDGE CORRELATES WITH AN AREA OF WARMER THAN NORMAL SEA SURFACE
TEMPERATURES CLUSTERING OVER THE EASTERN PACIFIC BETWEEN LA SERENA
CHILE AND THE SOUTH COAST OF PERU. UNDER INFLUENCE OF THE WARMER
SST...THE UPPER LEVEL RIDGE IS TO REMAIN NEARLY STATIONARY DURING
THE NEXT SEVERAL DAYS. AS THE UPPER LEVEL RIDGE HOLDS...SHORT WAVE
PERTURBATIONS STREAMING ACROSS CENTRAL CHILE AND ARGENTINA THEN
AMPLIFY ACROSS SOUTHERN BRASIL/PARAGUAY TO THE SOUTHEAST STATES OF
BRASIL. THIS WILL HELP SUSTAIN AN UPPER LEVEL TROUGH THAT
AMPLIFIES ACROSS SAO PAULO TO MATO GROSSO EARLY IN THE
CYCLE...WHERE IT WILL REMAIN THROUGH SATURDAY. THEN RAPIDLY WEAKEN
WHILE SHEARING TO THE EAST-SOUTHEAST. AT LOW LEVELS THE DEEPENING
MID/UPPER LEVEL TROUGH WILL HELP SUSTAIN THE SOUTH AMERICA
CONVERGENCE ZONE (SACZ) AS IT EXTENDS ACROSS SOUTHEAST BRASIL TO
MATO GROSSO/EASTERN BOLIVIA. IN RESPONSE...CONDITIONS ARE TO
REMAIN FAVORABLE FOR MCS GENERATION BETWEEN NORTHERN SAO PAULO/RIO
DE JANEIRO-MINAS GERAIS/GOIAS TO MATO GROSSO...WITH DAILY MAXIMA
OF 75-150MM EXPECTED THE NEXT TWO DAYS...TO THEN GRADUALLY WEAKEN
DURING THE WEEKEND AS THE MID/UPPER LEVEL TROUGH DISSIPATES.

CONSISTENT WITH PREVIOUS FORECAST...A DEEPENING TUTT LOW CLOSES
OFF THE NORTHEAST COAST OF BRASIL NEAR 10S 40W LATER ON
FRIDAY/EARLY ON SATURDAY MORNING. THE CLOSED LOW WILL THEN EXTEND
A SHORT WAVE TROUGH WEST ACROSS NORTHERN BRASIL TO THE
GUIANAS/AMAZON RIVER DELTA REGION. AT LOW LEVELS THE UPPER LEVEL
TROUGH WILL THEN INTERACT WITH THE NEAR EQUATORIAL TROUGH OVER
NORTHERN SOUTH AMERICA...WITH MOST ACTIVE CONVECTION CLUSTERING
BETWEEN PARA AND RIO GRANDE DO NORTE...WITH MAXIMA OF 25-50MM/DAY
IN SCATTERED DEEP CONVECTION. THROUGH THE WEEKEND IT WILL DECREASE
TO 20-35MM/DAY WHILE BUILDING WEST ALONG THE AMAZON RIVER BASIN.
HIGHER RAINFALL AMOUNTS...HOWEVER...ARE EXPECTED ACROSS AMAPA TO
FRENCH GUIANA AS THE UPPER LEVEL TROUGH INTERACTS WITH THE ITCZ TO
THE NORTH. IN THIS AREA ECHO TRAINING CONDITIONS APPEAR HIGHLY
LIKELY DURING THE NEXT SEVERAL DAYS...WITH AN ENHANCED RISK OF
RAINFALL AMOUNTS EXCEEDING SUGGESTED MODEL GUIDANCE FOR THE REGION.

DAVISON/GALVEZ...WPC (USA)
$$

692 
FXSA20 KWBC 291902
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
202 PM EST WED DEC 29 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 29/19UTC: A WELL ENTRENCHED MID/UPPER
LEVEL RIDGE EXTENDS SOUTH OVER THE PACIFIC ALONG 120W/130W. THE
RIDGE IS TO GENERALLY HOLD THROUGH THE MEDIUM RANGE PERIOD. AS IT
PERSISTS TO THE WEST...THE RIDGE IS TO STEER PROGRESSIVE
PERTURBATIONS EASTWARD ACROSS THE SOUTHEAST PACIFIC TO THE
SOUTHERN CONE OF SOUTH AMERICA. IN THIS PATTERN A ROBUST
PERTURBATION IS TO STREAM ACROSS SOUTHERN CHILE TO PATAGONIA IN
ARGENTINA LATER THIS EVENING...SETTING THE STAGE FOR A WEAKER
PERTURBATION THAT MAKES LANDFALL ON THURSDAY AFTERNOON. THE INFLOW
OF SUCCESSIVE SHORT WAVE PERTURBATIONS WILL THEN RESULT IN A
PERSISTENT WEAKNESS IN THE MID/UPPER LEVEL HEIGHT FIELD.
THIS...IN-TURN...WILL THEN ALLOW FOR AN UNUSUALLY DEEP TROUGH TO
AMPLIFY OVER THE SOUTHEAST PACIFIC BETWEEN THE BELLINGSHAUSEN SEA
AND THE SOUTHERN REGIONS OF CHILE DURING THE WEEKEND...WITH AXIS
EVOLVING INTO AN UNUSUALLY DEEP LOW ACROSS THE DRAKE PASSAGE. THE
DEEPENING TROUGH IS TO THEN FOCUS A VERY STRONG POLAR JET ACROSS
THE SOUTHERN REGIONS OF CHILE TO PATAGONIA IN ARGENTINA...WITH
UPPER LEVEL WINDS OF 150-170KT.

AT LOW LEVELS A PROGRESSIVE FRONT IS TO SPEARHEAD THE PATTERN
TRANSITION OVER CHILE AND ARGENTINA...WITH FRONTAL BOUNDARY
TRIGGERING A SEVERE WEATHER PRODUCING PREFRONTAL SQUALL LINE AS IT
RACES ACROSS PATAGONIA TO LA PAMPA THIS AFTERNOON. LOSING ITS
MOMENTUM...THE FRONT STALLS OVER CENTRAL ARGENTINA/RIO DE LA PLATA
BASIN ON THURSDAY-FRIDAY...WHERE IT IS TO SUSTAIN LIGHT TO
MODERATE RAINFALL AMOUNTS. A BROAD FRONTAL TROUGH IS TO
SIMULTANEOUSLY DEEPEN ACROSS THE SOUTHEAST PACIFIC INTO THE
SOUTHERN REGIONS OF CHILE ON THURSDAY-FRIDAY...AND DURING THE
WEEKEND THIS INTENSIFIES WHILE ANCHORING ON A DEEP OCCLUDED LOW
OVER TIERRA DEL FUEGO/SOUTHERN PATAGONIA. UNDER INFLUENCE OF THE
DEEPENING TROUGH EXPECTING SEVERAL DAYS OF HEAVY RAINFALL AMOUNTS
TO AFFECT CHILE BETWEEN TEMUCO AND ISLA DE CHILOE (40S-50S)...WITH
MAXIMA INCREASING FROM 10-15MM TODAY TO 20-45MM ON THURSDAY.
THROUGH SUNDAY THIS WILL CONTINUE TO INTENSIFY...WITH MAXIMA
INCREASING TO 30-60MM...WITH MODERATE TO HEAVY RAINFALL AMOUNTS
PERSISTING THROUGH THE WEEKEND TO EARLY NEXT WEEK. ALTHOUGH LESSER
AMOUNTS ARE EXPECTED ACROSS TIERRA DEL FUEGO IN EXTREME SOUTHERN
CHILE...IN A COLD ADVECTIVE PATTERN THERE IS A CHANCE FOR SOLID
PRECIPITATION (SNOW) LATER DURING THE WEEKEND.

NORTH OVER THE CONTINENT...AT 250 HPA...A WEAKER THAN NORMAL CELL
OF THE SUBTROPICAL RIDGE CONFINES BETWEEN BOLIVIA-PERU AND NORTH
COAST OF CHILE. THIS SEEMS TO BE RESPONDING TO AN AREA OF WARMER
THAN NORMAL SEA SURFACE TEMPERATURES CLUSTERING OVER THE EASTERN
PACIFIC BETWEEN LA SERENA CHILE AND SOUTHERN COAST OF PERU. AS A
RESULT...THE UPPER LEVEL RIDGE IS TO HOLD NEARLY STATIONARY DURING
THE NEXT SEVERAL DAYS. UNDER THE INFLUENCE OF THIS RIDGE SHORT
WAVE PERTURBATIONS STREAMING TO THE SOUTH ARE TO AMPLIFY ALONG THE
EASTERN FRINGES OF THE RIDGE AND ACROSS THE SOUTHERN/SOUTHEAST
STATES OF BRASIL. THROUGH FRIDAY THE UPPER LEVEL TROUGH WILL REACH
MAXIMUM AMPLITUDE ACROSS SAO PAULO TO MATO GROSSO IN BRASIL. THE
DEEPENING MID/UPPER LEVEL TROUGH WILL THEN STRENGTHEN THE SOUTH
AMERICA CONVERGENCE ZONE AS IT EXTENDS ACROSS SOUTHEAST BRASIL TO
MATO GROSSO/EASTERN BOLIVIA. THROUGH THURSDAY CONVECTION ACROSS
NORTHERN SAO PAULO/RIO DE JANEIRO-MINAS GERAIS AND GOIAS IS TO
INTENSIFY...INCREASING FROM 30-60MM IN SCATTERED DEEP CONVECTION
TO 75-125MM IN ORGANIZED DEEP CONVECTION. DURING THE WEEKEND THE
CONVECTION WILL THEN START TO WEAKEN...GRADUALLY DECREASING TO
25-50MM/DAY LATER ON SUNDAY.

 SIMULTANEOUSLY...A DEEPENING TUTT LOW TO THE NORTH WILL CLOSE OFF
THE NORTHEAST COAST OF BRASIL NEAR 10S 40W...WITH CLOSED
CIRCULATION EXTENDING A SHORT WAVE TROUGH ALONG THE NORTH COAST TO
THE AMAZON RIVER DELTA REGION. THE UPPER LEVEL TROUGH WILL THEN
INTERACT WITH THE NEAR EQUATORIAL TROUGH OVER NORTHERN SOUTH
AMERICA...WITH MOST ACTIVE CLUSTERING BETWEEN PARA AND RIO GRANDE
DO NORTE...WITH MAXIMA OF 25-50MM/DAY IN SCATTERED DEEP
CONVECTION. THROUGH THE WEEKEND IT WILL DECREASE TO 20-35MM/DAY
WHILE BUILDING WESTWARD ACROSS AMAZONAS. HIGHER
AMOUNTS...HOWEVER...ARE EXPECTED ACROSS AMAPA TO FRENCH GUIANA AS
IT INTERACTS WITH THE ITCZ TO THE NORTH. IN THIS AREA ECHO
TRAINING CONDITIONS APPEAR HIGHLY LIKELY DURING THE NEXT SEVERAL
DAYS...WITH AN ENHANCED RISK OF RAINFALL AMOUNTS EXCEEDING
SUGGESTED MODEL GUIDANCE FOR THE REGION.

DAVISON/GALVEZ...WPC (USA)
$$

563 
FXSA20 KWBC 211545
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1044 AM EST TUE DEC 21 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 21/16UTC: DISCUSSION NOT ISSUED.

DAVISON/GALVEZ...WPC (USA)
$$

759 
FXSA20 KWBC 201630
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1130 AM EST MON DEC 20 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 20/16UTC: DISCUSSION NOT ISSUED.

DAVISON/GALVEZ...WPC (USA)
$$

766 
FXSA20 KWBC 161657
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1157 AM EST THU DEC 16 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 16/17UTC: NORTH OVER THE
CONTINENT...LITTLE HAS CHANGED OVER THE LAST FEW DAYS...WITH BROAD
UPPER LEVEL CELL OF THE SUBTROPICAL RIDGE DOMINATING CONTINENTAL
AREA TO THE NORTH OF 30S. AT 250 HPA THE UPPER LEVEL RIDGE ANCHORS
ON A CLOSED HIGH OVER MATO GROSSO IN BRASIL. THROUGH SATURDAY THE
RIDGE WILL BUILD SOUTH ACROSS PARAGUAY TO CENTRAL/NORTHERN
PROVINCES IN ARGENTINA...WHILE THE CLOSED HIGH GRADUALLY RELOCATES
TO MEANDER BETWEEN EL CHACO PARAGUAYO AND SOUTHEAST BOLIVIA. AS
THE RIDGE HOLDS OVER THE CONTINENT...A SUBTROPICAL JET BOUNDS THE
SOUTHERN FRINGES OF THIS RIDGE. THE JET IT SO INITIALLY EXTEND
WEST TO EAST ACROSS THE CONTINENT ALONG 30S/33S. BUT AS THE RIDGE
BUILDS...THIS WILL DISPLACE THE JET FARTHER SOUTH ACROSS CENTRAL
CHILE-BUENOS AIRES PROVINCE IN ARGENTINA WHILE TAKING A MORE
PRONOUNCED ANTICYCLONIC CURVATURE. EAST OF THE CONTINENTAL
RIDGE...OVER THE TROPICAL ATLANTIC...A TUTT LOW NEAR 15S 30W
EXTENDS A TROUGH TO NORTH-NORTHWEST ALONG 00N 40W TO 10N 43W.
THROUGH SATURDAY MORNING THE LOW WEAKENS INTO AN OPEN TROUGH WHILE
GRADUALLY PHASING WITH A SHORT WAVE TROUGH STREAMING TO THE
SOUTH...WITH AXIS TO THEN WEAKEN WHILE SHEARING SHORT WAVE ENERGY
TO THE SOUTH-SOUTHEAST. AS IT WEAKENS...ANOTHER TROUGH WILL THEN
AMPLIFY TO TAKE ITS PLACE OFF THE NORTHEAST COAST OF BRASIL.

AT LOW LEVELS...THE SOUTH AMERICA CONVERGENCE ZONE (SACZ) EXTENDS
TO THE NORTHWEST ACROSS SAO PUALO-MATO GROSSO IN BRASIL TO
NORTHERN BOLIVIA...WITH AXIS CENTERING ON A CLOSED LOW OVER MATO
GROSSO. THE CONVERGENCE ZONE IS NOW EXPECTED TO LINGER DURING THE
NEXT THREE DAYS...WEAKENING TO AN OPEN TROUGH LATER ON SUNDAY.
MEANWHILE...THIS WILL ENHANCE LOW LEVEL MOISTURE
CONVERGENCE...WHILE THE RIDGE ALOFT IS TO SUSTAIN AN UPPER
DIVERGENT PATTERN. ALTHOUGH THE GFS PROPERLY INITIALIZES AND
FORECAST THIS FEATURE...IT IS FAILING TO PROPERLY RESOLVE
CONVECTION ALONG THE CONVERGENCE ZONE...WITH THE MODEL
UNDERESTIMATING POTENTIAL FOR FORMATION OF MESO SCALE CONVECTIVE
SYSTEMS ACROSS THE CENTRAL STATES OF BRASIL AND...AS A
RESULT...OVERESTIMATING POTENTIAL FOR DEVELOPMENT ACROSS
EQUATORIAL SOUTH AMERICA. THE GFS ENSEMBLE MEMBERS ARE ALSO DOING
A POOR JOB IN RESOLVING ORGANIZED CONVECTION IN THIS REGION. THERE
RAINFALL FORECAST WEIGHS IN HEAVILY IN FAVOR OF THE EUROPEAN
MODELS AND GDI FORECAST GUIDANCE FOR THE NEXT FIVE DAYS. MOST
INTENSE IS TO INITIALLY CLUSTER OVER MATO GROSSO IN BRASIL...WITH
MAXIMA OF 60-120MM. THROUGH SATURDAY THE FOCUS OF THE MCS
FORMATION SHIFTS WEST ACROSS RONDONIA TO NORTHERN BOLIVIA...WHERE
IT IS TO CONTINUE FAVORING HEAVY RAINFALL AMOUNTS. LATER DURING
THE WEEKEND TO EARLY NEXT WEEK...AS THE SACZ WEAKENS...ACTIVITY IS
TO THEN CONVERGE ALONG THE LEE OF THE BOLIVIAN
ANDES/ALTIPLANO...WITH DAILY MAXIMA OF 35-70MM. OTHER CONVECTION
IS TO AFFECT SAO PAULO/RIO DE JANEIRO AND MINAS GERAIS/ESPIRITO
SANTO...WITH ACCUMULATION OF 20-40MM/DAY EXPECTED OVER THE NEXT
THREE DAYS. THROUGH SUNDAY FOCUS OF THE ACTIVITY SHIFTS TO
BAHIA/MINAS GERAIS-ESPIRITO SANTO AS ANOTHER TUTT DEEPENS ALONG
THE SOUTHEAST COAST OF BRASIL. DURING THIS PERIOD THE DAILY MAXIMA
INCREASES TO 35-70MM.

SIMULTANEOUSLY...UNDER THE STEERING INFLUENCE OF THE BUILDING
SUBTROPICAL RIDGE OVER BRASIL...A CLOSED LOW ON THE NORTHERN
STREAM OVER THE EASTERN PACIFIC WILL THEN MEANDER TO THE
EAST-SOUTHEAST TOWARDS THE CENTRAL REGIONS OF CHILE LATER TODAY.
WEAKENING TO AN OPEN TROUGH...THIS WILL THEN SPILL ACROSS THE
ANDES INTO LA PAMPA/PATAGONIA IN ARGENTINA. OVER THE SOUTHERN CONE
THIS WILL THEN PHASE WITH A SHORT WAVE TROUGH LIFTING ACROSS
SOUTHERN CHILE. THIS MEANDERS OVER THE SOUTHERN CONE THROUGH
SATURDAY EVENING...THEN ACCELERATES INTO THE SOUTHEAST PACIFIC
WHILE YIELDING TO A HIGHER AMPLITUDE TROUGH STREAMING ACROSS THE
SOUTHEAST PACIFIC. AT LOW LEVELS...THE MID LEVEL VORTEX WILL THEN
SUSTAIN A FRONTAL LOW OVER CENTRAL PATAGONIA ON FRIDAY. THIS WILL
SUSTAIN A SURFACE FRONT THAT MEANDERS NORTH ACROSS LA PAMPA ON
SATURDAY/EARLY SUNDAY MORNING. UNDER FAVORABLE UPPER
DYNAMICS...THE ENSUING LOW LEVEL CIRCULATION WILL SUSTAIN
ORGANIZED DEEP CONVECTION ACROSS NORTHERN PATAGONIA/LA PAMPA ON
FRIDAY TO SATURDAY...WITH MAXIMA OF 20-35MM IN POTENTIALLY SEVERE
CONVECTION. ON SATURDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
15-20MM WHILE BUILDING NORTH ACROSS THE BUENOS AIRES
PROVINCE/CENTRAL ARGENTINA. REGENERATION IS POSSIBLE FARTHER TO
THE NORTH EARLY NEXT WEEK AS A DEEPER TROUGH STREAMS ACROSS THE
DRAKE PASSAGE/SOUTHERN CONE.

DAVISON/GALVEZ...WPC (USA)
$$

159 
FXSA20 KWBC 151843
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
142 PM EST WED DEC 15 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 15/19UTC: A BUILDING UPPER LEVEL CELL
OF THE SUBTROPICAL RIDGE REMAINS THE DOMINANT FEATURE...WITH AXIS
ANCHORING ON A 250 HPA HIGH THAT MEANDERS BETWEEN MATO GROSSO AND
SANTA CRUZ IN EASTERN BOLIVIA. THROUGH SATURDAY THE RIDGE WILL
BUILD SOUTH ACROSS PARAGUAY TO CENTRAL/NORTHERN PROVINCES IN
ARGENTINA...WHILE THE CLOSED HIGH RELOCATES TO EL CHACO PARAGUAYO.
AS THE RIDGE BUILDS...IT WILL DISPLACE A JET TO THE SOUTH...WITH
AXIS TO GRADUALLY RELOCATE FROM NORTHERN
ARGENTINA/URUGUAY-SOUTHERN BRASIL EARLY IN THE CYCLE TO CENTRAL
REGIONS OF CHILE-THE BUENOS AIRES PROVINCE DURING THE WEEKEND. A
TUTT LOW (CAVADO DO NORDESTE) LIES TO THE EAST OF THIS
RIDGE...CENTERING ON A CLOSED LOW NEAR 15S 30W. THROUGH THE END OF
THE WEEK THE LOW WILL WEAKEN TO AN OPEN TROUGH THAT IS TO THEN
EXTEND INTO NORTHEAST BRASIL. AT LOW LEVELS...THE RIDGE ALOFT IS
VENTING CONVECTION ALONG THE SOUTH AMERICA CONVERGENCE ZONE...AS
IT EXTENDS TO THE NORTHWEST ACROSS SAO PAULO-MATO GROSSO TO
EASTERN BOLIVIA. THIS IS TO PERSIST THROUGH FRIDAY...WEAKENING TO
A LOW LEVEL TROUGH ON SATURDAY-SUNDAY. ORGANIZED DEEP CONVECTION
IS TO GRADUALLY BUILDS WESTWARD ALONG THE CONVERGENCE ZONE...WITH
MOST ACTIVE TO INITIALLY CLUSTER BETWEEN SAO PAULO-GOIAS/WESTERN
MINAS GERAIS...WITH MAXIMA OF 60-120MM. ON THURSDAY TO FRIDAY
ACTIVITY ACROSS SAO PAULO WEAKENS TO 20-45MM/DAY...WHILE ACROSS
MATO GROSSO TO RONDONIA IT INCREASES TO 60-120MM. LATER DURING THE
WEEKEND...AS THE CONVERGENCE ZONE WEAKENS TO AN OPEN
TROUGH...FOCUS OF THE ACTIVITY SHIFTS TO CENTRAL/NORTHERN
BOLIVIA...WITH AN ENHANCED RISK OF HEAVY RAINFALL PRODUCING MCS TO
DEVELOP DURING THE MEDIUM RANGE PERIOD.

AS THE SUBTROPICAL RIDGE HOLDS TO THE NORTH...IT IS TO STEER A CUT
OFF LOW NEAR THE ARCHIPELAGO DE JUAN FERNANDEZ TOWARDS THE CENTRAL
REGIONS OF CHILE. THIS WILL MAKE LANDFALL NEAR CONCEPCION EARLY ON
FRIDAY MORNING...THEN WEAKEN TO AN OPEN TROUGH AS IT SPILLS ACROSS
THE SOUTHERN ANDES TO PATAGONIA IN SOUTHERN ARGENTINA LATER IN THE
DAY. AS IT SPILLS ACROSS THE ANDES A FINGER OF THE NORTHERN POLAR
IS TO ACCOMPANY THIS PERTURBATION...WITH ITS RIGHT EXIT REGION TO
FAVOR A BROAD AREA OF DIVERGENCE ACROSS CENTRAL/NORTHERN
PATAGONIA. THE STRONG UPWARD VERTICAL MOTION AND ENHANCED SHEAR
ALOFT IS LIKELY TO RESULT IN SEVERE CONVECTION BETWEEN LA PAMPA
AND NORTHERN PATAGONIA ON FRIDAY...WITH MAXIMA OF 20-30MM. ON
SATURDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 15-20MM AS THE
RISK OF SEVERE CONVECTION SPREADS NORTHWARD ACROSS LA PAMPA TO THE
BUENOS AIRES PROVINCE/SIERRA DE LA VENTANA AND TANDIL.

DAVISON/GALVEZ...WPC (USA)
$$

552 
FXSA20 KWBC 141705
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1205 PM EST TUE DEC 14 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 14/17UTC: UPPER FLOW PATTERN ACROSS
NORTHERN SOUTH AMERICA REMAINS UNDER THE DOMINANT INFLUENCE OF THE
SUBTROPICAL RIDGE. AT 250 HPA THE RIDGE SPANS BETWEEN NORTHERN
ARGENTINA AND BRASIL WHILE CENTERING ON A CLOSED HIGH OVER MATO
GROSSO. THIS WILL REMAIN NEARLY UNCHANGED DURING THE NEXT TWO
DAYS. LATER IN THE WEEK IT WILL THEN BUILD SOUTH TO CENTRAL
ARGENTINA WHILE THE CLOSED UPPER LEVEL HIGH RELOCATES TO SANTA
CRUZ IN EASTERN BOLIVIA. ALSO AT 250 HPA...A SUBTROPICAL JET
MAXIMA BOUNDS THE SOUTHERN FRINGES OF THIS RIDGE...WITH AXIS
TRAVERSING THE NORTHERN REGIONS OF CHILE/ARGENTINA TO URUGUAY-RIO
DE LA PLATA BASIN. BUT AS THE RIDGE BUILDS ACROSS NORTHERN TO
CENTRAL ARGENTINA...THE JET WILL ALSO SHIFT SOUTH TO EXTEND OVER
THE CONTINENT BETWEEN 30S-40S.

MEANWHILE...AS THE UPPER LEVEL RIDGE STRENGTHENS ITS FOOTHOLD OVER
SOUTH AMERICA...IT WILL STEER A SHORT WAVE TROUGH TO THE SOUTH
ACROSS NORTHERN ARGENTINA TO THE BUENOS AIRES PROVINCE/RIO DE LA
PLATA BASIN LATER TODAY. OVER THE WESTERN ATLANTIC THIS WILL THEN
FEED INTO A DIGGING MID/UPPER LEVEL TROUGH OFF THE NORTHEAST COAST
OF BRASIL. THROUGH THURSDAY THIS WILL EVOLVE INTO A CLOSED LOW
NEAR 13S 30W WHILE EXTENDING A SHORT WAVE TROUGH ACROSS RIO GRANDE
DO NORTE TO AMAPA/AMAZON RIVER DELTA REGION. PHASING WITH A SHORT
WAVE TO THE SOUTH...THE UPPER LOW WEAKENS TO AN OPEN TROUGH ON
FRIDAY. AT LOW LEVELS THE SOUTH AMERICA CONVERGENCE ZONE IS TO
GRADUALLY BECOME MORE ACTIVE/BETTER ORGANIZED AS IT IS TO EXTEND
ACROSS SAO PAULO TO SANTA CRUZ IN EASTERN BOLIVIA. THIS BOUNDARY
IS TO REMAIN WELL ORGANIZED THROUGH FRIDAY...WEAKENING DURING THE
WEEKEND. AS IT BECOMES BETTER ORGANIZED CONVECTION ALONG THIS
FEATURE WILL INTENSIFY. INITIALLY EXPECTING RAINFALL AMOUNTS OF
35-70MM...WITH MAXIMA ON WEDNESDAY-THURSDAY INCREASING TO
60-120MM/DAY. NOTE THAT SOME OF THE MODELS/ENSEMBLE MEMBERS SHOW
LOCALIZED MAXIMA IN EXCESS OF 150-200MM CLUSTERING BETWEEN MATO
GROSSO AND SOUTHEAST BOLIVIA. DURING THE WEEKEND ACTIVITY ACROSS
CENTRAL BRASIL IS TO WEAKEN...WHILE CONVECTION OVER CENTRAL
BOLIVIA IS TO INTENSIFY...WITH MAXIMA OF 35-70MM ON SATURDAY AND
40-80MM ON SUNDAY.

AS THE PATTERN TO THE NORTH EVOLVES...ANOTHER MID/UPPER LEVEL
SHORT WAVE TROUGH ON THE NORTHERN STREAM IS TO LIFT ACROSS THE
EASTERN PACIFIC WHILE GRADUALLY EVOLVING INTO A CLOSED LOW NEAR
THE ARCHIPELAGO DE JUAN FERNANDEZ LATER TODAY. THIS IS TO REMAIN
NEARLY STATIONARY THROUGH THURSDAY...WHILE LATER IN THE WEEK IT IS
TO THEN SHEAR ACROSS THE CENTRAL/SOUTHERN ANDES OF CHILE INTO
NORTHERN PATAGONIA/LA PAMPA IN ARGENTINA. AS IT SPILLS ACROSS THE
ANDES A NORTHERN POLAR JET MAXIMA WILL ACCOMPANY THIS
PERTURBATION. THIS WILL FAVOR AN UPPER DIVERGENT PATTERN ACROSS
NORTHERN PATAGONIA AND LA PAMPA LATER DURING THE WORKWEEK. AT LOW
LEVELS...THE MID LEVEL VORTEX WILL SUSTAIN CYCLOGENESIS OFF THE
CENTRAL/SOUTHERN COAT OF CHILE ON THURSDAY...WITH BOUNDARY MOVING
INLAND ACROSS PATAGONIA TO LA PAMPA ON SATURDAY. UNDER FAVORABLE
UPPER DYNAMICS THIS IS TO SUSTAIN SCATTERED DEEP CONVECTION
BETWEEN LA PAMPA AND NORTHERN PATAGONIA...WITH STABILITY INDICES
DURING THIS PERIOD SHOWING POSSIBILITY OF SEVERE CONVECTION.

ANOTHER MID/UPPER LEVEL RIDGE EXTENDS OVER THE SOUTHEAST
PACIFIC...WHERE IT IS TO REMAIN DURING THE NEXT 96-120 HRS. AS THE
RIDGE HOLDS...IT WILL STEER SHORT WAVE PERTURBATIONS ACROSS THE
ANTARCTIC PENINSULA/DRAKE PASSAGE. THE INFLOW OF SHORT WAVE ENERGY
WILL HELP SUSTAIN A DIGGING TROUGH OVER THE SOUTHWEST ATLANTIC
LATER IN THE WEEK. AT LOW LEVELS...FRONTAL PERTURBATIONS IN THE
SOUTHERN STREAM WILL CONFINE BETWEEN THE ANTARCTIC PENINSULA AND
EXTREME SOUTHERN CHILE/TIERRA DEL FUEGO. IN THIS
PATTERN...MEASURABLE RAINFALL AMOUNTS OVER CHILE WILL LIMIT TO
TIERRA DEL FUEGO...WITH ACCUMULATION INCREASING FROM 05-10MM TODAY
TO 15-20MM ON WEDNESDAY TO THURSDAY. BUT THIS IS TO RAPIDLY WEAKEN
DURING THE WEEKEND.

DAVISON/GALVEZ...WPC (USA)
$$

576 
FXSA20 KWBC 131700
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EST MON DEC 13 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 13/17UTC: AT 250 HPA...BROAD CELL OF
THE SUBTROPICAL RIDGE DOMINATES FLOW OVER THE CONTINENT TO THE
NORTH OF 34S AND TO THE WEST OF 40W...WITH AXIS CENTERING ON A
CLOSED HIGH THAT MEANDERS BETWEEN MATO GROSSO AND SOUTHERN PARA.
AN UPPER TROUGH TO THE EAST BOUNDS THE EASTERN FRINGES OF THIS
RIDGE...WITH AXIS NORTH ALONG 28W TO THE EQUATORIAL ATLANTIC. THE
RIDGE ALOFT WILL VENT DEEP CONVECTION ACROSS TROPICAL SOUTH
AMERICA...WITH CONVECTION CLUSTERING ALONG PERTURBATIONS IN THE
EASTERLY TRADES PROPAGATING ALONG THE NEAR EQUATORIAL TROUGH TO
THE NORTH. OVER THE NEXT COUPLE OF DAYS THIS WILL RESULT IN
RAINFALL MAXIMA OF 20-45MM/DAY IN SCATTERED DEEP CONVECTION...WITH
ACTIVITY DECREASING TO 20-35MM/DAY ON WEDNESDAY WHILE GRADUALLY
SPREADING ACROSS BRASIL BETWEEN 45W AND THE NORTHERN JUNGLE OF
PERU/STATE OF AMAZONAS.

AS THE RIDGE HOLDS OVER THE CONTINENT...IT IS TO STEER A SHORT
WAVE TROUGH TO THE SOUTH ACROSS THE CENTRAL/NORTHERN STATES OF
CHILE TO CUYO/CENTRAL ARGENTINA. THIS IS TO SLOWLY SHEAR EASTWARD
ACROSS THE BUENOS AIRES PROVINCE/ENTRE RIOS TO THE RIO DE LA PLATA
BASIN...WHILE SIMULTANEOUSLY ANOTHER SHORT WAVE TROUGH ON THE
NORTHERN STREAM LIFTS ALONG 80W WHILE EVOLVING INTO A CLOSED LOW
OVER THE ARCHIPELAGO DE JUAN FERNANDEZ. THE LATTER...STEERING BY
THE BUILDING RIDGE OVER BRASIL...IS TO MAKE LANDFALL BETWEEN
TEMUCO-CONCEPCION IN CENTRAL CHILE LATER ON THURSDAY. THIS IS TO
THEN WEAKEN WHILE SHEARING ACROSS NORTHERN APTAGONIA AND LA PAMPA
IN CENTRAL ARGENTINA. EARLY IN THE CYCLE THE INFLOW OF MID LEVEL
SHORT WAVE ENERGY ACROSS CHILE TO ARGENTINA WILL HELP SUSTAIN A
BAROCLINIC BOUNDARY ACROSS URUGUAY-NORTHERN ARGENTINA LATER TODAY.
THE FRONT IS TO THEN RETROGRESS ALONG 30S ACROSS SOUTHERN BRASIL
TO CORDOBA IN ARGENTINA ON TUESDAY...TO THEN REMAIN NEARLY
STATIONARY THROUGH THURSDAY MORNING. OVER SOUTHERN BRASIL TO
NORTHERN ARGENTINA THIS WILL SUSTAIN SCATTERED/POTENTIALLY SEVERE
CONVECTION...WITH ACCUMULATION OF 25-50MM. THIS WILL THEN
REINFORCE CONVECTION ALONG A SURFACE TROUGH OVER MATO GROSSO DO
SUL-NORTHERN SAO PAULO IN BRASIL...WITH CONDITIONS TO BECOME
FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS...WITH RAINFALL
MAXIMA OF 40-80MM TO CLUSTER OVER MATO GROSSO DO SUL AND PORTIONS
OF MINAS GERAIS/NORTHERN SAO PAULO. ON TUESDAY THE FOCUS OF THE
HEAVY CONVECTION SHIFTS TO CENTRAL BOLIVIA...WITH MAXIMA OF
40-80MM...WHILE ACROSS SOUTHEAST BRASIL AND MATO GROSSO DO SUL THE
MAXIMA WEAKENS TO 30-60MM WHILE CLUSTERING ALONG AND NORTH OF THE
SURFACE TROUGH. THROUGH WEDNESDAY THE LOW LEVEL TROUGH BECOMES
BETTER ORGANIZED WHILE ALSO MANIFESTING AT 700 HPA. THE DEEP LAYER
FEATURE COULD THEN EVOLVE ONCE AGAIN INTO THE SOUTH AMERICA
CONVERGENCE ZONE (SACZ). AS THE CONVERGENCE ZONE
STRENGTHENS...ENVIRONMENTAL CONDITIONS WILL BECOME MORE FAVORABLE
FOR HEAVY CONVECTION TO BUILD BETWEEN CENTRAL BOLIVIA AND
GOIAS/SAO PAULO IN BRASIL...WITH MAXIMA OF 60-120MM. THE HEAVY
RAINFALL WILL PERSIST THROUGH FRIDAY MORNING...WITH AN ADDITIONAL
35-70MM EXPECTED LATER IN THE WEEK.

ANOTHER RIDGE TO THE SOUTH AND WEST DOMINATES THE MID/UPPER LEVEL
FLOW OVER THE SOUTHEAST PACIFIC. PROGRESSIVE SHORT WAVE
PERTURBATIONS REVOLVE AROUND THIS AXIS...AND UNDER THE STEERING
INFLUENCE OF THE MID/UPPER LEVEL RIDGE THEY THEN STREAM ACROSS THE
ANTARCTIC PENINSULA/THE DRAKE PASSAGE TO THE SOUTHWEST ATLANTIC.
AT LOW LEVELS...FRONTAL PERTURBATIONS WILL CONFINE BETWEEN THE
ANTARCTIC PENINSULA AND EXTREME SOUTHERN CHILE/TIERRA DEL FUEGO.
IN THIS PATTERN...MEASURABLE RAINFALL AMOUNTS OVER CHILE WILL
LIMIT TO TIERRA DEL FUEGO...WITH ACCUMULATION INCREASING FROM
10-15MM EARLY IN THE CYCLE TO 15-20MM ON WEDNESDAY TO THURSDAY.

DAVISON/GALVEZ...WPC (USA)
$$

793 
FXSA20 KWBC 101635
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1134 AM EST FRI DEC 10 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

GOVERNMENT OF BRASIL IS ISSUING WARNINGS FOR SUBTROPICAL STORM
UBA. PLEASE VISIT THE CENTRO DE HIDROGRAFIA DA MARINHA DO BRASIL
FOR THE OFFICIAL FORECAST.

FORECAST DISCUSSION FROM DEC 10/16UTC: A BUILDING CELL OF THE
SUBTROPICAL RIDGE IS TO GRADUALLY BECOME THE DOMINANT
MESO-SYNOPTIC FEATURE OVER NORTHERN SOUTH AMERICA...WITH AXIS TO
STRENGTHEN ITS FOOTHOLD OVER THE CONTINENT TO THE NORTH OF 30S AND
WEST OF 40W. THE BUILDING RIDGE IS TO THEN CENTER ON A CLOSED HIGH
OVER MATO GROSSO IN BRASIL. AT LOW LEVELS...THE RIDGE ALOFT IS
VENTING CONVECTION ALONG THE SOUTH AMERICA CONVERGENCE ZONE...AS
THE LATTER EXTENDS ACROSS ESPIRITO SANTO/BAHIA IN BRASIL TO
RONDONIA/NORTHERN BOLIVIA. EARLY ON SATURDAY THIS WEAKENS TO AN
OPEN TROUGH THAT MEANDERS SOUTH ACROSS SOUTHEAST BRASIL TO THE
CHACO PARAGUAYO/SOUTHEAST BOLIVIA EARLY NEXT WEEK. MOST ACTIVE
CONVECTION WITH THIS FEATURE IS EXPECTED TODAY...WITH MAXIMA OF
75-125MM OVER ESPIRITO SANTO...WHILE OVER BAHIA/MINAS GERAIS AND
TOCANTINS/GOIAS THE MAXIMA PEAK AT 30-60MM. ON SATURDAY THIS
WEAKENS TO 20-35MM WHILE SPREADING ACROSS MINAS/BAHIA AND GOIAS.
EARLY NEXT WEEK...AS THE LOW LEVEL TROUGH SETTLES OVER SOUTHEAST
BRASIL-PARAGUAY...MODELS AGREE ON POTENTIAL FOR AN MCS TO DEVELOP
ACROSS PARAGUAY-MATO GROSSO DO SUL TO SAO PAULO. IN THIS AREA
EXPECTING MAXIMA OF 40-80MM IN ORGANIZED DEEP CONVECTION.

FARTHER SOUTH...THE SYSTEM OF CONCERN IS A DEEPENING MID/UPPER
LEVEL TROUGH THAT REACHES SOUTHERN CHILE EARLY ON SATURDAY
MORNING. THE DEEP CLOSED LOW IS TO MEANDER EAST ACROSS SOUTHERN
CHILE TO PATAGONIA IN ARGENTINA LATER IN THE DAY...AND THROUGH
SATURDAY MORNING IT MIGRATES TO THE WESTERN ATLANTIC WHILE
GRADUALLY MERGING WITH A SHORT WAVE TROUGH TO THE SOUTH. A
BUILDING MID/UPPER LEVEL RIDGE TO THE WEST IS TO THEN FAVOR THE
NORTHWARD AMPLIFICATION OF THIS TROUGH ACROSS THE SOUTHERN CONE TO
MID SECTIONS OF SOUTH AMERICA DURING THE WEEKEND/EARLY NEXT WEEK.
AT LOW LEVELS THIS WILL SUSTAIN A BROAD CYCLONIC CIRCULATION
ACROSS SOUTHERN CHILE LATER THIS EVENING. ON SATURDAY...AS IT
CLEARS THE COAST OF PATAGONIA...THE SURFACE LOW IS TO
DEEPEN/RAPIDLY INTENSIFY. THIS IS TO THEN FAVOR A MOIST
EAST-SOUTHEASTERLY ACROSS SOUTHERN PATAGONIA/THE SOUTHERN ANDES OF
CHILE. WINDS ARE TO THEN TAKE A SOUTHERLY COMPONENT ACROSS THE
SOUTHERN CONE AS THE FRONTAL LOW ENTERS THE WESTERN ATLANTIC. THE
SOUTHERLY WINDS WILL DRIVE THE FRONT NORTH ACROSS CENTRAL
ARGENTINA/RIO DE LA PLATA BASIN TO URUGUAY ON SATURDAY TO SUNDAY.
BUT LOSING UPPER LEVEL SUPPORT...THE FRONT IS TO THEN STALL AS IT
NEARS 30S LATER ON MONDAY. OVER SOUTHERN CHILE THE DEEP OCCLUDING
LOW WILL SUSTAIN RAINFALL MAXIMA OF 20-40MM ON SATURDAY TO SUNDAY.
BUT AS THE OCCLUDED LOW MEANDERS ACROSS PATAGONIA...THE ENSUING
SOUTHEASTERLY FLOW WILL ENHANCE MOISTURE TRANSPORT/CONVERGENCE
ACROSS SOUTHERN PATAGONIA IN ARGENTINA...WITH MAXIMA OF 40-80MM ON
SATURDAY. OVER CENTRAL ARGENTINA PREFRONTAL/POTENTIALLY SEVERE
CONVECTION IS TO THEN SUSTAIN RAINFALL AMOUNTS OF 25-50MM ON
SATURDAY. ON SUNDAY...AS THE FRONT MEANDERS NORTH ACROSS URUGUAY
TO NORTHERN ARGENTINA THE MOST INTENSE IS FORECAST ALONG THE LEE
OF THE ANDES OVER NORTHWEST ARGENTINA. IN THIS AREA EXPECTING
RAINFALL MAXIMA OF 30-60MM ON SUNDAY TO MONDAY.

DAVISON...WPC (USA)
$$

132 
FXSA20 KWBC 091629
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1128 AM EST THU DEC 09 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 09/16UTC: NORTH OVER THE
CONTINENT...AT 250 HPA...A BROAD RIDGE IS INITIALIZED TO THE NORTH
OF 30S AND WEST OF 50W...WITH AXIS CENTERING ON A CLOSED HIGH OVER
THE ALTIPLANO OF BOLIVIA. A CLOSED MID/UPPER LEVEL LOW TO THE
EAST-SOUTHEAST OF THIS AXIS LIES OFF THE COAST OF SAO PAULO/SANTA
CATARINA IN BRASIL. AT LOW LEVELS THIS SUSTAINS AN OCCLUDED LOW
THAT IS EXPECTED TO GRADUALLY TAKE WARM CORE CHARACTERISTICS.
THROUGH FRIDAY MORNING AS IT MEANDERS OVER WARMER THAN NORMAL SEA
SURFACE TEMPERATURES AND WANING UPPER LEVEL WIND SHEAR THIS COULD
THEN MAKE THE TRANSITION TO A SUBTROPICAL CYCLONE. THIS COULD
POTENTIALLY LAST THROUGH SATURDAY AFTERNOON... BUT AS IT MOVES TO
COLDER WATERS AND MERGES INTO THE SOUTHERN STREAM FLOW ON
SUNDAY...IT IS EXPECTED TO ONCE AGAIN TRANSITION TO AN
EXTRATROPICAL CYCLONE. IF REQUIRED...THE CENTRO DE HIDROGRAFIA DA
MARINHA DO BRASIL WILL ISSUE THE OFFICIAL FORECAST ADVISORY FOR
THIS SYSTEM.

FURTHERMORE...THIS ALSO PROVIDES SUPPORT TO THE SOUTH AMERICA
CONVERGENCE ZONE AS IT EXTENDS ACROSS RIO DE JANEIRO/MINAS
GERAIS-MATO GROSSO TO RONDONIA IN BRASIL AND THE SOUTHERN JUNGLE
OF PERU. THROUGH SATURDAY THE CONVERGENCE ZONE IS FORECAST TO
WEAKEN TO AN OPEN TROUGH AS THE SUBTROPICAL RIDGE BUILDS OVER THE
CONTINENT AND THE MID/UPPER LEVEL TROUGH TO THE EAST WEAKENS AS IT
MEANDERS TO THE EAST-SOUTHEAST. INITIALLY MOST ACTIVE CONVECTION
IS TO CLUSTER ACROSS ESPIRITO SANTO/MINAS GERAIS AND BAHIA IN
NORTHEAST BRASIL...WITH RAINFALL MAXIMA OF 75-125MM. ON FRIDAY
EXPECTING ADDITIONAL RAINFALL AMOUNT OF 30-60MM. OTHER CONVECTION
IS EXPECTED ALONG AND NORTH OF THE CONVERGENCE ZONE BETWEEN
AMAZONAS IN WESTERN BRASIL AND TOCANTINS/GOIAS...WITH RAINFALL
AMOUNTS OF 20-45MM/DAY. THROUGH SATURDAY THIS IS FORECAST TO
WEAKEN TO 10-15MM/DAY AND MAXIMA OF 20-35MM IN SCATTERED DEEP
CONVECTION. AS THE ACTIVITY OVER BRASIL WANES...CONVECTION ACROSS
CENTRAL/ SOUTHERN JUNGLE OF PERU SURGES...WITH MAXIMA OF 35-70MM
EARLY ON FRIDAY. ON FRIDAY TO SATURDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 25-50MM.

SOUTH OF THE SUBTROPICAL RIDGE...AN ELONGATED MID/UPPER LEVEL
TROUGH EXTENDS TO THE NORTHWEST FROM A LOW OVER LA PAMPA TO 25S
85W. THE TROUGH IS FOCUSING SHORT WAVE ENERGY ACROSS CENTRAL CHILE
AND ARGENTINA...PROVIDING DYNAMICAL SUPPORT TO A SURFACE FRONT
ACROSS THE BUENOS AIRES PROVINCE TO CORDOBA. THROUGH SATURDAY THE
SHORT WAVE TROUGH IS TO RAPIDLY WEAKEN WHILE SHEARING TO THE
SOUTHEAST AHEAD OF A DEEP MID LEVEL TROUGH. MEANWHILE...OVER
CENTRAL ARGENTINA EXPECTING MODERATE RAINFALL AMOUNTS WITH MAXIMA
OF 20-35MM. UNDER INFLUENCE OF A FINGER OF THE NORTHERN POLAR
JET...THERE IS AN ENHANCED RISK OF HAIL PRODUCING THUNDERSTORMS IN
THIS AREA. ON FRIDAY FOCUS OF THE ORGANIZED CONVECTION SHIFTS TO
NORTHWEST ARGENTINA...WITH RAINFALL AMOUNTS OF 20-40MM IN DEEP
CONVECTION.

OVER THE SOUTHERN CONE THE SYSTEM OF CONCERN IS A DEEP MID/UPPER
LEVEL LOW THAT REACHES SOUTHERN CHILE LATER ON FRIDAY/EARLY
MORNING HOURS ON SATURDAY. THIS IS TO THEN MEANDER EAST ACROSS
SOUTHERN CHILE TO PATAGONIA IN ARGENTINA LATER IN THE DAY/EARLY ON
SUNDAY MORNING...AND ON SUNDAY IT IS TO THEN MERGE WITH A
DEEPENING SOUTHERN STREAM TROUGH ENTERING THE SOUTH AMERICAN
DOMAIN. UNDER THE INFLUENCE OF A BUILDING RIDGE TO THE WEST THESE
WILL THEN EVOLVE INTO A LONG WAVE TROUGH THAT IS TO EXTEND FROM
THE ANTARCTIC PENINSULA TO CHILE/ARGENTINA EARLY NEXT WEEK. AS IT
NEARS THE SOUTH COAST OF CHILE ON FRIDAY...THIS WILL SUSTAIN A
DEEPENING OCCLUDING LOW. OVER SOUTHERN CHILE EXPECTING RAINFALL
AMOUNTS OF 15-20MM ON FRIDAY...WHILE ON SATURDAY IT INCREASES TO
20-40MM. THE OCCLUDED SURFACE LOW IS TO THEN MEANDER EAST ACROSS
PATAGONIA IN ARGENTINA TO THE WESTERN ATLANTIC ON SATURDAY TO
SUNDAY...MEANWHILE SUSTAINING A WARM/MOIST ADVECTIVE PATTERN THAT
IS TO FEED ORGANIZED DEEP CONVECTION ACROSS SOUTHERN PATAGONIA.
THE ONSHORE FLOW WILL BE ENHANCED BY TOPOGRAPHICAL FORCING TO
SUSTAIN HEAVY RAINFALL AMOUNTS WITH MAXIMA OF 40-80MM. ACROSS
CENTRAL ARGENTINA IT IS TO THEN TRIGGER RAINFALL MAXIMA OF 20-40MM
ON SATURDAY...WHILE ON SUNDAY THIS INCREASES TO 30-60MM WHILE
BUILDING ALONG THE LEE OF THE ANDES OVER NORTHWEST ARGENTINA.

DAVISON...WPC (USA)
$$

842 
FXSA20 KWBC 081739
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1239 PM EST WED DEC 08 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 08/18UTC: AT 250 HPA THE MODELS
INITIALIZE A BROAD UPPER LEVEL RIDGE THAT DOMINATES CONTINENTAL
AREA TO THE NORTH OF 35S AND WEST OF 50W WHILE CENTERING ON A
CLOSED HIGH OVER CENTRAL BOLIVIA. EAST OF THIS AXIS...A CUT OFF
LOW LIES OVER THE WESTERN ATLANTIC OFF THE SOUTH/SOUTHEAST COAST
OF BRASIL. AS THE TROUGH HOLDS TO THE EAST...A SUBTROPICAL JET
MAXIMA IS LIFTING ACROSS THE SOUTHEAST STATES OF BRASIL TO
SOUTHERN MINAS GERAIS/RIO DE JANEIRO AREA...WITH AXIS FAVORING A
BROAD UPPER DIVERGENT PATTERN ACROSS ESPIRITO SANTO-MINAS GERAIS
AND PORTIONS OF BAHIA. IN A SLOW TO EVOLVE PATTERN...THIS IS TO
REMAIN NEARLY UNCHANGED THROUGH THURSDAY EVENING. ON FRIDAY IT IS
TO THEN SLOWLY PULL AS IT MOVES ACROSS 40W...WITH AXIS WEAKENING
TO AN OPEN TROUGH EARLY ON SATURDAY MORNING. UNDER THE INFLUENCE
OF THIS LOW/TROUGH AND THE RIDGE TO THE WEST...THE SOUTH AMERICA
CONVERGENCE ZONE (SACZ) FORMED ACROSS THE BRAZILIAN STATES OF
ESPIRITO SANTO/MINAS GERAIS...TOCANTINS/GOIAS...TO SOUTHERN
AMAZONAS/ACRE IN WESTERN BRASIL. THIS IS FORECAST TO PERSIST
DURING THE NEXT 60-72 HRS...THEN WEAKEN TO A SHALLOW TROUGH OVER
BRASIL EARLY ON SATURDAY. MEANWHILE...HEAVY CONVECTION IS TO
AFFECT ESPIRITO SANTO-MINAS GERAIS AND PORTIONS OF BAHIA...WITH
MAXIMA OF 75-175MM EXPECTED THROUGH THURSDAY MORNING...WHILE ON
THURSDAY TO FRIDAY THE MAXIMA PEAKS AT 75-125MM WHILE BUILDING
NORTH ACROSS BAHIA. ON FRIDAY TO SATURDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 30-60MM. OVER TOCANTINS/GOIAS-MATO GROSSO
INITIALLY EXPECTING RAINFALL AMOUNTS OF 35-70MM. BUT THIS WEAKENS
TO 20-35MM/DAY ON THURSDAY AND ONWARD. OTHER CONVECTION IS
EXPECTED TO THE WEST ACROSS ACRE IN BRASIL TO SOUTHERN JUNGLE OF
PERU...WITH MAXIMA INCREASING FROM 20-35MM EARLY IN THE CYCLE TO
35-70MM ON THURSDAY. ON FRIDAY EXPECTING ADDITIONAL RAINFALL
AMOUNTS OF 25-50MM. DURING THE WEEKEND...AS THE SACZ WEAKENS TO A
TROUGH...FOCUS OF THE ACTIVITY SHIFTS TO CENTRAL BOLIVIA WITH
ACCUMULATION OF 35-70MM.

FURTHERMORE...UNDER THE INFLUENCE OF THE MID/UPPER LEVEL
TROUGH...A WANING BAROCLINIC BOUNDARY EXTENDS OFF THE SOUTHEAST
COAST OF BRASIL. A FRONTAL WAVE FORMS ALONG THIS BOUNDARY DURING
THE DAY TODAY...AND THROUGH THURSDAY IT IS FORECAST TO
DEEPEN/BECOME BETTER ORGANIZED. THE GFS AND GDI FORECAST
CONSISTENTLY SHOW CONVECTION DEEPENING AS MOISTURE WRAPS AROUND
THE LOW LEVEL CIRCULATION...WITH WEAKENING UPPER LEVEL WIND SHEAR
AND WARMER THAN NORMAL WATERS TO POTENTIALLY FAVOR TRANSITION TO A
SUBTROPICAL CYCLONE. HOWEVER...THIS WILL QUICKLY EVOLVE INTO
EXTRATROPICAL AS IT MOVES TO COLDER WATERS TO THE SOUTH AND MERGES
INTO THE POLAR FLOW. ADVISORIES...IF NEEDED...WILL BE ISSUED BY
THE SERVICIO DE HIDROGRAFIA DE LA MARINHA DO BRASIL.

ALSO...AS THE UPPER LEVEL RIDGE HOLDS TO THE NORTH OVER
BRASIL...IT IS TO STEER A SLOW TO EVOLVE MID/UPPER LEVEL SHORT
WAVE TROUGH ACROSS CENTRAL CHILE TO LA PAMPA/CENTRAL ARGENTINA.
THROUGH FRIDAY THIS IS TO THEN MEANDER EAST ACROSS CENTRAL
ARGENTINA TO THE RIO DE LA PLATA BASIN...MOVING OFF THE COAST TO
THE WESTERN ATLANTIC ON SATURDAY. IT IS TO THEN RAPIDLY SHEAR AS
IT INTERACTS WITH THE AFOREMENTIONED PERTURBATION OFF THE
SOUTHEAST COAST OF BRASIL. AT LOW LEVELS THIS SUSTAINS A SURFACE
FRONT ACROSS CENTRAL ARGENTINA...WITH BOUNDARY TO MEANDER OVER THE
BUENOS AIRES PROVINCE-MENDONZA DURING THE NEXT COUPLE OF DAYS.
LATER ON FRIDAY IT IS FORECAST TO FRONTOLIZE WHILE SHEARING TO THE
SOUTHEAST. INITIALLY MOST ACTIVE CONVECTION IS EXPECTED ALONG THE
LEE OF THE ANDES OVER CENTRAL ARGENTINA (CUYO)...WITH RAINFALL
MAXIMA OF 25-50MM IN POTENTIALLY SEVERE CONVECTION. ON THURSDAY TO
FRIDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 15-25MM WHILE
BUILDING NORTH ACROSS MENDOZA TO CORDOBA...WHILE OVER BUENOS AIRES
THE MAXIMA PEAKS AT 20-35MM. THIS WEAKENS TO AN ADDITIONAL 15-25MM
ON FRIDAY.

DURING THE MEDIUM RANGE PERIOD...THE SYSTEM OF CONCERN IS A
DEEPENING MID/UPPER LEVEL TROUGH THAT ENTERS THE SOUTHERN CONE
LATER ON FRIDAY. IN THIS CYCLE THE MODELS MADE ADJUSTMENTS IN
FAVOR OF A DEEPER AND SLOWER TO EVOLVE MID LEVEL LOW TO MOVE OVER
PATAGONIA IN ARGENTINA ON SATURDAY. BUT AS IT MOVES TO THE WESTERN
ATLANTIC THIS WILL THEN WEAKEN WHILE SHEARING TO THE
EAST-SOUTHEAST. AS IT ENTERS SOUTHERN CHILE ON FRIDAY...THIS WILL
SUSTAIN A DEEPENING OCCLUDING LOW...FORECAST TO TRIGGER MODERATE
RAINFALL AMOUNTS. ON FRIDAY THIS WILL SUSTAIN RAINFALL AMOUNTS OF
15-30MM...WHILE ON SATURDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS
OF 20-40MM. ALSO ON SATURDAY...THE DEEPENING OCCLUDED LOW IS NOW
FORECAST TO TRIGGER HEAVY/POTENTIALLY SEVERE CONVECTION ACROSS
CENTRAL PORTIONS OF PATAGONIA...WITH MAXIMA OF 40-80MM.

DAVISON...WPC (USA)
$$

919 
FXSA20 KWBC 071729
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1228 PM EST TUE DEC 07 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 07/17UTC: AT UPPER LEVELS A CELL OF
THE SUBTROPICAL RIDGE REMAINS WELL ENTRENCHED OVER SOUTH
AMERICA...WITH AXIS SPANNING FROM BRASIL TO LA PAMPA/PATAGONIA IN
SOUTHERN ARGENTINA. AT 250 HPA THIS AXIS ANCHORS ON A CLOSED HIGH
OVER CENTRAL BOLIVIA. AN ANTICYCLONICALLY CURVED SUBTROPICAL JET
MAXIMA BOUNDS THE SOUTHERN FRINGES OF THIS RIDGE AS IT EXTENDS
ACROSS CENTRAL CHILE/ARGENTINA INTO THE SOUTHERN/SOUTHEASTERN
STATES OF BRASIL...WITH THE JET EXITING OVER RIO DE
JANEIRO/ESPIRITO SANTO WHERE IT FAVORS AN UPPER DIVERGENT PATTERN.
ANOTHER FEATURE OF INTEREST IS A MID/UPPER LEVEL SHORT WAVE TROUGH
MEANDERING OFF THE SOUTHEAST COAST OF BRASIL. THE UPPER LEVEL
RIDGE IS TO REMAIN NEARLY UNCHANGED DURING THE NEXT 72-84
HRS...THEN FLATTEN TO THE SOUTH OF 30S. THE SHORT WAVE
TROUGH...MEANWHILE...UNDER THE INFLUENCE OF THE SUBTROPICAL JET IS
TO ORGANIZED INTO A DEEPENING CLOSED LOW OFF THE SOUTHEAST COAST
OF BRASIL EARLY ON WEDNESDAY MORNING. THIS IS TO THEN REMAIN
NEARLY STATIONARY THROUGH THURSDAY EVENING. LATER IN THE WEEK IT
IS TO ONCE AGAIN WEAKEN TO AN OPEN TROUGH WHILE PULLING ACROSS
37W. AT LOW LEVELS...UNDER THE INFLUENCE OF AN ATMOSPHERIC KELVIN
WAVE THAT IS TRAVERSING TROPICAL/SUBTROPICAL SOUTH AMERICA...A
TROUGH ACROSS BRASIL ORGANIZES INTO THE SOUTH AMERICA CONVERGENCE
ZONE (SACZ) EARLY IN THE CYCLE...WITH AXIS TO EXTEND ACROSS
ESPIRITO SANTO/MINAS GERAIS-GOIAS TO RONDONIA/ACRE IN WESTERN
BRASIL. EARLY ON SATURDAY MORNING...AS THE MID LEVEL TROUGH
WEAKENS...THE SACZ IS EXPECTED TO DISSIPATE. MEANWHILE...EXPECTING
HEAVY RAINFALL AMOUNTS TO AFFECT THE BRAZILIAN STATES OF ESPIRITO
SANTO...MINAS GERAIS AND PORTIONS OF BAHIA...WITH STORM TOTAL
AMOUNTS OF 350-500MM EXPECTED THROUGH FRIDAY. OTHER CONVECTION IS
EXPECTED ALONG AND NORTH OF THE SACZ TO AFFECT
TOCANTINS/GOIAS-MATO GROSSO AND ACRE/RONDONIA...WITH STORM TOTAL
AMOUNTS OF 100-200MM...WHILE OVER SOUTHERN/CENTRAL JUNGLE OF PERU
THE MOST INTENSE IS EXPECTED ON THURSDAY THROUGH SATURDAY...WITH
STORM TOTAL AMOUNTS OF 75-125MM. FURTHERMORE...UNDER THE INFLUENCE
OF THE MID LEVEL TROUGH/CLOSED LOW...THE MODELS CONSISTENTLY
FORECAST A CLOSED SURFACE LOW TO FORM TO THE SOUTH-SOUTHEAST OF
RIO DE JANEIRO ON WEDNESDAY. JET ALOFT/UPPER WIND SHEAR IS LIKELY
TO INHIBIT TRANSITION TO A SUBTROPICAL CYCLONE THROUGH THURSDAY
MORNING...WITH A BRIEF PERIOD LATER ON THURSDAY/EARLY ON FRIDAY
WHEN THE JET ALOFT WEAKENS. AT THAT TIME IT COULD MAKE THE
TRANSITION TO A SUBTROPICAL CYCLONE.

SOUTH OVER THE EASTERN PACIFIC...A SHORT WAVE TROUGH ON THE
NORTHERN STREAM MEANDERS OFF THE CENTRAL COAST OF CHILE. UNDER THE
STEERING INFLUENCE OF THE UPPER LEVEL RIDGE TO THE NORTH...THE
SHORT WAVE TROUGH SPILLS ACROSS THE CENTRAL ANDES OF CHILE TO CUYO
IN ARGENTINA/LA PAMPA LATER TODAY. IN A LIGHT MEANDERING STEERING
FLOW...THIS IS TO THEN REMAIN NEARLY STATIONARY OVER CENTRAL
ARGENTINA THROUGH FRIDAY MORNING...THEN RAPIDLY WEAKEN WHILE
SHEARING TO THE SOUTHEAST AHEAD OF A DEEPER/LONGER AMPLITUDE
TROUGH ENTERING THE SOUTHERN CONE LATER IN THE WEEK.
MEANWHILE...THE MID LEVEL VORTEX WILL SUSTAIN CYCLOGENESIS OVER LA
PAMPA AND FRONTOGENESIS OVER CENTRAL ARGENTINA LATER TODAY. OVER
THE NEXT TWO DAYS THE FRONT MEANDERS NORTH...BUT AS IT PRESSES
AGAINST THE SUBTROPICAL RIDGE TO THE NORTH IS TO STALL ACROSS THE
BUENOS AIRES PROVINCE-CORDOBA IN ARGENTINA. MOST ACTIVE CONVECTION
IS EXPECTED THIS AFTERNOON/EVENING TO AFFECT NORTHERN PATAGONIA
AND CENTRAL ARGENTINA...WITH RAINFALL MAXIMA OF 25-50MM IN
POTENTIALLY SEVERE CONVECTION. THIS WILL PERSIST THROUGH WEDNESDAY
WHILE CLUSTERING ALONG THE LEE OF THE CENTRAL ANDES...WHILE LATER
ON THURSDAY ACTIVITY IS TO THEN SPREAD ACROSS THE BUENOS AIRES
PROVINCE.

DURING THE MEDIUM RANGE PERIOD THE SYSTEM OF CONCERN IS A
DEEPENING MID/UPPER LEVEL TROUGH THAT ENTERS THE SOUTHERN CONE. AT
LOW LEVELS THE FRONTAL TROUGH REACHES SOUTHERN CHILE LATER ON
THURSDAY...AND ON FRIDAY IT DEEPENS WHILE AMPLIFYING ACROSS
PATAGONIA TO CENTRAL ARGENTINA. THIS IS TO THEN EVOLVE INTO A DEEP
OCCLUDED LOW OFF THE COAST OF PATAGONIA LATER ON FRIDAY. OVER
SOUTHERN CHILE THIS WILL SUSTAIN MODERATE RAINFALL AMOUNTS LATER
ON FRIDAY...WITH MAXIMA OF 20-35MM. ON SATURDAY THE OCCLUDING
SURFACE LOW IS TO SUSTAIN SIMILAR AMOUNTS ACROSS CENTRAL
PATAGONIA...WHILE OVER THE BUENOS AIRES PROVINCE/CENTRAL ARGENTINA
THIS INCREASES TO 20-45MM AS ENHANCED BY THE ASSOCIATED SURFACE
FRONT.

DAVISON...WPC (USA)
$$

019 
FXSA20 KWBC 031517
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1016 AM EST FRI DEC 03 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

LAST NO AMENDS...NEXT TO BE ISSUED O/A DEC 07

FORECAST DISCUSSION FROM DEC 03/15UTC: BROAD CELL OF THE
SUBTROPICAL RIDGE REMAINS THE DOMINANT MESO/SYNOPTIC FEATURE OVER
SOUTH AMERICA...WITH AXIS SLOWLY BUILDING SOUTHWARD ACROSS
BOLIVIA/PARAGUAY TO THE NORTHERN PROVINCES OF ARGENTINA. AT 250
HPA THIS IS TO INITIALLY BOTTOM OUT OVER THE CONTINENT TO THE
NORTH OF 30S...BUT THROUGH THE WEEKEND IT IS TO BUILD FARTHER
SOUTH ACROSS ARGENTINA TO 40S...MEANWHILE CENTERING ON A CLOSED
HIGH THAT IS TO MEANDER BETWEEN NORTHERN BOLIVIA AND MATO
GROSSO/RONDONIA IN BRASIL. IN A TIGHT GRADIENT TO THE SOUTH...A
SUBTROPICAL JET IS TO BOUND THE SOUTHERN FRINGES OF THIS RIDGE.
INITIALLY THIS IS TO EXTEND BETWEEN 26S AND 35S...BUT AS THE RIDGE
BUILDS ACROSS ARGENTINA IT IS TO ALSO RELOCATE ACROSS THE
CONTINENT TO 30S-37S DURING THE WEEKEND/EARLY NEXT WEEK.

THE UPPER LEVEL RIDGE AND JET MAXIMA OVER SOUTH AMERICA ARE TO
STEER SHORT WAVE PERTURBATIONS ON THE NORTHERN STREAM ACROSS CHILE
TO ARGENTINA...AND AS THEY CLEAR THE SOUTHERN FRINGES OF THE
SUBTROPICAL RIDGE THESE ARE TO THEN AMPLIFY OVER THE WESTERN
ATLANTIC. IN THIS PATTERN A DEEPENING MID/UPPER LEVEL TROUGH IS
INITIALIZED OFF THE SOUTHEAST COAST OF BRASIL...WITH AXIS NORTH
ALONG 37W/40W TO ESPIRITO SANTO/BAHIA. THROUGH SUNDAY MORNING THIS
WILL REACH MAXIMUM AMPLITUDE WITH AXIS AMPLIFYING TO RIO GRANDE DO
NORTE IN NORTHEAST BRASIL. THIS IS TO THEN RAPIDLY DAMPEN WHILE
YIELDING TO ANOTHER SHORT WAVE TROUGH DEEPENING TO THE SOUTH.
THROUGH EARLY NEXT WEEK THE LATTER IS TO THEN BECOME THE DOMINANT
FEATURE OFF THE SOUTH/SOUTHEAST COAST OF BRASIL.

AS THE MID/UPPER LEVEL SHORT WAVE PERTURBATIONS STREAM ACROSS THE
SOUTHERN CONE...THE INFLOW OF ENERGY/FAVORABLE JET DYNAMICS WILL
HELP SUSTAIN A BAROCLINIC BOUNDARY ACROSS THE BUENOS AIRES
PROVINCE/CENTRAL ARGENTINA. EARLY IN THE CYCLE THIS WILL BE THE
FOCUS OF ORGANIZED DEEP CONVECTION...WITH POTENTIAL FOR MODERATE
TO HEAVY RAINFALL AMOUNTS...WITH MAXIMA OF 25-50MM. THIS WILL
PERSIST THROUGH SATURDAY WHILE BUILDING EAST ACROSS THE BUENOS
AIRES PROVINCE TO SOUTHERN URUGUAY/RIO DE LA PLATA BASIN. BUT
HIGHER AMOUNTS ARE EXPECTED TO THE NORTH...BETWEEN JUJUY/SALTA AND
SOUTHERN BOLIVIA...WHERE CONDITIONS REMAIN FAVORABLE FOR AN MCS TO
DEVELOP LATER ON SATURDAY/EARLY ON SUNDAY MORNING. IN THIS
AREA...UNDER THE INFLUENCE OF AN ATMOSPHERIC KELVIN
WAVE...ACTIVITY IS EXPECTED TO SURGE...WITH MAXIMA OF 60-120MM. ON
SUNDAY-MONDAY FOCUS OF THE CONVECTION SHIFTS NORTH TO
CENTRAL/NORTHERN BOLIVIA AND POTENTIALLY THE SOUTHERN JUNGLE OF
PERU...WITH MAXIMA OF 40-80MM. THIS PERSISTS WHILE BUILDING NORTH
ACROSS RONDONIA/MATO GROSSO IN BRASIL...WITH MAXIMA OF 35-70MM.

ALSO...THE BUILDING CELL OF THE SUBTROPICAL RIDGE IS TO VENT
ORGANIZED DEEP CONVECTION ACROSS NORTHERN SOUTH AMERICA...WITH
MOST INTENSE EXPECTED BETWEEN PARA AND AMAZONAS IN NORTHERN
BRASIL...WITH MAXIMA OF 30-60MM IN SCATTERED DEEP CONVECTION. OVER
THE NEXT FEW DAYS ACTIVITY IN THIS AREA WAXES AND WANES...WHILE
ALSO REACTING TO THE INFLUENCE OF THE AFOREMENTIONED ATMOSPHERIC
KELVIN WAVE. HIGHER AMOUNTS...HOWEVER...ARE TO AFFECT ESPIRITO
SANTO/MINAS GERAIS IN EASTERN BRASIL...WITH MAXIMA OF 40-80MM
EXPECTED TODAY THROUGH SATURDAY MORNING. THROUGH SATURDAY THIS
WILL BUILD NORTH AND WEST ACROSS BAHIA TO TOCANTINS/GOIAS-MATO
GROSSO...WITH ACCUMULATION OF 25-50MM. BUT EARLY NEXT WEEK IT IS
EXPECTED TO SURGE AGAIN AS A DEEPENING/POTENTIAL SUBTROPICAL
CYCLONE FORMS OFF THE SOUTHEAST COAST OF BRASIL.

IN A TIGHTER GRADIENT MORE PROGRESSIVE PERTURBATIONS ARE TO STREAM
ACROSS THE DRAKE PASSAGE/EXTREME SOUTHERN PORTIONS OF CHILE. THESE
ARE TO FOCUS A PLUME OF SUBTROPICAL MOISTURE ACROSS SOUTHERN
CHILE/TIERRA DEL FUEGO...TO HELP SUSTAIN PERIODS OF MODERATE TO
HEAVY CONVECTION. INITIALLY EXPECTING MAXIMA OF 15-20MM...BUT THIS
INCREASES ON SATURDAY TO 20-35MM. SIMILAR AMOUNTS ARE EXPECTED
EARLY NEXT WEEK.

DAVISON...WPC (USA)
$$

063 
FXSA20 KWBC 021454
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
953 AM EST THU DEC 02 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 02/15UTC: Discussion not issued


DAVISON...WPC (USA)
$$

147 
FXSA20 KWBC 011715
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1214 PM EST WED DEC 01 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM DEC 01/15UTC: BROAD CELL OF THE
SUBTROPICAL RIDGE HAS BECOME THE DOMINANT SYNOPTIC SCALE FEATURE
OVER NORTHERN SOUTH AMERICA...WITH AXIS ENVELOPING AREA TO THE
NORTH OF 25S WHILE CENTERING AT 250 HPA ON A CLOSED HIGH THAT
MEANDERS BETWEEN RONDONIA IN WESTERN BRASIL AND CENTRAL/NORTHERN
BOLIVIA DURING THE NEXT 5-6 DAYS. AS THE RIDGE HOLDS...SHORT WAVE
TROUGHS ARE TO STREAM ACROSS CHILE/ARGENTINA ALONG THE SOUTHERN
FRINGES OF THIS RIDGE. AS THEY ENTER THE WESTERN ATLANTIC...THESE
WILL HELP SUSTAIN THE REGENERATION OF A TUTT (TROPICAL UPPER
TROPOSPHERIC TROUGH) OFF THE COAST OF BRASIL...WITH TROUGH AXIS TO
WANE EARLY THIS CYCLE WHILE YIELDING TO A DEEPENING UPPER LEVEL
TROUGH TO THE SOUTH. THROUGH FRIDAY EVENING/SATURDAY MORNING THE
TROUGH IS TO AMPLIFY BETWEEN 45W-20W TO THE EQUATOR. THE
PERSISTENT UPPER LEVEL RIDGE WILL VENT DEEP CONVECTION ACROSS
TROPICAL SOUTH AMERICA...WITH MOST ACTIVE TO INITIALLY CLUSTER
ALONG AND NORTH OF A SURFACE TROUGH OVER BRASIL. OVER AMAZONAS AND
PARA TO TOCANTINS/GOIAS INITIALLY EXPECTING ACCUMULATION OF
35-70MM/DAY...TO GRADUALLY WEAKEN TO 20-45MM/DAY ON FRIDAY THROUGH
SUNDAY. OTHER CONVECTION IS EXPECTED ACROSS THE EASTERN STATES OF
BAHIA-MINAS GERAIS-ESPIRITO SANTO...WHERE UNDER THE INFLUENCE OF A
WANING SURFACE FRONT EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND
MAXIMA OF 25-50MM. UNDER THE INFLUENCE OF THE DEEPENING UPPER
TROUGH (TUTT) ACTIVITY ACROSS ESPIRITO SANTO AND MINAS GERAIS IS
FORECAST TO INTENSIFY ON THURSDAY-FRIDAY...WITH RAINFALL MAXIMA OF
30-60MM. ON FRIDAY TO SATURDAY ENVIRONMENTAL CONDITIONS BECOME
FAVORABLE FOR AN MCS TO DEVELOP AS THE DEEPENING UPPER LEVEL
TROUGH INDUCES A SURFACE TROUGH EXTENDING FROM THE WESTERN
ATLANTIC INLAND TO NORTHEAST BRASIL. THROUGH
SATURDAY...HOWEVER...ACTIVITY IS TO WEAKEN AS THE UPPER TROUGH
SETTLES TO THE EAST...WITH DAILY MAXIMA DECREASING TO 20-45MM IN
SCATTERED DEEP CONVECTION. THE RIDGE ALOFT IS TO ALSO VENT DIURNAL
CONVECTION CLUSTERING OVER THE CENTRAL/SOUTHERN JUNGLE OF PERU TO
CENTRAL BOLIVIA. THIS IS TO GRADUALLY INTENSIFY OVER THE NEXT FEW
DAYS...INCREASING FROM 20-30MM EARLY IN THE CYCLE TO 25-50MM ON
THURSDAY. ON SUNDAY TO MONDAY THERE IS A STRONG CONSENSUS AMONG
THE GLOBAL MODEL GUIDANCE ON THE POSSIBILITY OF AN MCS FORMING
ACROSS NORTHERN BOLIVIA TO MATO GROSSO IN BRASIL...WHILE THE
MAXIMA INCREASES TO 40-80MM/DAY.

AS THE UPPER LEVEL RIDGE HOLDS TO THE NORTH...A FINGER OF THE
SUBTROPICAL JET IS TO BOUND THE SOUTHERN FRINGES OF THE UPPER
LEVEL RIDGE WHILE EXTENDING ACROSS CENTRAL/NORTHERN CHILE INTO
ARGENTINA/MESOPOTAMIA VALLEY TO THE SOUTHERN STATES OF BRASIL.
THIS IS TO THEN DRAW SHORT WAVE PERTURBATIONS ON THE NORTHERN
STREAM ACROSS CENTRAL CHILE TO CENTRAL/NORTHERN ARGENTINA-RIO DE
LA PLATA BASIN. IN THIS PATTERN A LONGER AMPLITUDE PERTURBATION
ENTERS THE SOUTHERN CONE LATER TODAY...AND AS IT STREAMS ACROSS
SOUTHERN CHILE/PATAGONIA-THE DRAKE PASSAGE IT IS TO SHEAR A SHORT
WAVE TROUGH TO THE NORTH. THE LATTER IS EXPECTED TO DEEPEN ALONG
THE CENTRAL COAST OF CHILE ON THURSDAY...SPILLING ACROSS THE ANDES
INTO LA PAMPA/CENTRAL ARGENTINA ON FRIDAY. THE SLOW TO EVOLVE
PERTURBATION IS TO THEN MEANDER EAST TO THE BUENOS AIRES
PROVINCE/RIO DE LA PLATA BASIN DURING THE WEEKEND. AT 250 HPA A
FINGER OF THE NORTHERN POLAR IS TO ACCOMPANY THIS PERTURBATION AS
IT STREAMS ACROSS THE SOUTHERN CONE...AND IN INTERACTION WITH THE
SUBTROPICAL JET TO THE NORTH IS TO SUSTAIN A BROAD AREA OF UPPER
DIVERGENCE THAT IS TO VENT ORGANIZED DEEP CONVECTION. IN
RESPONSE...CONVECTIVE ACTIVITY ON THURSDAY SURGES AHEAD OF A
SURFACE FRONT...WITH MAXIMA OF 30-60MM IN A MODERATE RISK OF LARGE
HAIL PRODUCING SEVERE THUNDERSTORMS. ALTHOUGH THE RISK OF SEVERE
THUNDERSTORMS WEAKENS ON FRIDAY...MODERATE TO HEAVY RAINFALL
AMOUNTS ARE TO PERSIST ACROSS CENTRAL ARGENTINA/BUENOS AIRES
PROVINCE THROUGH SATURDAY. CONSISTENT WITH PREVIOUS GUIDANCE...A
HEAVY RAINFALL PRODUCING MCS IS LIKELY TO DEVELOP TO THE NORTH
ACROSS JUJUY/SALTA TO SOUTHERN BOLIVIA/CHACO PARAGUAYO LATER ON
SATURDAY/EARLY ON SUNDAY MORNING...WITH CONSENSUS OF THE ENSEMBLE
MODELS SHOWING RAINFALL MAXIMA RANGING BETWEEN 75-150MM. THIS
COULD LEAD TO FLASH FLOODING ACROSS NORTHWEST ARGENTINA-SOUTHERN
BOLIVIA DURING THE WEEKEND.

DAVISON...WPC (USA)
$$

339 
FXSA20 KWBC 301526
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1026 AM EST TUE NOV 30 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 30/15UTC: IN A SUMMER TRANSITION
PATTERN...THE UPPER LEVELS CELL OF THE SUBTROPICAL RIDGE IS TO
GRADUALLY STRENGTHEN ITS FOOTHOLD ACROSS NORTHERN SOUTH
AMERICA...WITH AXIS BECOMING THE DOMINANT MESO-SYNOPTIC FEATURE
OVER THE CONTINENT TO THE NORTH OF 25S. AT 250 HPA THIS IS TO
ANCHOR ON A CLOSED HIGH THAT MEANDERS BETWEEN CENTRAL AND NORTHERN
BOLIVIA DURING THE NEXT 120-144 HRS. AS THE RIDGE INTENSIFIES
ACROSS NORTHERN SOUTH AMERICA...TROPICAL UPPER TROPOSPHERIC
TROUGHS (TUTT) ARE TO AMPLIFY FROM TIME-TO-TIME ALONG THE EASTERN
FRINGES OF THIS RIDGE WHILE CONFINING TO THE OFFSHORE WATERS OF
NORTHEASTERN BRASIL. AT LOW LEVELS...A WANING SURFACE FRONT IS TO
EXTEND FROM A LOW JUST EAST OF THE SOUTH GEORGIA ISLANDS TO SAO
PAULO/MATO GROSSO DO SUL LATER TODAY. THROUGH THURSDAY MORNING
THIS IS TO WEAKEN TO AN OPEN TROUGH ACROSS ESPIRITO SANTO/MINAS
GERAIS TO MATO GROSSO...WHERE IT IS TO THEN PERSIST THROUGH THE
END OF THE WEEK. MOST ACTIVE CONVECTION IS EXPECTED ALONG AND
NORTH OF THIS FEATURE...WITH ORGANIZED DEEP CONVECTION ACROSS
PORTIONS OF SAO PAULO/MINAS GERAIS TO INITIALLY FAVOR RAINFALL
MAXIMA OF 25-50MM. THROUGH FRIDAY THIS IS EXPECTED TO GRADUALLY
INTENSIFY WHILE SLOWLY BUILDING NORTH ACROSS ESPIRITO SANTO AND
MINAS GERAIS TO BAHIA...WITH MAXIMA INCREASING TO 40-80MM IN AN
ENHANCED RISK OF MCS. DURING THE WEEKEND...HOWEVER...ACTIVITY IS
TO GRADUALLY FIZZLE. OTHER CONVECTION IS EXPECTED ACROSS CENTRAL
AND WESTERN BRASIL...WITH DAILY MAXIMA OF 20-35MM/DAY. THROUGH
WEDNESDAY THIS INCREASES TO 20-45MM/DAY WHILE BUILDING NORTH
ACROSS PARA AND AMAZONAS.

SOUTH OVER THE CONTINENT...PROGRESSIVE MID/UPPER LEVEL
PERTURBATIONS ON THE SOUTHERN STREAM ARE TO GENERALLY CONFINE TO
THE DRAKE PASSAGE/EXTREME SOUTHERN PORTIONS OF CHILE AND PATAGONIA
IN ARGENTINA...WITH SLOWER TO EVOLVE SHORT WAVE PERTURBATIONS TO
THE NORTH TO FOCUS THEIR SHORT WAVE ENERGY ACROSS CENTRAL/NORTHERN
CHILE TO ARGENTINA-RIO DE LA PLATA BASIN/SOUTHERN STATES OF
BRASIL. EARLY IN THE CYCLE ONE IS TO SPILL ACROSS THE CENTRAL
ANDES OF CHILE AS ANOTHER MEANDERS OFF THE COAST OF URUGUAY. THE
LATTER IS TO GRADUALLY PULL TO THE EAST-SOUTHEAST AS THE LATTER
MEANDERS ACROSS CENTRAL ARGENTINA TO URUGUAY. A DEEPER
PERTURBATION FOLLOWS LATER IN THE WEEK...WITH THE DEEP MID LEVEL
TROUGH REACHING CENTRAL CHILE EARLY ON FRIDAY MORNING. AT 250 HPA
A FINGER OF THE NORTHERN POLAR IS TO ACCOMPANY THIS TROUGH AS IT
MAKES LANDFALL ACROSS CHILE TO ARGENTINA. THIS WILL THEN COUPLE
WITH A FINGER OF THE SUBTROPICAL JET TO THE NORTH IN SUPPORT OF A
BROAD AREA OF DIVERGENCE ACROSS CENTRAL ARGENTINA-RIO DE LA PLATA
BASIN. THE INFLOW OF SHORT WAVE ENERGY WILL FEED CONVECTIVE
DEVELOPMENT ALONG THE LEE OF THE ANDES OVER CENTRAL ARGENTINA
DURING THE DAY TODAY...WITH MAXIMA OF 15-20MM IN A MODERATE RISK
OF HAIL PRODUCING SEVERE THUNDERSTORMS. THROUGH THURSDAY ACTIVITY
IS TO INTENSIFY WHILE FOCUSING ALONG A PREFRONTAL TROUGH OVER LA
PAMPA/BUENOS AIRES PROVINCE...WITH MAXIMA INCREASING TO 30-60MM.
ON FRIDAY AND SATURDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
25-50MM WHILE SPREADING EAST AND NORTH ACROSS BUENOS AIRES
PROVINCE TO RIO DE LA PLATA BASIN. LATER DURING THE
WEEKEND...CONDITIONS BECOME HIGHLY FAVORABLE FOR A HEAVY RAINFALL
PRODUCING MCS TO DEVELOP BETWEEN NORTHWEST ARGENTINA AND SOUTHERN
BOLIVIA...WITH MAXIMA IN THIS AREA OF 50-100MM.

DAVISON...WPC (USA)
$$

677 
FXSA20 KWBC 291516
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1015 AM EST MON NOV 29 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 29/17UTC: PRODUCT NOT ISSUED.

DAVISON...WPC (USA)
$$

702 
FXSA20 KWBC 241726
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1226 PM EST WED NOV 24 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 24/17UTC: THE GLOBAL MODELS
INITIALIZE A LONG WAVE TROUGH OVER THE WESTERN ATLANTIC...WITH
AXIS NORTH ALONG 35W/40W TO 18S. THROUGH THURSDAY MORNING THE
TROUGH IS EXPECTED TO SLOWLY PULL TO THE EAST-SOUTHEAST...AND
LATER IN THE WEEK IT ACCELERATES ACROSS THE CENTRAL SOUTH
ATLANTIC. MEANWHILE...THIS SUSTAINS AN ELONGATED FRONT THAT
EXTENDS FROM THE CENTRAL ATLANTIC...WEAKENING INTO A MEANDERING
SHEAR LINE OVER BAHIA IN BRASIL. THE SHEAR LINE WILL ENHANCE LOW
LEVEL MOISTURE CONVERGENCE AND COULD LIKELY FAVOR AN ECHO TRAINING
PATTERN ACROSS EASTERN BAHIA. IN THIS AREA INITIALLY EXPECTING
RAINFALL AMOUNTS OF 20-35MM...INCREASING TO 25-50MM ON THURSDAY.
LOCALLY HIGHER AMOUNTS ARE HIGHLY PROBABLE ALONG THE COAST.

SIMULTANEOUSLY...AT 250 HPA...A BROAD CELL OF THE SUBTROPICAL
RIDGE OVER NORTHERN SOUTH AMERICA IS TO STEER SHORT WAVE TROUGHS
ON THE NORTHERN STREAM ACROSS THE CENTRAL REGIONS OF CHILE INTO
CENTRAL/NORTHERN ARGENTINA...WITH ONE TO SPILL ACROSS THE ANDES
INTO CUYO IN ARGENTINA EARLY IN THE CYCLE. AS IT NEARS
URUGUAY/BUENOS AIRES PROVINCE EARLY ON THURSDAY MORNING...UNDER
THE INFLUENCE OF COUPLED JETS ALOFT THIS PERTURBATION IS TO
STRENGTHEN/DEEPEN. CLEARING THE SOUTH COAST OF BRASIL/URUGUAY ON
FRIDAY MORNING...THIS WILL THEN AMPLIFY ALONG THE EASTERN FRINGES
OF THE SUBTROPICAL RIDGE...WITH AXIS TO THEN AMPLIFY NORTH ACROSS
ESPIRITO SANTO/MINAS GERAIS TO BAHIA DURING THE WEEKEND. EARLY IN
THE CYCLE...IN INTERACTION WITH THE REMNANTS OF AN OLD BAROCLINIC
BOUNDARY...THIS WILL SUSTAIN CYCLOGENESIS/FRONTOGENESIS OVER
CENTRAL ARGENTINA...WHILE ALSO TRIGGERING ORGANIZED DEEP
CONVECTION. DURING THE DAY THIS WILL EVOLVE INTO A SEVERE WEATHER
PRODUCING SQUALL LINE...WHILE SUSTAINING RAINFALL MAXIMA OF
40-80MM ACROSS ENTRE RIOS/CORRIENTES-CORDOBA IN ARGENTINA AND
PORTIONS OF URUGUAY. ON THURSDAY THE FOCUS OF THE HEAVY CONVECTION
SHIFTS TO SOUTHERN BRASIL-MISIONES IN ARGENTINA/URUGUAY AND
SOUTHEAST PARAGUAY...WITH MAXIMA OF 40-80MM...WITH SIMILAR AMOUNTS
BUILDING ACROSS CENTRAL BOLIVIA AHEAD OF THE ASSOCIATED SURFACE
BOUNDARY. ON FRIDAY THE FRONTAL LOW DEEPENS OFF THE COAST OF
URUGUAY/SOUTHERN BRASIL WHILE THE FRONT ADVANCES ACROSS SAO PAULO.
BUT THIS IS TO THEN RAPIDLY WEAKEN DURING THE WEEKEND.
MEANWHILE...MODERATE CONVECTION IS EXPECTED ACROSS MATO GROSSO DO
SUL/RIO DE JANEIRO AND SAO PAULO ON FRIDAY...WITH RAINFALL MAXIMA
OF 20-45MM. ON SATURDAY THE AMPLIFYING MID LEVEL TROUGH WILL
SUSTAIN SIMILAR RAINFALL AMOUNTS ACROSS MINAS GERAIS-BAHIAS AND
TOCANTINS/GOIAS IN BRASIL.

ANOTHER MID/UPPER LEVEL SHORT WAVE TROUGH ON THE NORTHERN STREAM
IS TO CLOSELY FOLLOW...WITH THE MID LEVEL VORTEX MAKING LANDFALL
OVER CENTRAL CHILE LATER ON FRIDAY. AS IT CLASHES WITH THE CENTRAL
ANDES...THE DEEP PERTURBATION IS TO BRIEFLY STALL OVER THE EASTERN
PACIFIC. BUT LATER IN THE DAY IT IS TO ALSO SPILL ACROSS CUYO TO
CENTRAL ARGENTINA UNDER THE INFLUENCE OF THE BROAD CELL OF THE
SUBTROPICAL RIDGE TO THE NORTH. THROUGH SUNDAY THIS IS TO THEN
LIFT ACROSS URUGUAY/BUENOS AIRES PROVINCE...CLEARING THE COAST
EARLY ON MONDAY MORNING. THE NORTHERN STREAM VORTEX IS TO ALSO
PROVIDE SUPPORT TO A SURFACE FRONT OVER CENTRAL ARGENTINA ON
FRIDAY...WITH BOUNDARY SURGING ACROSS CENTRAL TO NORTHERN
ARGENTINA ON SATURDAY. THE RAPID DISPLACEMENT AND ENSUING HELICITY
VALUES WILL LIKELY RESULT IN A SEVERE WEATHER PRODUCING EVENT.
OVER CENTRAL ARGENTINA/BUENOS AIRES PROVINCE THIS WILL SUSTAIN
MAXIMA OF 25-50MM ON SATURDAY...WHILE OVER CHACO/CORRIENTES TO THE
NORTH THE MAXIMA PEAKS AT 35-70MM. ON SUNDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 20-35MM ACROSS URUGUAY-RIO GRANDE DO SUL IN
BRASIL...WHILE OVER PARAGUAY/MATO GROSSO DO SUL THE MAXIMA PEAKS
AT 25-50MM. HIGHER AMOUNTS ARE EXPECTED OVER CENTRAL BOLIVIA AHEAD
OF THIS BOUNDARY AND A SOUTHERLY LOW LEVEL JET...WITH RAINFALL
MAXIMA OF 75-125MM ON SUNDAY TO MONDAY.

DURING THE MEDIUM RANGE PERIOD THE MODELS CONSISTENTLY FORECAST A
DEEPENING MID/UPPER LEVEL TROUGH ON THE SOUTHERN STREAM FLOW TO
RACE ACROSS THE SOUTHEAST PACIFIC TO THE SOUTHERN REGIONS OF
CHILE/DRAKE PASSAGE EARLY ON SUNDAY MORNING. AT LOW LEVELS THIS
WILL SUSTAIN A BROAD TROUGH ACROSS THE SOUTHEAST PACIFIC THAT
ENTERS SOUTHERN CHILE LATER ON SATURDAY. THIS WILL THEN MEANDER
EAST ACROSS THE SOUTHERN CONE ON SUNDAY...MEANWHILE FAVORING
STRONG BOUNDARY LAYER WINDS ACROSS SOUTHERN CHILE TO PATAGONIA IN
ARGENTINA. AS IT MAKES LANDFALL...THIS WILL SUSTAIN MODERATE TO
HEAVY RAINFALL AMOUNTS ACROSS CHILE TO THE SOUTH OF PUERTO
MONTT...WITH RAINFALL MAXIMA OF 20-30MM ON SATURDAY. ON SUNDAY
EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 20-30MM...WITH MOST
INTENSE EXPECTED BETWEEN TIERRA DEL FUEGO AND ISLA DE CHILOE TO
THE NORTH.

DAVISON...WPC (USA)
$$

968 
FXSA20 KWBC 231759
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1259 PM EST TUE NOV 23 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 23/16UTC: A POLAR TROUGH IS
INITIALIZED OVER THE WESTERN ATLANTIC...WITH AXIS NORTH ALONG 50W
TO URUGUAY/RIO DE LA PLATA BASIN. THIS REACHES MAXIMUM AMPLITUDE
THROUGH WEDNESDAY MORNING...WITH AXIS ALONG 35W TO 20S. THE TROUGH
IS TO THEN GRADUALLY PULL WHILE MIGRATING TO THE EAST-SOUTHEAST
ACROSS THE CENTRAL SOUTH ATLANTIC. SIMULTANEOUSLY...A SHORT WAVE
TROUGH ON THE NORTHERN STREAM FLOW IS TO CLOSELY FOLLOW...WITH THE
MID LEVEL VORTEX NEARING THE CENTRAL REGIONS OF CHILE LATER TODAY.
DRAWN BY A SUBTROPICAL JET MAXIMA TO THE NORTH...THE SHORT WAVE
TROUGH WILL THEN SPILL ACROSS THE CENTRAL ANDES TO CUYO IN
ARGENTINA ON WEDNESDAY...WITH AXIS FOCUSING ITS SHORT WAVE ENERGY
BETWEEN THE BUENOS AIRES PROVINCE AND MENDOZA. THROUGH THURSDAY
THIS IS TO THEN SLOWLY LIFT ACROSS URUGUAY AND THE SOUTHERN STATES
OF BRASIL...CLEARING THE COAST EARLY ON FRIDAY MORNING. AT LOW
LEVELS...AN OCCLUDING FRONTAL LOW IS TO RAPIDLY INTENSIFY TO THE
EAST-NORTHEAST OF THE SOUTH GEORGIA ISLANDS...WHILE THE ASSOCIATED
SURFACE FRONT RACES ACROSS URUGUAY TO SOUTHERN BRASIL-NORTHERN
ARGENTINA. UNDER THE INFLUENCE OF THE TRAILING MID LEVEL
VORTEX...THE BOUNDARY IS TO BECOME BETTER ORGANIZED ON
WEDNESDAY...WITH ENSUING LOW LEVEL LOW EXPECTED TO DEEPEN AS IT
MIGRATES ACROSS URUGUAY TO SOUTHERN BRASIL ON THURSDAY.
THIS...IN-TURN...WILL FAVOR A SOUTHERLY LOW LEVEL JET THAT DRIVES
THE FRONT NORTH ACROSS SOUTHERN BRASIL TO PARAGUAY...WITH BOUNDARY
THEN STALLING OVER SAO PAULO-MATO GROSSO DO SUL ON SATURDAY. OVER
CENTRAL ARGENTINA...UNDER THE INFLUENCE OF COUPLED
JETS...ORGANIZED DEEP CONVECTION IS EXPECTED THROUGH WEDNESDAY
MORNING...WITH LARGE HAIL PRODUCING SEVERE THUNDERSTORMS EXPECTED
THROUGH THE LATE EVENING HOURS. OVER CENTRAL ARGENTINA THIS WILL
SUSTAIN RAINFALL MAXIMA OF 25-50MM...WHILE OVER URUGUAY/ENTRE
RIOS-CORDOBA THE MAXIMA PEAKS AT 40-80MM. SIMILAR AMOUNTS ARE
EXPECTED ACROSS SOUTHERN BRASIL AND CENTRAL BOLIVIA IN PREFRONTAL
CONVECTION ON THURSDAY. LATER IN THE WEEK MOST INTENSE CONVECTION
IS TO CLUSTER BETWEEN SAO PAULO-RIO DE JANEIRO AND MATO GROSSO DO
SUL...WITH MAXIMA OF 20-40MM IN SCATTERED DEEP CONVECTION. THIS
SHIFTS NORTH TO BAHIA-MINAS GERAIS/ESPIRITO SANTO ON SATURDAY.

ANOTHER MID/UPPER LEVEL SHORT WAVE TROUGH ON THE NORTHERN STREAM
FLOW IS TO PROPAGATE ACROSS THE EASTERN PACIFIC TO CENTRAL CHILE
LATER ON FRIDAY. STEERED BY A BROAD CELL OF THE SUBTROPICAL RIDGE
TO THE NORTH...THE SHORT WAVE TROUGH IS TO ALSO SPILL ACROSS THE
CENTRAL ANDES INTO ARGENTINA ON SATURDAY. COUPLED JETS ARE TO
ACCOMPANY THIS PERTURBATION AS IT STREAMS ACROSS CENTRAL
ARGENTINA...FAVORING A BROAD AREA OF UPPER LEVEL DIVERGENCE. AT
LOW LEVELS THIS IS TO ALSO INDUCE CYCLOGENESIS/FRONTOGENESIS OVER
CENTRAL ARGENTINA ON SATURDAY...TRIGGERING POTENTIALLY SEVERE
CONVECTION AND HEAVY RAINFALL AMOUNTS...WITH MAXIMA OF 35-70MM. ON
SUNDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 15-20MM ACROSS THE
BUENOS AIRES PROVINCE/URUGUAY AND ENTRE RIOS IN ARGENTINA...WHILE
ALONG THE PARAGUAY/SOUTHERN BOLIVIA BORDER PREFRONTAL CONVECTION
IS TO SUSTAIN RAINFALL MAXIMA OF 20-35MM.

NORTH OVER THE CONTINENT...AT 250 HPA...A BROAD CELL OF THE
SUBTROPICAL RIDGE DOMINATES THE UPPER FLOW PATTERN. THE RIDGE
ALOFT IS TO CENTER ON A CLOSED HIGH THAT MEANDERS OVER CENTRAL
BOLIVIA DURING THE NEXT 72-96 HRS...WITH CLOSED HIGH TO THEN
RELOCATE ACROSS THE ALTIPLANO TO NORTHERN CHILE DURING THE
WEEKEND. AS THE RIDGE HOLDS...A SHORT WAVE TROUGH TO THE NORTH IS
TO RETROGRESS ACROSS EQUATORIAL SOUTH AMERICA...MOVING ACROSS THE
GUIANAS/NORTHERN PARA EARLY ON WEDNESDAY...REACHING NORTHERN
PERU/AMAZONIA IN COLOMBIA LATER ON FRIDAY. UNDER INFLUENCE OF THE
UPPER LEVEL TROUGH CONVECTION ACROSS PARA IN BRASIL IS TO
GRADUALLY INTENSIFY THROUGH THURSDAY...WITH SCATTERED DEEP
CONVECTION TO SUSTAIN RAINFALL MAXIMA OF 20-35MM. ON FRIDAY TO
SATURDAY THIS IS TO GRADUALLY INTENSIFY WHILE BUILDING WEST ACROSS
NORTHERN AMAZONAS...WITH MAXIMA OF 20-45MM.

DAVISON...WPC (USA)
$$

969 
FXSA20 KWBC 221621
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1120 AM EST MON NOV 22 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 22/16UTC: THE MID/UPPER LEVEL
ANALYSIS SHOWS A LONG WAVE RIDGE OVER THE EASTERN PACIFIC WITH
AXIS SOUTH ALONG 95W TO THE POLAR ICECAP. A BROAD TROUGH LIES TO
THE EAST...DOMINATING AREA BETWEEN 80W-25W AND TO THE SOUTH OF
40S. UNDER THE INFLUENCE OF THE RIDGE TO THE WEST...A PROGRESSIVE
SHORT WAVE TROUGH ON THE SOUTHERN STREAM LIFTS ACROSS THE DRAKE
PASSAGE TO TIERRA DEL FUEGO EARLY IN THE CYCLE. OVER THE WESTERN
ATLANTIC THIS IS TO THEN AMPLIFY ALONG 50W/53W TO THE RIO DE LA
PLATA BASIN LATER TODAY...WITH AXIS REACHING MAXIMUM AMPLITUDE ON
TUESDAY WHEN IT WILL EXTEND ALONG 36W/37W TO 20S. THIS WILL THEN
REMAIN NEARLY UNCHANGED THROUGH WEDNESDAY EVENING...THEN RAPIDLY
WEAKEN WHILE SHEARING SHORT WAVE ENERGY UNDER A RIDGE TO THE EAST.
AT LOW LEVELS...A POLAR TROUGH AMPLIFIES OVER THE WESTERN ATLANTIC
AS A RIDGE BUILDS ACROSS PATAGONIA TO CENTRAL ARGENTINA. THE
ENSUING SOUTHERLY LOW LEVEL JET THEN DISPLACES A PROGRESSIVE FRONT
NORTH ACROSS URUGUAY/CENTRAL ARGENTINA LATER TODAY...WITH BOUNDARY
REACHING SOUTHERN BRASIL-NORTHERN ARGENTINA LATER ON TUESDAY.
EARLY IN THE CYCLE THIS WILL TRIGGER LIGHT/POTENTIALLY SEVERE
CONVECTION AS IT SURGES ACROSS BUENOS AIRES TO URUGUAY...WHILE
OVER NORTHWEST ARGENTINA EXPECTING MODERATE RAINFALL AMOUNTS WITH
MAXIMA OF 15-30MM. UNDER THE INFLUENCE OF AN ANTICYCLONICALLY
CURVED FINGER OF THE SUBTROPICAL JET...THE CONVECTION OVER
NORTHWEST ARGENTINA IS ALSO LIKELY TO GROW SEVERE ON TUESDAY.

ON THE NORTHERN STREAM FLOW...A MID LEVEL LOW CENTERING NEAR 30S
80W ANCHORS A SHORT WAVE TROUGH OVER THE EASTERN PACIFIC. THIS
NEARS CENTRAL CHILE LATER ON TUESDAY...TO THEN SPILL ACROSS THE
CENTRAL ANDES TO CENTRAL ARGENTINA ON WEDNESDAY. MODELS THEN AGREE
ON A SLOW EVOLUTION OF THIS VORTEX...WITH AXIS TO INTENSIFY AS IT
MOVES ACROSS URUGUAY/SOUTHERN BRASIL TO THE WESTERN ATLANTIC ON
THURSDAY. AS IT SPILLS ACROSS THE ANDES...AN ANTICYCLONICALLY
CURVED FINGER OF THE SUBTROPICAL JET WILL ACCOMPANY THIS
PERTURBATION...TO FAVOR A BROAD AREA OF UPPER DIVERGENCE AS IT
MOVES ACROSS CORDOBA TO URUGUAY/SOUTHERN BRASIL. AT LOW
LEVELS...THESE WILL COMBINE IN SUPPORT OF
CYCLOGENESIS/FRONTOGENESIS OVER CENTRAL ARGENTINA. THE MODELS
STRONGLY AGREE ON THIS EVOLUTION...WITH CLOSED LOW DEEPENING AS IT
MOVES ACROSS URUGUAY TO THE WESTERN ATLANTIC ON THURSDAY. THE HIGH
RATE OF INTENSIFICATION WILL SUSTAIN A SOUTHERLY LOW LEVEL JET
THAT DRIVES THE SURFACE FRONT NORTH AND EAST TO SOUTHERN
BRASIL-NORTHERN ARGENTINA/PARAGUAY ON THURSDAY...WITH THE FRONT
ACCELERATING ACROSS SOUTHEAST BRASIL TO MATO GROSSO DO SUL LATER
ON FRIDAY. AS THE FRONT RACES NORTH ACROSS ARGENTINA...IT WILL
SUSTAIN A PREFRONTAL SQUALL LINE AND POTENTIALLY SEVERE
CONVECTION. OVER CENTRAL ARGENTINA THIS WILL FAVOR RAINFALL
AMOUNTS OF 25-50MM...WHILE OVER URUGUAY-ENTRE RIOS/CORDOBA THE
MAXIMA PEAKS AT 40-80MM. OVER SOUTHERN BRASIL AND CENTRAL BOLIVIA
ALSO EXPECTING MAXIMA OF 40-80MM ON THURSDAY...WHILE ACROSS
PARAGUAY TO RIO GRANDE DO SUL THE MAXIMA PEAKS AT 20-45MM. ON
FRIDAY ACTIVITY ACROSS MATO GROSSO DO SUL-SAO PAULO/SANTA CATARINA
IN BRASIL WILL RESULT IN ACCUMULATION OF 25-50MM...WHILE REMAINING
CONVECTION ACROSS CENTRAL BOLIVIA AND SOUTHEAST JUNGLE OF PERU
WEAKENS TO 15-30MM.

PATTERN TO THE NORTH REMAINS UNDER THE INFLUENCE OF A BROAD CELL
OF THE SUBTROPICAL RIDGE...WITH UPPER LEVEL RIDGE TO INITIALLY
ANCHOR ON A CLOSED HIGH NEAR SANTA CRUZ IN EASTERN BOLIVIA. OVER
THE NEXT COUPLE OF DAYS THIS IS TO REMAIN NEARLY UNCHANGED...BUT
DURING THE SECOND HALF OF THE WEEK THE HIGH RELOCATES TO THE
ALTIPLANO OF BOLIVIA/NORTHERN CHILE. OVER NORTHERN BRASIL THIS
WILL SUSTAIN A TIGHT GRADIENT...WITH UPPER LEVEL WINDS TO THE
NORTH OF 10S EXPECTED TO PEAK AT 35-45KT. THROUGH THURSDAY THE
WINDS OVER PARA AND TO THE EAST OF 60W WEAKEN AS THE HIGH/RIDGE
RELOCATES ACROSS BOLIVIA...WHILE OVER AMAZONAS AND
CENTRAL/NORTHERN PERU THEY ARE FORECAST TO INTENSIFY. UNDER THE
INFLUENCE OF THE UPPER LEVEL RIDGE...MOST ACTIVE CONVECTION IS TO
INITIALLY CLUSTER BETWEEN AMAZONAS AND TOCANTINS/GOIAS IN
BRASIL...WITH ACCUMULATION OF 20-45MM IN SCATTERED DEEP
CONVECTION. BUT AS THE UPPER LEVEL RIDGE PATTERN EVOLVES...THIS IS
TO GRADUALLY WEAKEN AND BECOME MORE DISORGANIZED. THE OPPOSITE IS
TRUE FOR NORTHERN PERU-AMAZONAS/ACRE IN BRASIL...WITH ACTIVITY
EXPECTED TO BECOME BETTER ORGANIZED ON WEDNESDAY-THURSDAY WITH
MAXIMA OF 20-45MM. ON THURSDAY TO FRIDAY EXPETING ADDITIONAL
RAINFALL AMOUNTS OF 15-30MM.

DAVISON...WPC (USA)
$$

605 
FXSA20 KWBC 181621
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1121 AM EST THU NOV 18 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 18/16UTC: NORTH OVER THE
CONTINENT...AT 250 HPA...A BROAD CELL OF THE SUBTROPICAL RIDGE
DOMINATES AREA TO THE NORTH OF 20S. THROUGH SATURDAY THE
MEANDERING UPPER LEVEL RIDGE IS TO REMAIN NEARLY UNCHANGED...THEN
BUILD SOUTH ACROSS PARAGUAY TO NORTHERN ARGENTINA ON
SUNDAY-MONDAY. A SUBTROPICAL JET BOUNDS THE SOUTHERN FRINGES OF
THIS RIDGE OVER THE CONTINENT...WITH AXIS TRAVERSING THE NORTHERN
ANDES OF CHILE/SOUTHERN BOLIVIA-PARAGUAY TO SOUTHERN BRASIL. BUT
AS THE UPPER LEVEL RIDGE BUILDS EARLY NEXT WEEK...IT WILL DISPLACE
THE UPPER LEVEL JET SOUTH TO CENTRAL CHILE/ARGENTINA-RIO DE LA
PLATA BASIN.

A HIGHER AMPLITUDE RIDGE TO THE SOUTH AND WEST DOMINATES THE
SOUTHERN/NORTHERN STREAM FLOW OVER THE EASTERN PACIFIC...WITH MID
LEVEL AXIS EXTENDING SOUTH BETWEEN 115W-75W TO THE POLAR ICECAP.
THE RIDGE IS TO HOLD DURING THE NEXT SEVERAL DAYS.
MEANWHILE...SHORT WAVE PERTURBATIONS STREAMING TO THE SOUTH OF
THIS AXIS ARE TO LIFT ACROSS THE DRAKE PASSAGE/TIERRA DEL FUEGO TO
THE WESTERN ATLANTIC...WITH A STRONG VORTEX EARLY IN THE CYCLE TO
FEED INTO A DEEPENING TROUGH OVER THE WESTERN SOUTH ATLANTIC. AN
EQUALLY STRONG SHORT WAVE TROUGH IS TO THEN LIFT ACROSS THE
BELLINGSHAUSEN SEA TO TIERRA DEL FUEGO ON FRIDAY AFTERNOON...TO
HELP SUSTAIN THE HIGHLY AMPLIFIED TROUGH TO THE EAST...WHILE
ANOTHER IS TO ENTER TIERRA DEL FUEGO LATER ON SUNDAY EVENING/EARLY
ON MONDAY MORNING. THE MID/UPPER LEVEL RIDGE IS TO ALSO STEER A
SHORT WAVE TROUGH ON THE NORTHERN STREAM TOWARDS THE ARCHIPELAGO
OF JUAN FERNANDEZ LATER ON FRIDAY. THIS IS TO MEANDER WEST OF LA
SERENA THROUGH MONDAY MORNING...BUT LATER IN THE DAY IT IS TO
SPILL ACROSS THE ANDES INTO ARGENTINA AS IT PHASES WITH THE
SUBTROPICAL JET TO THE NORTH AND EAST OVER ARGENTINA.

THE SOUTHERN STREAM PERTURBATIONS...AS THEY LIFT ACROSS THE DRAKE
PASSAGE...ARE TO SUSTAIN PROGRESSIVE SURFACE FRONTS THAT ARE TO
ALSO LIFT ACROSS THE SOUTHEAST PACIFIC INTO EXTREME SOUTHERN
PORTIONS OF CHILE AND ARGENTINA FROM TIME-TO-TIME. IN THIS PATTERN
A FAIRLY DEEP FRONTAL TROUGH LIFTS ACROSS THE BELLINGSHAUSEN SEA
TO THE DRAKE PASSAGE/TIERRA DEL FUEGO LATER TODAY...TO CONTINUE
EAST INTO THE SOUTHWEST ATLANTIC LATER ON FRIDAY EVENING. A
SECONDARY PERTURBATION IS TO CLOSELY FOLLOW...STREAMING ACROSS
SOUTHERN REGIONS OF CHILE TO PATAGONIA IN ARGENTINA ON SATURDAY
AFTERNOON. IN A TIGHT GRADIENT...THESE ARE TO FAVOR STRONG
BOUNDARY LAYER WINDS OF 35-50KT DURING THE NEXT THREE DAYS. THIS
WILL HELP SUSTAIN A MOIST ADVECTIVE PATTERN WHILE ALSO ENHANCING
TOPOGRAPHICALLY INDUCED CONVECTION ACROSS SOUTHERN CHILE. MOST
ACTIVE IS TO CLUSTER BETWEEN TIERRA DEL FUEGO AND ISLA DE
CHILOE...WITH THE DAILY MAXIMA INCREASING FROM 15-25MM LATER
TODAY...TO 20-35MM ON FRIDAY. ON SATURDAY THIS SURGES TO
20-45MM/DAY IN SCATTERED CONVECTION. OVER TIERRA DEL FUEGO THE
PRECIPITATION IS EXPECTED TO TRANSITION FROM ALTHOUGH THESE FRONTS
ARE TO INITIALLY CONFINE TO SOUTHERN PATAGONIA/TIERRA DEL
FUEGO...EARLY ON SATURDAY THE FRONTS WILL MOVE FARTHER NORTH
ACROSS LA PAMPA TO THE BUENOS AIRES PROVINCE. THIS SETS THE STAGE
FOR A STRONGER/DEEPER BOUNDARY TO LIFT ACROSS CENTRAL ARGENTINA
LATER ON MONDAY EVENING. UNDER THE INFLUENCE OF THE INTENSIFYING
SUBTROPICAL JET MAXIMA OVER ARGENTINA AND THE MID LEVEL VORTEX
SPILLING ACROSS THE CENTRAL ANDES...THIS BOUNDARY WILL SUSTAIN A
ROUND OF SEVERE CONVECTION BETWEEN THE PROVINCES OF MENDOZA AND
CORDOBA ON MONDAY AFTERNOON...WITH A MAXIMA OF 25-50MM. INITIALLY
TO FAVOR LIQUID PRECIPITATION ACROSS SOUTHERN CHILE... ATMOSPHERIC
COOLING OVER THE SOUTHERN CONE ON FRIDAY WILL SUSTAIN A PHASE
CHANGE TO SOLID PRECIPITATION.DAY. ALTHOUGH THIS IS LIKELY TO LAST
THROUGH SUNDAY...THE MOST ACTIVE CONVECTION WITH THIS SYSTEM IS
EXPECTED ON FRIDAY WHEN THE MAXIMA PEAKS AT 10-15CM. THEREAFTER
EXPECTING ACCUMULATION OF 03-05CM/DAY.

AN OLD BOUNDARY TO THE NORTH...MEANWHILE...IS TO EXTEND FROM THE
CENTRAL ATLANTIC TO SOUTHEAST BRASIL/MATO GROSSO DO SUL-NORTHERN
BOLIVIA. THE PORTION OF THE FRONT OVER THE CONTINENT LOSES UPPER
LEVEL SUPPORT...AND AS SUCH IT IS FORECAST TO GRADUALLY
FRONTOLIZE. THE PORTION OVER THE ATLANTIC WILL BE MORE
RESILIENT...AND THROUGH FRIDAY IT IS TO MOVE NORTH ACROSS SAO
PAULO TO RIO DE JANEIRO. LATER DURING THE WEEKEND IT IS TO MEANDER
FARTHER NORTH ACROSS ESPIRITO SANTO TO SOUTHERN MINAS GERAIS. AS
IT MEANDERS OVER THE CONTINENT THE FRONT WILL ENHANCE LOW LEVEL
MOISTURE CONVERGENCE. ACROSS SOUTHERN BRASIL AND SAO PAULO THIS
WILL SUSTAIN HEAVY RAINFALL AMOUNTS WITH ACCUMULATION OF
35-70MM...WHILE OVER NORTHERN BOLIVIA/RONDONIA AND AMAZONAS TO THE
NORTHWEST EXPECTING MAXIMA OF 50-100MM LATER TODAY THROUGH FRIDAY
MORNING. ON FRIDAY THE FOCUS OF THE HEAVIEST CONVECTION SHIFTS TO
NORTHERN SAO PAULO/RIO DE JANEIRO WITH MAXIMA OF 50-100MM AS
ENHANCED BY A MOIST SOUTHEASTERLY FLOW...WHILE INLAND THE MAXIMA
PEAKS AT 30-60MM. A SECOND ROUND OF HEAVY CONVECTION IS TO THEN
AFFECT ESPIRITO SANTO/SOUTHERN MINAS GERAIS ON SATURDAY...WITH
MAXIMA OF 40-80MM. OTHER CONVECTION IS EXPECTED TO THE NORTH
ACROSS EQUATORIAL SOUTH AMERICA...WHERE UNDER THE INFLUENCE OF THE
 SUBTROPICAL RIDGE MODERATE RAINFALL AMOUNTS ARE EXPECTED DURING
THE NEXT FEW DAYS...WITH THE DAILY MAXIMA OF 20-35MM BETWEEN PARA
AND AMAZONAS IN BRASIL.

DAVISON...WPC (USA)
$$

416 
FXSA20 KWBC 171556
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1055 AM EST WED NOV 17 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 17/16UTC: UPSTREAM OVER THE EASTERN
PACIFIC...THE MODELS AGREE ON THEIR FORECAST OF A HIGH AMPLITUDE
LONG WAVE RIDGE TO BUILD SOUTH BETWEEN 110W-80W TO 70S EARLY IN
THE CYCLE. IN RESPONSE TO THIS FEATURE...IN A SINUSOIDAL WAVE
PATTERN...A BROAD TROUGH IS TO THEN AMPLIFY BETWEEN THE SOUTHERN
CONE AND THE WESTERN ATLANTIC...WITH AXIS TO GRADUALLY BECOME THE
DOMINANT LONG WAVE FEATURE BETWEEN 65W-30W AND TO THE SOUTH OF
25S. AS THE RIDGE HOLDS TO THE WEST...SHORT WAVE PERTURBATIONS ON
THE SOUTHERN STREAM ARE TO LIFT ACROSS THE BELLINGSHAUSEN
SEA/DRAKE PASSAGE TO EXTREME SOUTHERN PORTIONS OF CHILE/PATAGONIA
IN ARGENTINA. THESE WILL THEN FEED INTO THE LONG WAVE TROUGH AS IT
MEANDERS TO THE EAST.

IN THIS PATTERN...PROGRESSIVE FRONTS ON THE SOUTHERN STREAM ARE TO
ALSO LIFT ACROSS THE SOUTHEAST PACIFIC INTO EXTREME SOUTHERN
PORTIONS OF CHILE AND ARGENTINA FROM TIME-TO-TIME...WITH A FAIRLY
DEEP FRONTAL TROUGH LIFTING ACROSS THE BELLINGSHAUSEN SEA LATER ON
THURSDAY EVENING. THIS WILL FOCUS SHORT WAVE ENERGY AND
SUBTROPICAL MOISTURE ACROSS CHILE TO THE SOUTH OF ISLA DE CHILOE.
AS A RESULT...CONVECTION IN THIS AREA IS EXPECTED TO
INTENSIFY...INCREASING FROM 15-25MM/DAY EARLY IN THE FORECAST
CYCLE TO 20-35MM/DAY ON FRIDAY AND SUNDAY...WITH A RAINFALL MAXIMA
OF 20-45MM ON SATURDAY. THE DEEP FRONTAL INCURSION WILL ALSO LEAD
TO PRECIPITATION PHASE CHANGES ACROSS TIERRA DEL FUEGO...WITH
LIQUID PRECIPITATION OVER THE NEXT TWO DAYS SHIFTING TO SNOW ON
FRIDAY-SUNDAY. THIS WILL RESULT IN MODERATE SNOWFALL
AMOUNTS...WITH ACCUMULATION OF 05-10CM/DAY AND MAXIMA OF 15CM.

ON THE NORTHERN STREAM FLOW...MEANWHILE...THE DEEPENING MID/UPPER
LEVEL TROUGH IS TO INTERACT WITH A SURFACE FRONT MEANDERING OVER
THE WESTERN ATLANTIC INTO SUBTROPICAL PORTIONS OF SOUTH AMERICA.
EARLY IN THE CYCLE THE FRONT WILL EXTEND ACROSS PARANA/SOUTHERN
SAO PAULO IN SOUTHEAST BRASIL TO NORTHERN BOLIVIA. PORTION OF THE
FRONT OVER THE CONTINENT LOSES UPPER LEVEL SUPPORT...AND AS SUCH
IT IS FORECAST TO GRADUALLY FRONTOLIZE. PORTION OVER THE ATLANTIC
WILL BE MORE RESILIENT...AND THROUGH FRIDAY IT IS TO MOVE NORTH
ACROSS SAO PAULO TO RIO DE JANEIRO. LATER DURING THE WEEKEND IT IS
TO MEANDER FARTHER NORTH ACROSS ESPIRITO SANTO TO SOUTHERN MINAS
GERAIS. AS IT MEANDERS OVER THE CONTINENT THE FRONT WILL ENHANCE
LOW LEVEL MOISTURE CONVERGENCE. ACROSS SOUTHERN BRASIL THIS WILL
SUSTAIN HEAVY RAINFALL AMOUNTS WITH ACCUMULATION OF
30-60MM...WHILE OVER NORTHERN BOLIVIA TO RONDONIA IN BRASIL
EXPECTING MAXIMA OF 40-80MM. HIGHER AMOUNTS ARE EXPECTED OVER
SOUTHERN JUNGLE OF PERU...WHERE CONDITIONS ARE TO REMAIN FAVORABLE
FOR A HEAVY RAINFALL PRODUCING MCS TO DEVELOP...WITH MAXIMA OF
75-125MM. ON THURSDAY ACTIVITY ACROSS SOUTHEAST BRASIL INTENSIFIES
TO 35-70MM...WHILE OVER NORTHERN BOLIVIA-RONDONIA TO AMAZONAS IN
BRASIL THE MAXIMA PEAKS AT 50-100MM. AS THE FRONT WEAKENS ON
FRIDAY ACTIVITY OVER CENTRAL BRASIL DECREASES TO
15-25MM/DAY...WHILE OVER MINAS/NORTHERN SAO PAULO THE MAXIMA
WEAKENS TO 30-60MM. HIGHER AMOUNTS...HOWEVER...ARE EXPECTED ALONG
THE NORTH COAST OF SAO PAULO AND RIO DE JANEIRO AS ENHANCED BY AN
ONSHORE SOUTH-SOUTHEASTERLY FLOW...WITH RAINFALL MAXIMA OF
50-100MM. THIS PERSISTS WHILE BUILDING NORTH ACROSS ESPIRITO SANTO
ON SATURDAY.

OTHER CONVECTION IS EXPECTED TO THE NORTH ACROSS EQUATORIAL SOUTH
AMERICA...WHERE UNDER THE INFLUENCE OF A BROAD CELL OF THE
SUBTROPICAL RIDGE MODERATE TO HEAVY RAINFALL AMOUNTS ARE EXPECTED
DURING THE NEXT FEW DAYS. MOST INTENSE IS EXPECTED EARLY IN THE
FORECAST CYCLE BETWEEN PARA AND AMAZONAS IN NORTHERN BRASIL...WITH
MAXIMA OF 35-70MM. THIS...HOWEVER...WEAKENS ON THURSDAY TO
SATURDAY...WITH THE DAILY MAXIMA DECREASING TO 20-35MM. THIS HAS
THE POTENTIAL OF SURGING ONCE AGAIN LATER DURING THE WEEKEND AS
THE NEAR EQUATORIAL TROUGH (NET) MEANDERS SOUTH ACROSS NORTHERN
SOUTH AMERICA TO NORTHERN BRASIL.

DAVISON...WPC (USA)
$$

874 
FXSA20 KWBC 161607
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1106 AM EST TUE NOV 16 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 16/19UTC: THE MID/UPPER LEVEL
ANALYSIS SHOWS A LONG WAVE TROUGH TRAVERSING THE SOUTHERN CONE AS
IT EXTENDS FROM A CLOSED LOW NEAR 64S 40W...ACROSS NORTHERN
PATAGONIA/LA PAMPA IN ARGENTINA...CENTRAL CHILE TO 20S 100W.
BUILDING RIDGE TO THE WEST WILL SUSTAIN THE NORTHWARD
AMPLIFICATION OF THIS TROUGH ACROSS CENTRAL ARGENTINA EARLY IN THE
CYCLE...WITH AXIS TO THEN SPLIT IN TWO AS THE SOUTHERN HALF
ACCELERATES ACROSS THE CENTRAL ATLANTIC WHILE THE REMAINING
NORTHERN STREAM VORTEX EVOLVES INTO A CLOSED LOW TO THE SOUTHEAST
OF THE BUENOS AIRES PROVINCE. THE LATTER IS TO SLOWLY PULL TO THE
EAST SOUTHEAST AS A BROAD TROUGH DEEPENS OVER THE SOUTHWEST
ATLANTIC/ANTARCTIC PENINSULA LATER ON WEDNESDAY. AT 250 HPA A
FINGER OF THE NORTHERN POLAR JET IS TO ACCOMPANY THIS TROUGH AS IT
AMPLIFIES ACROSS CENTRAL ARGENTINA. OVER THE CONTINENT THE JET
PHASES WITH AN ANTICYCLONICALLY CURVED SUBTROPICAL JET OVER
NORTHERN ARGENTINA/SOUTHERN BRASIL. AS THEY INTERACT...THE JET
ALOFT WILL SUSTAIN A BROAD AREA OF UPPER DIVERGENCE OVER MID
SECTIONS OF SOUTH AMERICA. THIS WILL VENT ORGANIZED DEEP
CONVECTION AND LIKELY FAVOR THE GENERATION OF MESO SCALE
CONVECTIVE SYSTEMS.

AT LOW LEVELS...A POLAR RIDGE BUILDS ACROSS CENTRAL ARGENTINA
EARLY IN THE CYCLE. AS THE GRADIENT TIGHTENS THIS WILL FAVOR A
SOUTHERLY LOW LEVLE JET ACROSS NORTHERN ARGENTINA TO BOLIVIA.
THIS...IN-TURN...DRIVES A PROGRESSIVE COLD FRONT NORTH ACROSS
SOUTHERN BRASIL-PARAGUAY TO SOUTHEAST BOLIVIA LATER TODAY. ON
WEDNESDAY THE FRONT IS TO CONTINUE FARTHER NORTH ACROSS MATO
GROSSO DO SUL IN BRASIL TO NORTHERN BOLIVIA/SOUTHERN JUNGLE OF
PERU. THROUGH FRIDAY THE FRONT IS TO MEANDER FARTHER NORTH ACROSS
SOUTHEAST BRASIL TO MATO GROSSO. BUT LOSING UPPER LEVEL
SUPPORT...THE FRONT IS TO WEAKEN TO A TROUGH LATER DURING THE
WEEKEND. AS THE FRONT SURGES ACROSS MID SECTIONS OF SOUTH AMERICA
IT IS TO TRIGGER HEAVY/POTENTIALLY SEVERE CONVECTION. ACROSS
SOUTHERN BRASIL THIS WILL SUSTAIN RAINFALL AMOUNTS OF 35-70MM
WHILE GRADUALLY BUILDING NORTH ACROSS MATO GROSSO DO SUL/SANTA
CATARINA TO PARANA-SAO PAULO ON THURSDAY. ON FRIDAY COASTAL
CONVECTION BETWEEN RIO DE JANEIRO AND NORTHERN SAO PAULO
INTENSIFIES TO 50-100MM AS ENHANCED BY AN ONSHORE SOUTHEASTERLY
FLOW. HEAVIER AMOUNTS ARE EXPECTED TO THE WEST...TO FAVOR RAINFALL
AMOUNTS OF 75-125MM ACROSS CORRIENTES/MISIONES IN ARGENTINA TO
PARAGUAY/SOUTHEAST BOLIVIA LATER TODAY...WHILE OVER CENTRAL
BOLIVIA THE MAXIMA PEAKS AT 100-175MM. ON WEDNESDAY THE ACTIVITY
OVER NORTHERN BOLIVIA WEAKENS TO 40-80MM/DAY...AND THROUGH THE END
OF THE WEEK IT WILL DECREASE TO 15-25MM/DAY WHILE BUILDING NORTH
ACROSS MATO GROSSO DO SUL TO MATO GROSSO. OVER PERU HEAVY
PREFRONTAL CONVECTION IS TO CLUSTER OVER THE SOUTHERN
JUNGLE...WITH CONVECTION SURGING FROM 30-60MM DURING THE DAY TODAY
TO 75-125MM ON WEDNESDAY...WHILE ON THURSDAY THE MAXIMA IN THIS
AREA PEAKS AT 25-50MM/DAY.

ON THE SOUTHERN STREAM...SIMULTANEOUSLY...A BROAD POLAR TROUGH
STREAMS ACROSS THE BELLINGSHAUSEN SEA TO THE ANTARCTIC
PENINSULA/DRAKE PASSAGE LATER THIS EVENING...WHILE A DEEPER TROUGH
LIFTS ACROSS THE DRAKE PASSAGE TO SOUTHERN CHILE EARLY ON SATURDAY
MORNING. AT LOW LEVELS...THE FORMER WILL SUSTAIN A PROGRESSIVE
FRONT ACROSS THE DRAKE PASSAGE TO THE SOUTHERN CONE LATER ON
THURSDAY. IN A MOIST ADVECTIVE PATTERN THIS WILL SUSTAIN MODERATE
RAINFALL AMOUNTS OVER SOUTHERN CHILE...WITH ACCUMULATION OF
20-35MM. A BROAD POLAR TROUGH IS TO CLOSELY FOLLOW...WITH AXIS
ENTERING THE SOUTHERN CONE LATER ON FRIDAY. THIS IS TO ALSO FAVOR
MODERATE TO HEAVY RAINFALL AMOUNTS...WITH MAXIMA OF 20-45MM/DAY ON
FRIDAY AND SATURDAY.

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE CONTINUES TO DOMINATE THE UPPER FLOW PATTERN
OVER BOLIVIA-PERU AND BRASIL. THIS WILL VENT DIURNAL CONVECTION
ACROSS BRASIL-EQUATORIAL SOUTH AMERICA...WITH MOST INTENSE TO
CLUSTER BETWEEN AMAZONAS-SOUTHERN PARA WITH MAXIMA OF 30-60MM. ON
THURSDAY TO FRIDAY THIS WEAKENS TO 20-45MM...WHILE LATER DURING
THE WEEKEND IT WILL FAVOR RAINFALL AMOUNTS OF 20-35MM/DAY.

DAVISON...WPC (USA)
$$

011 
FXSA20 KWBC 151906
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
205 PM EST MON NOV 15 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 15/19UTC: A BROAD MID/UPPER LEVEL
TROUGH IS INITIALIZED OVER THE SOUTHERN CONE. UNDER THE INFLUENCE
OF A RIDGE TO THE WEST THE TROUGH IS TO AMPLIFY ACROSS CENTRAL
ARGENTINA TO THE RIO DE LA PLATA BASIN EARLY ON TUESDAY MORNING.
BUT AS IT PRESSES AGAINST A BROAD CELL OF THE SUBTROPICAL RIDGE TO
THE NORTH THE TROUGH IS TO THEN STALL OVER NORTHERN ARGENTINA
LATER IN THE DAY. AT 250 HPA...A NORTHERN BRANCH OF THE POLAR JET
ADVANCES TO CENTRAL ARGENTINA LATER TODAY...WHILE AN
ANTICYLONICALLY CURVED SUBTROPICAL JET EXTENDS ACROSS NORTHERN
CHILE/ARGENTINA TO SOUTHERN BRASIL. AS THEY EXTEND OVER NORTHERN
ARGENTINA THEY ARE EXPECTED TO COUPLE ON THEIR RESPECTIVE
DIVERGENT ENTRANCE/EXIT REGION...WITH ENSUING AREA OF DIVERGENCE
ALOFT TO VENT ORGANIZED DEEP CONVECTION AND LIKELY FAVOR
GENERATION OF A MESO SCALE CONVECTIVE SYSTEM.

AT LOW LEVELS...A BUILDING POLAR RIDGE OVER PATAGONIA IN SOUTHERN
ARGENTINA WILL SUSTAIN A SOUTHERLY PAMPERO LOW LEVEL JET THIS
AFTERNOON. THIS WILL DRIVE A PROGRESSIVE COLD FRONT NORTH ACROSS
RIO DE LA PLATA-CORDOBA/MENDOZA IN ARGENTINA LATER TODAY...WITH
THE SURGING FRONT TRIGGERING A SEVERE WEATHER PRODUCING PREFRONTAL
SQUALL LINE OVER NORTHERN ARGENTINA. OVER CENTRAL ARGENTINA THIS
WILL FAVOR MODERATE RAINFALL AMOUNTS WITH ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-25MM. OVER NORTHERN ARGENTINA THE
MAXIMA INCREASES TO 35-70MM IN ASSOCIATION WITH THE SQUALL
LINE...WHILE FAVORING MODERATE RISK OF LARGE HAIL PRODUCING SEVERE
THUNDERSTORMS. OVER PARAGUAY TO SOUTHEAST BOLIVIA THIS IS TO
INTENSIFY ON TUESDAY...WITH MAXIMA OF 75-125MM AS CONDITIONS
BECOME FAVORABLE FOR CONVECTION TO ORGANIZE INTO AN MCS OVER MID
SECTIONS OF SOUTH AMERICA.. THIS...HOWEVER...DECREASES TO 20-45MM
ON WEDNESDAY. HIGHER AMOUNTS ARE EXPECTED OVER CENTRAL BOLIVIA IN
PREFRONTAL CONVECTION...WITH MAXIMA OF 75-150MM EARLY ON
TUESDAY...WHILE ON TUESDAY TO WEDNESDAY THIS SURGES TO 100-175MM.
ACROSS SOUTHERN PERU THIS WILL GRADUALLY INCREASE FROM 30-60MM
EARLY IN THE CYCLE TO 50-100MM ON WEDNESDAY.

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE WILL DOMINATE THE UPPER FLOW PATTERN DURING THE
NEXT FEW DAYS. THIS WILL VENT DIURNAL CONVECTION ACROSS
BRASIL-EQUATORIAL SOUTH AMERICA...WITH MAXIMA OF 20-45MM IN
SCATTERED DEEP CONVECTION. ON TUESDAY THIS INCREASES TO 30-60MM
WHILE BUILDING NORTH AND WEST ACROSS PARA TO AMAZONAS IN
BRASIL...BUT THIS WEAKENS TO 20-45MM ON WEDNESDAY. LESSER AMOUNTS
ARE EXPECTED ACROSS AMAPA/AMAZON RIVER DELTA REGION...WHERE ITCZ
RELATED CONVERGENCE IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15-25MM/DAY.

DAVISON...WPC (USA)
$$

343 
FXSA20 KWBC 081628
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1127 AM EST MON NOV 08 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 04/17UTC: A LONG WAVE TROUGH IS
INITIALIZED OVER THE SOUTHERN CONE...WITH MID/UPPER LEVEL AXIS
EXTENDING TO THE NORTH-NORTHWEST FROM THE ANTARCTIC
PENINSULA...ACROSS TIERRA DEL FUEGO/PATAGONIA TO 27S 87W. UNDER
THE INFLUENCE OF A BROAD RIDGE TO THE WEST...THE TROUGH AMPLIFIES
ACROSS CENTRAL ARGENTINA/CHILE LATER TODAY. ON FRIDAY...WHILE
PRESSING AGAINST A RIDGE TO THE EAST...THE TROUGH WILL SPLIT IN
TWO. THE SOUTHERN HALF OF THE TROUGH IS TO RAPIDLY DAMPEN WHILE
SHEARING UNDER THE RIDGE...WHILE ITS NORTHERN SEGMENT EVOLVES INTO
A DEEP/CLOSED LOW TO THE EAST-SOUTHEAST OF URUGUAY. THIS IS TO
THEN MEANDER NEAR 37S 30W THROUGH THE WEEKEND TO EARLY NEXT WEEK.
AT LOW LEVELS...UNDER THE INFLUENCE OF A BUILDING POLAR RIDGE TO
THE SOUTH AND WEST...A 35-50KT SOUTHERLY PAMPERO LOW LEVEL JET
WILL DRIVE THE ASSOCIATED FRONT NORTH ACROSS CENTRAL TO NORTHERN
ARGENTINA LATER TODAY. THE FRONT CONTINUES FARTHER NORTH ACROSS
SOUTHERN BRASIL-PARAGUAY TO SOUTHEAST BOLIVIA ON FRIDAY...INTO
MATO GROSSO-ACRE/RONDONIA TO SOUTHERN PERU ON SATURDAY. LOSING
UPPER LEVEL SUPPORT...THE FRONT IS TO THEN FRONTOLIZE EARLY NEXT
WEEK.

AS IT SURGES ACROSS CENTRAL TO NORTHERN ARGENTINA THE FRONT WILL
TRIGGER ORGANIZED DEEP CONVECTION...WITH MAXIMA OF 35-70MM BETWEEN
CORDOBA AND ENTRE RIOS...WHILE TO THE NORTH THIS SURGES TO
75-150MM IN POTENTIALLY SEVERE CONVECTION. AS IT BUILDS ACROSS
PARAGUAY TO MATO GROSSO DO SUL ON FRIDAY THIS DECREASES TO
25-50MM. OVER CENTRAL BOLIVIA...AS ENHANCED BY THE LOW LEVEL
JET...CONDITIONS APPEAR FAVORABLE FOR AN ECHO TRAINING PATTERN TO
DEVELOP ALONG AND AHEAD OF THE SURFACE FRONT...WITH MAXIMA OF
75-150MM ON FRIDAY TO SATURDAY. ON SATURDAY FRONTAL CONVECTION
ACROSS CENTRAL BRASIL WEAKENS TO 2O-35MM...WHILE OVER SOUTHEAST
PARAGUAY/MISIONES IN ARGENTINA TO PARANA/SANTA CATARINA IN
SOUTHERN BRASIL THIS IS TO SUSTAIN MAXIMA OF 20-45MM. HIGHER
AMOUNTS ARE EXPECTED OVER SOUTHERN PERU WHERE THE LEADING
CONVECTION IS TO RESULT IN RAINFALL AMOUNTS OF 40-80MM ON SATURDAY
TO SUNDAY. ON SUNDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-35MM WHILE BUILDING NORTH ACROSS CENTRAL PERU AND AMAZONAS IN
BRASIL.

NORTH OVER THE CONTINENT...AT 250 HPA...A BROAD CELL OF THE
SUBTROPICAL RIDGE REMAINS WELL ENTRENCHED ACROSS PERU AND BRASIL.
AS THE RIDGE HOLDS OVER NORTHERN SOUTH AMERICA...SHORT WAVE
PERTURBATIONS ARE TO REVOLVE AROUND THIS AXIS...FIRST STREAMING
ACROSS NORTHERN CHILE/ARGENTINA...THEN LIFTING ACROSS THE WESTERN
ATLANTIC. UNDER THE INFLUENCE OF THESE VORTICES...ORGANIZED DEEP
CONVECTION IS FORECAST TO BUILD ACROSS BAHAIA-ESPIRITO SANTO IN
BRASIL...WITH MAXIMA IN THIS AREA INCREASING FROM 35-70MM EARLY IN
THE CYCLE TO 40-80MM ON FRIDAY. ON SATURDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 30-60MM. LATER DURING THE WEEKEND THE FOCUS OF
THE ORGANIZED CONVECTION SHIFTS TO TOCANTINS/GOIAS-PARA TO
AMAZONAS/ACRE IN WESTERN BRASIL...WITH RAINFALL AMOUNTS OF 20-35MM
AND MAXIMA OF 30-60MM. EARLY NEXT WEEK EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 25-50MM/DAY BETWEEN MATO GROSSO AND AMAZONAS
IN BRASIL.

DAVISON...WPC (USA)
$$

423 
FXSA20 KWBC 041643
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1243 PM EDT THU NOV 04 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 04/17UTC: A LONG WAVE TROUGH IS
INITIALIZED OVER THE SOUTHERN CONE...WITH MID/UPPER LEVEL AXIS
EXTENDING TO THE NORTH-NORTHWEST FROM THE ANTARCTIC
PENINSULA...ACROSS TIERRA DEL FUEGO/PATAGONIA TO 27S 87W. UNDER
THE INFLUENCE OF A BROAD RIDGE TO THE WEST...THE TROUGH AMPLIFIES
ACROSS CENTRAL ARGENTINA/CHILE LATER TODAY. ON FRIDAY...WHILE
PRESSING AGAINST A RIDGE TO THE EAST...THE TROUGH WILL SPLIT IN
TWO. THE SOUTHERN HALF OF THE TROUGH IS TO RAPIDLY DAMPEN WHILE
SHEARING UNDER THE RIDGE...WHILE ITS NORTHERN SEGMENT EVOLVES INTO
A DEEP/CLOSED LOW TO THE EAST-SOUTHEAST OF URUGUAY. THIS IS TO
THEN MEANDER NEAR 37S 30W THROUGH THE WEEKEND TO EARLY NEXT WEEK.
AT LOW LEVELS...UNDER THE INFLUENCE OF A BUILDING POLAR RIDGE TO
THE SOUTH AND WEST...A 35-50KT SOUTHERLY PAMPERO LOW LEVEL JET
WILL DRIVE THE ASSOCIATED FRONT NORTH ACROSS CENTRAL TO NORTHERN
ARGENTINA LATER TODAY. THE FRONT CONTINUES FARTHER NORTH ACROSS
SOUTHERN BRASIL-PARAGUAY TO SOUTHEAST BOLIVIA ON FRIDAY...INTO
MATO GROSSO-ACRE/RONDONIA TO SOUTHERN PERU ON SATURDAY. LOSING
UPPER LEVEL SUPPORT...THE FRONT IS TO THEN FRONTOLIZE EARLY NEXT
WEEK.

AS IT SURGES ACROSS CENTRAL TO NORTHERN ARGENTINA THE FRONT WILL
TRIGGER ORGANIZED DEEP CONVECTION...WITH MAXIMA OF 35-70MM BETWEEN
CORDOBA AND ENTRE RIOS...WHILE TO THE NORTH THIS SURGES TO
75-150MM IN POTENTIALLY SEVERE CONVECTION. AS IT BUILDS ACROSS
PARAGUAY TO MATO GROSSO DO SUL ON FRIDAY THIS DECREASES TO
25-50MM. OVER CENTRAL BOLIVIA...AS ENHANCED BY THE LOW LEVEL
JET...CONDITIONS APPEAR FAVORABLE FOR AN ECHO TRAINING PATTERN TO
DEVELOP ALONG AND AHEAD OF THE SURFACE FRONT...WITH MAXIMA OF
75-150MM ON FRIDAY TO SATURDAY. ON SATURDAY FRONTAL CONVECTION
ACROSS CENTRAL BRASIL WEAKENS TO 2O-35MM...WHILE OVER SOUTHEAST
PARAGUAY/MISIONES IN ARGENTINA TO PARANA/SANTA CATARINA IN
SOUTHERN BRASIL THIS IS TO SUSTAIN MAXIMA OF 20-45MM. HIGHER
AMOUNTS ARE EXPECTED OVER SOUTHERN PERU WHERE THE LEADING
CONVECTION IS TO RESULT IN RAINFALL AMOUNTS OF 40-80MM ON SATURDAY
TO SUNDAY. ON SUNDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-35MM WHILE BUILDING NORTH ACROSS CENTRAL PERU AND AMAZONAS IN
BRASIL.

NORTH OVER THE CONTINENT...AT 250 HPA...A BROAD CELL OF THE
SUBTROPICAL RIDGE REMAINS WELL ENTRENCHED ACROSS PERU AND BRASIL.
AS THE RIDGE HOLDS OVER NORTHERN SOUTH AMERICA...SHORT WAVE
PERTURBATIONS ARE TO REVOLVE AROUND THIS AXIS...FIRST STREAMING
ACROSS NORTHERN CHILE/ARGENTINA...THEN LIFTING ACROSS THE WESTERN
ATLANTIC. UNDER THE INFLUENCE OF THESE VORTICES...ORGANIZED DEEP
CONVECTION IS FORECAST TO BUILD ACROSS BAHAIA-ESPIRITO SANTO IN
BRASIL...WITH MAXIMA IN THIS AREA INCREASING FROM 35-70MM EARLY IN
THE CYCLE TO 40-80MM ON FRIDAY. ON SATURDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 30-60MM. LATER DURING THE WEEKEND THE FOCUS OF
THE ORGANIZED CONVECTION SHIFTS TO TOCANTINS/GOIAS-PARA TO
AMAZONAS/ACRE IN WESTERN BRASIL...WITH RAINFALL AMOUNTS OF 20-35MM
AND MAXIMA OF 30-60MM. EARLY NEXT WEEK EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 25-50MM/DAY BETWEEN MATO GROSSO AND AMAZONAS
IN BRASIL.

DAVISON...WPC (USA)
$$

373 
FXSA20 KWBC 031630
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1229 PM EDT WED NOV 03 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 03/16UTC: AT UPPER LEVELS...A BROAD
CELL OF THE SUBTROPICAL RIDGE REMAINS WELL ENTRENCHED ACROSS PERU
AND BRASIL. AS THE RIDGE HOLDS TO THE NORTH...IT IS STEERING A
SHORT WAVE TROUGH OFF THE COAST OF SAO PAULO TOWARDS THE CENTRAL
ATLANTIC. ANOTHER PERTURBATION STREAMING ACROSS CENTRAL
ARGENTINA/MESOPOTAMIA VALLEY CLOSELY FOLLOWS...WITH THE LATTER TO
MOVE ACROSS SOUTHERN BRASIL LATER THIS EVENING. IT IS TO THEN ALSO
TRACK TO THE EAST-NORTHEAST TOWARDS THE CENTRAL ATLANTIC WHERE IT
IS FORECAST TO DEEPEN WHILE MERGING WITH A SHORT WAVE TROUGH TO
THE SOUTH. AT LOW LEVELS THE FORMER SUSTAINS A POTENTIAL
SUBTROPICAL CYCLONE OFF THE COAST OF SAO PAULO...WHILE THE LATTER
SUPPORTS A FRONTAL LOW OVER URUGUAY. THROUGH THURSDAY EVENING THE
FRONTAL LOW IS TO DISSIPATE WHILE THE POTENTIAL SUBTROPICAL
CYCLONE TRANSITIONS TO AN EXTRA TROPICAL STORM. MEANWHILE...THIS
WILL SUSTAIN SEVERAL DAYS OF HEAVY RAINFALL AMOUNTS ACROSS
ESPIRITO SANTO...BAHIA AND PORTIONS OF MINAS GERAIS IN NORTHEAST
BRASIL. INITIALLY EXPECTING RAINFALL MAXIMA OF 30-60MM...BUT AS
THE MID LEVEL TROUGH DEEPENS OFF THE COAST ON
THURSDAY-FRIDAY...CONVECTION IS TO INTENSIFY...WITH THE DAILY
MAXIMA INCREASING TO 40-80MM. HEAVY CONVECTION WILL PERSIST
THROUGH SATURDAY MORNING. ON SATURDAY TO SUNDAY THE FOCUS OF THE
CONVECTION IS TO SHIFT WESTWARD BETWEEN MINAS
GERAIS...TOCANTINS/GOIAS TO PARA...WITH MAXIMA OF 30-60MM.

A HIGH AMPLITUDE LONG WAVE TROUGH FOLLOWS...WITH THE POSITIVELY
TILTED MID/UPPER LEVEL TROUGH TO EXTEND FROM THE DRAKE
PASSAGE/TIERRA DEL FUEGO TO 25S 85W LATER THIS EVENING. THROUGH
THURSDAY AFTERNOON THE TROUGH WILL PULL ACROSS CHILE/ARGENTINA TO
THE WESTERN ATLANTIC. IT IS TO THEN SPLIT IN TWO WHILE PRESSING
AGAINST A LONG WAVE RIDGE TO THE EAST...WITH ITS SOUTHERN HALF
ACCELERATING ACROSS THE SOUTH ATLANTIC WHILE THE REMAINING
NORTHERN STREAM PORTION IS TO EVOLVE INTO A CLOSED LOW AS IT
MEANDER ACROSS 40S 40W LATER ON SATURDAY. AT LOW LEVELS...THE
TROUGH SUSTAINS A PROGRESSIVE SURFACE FRONT THAT LIFTS ACROSS LA
PAMPA IN CENTRAL ARGENTINA WHILE A RIDGE BUILDS TO THE SOUTH AND
WEST. ON THURSDAY...UNDER THE INFLUENCE OF A BUILDING POLAR RIDGE
TO THE SOUTH AND WEST...A 35-50KT SOUTHERLY PAMPERO LOW LEVEL JET
WILL DRIVE THE FRONT FARTHER NORTH ACROSS CENTRAL TO NORTHERN
ARGENTINA. THE FRONT CONTINUES FARTHER NORTH ACROSS SOUTHERN
BRASIL-PARAGUAY TO SOUTHEAST BOLIVIA ON FRIDAY...INTO MATO
GROSSO-ACRE/RONDONIA TO SOUTHERN PERU ON SATURDAY. SURGING ACROSS
LA PAMPA/CENTRAL ARGENTINA THIS WILL SUSTAIN RAINFALL MAXIMA OF
15-25MM EARLY IN THE CYCLE. ON THURSDAY THIS INCREASES TO 20-45MM
WHILE BUILDING NORTH ACROSS CORDOBA IN CENTRAL ARGENTINA. HIGHER
RAINFALL AMOUNTS ARE EXPECTED TO THE NORTH ACROSS CORRIENTES/CHACO
IN ARGENTINA TO PARAGUAY...WHERE THE SURGING FRONT IS TO TRIGGER A
SEVERE WEATHER PRODUCING MCS EARLY ON FRIDAY MORNING...WITH MAXIMA
OF 75-125MM. AS IT BUILDS ACROSS PARAGUAY TO MATO GROSSO DO SUL ON
FRIDAY THIS DECREASES TO 25-50MM...WHILE OVER CENTRAL BOLIVIA IN
AN ECHO TRAINING PATTERN THE SURGING BOUNDARY WILL SUSTAIN
RAINFALL MAXIMA OF 75-150MM. ON SATURDAY FRONTAL CONVECTION ACROSS
CENTRAL BRASIL WEAKENS TO 2O-35MM...WHILE SIMULTANEOUSLY EXPANDING
TO THE SOUTHERN AND CENTRAL JUNGLE OF PERU...WHERE IT IS TO
SUSTAIN RAINFALL MAXIMA OF 40-80MM. ON SUNDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 30-60MM WHILE BUILDING NORTH ACROSS CENTRAL
PERU.

DAVISON...WPC (USA)
$$

785 
FXSA20 KWBC 021630
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1230 PM EDT TUE NOV 02 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 02/16UTC: NORTH OVER THE
CONTINENT...AT UPPER LEVELS...A BROAD CELL OF THE SUBTROPICAL
RIDGE REMAINS THE DOMINANT FEATURE TO THE NORTH OF 20S. UNDER THE
STEERING INFLUENCE OF THIS RIDGE...A MID/UPPER LEVEL SHORT WAVE
TROUGH LIFTS ACROSS SOUTHEAST BRASIL...MOVING OFF THE COAST OF SAO
PAULO EARLY IN THE CYCLE. AT LOW LEVELS THIS SUSTAINS A CYCLONIC
CIRCULATION THAT IS LIKELY TO EVOLVE INTO A SUBTROPICAL CYCLONE
LATER TODAY/EARLY ON WEDNESDAY MORNING. THIS SYSTEM IS TO RETAIN
ITS HYBRID CHARACTERISTICS THROUGH WEDNESDAY EVENING...BUT AS IT
MOVES OVER COLDER WATERS ON THURSDAY IT IS TO RAPIDLY TRANSITION
TO AN EXTRA TROPICAL CYCLONE. MEANWHILE...THIS WILL TRIGGER
MODERATE TO HEAVY CONVECTION ACROSS ESPIRITO SANTO...MINAS GERAIS
AND BAHIA IN BRASIL. IN THIS AREA INITIALLY EXPECTING RAINFALL
AMOUNTS OF 20-45MM. BUT AS THE LOW LEVEL CYCLONE BECOMES BETTER
ORGANIZED...THIS WILL GRADUALLY INCREASE TO 35-70MM ON THURSDAY.

CONSISTENT WITH PREVIOUS FORECAST...A SECONDARY MID LEVEL
PERTURBATION ON THE NORTHERN STREAM IS TO CLOSELY FOLLOW. THE
SHORT WAVE TROUGH SPILLS ACROSS THE CENTRAL ANDES OF CHILE INTO
ARGENTINA EARLY IN THE CYCLE...AND THROUGH WEDNESDAY MORNING IT IS
TO TRACK ACROSS URUGUAY/MESOPOTAMIA VALLEY IN ARGENTINA TO
SOUTHERN BRASIL. OVER THE WESTERN ATLANTIC THE TROUGH IS THEN
FORECAST TO INTENSIFY WHILE LIFTING TO THE EAST-NORTHEAST.
MEANWHILE...OVER ARGENTINA...IN INTERACTION WITH A SURFACE
FRONT...THE MID LEVEL VORTEX WILL TRIGGER CYCLOGENESIS OVER ENTRE
RIOS/WESTERN URUGUAY. AS IT MOVES ACROSS URUGUAY TO SOUTHERN
BRASIL...IT IS TO ALSO SUPPORT ORGANIZED DEEP CONVECTION WITH
RAINFALL AMOUNTS OF 25-50MM/DAY IN POTENTIALLY SEVERE CONVECTION
THROUGH WEDNESDAY EVENING.

UPSTREAM OVER THE EASTERN PACIFIC...THE SYSTEM OF CONCERN IS A
HIGH AMPLITUDE LONG WAVE TROUGH WITH AXIS NORTH ALONG 100W TO 30S.
AS IT ENTERS THE DRAKE PASSAGE/SOUTHERN CONE ON WEDNESDAY...THE
TROUGH WILL TAKE A POSITIVE TILT WHILE SLOWLY SHEARING UNDER A
BROAD RIDGE TO THE EAST. THROUGH THURSDAY EVENING THE DEEP TROUGH
IS TO MEANDER EAST ACROSS SOUTHERN ARGENTINA TO THE WESTERN
PACIFIC...WHILE TRAILING ACROSS LA PAMPA TO CUYO IN ARGENTINA.
THIS IS TO THEN SLOWLY LIFT ACROSS THE CENTRAL ATLANTIC LATER IN
THE WEEK/DURING THE WEEKEND. AT LOW LEVELS...THE TROUGH SUSTAINS A
PROGRESSIVE SURFACE FRONT THAT ENTERS SOUTHERN CHILE LATER TODAY.
ON WEDNESDAY THE FRONT WILL LIFT ACROSS PATAGONIA/LA PAMPA IN
ARGENTINA TO CENTRAL CHILE. ON THURSDAY...UNDER THE INFLUENCE OF A
BUILDING POLAR RIDGE TO THE SOUTH AND WEST...A 35-50KT SOUTHERLY
PAMPERO LOW LEVEL JET WILL DRIVE THE FRONT FARTHER NORTH ACROSS
CENTRAL TO NORTHERN ARGENTINA. AS IT PROPAGATES ACROSS MID
SECTIONS OF SOUTH AMERICA...THE ACCELERATING FRONT WILL THEN
TRIGGER A SEVERE WEATHER PRODUCING SQUALL LINE ACROSS NORTHERN
ARGENTINA/PARAGUAY.

AS IT MAKES LANDFALL OVER SOUTHERN CHILE EARLY IN THE CYCLE...THIS
WILL SUSTAIN RAINFALL MAXIMA OF 20-30MM IN SCATTERED
CONVECTION...WITH AN ADDITIONAL 20-40MM ON WEDNESDAY. SURGING
ACROSS LA PAMPA/CENTRAL ARGENTINA THIS WILL SUSTAIN RAINFALL
MAXIMA OF 15-20MM ON WEDNESDAY...INCREASING TO 20-45MM WHILE
BUILDING NORTH ACROSS CORDOBA. HIGHER AMOUNTS ARE EXPECTED TO THE
NORTH OVER NORTHERN ARGENTINA-PARAGUAY IN ASSOCIATION WITH THE
PREFRONTAL SQUALL LINE...WITH RAINFALL MAXIMA OF 75-125MM IN
LIKELY SEVERE CONVECTION. AS THE FRONT SPREADS ACROSS PARAGUAY TO
MATO GROSSO DO SUL IN BRASIL THE MAXIMA DECREASES TO
25-50MM/DAY...WHILE ACROSS CENTRAL BOLIVIA THE SOUTHERLY LOW LEVEL
JET WILL ENHANCE MOISTURE CONVERGENCE ALONG THE LEE OF THE
ALTIPLANO. IN THIS AREA EXPECTING RAINFALL MAXIMA OF 75-150MM IN
AN ECHO TRAINING PATTERN ON FRIDAY. THE CONVECTION WILL SPILL
ALONG THE LEE OF THE ANDES TO THE SOUTHERN JUNGLE OF PERU ON
SATURDAY...FAVORING RAINFALL MAXIMA OF 40-80MM.

DAVISON...WPC (USA)
$$

940 
FXSA20 KWBC 011615
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1215 PM EDT MON NOV 01 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM NOV 01/16UTC: UNDER THE STEERING
INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTH...A SHORT WAVE
TROUGH WILL LIFT ACROSS THE SOUTHEAST STATES OF BRASIL EARLY IN
THE CYCLE...AND THROUGH TUESDAY AFTERNOON IT IS TO PULL ACROSS RIO
DE JANEIRO-MINAS GERAIS/ESPIRITO SANTO. BUT AS IT REMAINS CUT OFF
FROM THE FLOW...THE SHORT WAVE TROUGH IS TO THEN RAPIDLY WEAKEN.
MEANWHILE...AT LOW LEVELS...THIS WILL INDUCE CYCLOGENESIS OFF THE
COAST OF SAO PAULO EARLY IN THE CYCLE. ON TUESDAY...AS IT MEANDERS
OVER WARMER WATERS OFF THE COAST OF BRASIL...THE MODELS
CONSISTENTLY SUGGEST POSSIBILITY OF THIS PERTURBATION BRIEFLY
EVOLVING INTO A SUBTROPICAL CYCLONE. THIS COULD RETAIN SUBTROPICAL
CHARACTERISTICS THROUGH WEDNESDAY EVENING...THEN TRANSITION INTO
AN EXTRA TROPICAL LOW ON THURSDAY. MEANWHILE...HEAVY CONVECTION IS
TO AFFECT MINAS GERAIS-ESPIRTO SANTO/RIO DE JANEIRO THROUGH
TUESDAY MORNING...WITH MAXIMA OF 40-80MM. ON TUESDAY-THURSDAY
EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 25-50MM AS THE SURFACE
LOW MEANDERS OFF THE SOUTHEAST COAST OF BRASIL.

A SECONDARY PERTURBATION ON THE NORTHERN STREAM IS TO CLOSELY
FOLLOW...WITH THE MID LEVEL AXIS TO REACH CENTRAL/NORTHERN CHILE
EARLY IN THE CYCLE. THROUGH TUESDAY MORNING THE SHORT WAVE TROUGH
SPILLS ACROSS THE ANDES INTO MENDOZA/NORTHWEST ARGENTINA. EARLY ON
WEDNESDAY MORNING THE SHORT WAVE TROUGH WILL THEN LIFT ACROSS
ENTRE RIOS/BUENOS AIRES PROVINCE TO URUGUAY/SOUTHERN BRASIL...AND
OFF THE SOUTH COAST OF BRASIL TO THE WESTERN ATLANTIC EARLY ON
THURSDAY. AS IT MOVES ACROSS CHILE TO ARGENTINA...THE MID LEVEL
VORTEX WILL INTERACT WITH A SURFACE FRONT EXTENDING ACROSS URUGUAY
TO MENDOZA IN ARGENTINA...TRIGGERING ORGANIZED DEEP CONVECTION
ALONG THIS BOUNDARY WITH MAXIMA OF 35-70MM. ON TUESDAY AFTERNOON
THIS WILL THEN TRIGGER A SEVERE WEATHER PRODUCING SQUALL LINE
ACROSS URUGUAY/CORRIENTES IN ARGENTINA-SOUTHEAST PARAGUAY...WITH
MAXIMA OF 25-50MM/DAY. FRONTAL BOUNDARY IS TO THEN FRONTOLIZE ON
THURSDAY AS IT LOSES ITS UPPER LEVEL SUPPORT.

A DEEPER/HIGHER AMPLITUDE LONG WAVE TROUGH IS TO LIFT ACROSS THE
EASTERN PACIFIC LATER TODAY...WITH MID/UPPER LEVEL AXIS TO EXTEND
NORTH ALONG 100W TO 30S THIS AFTERNOON. AS IT ENTERS THE DRAKE
PASSAGE/SOUTHERN CONE EARLY ON WEDNESDAY MORNING...THE TROUGH WILL
TAKE A POSITIVE TILT WHILE PRESSING AGAINST A RIDGE TO THE EAST.
THROUGH THURSDAY EVENING THE DEEP TROUGH IS TO MEANDER EAST ACROSS
SOUTHERN ARGENTINA TO THE WESTERN PACIFIC...WHILE TRAILING ACROSS
LA PAMPA TO CUYO. LATER IN THE WEEK THE TROUGH IS EXPECTED TO
SPLIT...WITH ITS SOUTHERN HALF TO ACCELERATE UNDER THE RIDGE WHILE
THE REMNANTS OF THE TROUGH EVOLVE INTO A CLOSED LOW OVER CENTRAL
ARGENTINA. THE TROUGH WILL SUSTAIN A PROGRESSIVE FRONT ACROSS
SOUTHERN CHILE LATER ON TUESDAY...WITH THE BOUNDARY THEN LIFTING
ACROSS PATAGONIA/LA PAMPA TO CENTRAL CHILE ON WEDNESDAY. BUILDING
POLAR RIDGE TO THE SOUTH AND WEST...AND THE ENSUING PAMPERO JET
(LOW LEVEL SOUTHERLY WIND)...WILL THEN DRIVE THE FRONT NORTH
ACROSS CENTRAL TO NORTHERN ARGENTINA. THE ACCELERATING FRONT WILL
THEN TRIGGER A SEVERE WEATHER PRODUCING SQUALL LINE ACROSS
NORTHERN ARGENTINA/URUGUAY. ACROSS SOUTHERN CHILE EXPECTING
RAINFALL AMOUNTS OF 20-30MM ON TUESDAY...WITH AN ADDITIONAL
20-40MM ON WEDNESDAY. OVER LA PAMPA EXPECTING ACCUMULATION OF
15-20MM ON WEDNESDAY...INCREASING TO 20-45MM WHILE BUILDING NORTH
ACROSS LA PAMPA AND THE BUENOS AIRES PROVINCE. HIGHER AMOUNTS ARE
EXPECTED TO THE NORTH IN ASSOCIATION WITH THE PREFRONTAL SQUALL
LINE...WITH RAINFALL MAXIMA OF 75-125MM. ON FRIDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 20-40MM TO CLUSTER BETWEEN RIO
GRANDE DO SUL AND URUGUAY. OVER CENTRAL BOLIVIA...ALONG THE LEE OF
THE ANDES...THE MAXIMA ON FRIDAY IS TO PEAK AT 50-100MM...WHILE
OVER MATO GROSSO DO SUL-SANTA CRUZ IN NORTHEAST BOLIVIA EXPECTING
MAXIMA OF 50-100MM ON FRIDAY TO SATURDAY.

DAVISON...WPC (USA)
$$

272 
FXSA20 KWBC 291536
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1136 AM EDT FRI OCT 29 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 29/16UTC: INITIAL CONDITIONS SHOW A
BROAD MID/UPPER LEVEL RIDGE EXTENDING BETWEEN THE SOUTHERN CONE OF
SOUTH AMERICA AND THE WESTERN ATLANTIC...WHILE A HIGH AMPLITUDE
TROUGH TO THE WEST EXTENDS NORTH ALONG 90W TO 25S. DRAWN BY A
POLAR JET MAXIMA...THE TROUGH WILL TAKE A POSITIVE TILT WHILE
SHEARING UNDER THE RIDGE TO THE EAST...WITH AXIS TO EXTEND FROM
THE WEDDELL SEA TO PATAGONIA IN ARGENTINA LATER TODAY. THROUGH
SATURDAY THE RIDGE IS TO FLATTEN AS THE TROUGH MOVES FARTHER EAST
INTO THE CENTRAL SOUTH ATLANTIC...WHILE SIMULTANEOUSLY SHEARING A
SHORT WAVE TROUGH OFF THE COAST OF PATAGONIA. THE SHORT WAVE
VORTEX IS TO THEN MEANDER TO THE EAST-NORTHEAST...REACHING 30S 40W
LATER ON MONDAY. IT IS TO THEN GRADUALLY FILL WHILE MERGING WITH A
DEEPENING TROUGH TO THE SOUTH AND EAST. AT LOW LEVELS...THIS
SUSTAINS A FRONT THAT LIFTS ACROSS PATAGONIA IN ARGENTINA TO LA
PAMPA AS A RIDGE BUILDS TO THE WEST AND SOUTH. THIS WILL THEN
DRIVE THE FRONT NORTH ACROSS THE RIO DE LA PLATA BASIN TO MENDOZA
ON SATURDAY...WITH THE BOUNDARY SLOWLY MOVING NORTH ALONG THE
BORDER WITH PARAGUAY LATER ON MONDAY. OVER LA PAMPA/CENTRAL
ARGENTINA...INITIALLY EXPECTING RAINFALL MAXIMA OF 10-15MM. ON
SATURDAY THIS INCREASES TO 15-25MM WHILE BUILDING NORTH ACROSS
CENTRAL ARGENTINA...WITH A RISK OF SEVERE CONVECTION. ON
SUNDAY...UNDER INFLUENCE OF A MID LEVEL VORTEX AND FAVORABLE UPPER
LEVEL JET DYNAMICS...THE ACTIVITY ACROSS CENTRAL ARGENTINA IS TO
SURGE TO MAXIMA OF 35-70MM. SIMILAR AMOUNTS ARE EXPECTED ACROSS
NORTHWEST ARGENTINA BETWEEN CORRIENTES AND JUJUY/SALTO ON
MONDAY...WITH MAXIMA OF 35-70MM. THROUGH TUESDAY THIS IS EXPECTED
TO INTENSIFY TO MAXIMA OF 40-80MM WHILE BUILDING ACROSS AND WEST
ACROSS URUGUAY TO CORRIENTES IN ARGENTINA. OVER NORTHWEST
ARGENTINA EXPECTING MODERATE DEEP CONVECTION WITH THIS
FEATURE...TO SUSTAIN RAINFALL AMOUNTS OF 20-30MM ON
SATURDAY...INCREASING TO 25-50MM WHILE BUILDING NORTH ACROSS
SOUTHEAST BOLIVIA/SANTA CRUZ ON TUESDAY.

ALSO AT MID LEVELS...SHORT WAVE PERTURBATIONS POPULATE THE
NORTHERN STREAM FLOW ACROSS CENTRAL SOUTH AMERICA...WITH ONE
LIFTING ACROSS THE BUENOS AIRES PROVINCE AS ANOTHER REACHES
NORTHERN CHILE. THROUGH SATURDAY THE FORMER IS TO NEARLY DISSIPATE
AS A DEEPER SHORT WAVE PERTURBATION LIFTS ACROSS NORTHERN CHILE TO
NORTHERN ARGENTINA/PARAGUAY LATER TODAY. THIS WILL THEN CONTINUE
TO THE EAST-NORTHEAST TO THE SOUTHEAST STATES OF BRASIL EARLY ON
WEDNESDAY MORNING. THE INFLOW OF MID LEVEL ENERGY IS LIKELY TO
TRIGGER A HEAVY RAINFALL PRODUCING MCS OVER NORTHWEST ARGENTINA
LATER THIS EVENING...WITH MAXIMA OF 40-80MM. ON SATURDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 30-60MM WHILE BUILDING TO THE
EAST-NORTHEAST ACROSS PARAGUAY TO MATO GROSSO DO SUL. THROUGH
EARLY NEXT WEEK THE MID LEVEL PERTURBATION IS TOINDUCE A
NON-BAROCLINIC SURFACE LOW OFF THE COAST OF RIO DE
JANEIRO...TRIGGERING TWO DAYS OF HEAVY CONVECTION BETWEEN RIO DE
JANEIRO/ESPIRITO SANTO AND MINAS GERAIS IN BRASIL THIS WILL HELP
SUSTAIN RAINFALL AMOUNTS OF 30-60MM/DAY ON BOTH SATURDAY AND
SUNDAY.

NORTH OVER THE CONTINENT...AT 250 HPA...A CELL OF THE SUBTROPICAL
RIDGE BRANCHES BETWEEN THE EASTERN TROPICAL PACIFIC/PERU AND THE
SOUTHEAST STATES OF BRASIL. UNDER THE STEERING INFLUENCE OF THIS
RIDGE...A RETROGRESSING TUTT TO THE NORTH IS MOVING ACROSS
NORTHERN BRASIL/AMAZON RIVER DELTA REGION TO PARA...WHERE IT IS TO
STALL THROUGH SUNDAY MORNING. BUT AS IT CUTS OFF FROM THE
FLOW...THE UPPER LEVEL TROUGH THEN GRADUALLY WEAKENS EARLY NEXT
WEEK. THE NEXT FEW DAYS THIS WILL SUSTAIN SCATTERED CONVECTION
ACROSS NORTHERN BRASIL AND PARA...WITH RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20MM. THROUGH SUNDAY THIS
INTENSIFIES...INCREASING TO 15-30MM/DAY WHILE SPREADING WEST
ACROSS RORAIMA TO NORTHERN AMAZONAS/SOUTHERN COLOMBIA.

DAVISON...WPC (USA)
$$

348 
FXSA20 KWBC 271555
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1155 AM EDT WED OCT 27 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 2/16UTC: AT MID/UPPER LEVELS A
BROAD/LOW AMPLITUDE RIDGE IS INITIALIZED ACROSS THE SOUTHERN CONE
TO THE DRAKE PASSAGE. IN A TIGHT GRADIENT...AN INTENSE POLAR JET
MAXIMA EXTENDS FROM THE SOUTHEAST PACIFIC...ACROSS SOUTHERN
CHILE/PATAGONIA IN ARGENTINA TO THE WESTERN ATLANTIC. THE JET...AS
IT PROPAGATES ACROSS THE SOUTHERN CONE...IS DRAWING A TROUGH
ACROSS THE SOUTHEAST PACIFIC...WITH THE LONG WAVE AXIS TO PULL
ACROSS 90W LATER ON THURSDAY. THROUGH FRIDAY MORNING THIS IS TO
THEN PROPAGATE ACROSS THE BELLINGSHAUSEN SEA/ANTARCTIC PENINSULA
TO THE SOUTHERN REGIONS OF CHILE. EARLY ON SATURDAY MORNING...AS
THE TROUGH ENTERS THE SOUTHWEST ATLANTIC...AXIS WILL START TO
SPLIT WHILE PRESSING AGAINST A RIDGE TO THE EAST...SHEARING A
SHORT WAVE VORTEX/MID LEVEL LOW TO THE SOUTH-SOUTHEAST OF THE
BUENOS AIRES PROVINCE EARLY ON SUNDAY MORNING. AT LOW LEVELS...A
BROAD/LOW AMPLITUDE TROUGH OVER THE SOUTHEAST PACIFIC IS PRESSING
AGAINST A CELL OF THE SUBTROPICAL RIDGE TO THE NORTH. THE ENSUING
GRADIENT FAVORS STRONG BOUNDARY LAYER WINDS ACROSS THE SOUTHERN
REGIONS OF CHILE TO PATAGONIA IN ARGENTINA...WHILE ALSO FAVORING A
WARM/MOIST ADVECTIVE PATTERN. POLAR FRONTS REVOLVE AROUND THIS
TROUGH...WITH ONE STREAMING ACROSS SOUTHERN CHILE/PATAGONIA AS
ANOTHER ENTERS THE DRAKE PASSAGE. THROUGH FRIDAY MORNING THIS IS
TO INTENSIFY...WITH THE TROUGH AMPLIFYING ACROSS THE SOUTHERN CONE
AS A RIDGE BUILDS TO THE WEST. THIS WILL THEN DRIVE THE SURFACE
FRONT NORTH ACROSS PATAGONIA TO LA PAMPA LATER ON FRIDAY. ON
SATURDAY...UNDER THE INFLUENCE OF THE MID LEVEL VORTEX...A
DEEPENING FRONTAL LOW FORMS TO THE SOUTHEAST OF THE BUENOS AIRES
PROVINCE. THIS WILL DRIVE THE FRONT FARTHER NORTH ACROSS THE RIO
DE LA PLATA BASIN TO CORDOBA IN ARGENTINA. LATER DURING THE
WEEKEND/EARLY NEXT WEEK...THE FRONT IS TO SLOW DOWN AS IT MOVES
ACROSS URUGUAY TO CENTRAL ARGENTINA. OVER SOUTHERN CHILE...IN
STRONG UPPER LEVEL JET DYNAMICS AND WITH PRECIPITABLE WATER
CONTENT NEARING 200 PERCENT OF NORMAL...THE ENVIRONMENTAL
CONDITIONS APPEAR FAVORABLE FOR A HEAVY RAINFALL EVENT EARLY IN
THE CYCLE. THE COMBINATION OF UPPER LEVEL DYNAMICS AND STRONG
TOPOGRAPHICAL FORCING WILL RESULT IN RAINFALL MAXIMA OF 75-125MM
DURING THE DAY TODAY. ON THURSDAY EXPECTING ADDITIONAL RAINFALL
AMOUNTS OF 25-50MM...WHILE ON FRIDAY IT WEAKENS TO 10-15MM. ACROSS
CENTRAL ARGENTINA...AS THE FRONT SURGES ACROSS THE SOUTHERN
CONE...THIS IS TO TRIGGER MODERATE RAINFALL AMOUNTS IN POTENTIALLY
SEVERE CONVECTION ON FRIDAY...WITH MAXIMA OF 15-20MM. THROUGH
SUNDAY THIS IS EXPECTED TO INTENSIFY...INCREASING TO MAXIMA OF
30-60MM.

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE IS TO DOMINATE AREA TO THE NORTH OF 20S. EARLY
IN THE CYCLE THIS IS TO STEER A SHORT WAVE TROUGH ALONG THE LEE OF
THE ANDES BETWEEN NORTHERN ARGENTINA AND BOLIVIA ACROSS PARAGUAY
TO SOUTHERN BRASIL. IN A PERTURBED PATTERN...ADDITIONAL LOWER
AMPLITUDE SHORT WAVE PERTURBATIONS ARE TO FOLLOW...STREAMING
BETWEEN 25S-40S INTO MID SECTIONS OF SOUTH AMERICA.
INITIALLY...UNDER THE INFLUENCE OF THE LONGER AMPLITUDE
TROUGH...MODERATE CONVECTION IS TO CLUSTER ACROSS SAO PAULO-MATO
GROSSO IN BRASIL...TO SUSTAIN MAXIMA OF 20-40MM. ON THURSDAY THIS
DECREASES TO 20-30MM WHILE BUILDING WESTWARD ACROSS MATO GROSSO DO
SUL TO NORTHERN BOLIVIA...WHILE ALONG THE COAST OF SAO PAULO IT
INCREASES TO 30-60MM AS ENHANCED BY AN ONSHORE FLOW. THE WESTWARD
AND THEN SOUTHWARD SHIFT OF THIS ACTIVITY WILL THEN BRING AN AREA
OF HEAVY RAINFALL AMOUNTS TO NORTHWEST ARGENTINA AND PORTIONS OF
PARAGUAY/SOUTHERN BOLIVIA ON FRIDAY TO SATURDAY. IN THIS AREA
CONDITIONS APPEAR FAVORABLE FOR AN MCS TO FORM LATER ON
FRIDAY/EARLY ON SATURDAY MORNING...WITH RAINFALL AMOUNTS OF
40-80MM IN POTENTIALLY SEVERE CONVECTION. THIS PERSISTS THROUGH
SATURDAY WHILE PROPAGATING ACROSS PARAGUAY TO MATO GROSSO DO
SUL/SAO PAULO IN BRASIL...MEANWHILE TRIGGERING SIMILAR RAINFALL
AMOUNTS. LATER IN THE CYCLE THE FOCUS OT THE ORGANIZED CONVECTION
WILL SHIFT TO NORTHERN SAO PAULO/RIO DE JANEIRO-SOUTHERN MINAS
GERAIS...WITH A MAXIMA OF 30-60MM.

DAVISON...WPC (USA)
$$

270 
FXSA20 KWBC 261635
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1234 PM EDT TUE OCT 26 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 26/17UTC: ON THE SOUTHERN STREAM
FLOW...AT 250 HPA...IN A TIGHT BELT OF MID LATITUDE WESTERLIES THE
ANALYSIS SHOWS A STRONG POLAR JET MAXIMA STREAMING ACROSS THE
SOUTHEAST PACIFIC INTO THE SOUTHERN REGIONS OF CHILE/PATAGONIA IN
ARGENTINA...WITH A WIND MAXIMA OF 200KT EMBEDDED IN THIS FLOW. THE
STRONG WINDS ARE TO PERSIST THROUGH WEDNESDAY MORNING...THEN
GRADUALLY WEAKEN AS A BROAD MID/UPPER LEVEL TROUGH LIFTING ACROSS
THE SOUTHEAST PACIFIC APPROACHES THE SOUTHERN CONE LATER IN THE
DAY/EARLY ON THURSDAY. AT LOW LEVELS...BROAD TROUGH DOMINATES THE
SOUTHEAST EAST PACIFIC WHILE A RIDGE REIGNS ON THE SUBTROPICAL
FLOW TO THE NORTH. THE RIDGE ANCHORS ON A CLOSED HIGH WEST OF THE
ARCHIPELAGO OF JUAN FERNANDEZ. THE ENSUING PRESSURE GRADIENT
FAVORS STRONG LOW LEVEL WINDS ACROSS THE SOUTHERN CONE...WITH 850
HPA WINDS OF 50-60KT. THE BROAD LOW LEVEL TROUGH IS TO PERSIST
THROUGH THURSDAY MORNING...WITH SUCCESSIVE FRONTS/FRONTAL WAVES TO
STREAM ACROSS SOUTHERN CHILE/PATAGONIA IN ARGENTINA. THIS WILL
ENHANCE MOISTURE TRANSPORT/CONVERGENCE ACROSS THE SOUTHERN
ANDES...WHILE UNDER THE INFLUENCE OF AN ATMOSPHERIC KELVIN WAVE
THE PWAT CONTENT OF 30MM IS 200 PERCENT OF NORMAL FOR THIS TIME OF
THE YEAR. THE STRONG LOW LEVEL FORCING AND FAVORABLE UPPER LEVEL
JET DYNAMICS WILL COMBINE IN SUPPORT OF AN EXTREME RAINFALL EVENT.
DURING THE NEXT THREE DAYS EXPECTING STORM TOTAL AMOUNTS OF
100-175MM...WITH THE MOST INTENSE ON WEDNESDAY WHEN THE MAXIMA
PEAKS AT 75-125MM. ON FRIDAY...AS THE MID/UPPER LEVEL TROUGH
ENTERS THE SOUTHERN CONE...THIS WILL THEN DRIVE THE SURFACE FRONT
NORTH ACROSS PATAGONIA. THIS BOUNDARY CONTINUES NORTH ACROSS LA
PAMPA/THE BUENOS AIRES PROVINCE TO CENTRAL ARGENTINA ON
SATURDAY...WHERE IT IS EXPECTED TO STALL. ACROSS CENTRAL ARGENTINA
THIS WILL THEN TRIGGER SCATTERED DEEP CONVECTION...WITH RAINFALL
MAXIMA OF 20-35MM ON SATURDAY...WITH POTENTIAL FOR LOCALLY HIGHER
AMOUNTS IN SEVERE CONVECTION.

ON THE NORTHERN STREAM...AT 200 HPA...A SHORT WAVE TROUGH
EXTENDING FROM NORTHWEST ARGENTINA TO WESTERN BRASIL SPLITS THE
SUBTROPICAL RIDGE IN TWO CELLS...WITH THE WESTERNMOST LOCATING
OVER THE EASTERN TROPICAL PACIFIC WHILE CENTERING AT 250 HPA ON A
CLOSED HIGH NEAR 15S 85W. THE EASTERNMOST...MEANWHILE...EXTENDS
OVER BRASIL BETWEEN BAHIA AND MINAS GERAIS. THROUGH WEDNESDAY THE
RIDGE OVER THE PACIFIC IS FORECAST TO GRADUALLY COLLAPSE...WHILE
THE ONE OVER BRASIL TENDS TO BUILD. AS THE LATTER INTENSIFIES...IT
WILL THEN STEER THE SHORT WAVE TROUGH ACROSS PARAGUAY TO SOUTHERN
BRASIL ON THURSDAY...WHILE SIMULTANEOUSLY STEERING A TUTT TO THE
NORTH ACROSS NORTHEAST BRASIL. UNDER THE INFLUENCE OF THE UPPER
LEVEL TROUGH/CONTINENTAL RIDGE...SCATTERED DEEP CONVECTION IS TO
CLUSTER BETWEEN RIO DE JANEIRO/SAO PAULO AND AMAZONAS IN
BRASIL/NORTHERN PERU-SOUTHERN COLOMBIA. IN THIS AREA EXPECTING
RAINFALL AMOUNTS OF 15-30MM/DAY WITH MAXIMA OF 20-45MM. THROUGH
THE END OF THE WEEK...AS THE SHORT WAVE TROUGH STARTS TO PROPAGATE
ACROSS MID SECTIONS OF SOUTH AMERICA...FOCUS OF THE ORGANIZED
CONVECTION WILL SHIFT TO NORTHWEST ARGENTINA-PARAGUAY...WHERE THE
ENVIRONMENTAL CONDITIONS WILL BECOME FAVORABLE FOR A HEAVY
RAINFALL PRODUCING MESO SCALE CONVECTIVE COMPLEX TO DEVELOP ON
SATURDAY TO SUNDAY. THIS WILL SUSTAIN RAINFALL AMOUNTS OF
40-80MM/DAY...WITH SOME OF THE MODELS SHOWING LOCALIZED MAXIMA OF
150-200MM AS IT BUILDS NORTH ACROSS PARAGUAY TO MATO GROSSO DO SUL
IN BRASIL.

DAVISON...WPC (USA)
$$

611 
FXSA20 KWBC 261634
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1233 PM EDT TUE OCT 26 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 26/17UTC: ON THE SOUTHERN STREAM
FLOW...AT 250 HPA...IN A TIGHT BELT OF MID LATITUDE WESTERLIES THE
ANALYSIS SHOWS A STRONG POLAR JET MAXIMA STREAMING ACROSS THE
SOUTHEAST PACIFIC INTO THE SOUTHERN REGIONS OF CHILE/PATAGONIA IN
ARGENTINA...WITH A WIND MAXIMA OF 200KT EMBEDDED IN THIS FLOW. THE
STRONG WINDS ARE TO PERSIST THROUGH WEDNESDAY MORNING...THEN
GRADUALLY WEAKEN AS A BROAD MID/UPPER LEVEL TROUGH LIFTING ACROSS
THE SOUTHEAST PACIFIC APPROACHES THE SOUTHERN CONE LATER IN THE
DAY/EARLY ON THURSDAY. AT LOW LEVELS...BROAD TROUGH DOMINATES THE
SOUTHEAST EAST PACIFIC WHILE A RIDGE REIGNS ON THE SUBTROPICAL
FLOW TO THE NORTH. THE RIDGE ANCHORS ON A CLOSED HIGH WEST OF THE
ARCHIPELAGO OF JUAN FERNANDEZ. THE ENSUING PRESSURE GRADIENT
FAVORS STRONG LOW LEVEL WINDS ACROSS THE SOUTHERN CONE...WITH 850
HPA WINDS OF 50-60KT. THE BROAD LOW LEVEL TROUGH IS TO PERSIST
THROUGH THURSDAY MORNING...WITH SUCCESSIVE FRONTS/FRONTAL WAVES TO
STREAM ACROSS SOUTHERN CHILE/PATAGONIA IN ARGENTINA. THIS WILL
ENHANCE MOISTURE TRANSPORT/CONVERGENCE ACROSS THE SOUTHERN
ANDES...WHILE UNDER THE INFLUENCE OF AN ATMOSPHERIC KELVIN WAVE
THE PWAT CONTENT OF 30MM IS 200 PERCENT OF NORMAL FOR THIS TIME OF
THE YEAR. THE STRONG LOW LEVEL FORCING AND FAVORABLE UPPER LEVEL
JET DYNAMICS WILL COMBINE IN SUPPORT OF AN EXTREME RAINFALL EVENT.
DURING THE NEXT THREE DAYS EXPECTING STORM TOTAL AMOUNTS OF
100-175MM...WITH THE MOST INTENSE ON WEDNESDAY WHEN THE MAXIMA
PEAKS AT 75-125MM. ON FRIDAY...AS THE MID/UPPER LEVEL TROUGH
ENTERS THE SOUTHERN CONE...THIS WILL THEN DRIVE THE SURFACE FRONT
NORTH ACROSS PATAGONIA. THIS BOUNDARY CONTINUES NORTH ACROSS LA
PAMPA/THE BUENOS AIRES PROVINCE TO CENTRAL ARGENTINA ON
SATURDAY...WHERE IT IS EXPECTED TO STALL. ACROSS CENTRAL ARGENTINA
THIS WILL THEN TRIGGER SCATTERED DEEP CONVECTION...WITH RAINFALL
MAXIMA OF 20-35MM ON SATURDAY...WITH POTENTIAL FOR LOCALLY HIGHER
AMOUNTS IN SEVERE CONVECTION.

ON THE NORTHERN STREAM...AT 200 HPA...A SHORT WAVE TROUGH
EXTENDING FROM NORTHWEST ARGENTINA TO WESTERN BRASIL SPLITS THE
SUBTROPICAL RIDGE IN TWO CELLS...WITH THE WESTERNMOST LOCATING
OVER THE EASTERN TROPICAL PACIFIC WHILE CENTERING AT 250 HPA ON A
CLOSED HIGH NEAR 15S 85W. THE EASTERNMOST...MEANWHILE...EXTENDS
OVER BRASIL BETWEEN BAHIA AND MINAS GERAIS. THROUGH WEDNESDAY THE
RIDGE OVER THE PACIFIC IS FORECAST TO GRADUALLY COLLAPSE...WHILE
THE ONE OVER BRASIL TENDS TO BUILD. AS THE LATTER INTENSIFIES...IT
WILL THEN STEER THE SHORT WAVE TROUGH ACROSS PARAGUAY TO SOUTHERN
BRASIL ON THURSDAY...WHILE SIMULTANEOUSLY STEERING A TUTT TO THE
NORTH ACROSS NORTHEAST BRASIL. UNDER THE INFLUENCE OF THE UPPER
LEVEL TROUGH/CONTINENTAL RIDGE...SCATTERED DEEP CONVECTION IS TO
CLUSTER BETWEEN RIO DE JANEIRO/SAO PAULO AND AMAZONAS IN
BRASIL/NORTHERN PERU-SOUTHERN COLOMBIA. IN THIS AREA EXPECTING
RAINFALL AMOUNTS OF 15-30MM/DAY WITH MAXIMA OF 20-45MM. THROUGH
THE END OF THE WEEK...AS THE SHORT WAVE TROUGH STARTS TO PROPAGATE
ACROSS MID SECTIONS OF SOUTH AMERICA...FOCUS OF THE ORGANIZED
CONVECTION WILL SHIFT TO NORTHWEST ARGENTINA-PARAGUAY...WHERE THE
ENVIRONMENTAL CONDITIONS WILL BECOME FAVORABLE FOR A HEAVY
RAINFALL PRODUCING MESO SCALE CONVECTIVE COMPLEX TO DEVELOP ON
SATURDAY TO SUNDAY. THIS WILL SUSTAIN RAINFALL AMOUNTS OF
40-80MM/DAY...WITH SOME OF THE MODELS SHOWING LOCALIZED MAXIMA OF
150-200MM AS IT BUILDS NORTH ACROSS PARAGUAY TO MATO GROSSO DO SUL
IN BRASIL.

DAVISON...WPC (USA)
$$

635 
FXSA20 KWBC 251643
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1243 PM EDT MON OCT 25 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 25/17UTC: AT MID/UPPER LEVELS...A
LONG WAVE TROUGH EXTENDS FROM THE WESTERN ATLANTIC TO MID SECTIONS
OF SOUTH AMERICA. EARLY IN THE CYCLE THE TROUGH IS TO BEGIN
PULLING WHILE PRESSING AGAINST A LONG WAVE RIDGE TO THE EAST. IN
THIS PROCESS...IT IS TO SHEAR A SHORT WAVE TROUGH ON THE NORTHERN
STREAM FLOW. THE SHORT WAVE TROUGH WILL EXTEND FROM NORTHWEST
ARGENTINA TO BOLIVIA...WITH AXIS SPLITTING THE SUBTROPICAL RIDGE
INTO TWO CELLS...WITH THE WESTERNMOST TO EXTEND OVER THE EASTERN
TROPICAL PACIFIC WHILE CENTERING AT 250 HPA ON A CLOSED HIGH NEAR
15S 90W. THE EASTERNMOST...MEANWHILE...IS TO EXTEND OVER BRASIL
BETWEEN BAHIA AND MINAS GERAIS. THROUGH WEDNESDAY THE RIDGE OVER
THE PACIFIC IS FORECAST TO GRADUALLY COLLAPSE...WHILE THE ONE OVER
BRASIL TENDS TO BUILD. AS THE LATTER INTENSIFIES...IT WILL THEN
STEER THE SHORT WAVE TROUGH ACROSS PARAGUAY TO SOUTHERN BRASIL ON
THURSDAY...WHILE SIMULTANEOUSLY STEERING A TUTT ACROSS NORTHEAST
BRASIL. AT LOW LEVELS...THE UPPER LEVEL TROUGH SUSTAINS AN
ELONGATED FRONT WITH AXIS TO THE WEST-NORTHWEST ACROSS THE CENTRAL
ATLANTIC TO ESPIRITO SANTO/MINAS GERAIS-MATO GROSSO IN BRASIL.
THROUGH TUESDAY EVENING THE FRONT OVER BRASIL WILL WEAKEN INTO AN
OPEN TROUGH. EARLY IN THE CYCLE...THIS WILL SUSTAIN AN MCS ACROSS
NORTHERN JUNGLE OF PERU/EASTERN ECUADOR-SOUTHERN AMAZONIA IN
COLOMBIA TO AMAZONAS IN BRASIL...WITH RAINFALL MAXIMA OF 75-125MM.
ON TUESDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 20-45MM. ON
WEDNESDAY IT WEAKENS TO 20-35MM...WHILE ON THURSDAY TO FRIDAY IT
IS TO ONCE AGAIN INTENSIFY TO 20-45MM/DAY. OTHER CONVECTION IS
EXPECTED BETWEEN ACRE IN WESTERN BRASIL AND RIO DE JANEIRO/MINAS
GERAIS...WITH MAXIMA OF 15-30MM/DAY. ON TUESDAY ACTIVITY ACROSS
ESPIRITO SANTO/MINAS GERAIS AND NORTHERN SAO PAULO/RIO DE JANEIRO
INTENSIFIES...WITH MAXIMA OF 20-40MM. ON THURSDAY ACTIVITY ALONG
THE COAST OF SAO PAULO SURGES TO 40-80MM AS BUILDING RIDGE TO THE
SOUTH STRENGTHENS THE ONSHORE FLOW ACROSS SOUTHEAST BRASIL. THE
ENHANCED MOISTURE CONVERGENCE/TRANSPORT IS TO ALSO ENHANCE
DEVELOPMENT ACROSS JUJUY/SALTA IN NORTHWEST ARGENTINA TO PORTIONS
OF PARAGUAY...TO SUSTAIN A HEAVY RAINFALL PRODUCING MCS WITH
MAXIMA OF 40-80MM.

SOUTH OVER THE CONTINENT...AT 250 HPA...IN A TIGHT BELT OF MID
LATITUDE WESTERLIES STRONG WINDS CONTINUE TO ENVELOP THE SOUTHERN
CONE...WITH JET MAXIMA OF 180-200KTS TO EXTEND ACROSS SOUTHERN
CHILE TO PATAGONIA IN ARGENTINA EARLY IN THE CYCLE. ON TUESDAY TO
WEDNESDAY THE GRADIENT STARTS TO SLACKEN AND THE UPPER LEVEL WINDS
DROP TO 140-160KT. LATER IN THE WEEK...UNDER THE INFLUENCE OF A
HIGHLY AMPLIFIED TROUGH ENTERING THE SOUTHERN CONE ON FRIDAY...THE
JET WILL FINALLY RELOCATE ACROSS THE SOUTHERN CONE. AT LOW
LEVELS...BROAD SURFACE TROUGH WILL DOMINATE THE FLOW OVER THE
SOUTHEAST PACIFIC DURING THE NEXT FEW DAYS...WITH POLAR FRONTS TO
REVOLVE AROUND THIS AXIS TO STREAM ACROSS SOUTHERN CHILE/PATAGONIA
IN ARGENTINA FROM TIME-TO-TIME. THESE WILL BE ACCOMPANIED BY
STRONG BOUNDARY LAYER WINDS OF 60-70KT. THE STRONGER WINDS WILL
ENHANCE MOISTURE TRANSPORT/CONVERGENCE ACROSS THE SOUTHERN REGIONS
OF CHILE DURING THE NEXT FOUR DAYS...WITH THE CONSENSUS OF THE
DETERMINISTIC MODELS SHOWING A RAINFALL MAXIMA OF 40-80MM/DAY FOR
TODAY AND ON THURSDAY...AND 35-70MM ON WEDNESDAY. BUT AS THE
PATTERN EVOLVES AND THE GRADIENT SLACKENS...WINDS ARE TO WEAKEN
AND MORE MODEST RAINFALL AMOUNTS ARE TO AFFECT THE SOUTHERN CONE
LATER IN THE WEEK.

DAVISON...WPC (USA)
$$

926 
FXSA20 KWBC 221609
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1209 PM EDT FRI OCT 22 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 22/16UTC: UNDER THE INFLUENCE OF A
MID/UPPER LEVEL RIDGE TO THE WEST...A LONG WAVE TROUGH EXTENDS
FROM THE WEDDELL SEA/ANTARCTIC PENINSULA...ACROSS PATAGONIA IN
ARGENTINA 40S 80W TO 25S 110W. THROUGH THE DAY THE TROUGH IS TO
MOVE NORTH ACROSS CENTRAL ARGENTINA/CHILE...MEANWHILE FOCUSING A
SUBTROPICAL JET ACROSS NORTHERN CHILE/ARGENTINA AND A NORTHERN
POLAR JET ACROSS THE RIO DE LA PLATA BASIN. ON SATURDAY THE JETS
ARE FORECAST TO COUPLE IN SUPPORT OF A BROAD AREA OF UPPER
DIVERGENCE ACROSS PARAGUAY-CORRIENTES/MISIONES IN ARGENTINA AND
THE SOUTHERN STATES OF BRASIL. THE TROUGH REACHES MAXIMUM
AMPLITUDE ON SUNDAY MORNING WHEN IT IS TO EXTEND ACROSS THE
WESTERN ATLANTIC TO SOUTHERN BRASIL-PARAGUAY.  AT LOW
LEVELS...THIS SUSTAINS A PROGRESSIVE FRONT THAT SURGES ACROSS LA
PAMPA IN ARGENTINA TO THE BUENOS AIRES PROVINCE/MENDOZA LATER THIS
EVENING...MEANWHILE TRIGGERING MODERATE CONVECTION WITH
ACCUMULATION OF 20-30MM. THROUGH SATURDAY MORNING ACTIVITY WILL
BUILD NORTH ACROSS NORTHERN ARGENTINA TO PARAGUAY...FAVORING
MAXIMA OF 20-40MM IN POTENTIALLY SEVERE CONVECTION. EARLY ON
SATURDAY THE FRONT ADVANCES ACROSS SOUTHERN BRASIL TO
PARAGUAY...WHERE UNDER FAVORABLE JET DYNAMICS A HEAVY RAINFALL
PRODUCING MCS IS TO DOMINATE THROUGH SUNDAY MORNING...WITH
RAINFALL MAXIMA OF 75-150MM. THROUGH SUNDAY...UNDER THE STEERING
INFLUENCE OF A SOUTHERLY JET...THE FRONT SURGES FARTHER ACROSS
SOUTHEAST BRASIL-MATO GROSSO TO NORTHERN BOLIVIA...WHERE IT IS
EXPECTED TO STALL. THROUGH EARLY NEXT WEEK THIS BOUNDARY IS TO
THEN FRONTOLIZE. MEANWHILE...OVER SAO PAULO-RIO DE JANEIRO THIS
WILL FAVOR MODERATE RAINFALL AMOUNTS WITH MAXIMA OF 25-50MM.
ACROSS MATO GROSSO EXPECTING MODERATE RAINFALL AMOUNTS WITH MAXIMA
OF 20-35MM ON SUNDAY...WHILE ON MONDAY-TUESDAY THIS INCREASES TO
25-50MM WHILE BUILDING TO THE SOUTHEAST ACROSS MATO GROSSO TO SAO
PAULO. AS ENHANCED BY THE LOW LEVEL JET...HEAVY RAINS ARE TO
CLUSTER OVER CENTRAL BOLIVIA...WITH MAXIMA INCREASING FROM 25-50MM
ON SATURDAY TO 30-60MM ON SUNDAY WHILE BUILDING WEST ACROSS THE
SOUTHERN JUNGLE OF PERU. EARLY NEXT WEEK...CONVECTION IS TO THEN
CLUSTER ALONG THE LEE OF THE PERUVIAN ANDES...WITH ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-25MM.

THE EASTERN PACIFIC RIDGE...MEANWHILE...IS TO REMAIN THE DOMINANT
SYNOPTIC FEATURE OVER THE SOUTHEAST PACIFIC DURING THE NEXT
120-132 HRS. AS THE RIDGE HOLDS...SHORT WAVE PERTURBATIONS ON THE
SOUTHERN STREAM WILL RACE ACROSS THE SOUTHEAST PACIFIC TO THE
SOUTHERN CONE. THESE ARE TO SUSTAIN A SUBTROPICAL CONNECTION AS
THEY ENTER THE SOUTHERN REGIONS OF CHILE...WITH THE GLOBAL MODELS
CONSISTENTLY SHOWING AN ELEVATED RISK FOR HEAVIER THAN NORMAL
RAINFALL AMOUNTS. AT 250 HPA...AS THE PERTURBATIONS PRESS AGAINST
THE SUBTROPICAL RIDGE THE UPPER LEVEL GRADIENT IS TO TIGHTEN. THIS
WILL THEN INDUCE THE RAPID INTENSIFICATION OF A JET MAXIMA
TRAVERSING THE SOUTHEAST PACIFIC/SOUTHERN CONE...WITH WINDS OF
175-220KT EXPECTED DURING THE NEXT FIVE DAYS. AT LOW LEVELS THESE
WILL HELP SUSTAIN PROGRESSIVE FRONTS THAT ARE TO STREAM ACROSS THE
CONTINENT TO THE SOUTH OF 40S. THESE WILL THEN ENHANCE THE
TRANSPORT OF DEEP LAYER MOISTURE ACROSS THE SOUTHEAST PACIFIC TO
THE SOUTHERN CONE OF SOUTH AMERICA. OVER SOUTHERN CHILE...IN
COMBINATION WITH STRONG TOPOGRAPHICAL FORCING...CONDITIONS ARE TO
FAVOR SEVERAL DAYS OF HEAVY RAINFALL AMOUNTS. MOST ACTIVE IS
EXPECTED BETWEEN PUERTO MONTT AND ISLA DE CHILOE IN SOUTHERN
CHILE...WITH MAXIMA OF 20-35MM EARLY IN THE CYCLE. THROUGH SUNDAY
THIS IS FORECAST TO INCREASE TO MAXIMA OF 25-50MM...WHILE ON
MONDAY THE MAXIMA SURGES TO 35-70MM. THIS IS TO THEN GRADUALLY
WEAKEN THROUGH THE MIDDLE OF THE WEEK...WITH MAXIMA OF
20-35MM/DAY. OVER TIERRA DEL FUEGO...IN A COLD ADVECTIVE
PATTERN...MODERATE TO HEAVY SNOWFALL AMOUNTS ARE EXPECTED...WITH
MAXIMA OF 15-20CM TODAY...WITH AN ADDITIONAL 10-15CM/DAY ON
SATURDAY AND SUNDAY. EARLY NEXT WEEK THIS IS FORECAST TO CHANGE TO
RAIN.

AT 250 HPA...A BROAD RIDGE DOMINATES PATTERN TO THE NORTH...WITH
AXIS ENVELOPING CONTINENTAL AREA TO THE NORTH OF 20S. THIS WILL
PERSIST THROUGH SATURDAY MORNING...THEN RAPIDLY EVOLVES DURING THE
WEEKEND...WITH THE RIDGE RELOCATING ACROSS PERU TO THE EASTERN
TROPICAL PACIFIC WHILE A SHORT WAVE TROUGH AMPLIFIES ACROSS
BOLIVIA TO RONDONIA/ACRE IN BRASIL. IN RESPONSE TO THE EVOLVING
UPPER LEVEL PATTERN...CONVECTION ACROSS TROPICAL PORTIONS OF SOUTH
AMERICA IS EXPECTED TO GRADUALLY BECOME MORE ACTIVE AND BETTER
ORGANIZED...WITH THE DETERMINISTIC MODELS AGREEING ON POTENTIAL
FOR HEAVY CONVECTION ACROSS CENTRAL PORTIONS OF BRASIL LATER
DURING THE WEEKEND/EARLY NEXT WEEK.

DAVISON...WPC (USA)
$$

698 
FXSA20 KWBC 211613
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1213 PM EDT THU OCT 21 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 21/16UTC: IN A SPLIT FLOW...THE
MID/UPPER LEVEL FLOW OVER THE EASTERN PACIFIC DIVIDES BETWEEN A
BROAD RIDGE ON THE SOUTHERN STREAM AND A SHORT WAVE TROUGH TO THE
NORTH. THE RIDGE DOMINATES AREA BETWEEN 60W-30W AND TO THE SOUTH
OF 40S...WHILE CENTERING ON A CLOSED HIGH NEAR 46S 46W. THE SHORT
WAVE TROUGH TO THE NORTH...MEANWHILE...ORIGINATES ON A CLOSED LOW
NEAR 38S 47W...AND EXTENDS NORTH TO THE SOUTHEAST STATES OF
BRASIL. THROUGH FRIDAY AFTERNOON THE RIDGE TO THE SOUTH IS TO
WEAKEN WHILE YIELDING TO A DEEPENING POLAR TROUGH TO THE SOUTH AND
WEST. THE CLOSED LOW...WHILE REMAINING CUT OFF FROM THE FLOW...IS
TO SIMULTANEOUSLY FILL TO AN OPEN TROUGH WHILE MEANDERING ACROSS
SOUTHERN/SOUTHEAST STATES OF BRASIL LATER TODAY. ON FRIDAY...UNDER
THE INFLUENCE OF THE AMPLIFYING POLAR TROUGH...THIS WILL THEN
START TO WEAKEN WHILE SHEARING SHORT WAVE ENERGY TO THE
SOUTH-SOUTHEAST. AT LOW LEVELS...THE TROUGH ALOFT IS INTERACTING
WITH AN ELONGATED FRONT THAT EXTENDS TO THE WEST/NORTHWEST ACROSS
THE CENTRAL SOUTH ATLANTIC TO ESPIRITO SANTO/MINAS GERAIS IN
BRASIL. LOSING UPPER LEVEL SUPPORT...THIS BOUNDARY IS TO
FRONTOLIZE OVER THE CONTINENT THROUGH SATURDAY MORNING...WHILE
PORTION OVER THE ATLANTIC IS TO BECOME ILL DEFINED LATER ON
SUNDAY. MEANWHILE...UNDER FAVORABLE JET DYNAMICS...EXPECTING
MODERATE/LOCALLY HEAVY CONVECTION ACROSS ESPIRITO SANTO-MINAS
GERAIS AND BAHIA IN BRASIL...TO RESULT IN ACCUMULATION OF
25-50MM/DAY. ON FRIDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-40MM...WHILE ON SATURDAY IT IS TO WEAKEN TO 20-35MM.

UPSTREAM OVER THE PACIFIC...A MID/UPPER LEVEL RIDGE IS TO BUILD
ACROSS THE EASTERN PACIFIC DURING THE NEXT COUPLE OF DAYS...WITH
AXIS TO BECOME THE DOMINANT FEATURE TO THE SOUTH OF 30S AND EAST
OF 130W LATER ON FRIDAY. AS THE RIDGE BUILDS...A LONG WAVE TROUGH
TO THE EAST WILL BE DISPLACED EAST ACROSS THE DRAKE
PASSAGE/SOUTHERN CONE LATER THIS EVENING. ON FRIDAY THIS WILL THEN
STRETCH FROM THE SOUTHWEST ATLANTIC...ACROSS CENTRAL
ARGENTINA/CHILE TO A CLOSED LOW NEAR 25S 100W. ON FRIDAY TO
SATURDAY THIS VORTEX IS TO THEN SHEAR OFF FROM THE MAIN
TROUGH...EVOLVING INTO A CLOSED LOW ON THE NORTHERN STREAM...WHILE
THE MAIN BODY OF THE TROUGH SETTLES OVER THE WESTERN ATLANTIC. AS
THE MID LEVEL RIDGE HOLDS TO THE WEST...IT IS TO STEER PROGRESSIVE
SHORT WAVE PERTURBATIONS ACROSS THE BELLINGSHAUSEN SEA/DRAKE
PASSAGE. OVER THE WESTERN ATLANTIC...THESE VORTICES WILL THEN HELP
SUSTAIN THE BROAD/LONG WAVE TROUGH. AT LOW LEVELS...A BUILDING
POLAR RIDGE OVER PATAGONIA TO CENTRAL ARGENTINA WILL DRIVE A
SURFACE FRONT NORTH ACROSS LA PAMPA TO THE BUENOS AIRES PROVINCE
ON FRIDAY. THROUGH THE WEEKEND THE FRONT WILL THEN MOVE FARTHER
NORTH ACROSS SOUTHERN BRASIL-PARAGUAY ...WITH BOUNDARY REACHING
SAO PAULO-MATO GROSSO-NORTHERN BOLIVIA LATER ON SUNDAY. OVER THE
BUENOS AIRES PROVINCE THIS WILL SUSTAIN MODERATE/POTENTIALLY
SEVERE CONVECTION DURING THE DAY...WITH MAXIMA OF 05-10MM. ON
FRIDAY THIS INCREASES TO 15-30MM WHILE BUILDING NORTH ACROSS THE
RIO DE LA PLATA BASIN...WHILE OVER NORTHERN ARGENTINA/URUGUAY THE
MAXIMA INCREASES TO 20-40MM WHILE THE RISK OF SEVERE THUNDERSTORMS
PERSISTS. ON SATURDAY...THE SUBTROPICAL AND NORTHERN POLAR JETS
ARE TO COUPLE ON THEIR DIVERGENT EXIT/ENTRANCE REGIONS AS THE
SURFACE FRONT SURGES ACROSS PARAGUAY. THIS WILL BE IDEAL FOR A
HEAVY RAINFALL PRODUCING MCS TO DEVELOP ACROSS PARAGUAY TO MATO
GROSSO DO SUL IN BRASIL...WITH RAINFALL MAXIMA OF 75-150MM. OVER
CENTRAL BOLIVIA PREFRONTAL CONVECTION ON FRIDAY WILL RESULT IN
RAINFALL AMOUNTS OF 25-50MM...WHILE ON SATURDAY THE MAXIMA
INCREASES TO 30-60MM WHILE BUILDING WEST ACROSS THE SOUTHERN
JUNGLE OF PERU. MODERATE TO HEAVY CONVECTION IS TO THEN PERSIST
ACROSS MATO GROSSO-SOUTHEAST BRASIL AS ENHANCED BY THE UPPER LEVEL
JET MAXIMA AND A MID/UPPER LEVEL SHORT WAVE TROUGH STREAMING
ACROSS MID SECTIONS OF SOUTH AMERICA.

MEANWHILE...THE SHORT WAVE PERTURBATIONS STREAMING UNDER THE
SOUTHEAST PACIFIC RIDGE ARE TO FAVOR A TIGHT GRADIENT...WITH
ENSUING JET MAXIMA FORECAST TO INTENSIFY TO 180-220KT ON FRIDAY TO
SUNDAY. AT LOW LEVELS THESE WILL SUSTAIN PROGRESSIVE FRONTS TO THE
SOUTH OF 40S THAT ARE TO STREAM ACROSS SOUTHERN CHILE/PATAGONIA IN
ARGENTINA FROM TIME TO TIME. THESE WILL ENHANCE MOISTURE TRANSPORT
AND CONVERGENCE ACROSS THE SOUTHERN REGIONS OF CHILE...WHERE IN
COMBINATION WITH STRONG TOPOGRAPHICAL FORCING THESE ARE LIKELY TO
TRIGGER HEAVY RAINFALL AMOUNTS. IN THIS AREA CONVECTION
INTENSIFIES ON FRIDAY WHEN IT IS TO FAVOR MAXIMA OF 20-35MM. ON
SATURDAY THIS INCREASES TO 25-50MM...WHILE ON SUNDAY UNDER THE
INFLUENCE OF THE JET ALOFT THE RAINFALL MAXIMA SURGES TO 35-70MM.
THE HEAVY RAINS ARE TO THEN SUBSIDE EARLY NEXT WEEK.

BROAD RIDGE TO THE NORTH REMAINS THE DOMINANT UPPER LEVEL FEATURE
OVER NORTHERN SOUTH AMERICA. STARTING ON FRIDAY THE RIDGE IS
EXPECTED TO AMPLIFY ACROSS BOLIVIA...WITH CLOSED HIGH/BROAD RIDGE
TO ROLL ACROSS THE ANDES OF PERU TO THE EASTERN PACIFIC ON SUNDAY
MORNING. THIS...IN-TURN...WILL THEN INDUCE THE NORTHWARD
AMPLIFICATION OF A SHORT WAVE TROUGH ACROSS NORTHWEST ARGENTINA TO
BOLIVIA LATER DURING THE WEEKEND. IN RESPONSE TO THE EVOLVING
UPPER LEVEL PATTERN...CONVECTION ACROSS TROPICAL PORTIONS OF SOUTH
AMERICA IS EXPECTED TO GRADUALLY BECOME MORE ACTIVE AND BETTER
ORGANIZED...WITH THE DETERMINISTIC MODELS AGREEING ON POTENTIAL
FOR HEAVY CONVECTION ACROSS CENTRAL PORTIONS OF BRASIL LATER
DURING THE WEEKEND/EARLY NEXT WEEK.

DAVISON...WPC (USA)
$$

954 
FXSA20 KWBC 201618
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1217 PM EDT WED OCT 20 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 20/16UTC: AS PREVIOUSLY
EXPECTED...THE MID/UPPER LEVEL RIDGE RELOCATED ACROSS THE SOUTHERN
CONE TO THE SOUTHWEST ATLANTIC/WEDDELL SEA WHILE YIELDING TO A
HIGH AMPLITUDE LONG WAVE TROUGH ENTERING THE EASTERN PACIFIC.
BROAD TROUGH TO THE EAST OF THIS RIDGE...MEANWHILE...DOMINATES THE
CENTRAL ATLANTIC WHILE TRAILING TO THE NORTHWEST TO THE SOUTHERN
STATES OF BRASIL. THROUGH THE DAY TODAY THE TROUGH WILL MEANDER
FARTHER EAST ACROSS THE SOUTH ATLANTIC...MEANWHILE SHEARING A
SHORT WAVE TROUGH/CUT OFF LOW TO THE EAST-SOUTHEAST OF URUGUAY.
THIS IS TO REMAIN NEARLY STATIONARY THROUGH THURSDAY
AFTERNOON...BUT AS IT IS TO REMAIN CUT OFF FROM THE FLOW...THE
CLOSED LOW FILLS TO AN OPEN TROUGH LATER IN THE DAY. DURING THE
WEEKEND THIS IS TO SLOWLY WEAKEN WHILE MEANDERING EAST. AT LOW
LEVELS...THE ASSOCIATED SURFACE FRONT TRAILS ACROSS THE CENTRAL
ATLANTIC TO SOUTHEAST BRASIL. LOSING ITS UPPER LEVEL SUPPORT...THE
FRONT IS TO GRADUALLY FRONTOLIZE THROUGH FRIDAY.
MEANWHILE...EXPECTING SCATTERED CONVECTION TO AFFECT ESPIRITO
SANTO AND EASTERN MINAS GERAIS IN BRASIL WITH RAINFALL AMOUNTS OF
25-50MM. THROUGH FRIDAY THIS IS TO WEAKEN TO MAXIMA OF
20-40MM/DAY...WITH LESSER AMOUNTS ON SATURDAY.

A HIGH AMPLITUDE MID/UPPER LEVEL TROUGH TO THE WEST IS TO EXTEND
OVER THE EASTERN PACIFIC LATER TODAY. AS IT NEARS THE SOUTHERN
CONE...THE TROUGH IS TO INITIALLY FOCUS ITS SHORT WAVE ENERGY AND
SUBTROPICAL MOISTURE ACROSS THE SOUTHERN REGIONS OF CHILE. THIS
WILL THEN DRAW THE TROUGH ACROSS THE SOUTHERN CONE/DRAKE PASSAGE
ON THURSDAY...WITH AXIS TAKING A POSITIVE TILT AS IT EXTENDS
ACROSS TIERRA DEL FUEGO/SOUTHERN PATAGONIA TO 30S 100W. A BUILDING
RIDGE TO THE WEST WILL THEN DISPLACE THE CONTINENTAL TROUGH
FARTHER TO THE EAST ACROSS THE WESTERN SOUTH ATLANTIC AND NORTH
ACROSS CENTRAL ARGENTINA/CHILE ON FRIDAY. SIMULTANEOUSLY...STEERED
BY THE BUILDING RIDGE OVER THE EASTERN PACIFIC...A SOUTHERN STREAM
VORTEX WILL LIFT ACROSS THE THE DRAKE PASSAGE TO TIERRA DEL FUEGO
LATER ON FRIDAY. AS IT ENTERS THE WESTERN ATLANTIC DURING THE
WEEKEND...THE SHORT WAVE TROUGH IS TO RAPIDLY AMPLIFY WHILE
MERGING WITH THE REMNANTS OF THE BROAD TROUGH TO THE EAST. AT LOW
LEVELS...THIS WILL SUSTAIN A DEEP/BROAD TROUGH OVER THE SOUTHEAST
PACIFIC/BELLINGSHAUSEN SEA LATER TODAY. THROUGH THURSDAY
EVENING...AS A POLAR RIDGE BUILDS OVER PATAGONIA IN
ARGENTINA...THE SURFACE FRONT WILL MOVE NORTH ACROSS CENTRAL
ARGENTINA TO THE BUENOS AIRES PROVINCE. THROUGH THE WEEKEND THE
FRONT WILL THEN MOVE FARTHER NORTH INTO SOUTHERN BRASIL WHILE
TRAILING ACROSS PARAGUAY TO BOLIVIA. AS IT ENTERS SOUTHERN CHILE
THIS FRONT WILL SUSTAIN MODERATE RAINFALL AMOUNTS...WITH RAINFALL
MAXIMA OF 15-30MM. ON THURSDAY EXPECTING ADDITIONAL RAINFALL
AMOUNTS OF 10-15MM. OVER SOUTHERN BUENOS AIRES PROVINCE/SIERRA DE
LA VENTANA...THIS WILL SUSTAIN LIGHT RAINFALL AMOUNTS ON THURSDAY.
IN THIS AREA THE MAXIMA PEAKS AT 05-10MM IN ISOLATED CONVECTION.
ON FRIDAY...AS THE FRONT ACCELERATES ACROSS CENTRAL
ARGENTINA...THIS WILL SUSTAIN MAXIMA OF 15-30MM ACROSS THE BUENOS
AIRES PROVINCE...WHILE ACROSS CORDOBA-ENTRE RIOS TO URUGUAY
EXPECTING MAXIMA OF 20-40MM IN POTENTIALLY SEVERE CONVECTION. OVER
SOUTHERN BRASIL ALSO EXPECTING RAINFALL AMOUNTS OF 20-40MM ON
SATURDAY...WHILE OVER PARAGUAY AND MATO GROSSO DO SUL UNDER
INFLUENCE OF A SUBTROPICAL JET MAXIMA THE ENVIRONMENTAL CONDITIONS
BECOME FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO FORM. THIS
WILL SUSTAIN MAXIMA OF 40-80MM IN POTENTIALLY SEVERE CONVECTION. 
DRIVEN BY A SOUTHERLY LOW LEVEL JET...THE FRONT MOVES FARTHER
NORTH INTO SOUTHEAST BRASIL ON SUNDAY...WHILE TRAILING ACROSS MATO
GROSSO DO CENTRAL BOLIVIA. MODERATE CONVECTION IS TO PERSIST ALONG
THIS BOUNDARY. MOST INTENSE...HOWEVER...IS TO AFFECT NORTHERN
BOLIVIA-SOUTHERN JUNGLE OF PERU LATER ON SUNDAY THROUGH
MONDAY...WITH MAXIMA OF 30-60MM.

AS THE MID/UPPER LEVEL RIDGE HOLDS TO THE WEST...OVER THE EASTERN
PACIFIC...SUCCESSIVE SHORT WAVE PERTURBATIONS ON THE SOUTHERN
STREAM ARE TO LIFT ACROSS THE BELLINGSHAUSEN SEA/SOUTHEAST PACIFIC
INTO THE DRAKE PASSAGE AND THE SOUTHERN CONE OF SOUTH AMERICA. AT
LOW LEVELS THESE WILL SUSTAIN PROGRESSIVE FRONTS ACROSS EXTREME
SOUTHERN CHILE/PATAGONIA IN ARGENTINA. UNDER THE INFLUENCE OF
THESE PERTURBATIONS THE MOST INTENSE CONVECTION IS EXPECTED OVER
SOUTHERN CHILE BETWEEN PUERTO MONTT AND ISLA DE CHILOE...WITH
MAXIMA OF 20-35MM ON FRIDAY. THROUGH SUNDAY THIS IS TO GRADUALLY
INTENSIFY...WITH MAXIMA IN THIS AREA INCREASING TO 25-50MM/DAY. IN
THIS AREA EXPECTING STORM TOTAL AMOUNTS OF 75-150MM DURING THE
MEDIUM RANGE PERIOD. OVER TIERRA DEL FUEGO...MEANWHILE...EXPECTING
MODERATE RAINFALL AMOUNTS IN MIXED PRECIPITATION. ON SUNDAY AND
MONDAY IT PHASE CHANGES TO SNOW...WITH ACCUMULATION OF 05-10CM PER
DAY.

NORTH OVER THE DOMAIN...AT 250 HPA...A BROAD UPPER LEVEL RIDGE
DOMINATES THE FLOW OVER THE CONTINENT TO THE NORTH OF 20S. THE
RIDGE WILL HOLD ITS GROUND THROUGH FRIDAY EVENING. DURING THE
WEEKEND...HOWEVER...IT WILL RELOCATE ACROSS THE ANDES OF PERU TO
THE EASTERN TROPICAL PACIFIC...WHERE THE GLOBAL MODELS FORESEE THE
GRADUAL INTENSIFICATION OF THIS RIDGE DURING THE WEEKEND TO EARLY
NEXT WEEK. IN RESPONSE TO THIS FEATURE...A TROUGH IS TO THEN
AMPLIFY ACROSS SOUTHEAST BRASIL TO MINAS GERAIS/BAHIA. IN THIS
PATTERN...SCATTERED CONVECTION IS TO CLUSTER ACROSS CENTRAL
BRASIL...WITH MAXIMA OF 15-25MM. HIGHER AMOUNTS ARE EXPECTED
ACROSS EQUATORIAL SOUTH AMERICA...WITH ACCUMULATION OF 10-15MM/DAY
AND MAXIMA OF 20-45MM AS ENHANCED BY TROPICAL/EASTERLY WAVES
STREAMING TO THE NORTH. ACTIVITY IS TO GRADUALLY INTENSIFY EARLY
NEXT WEEK AS THE SHORT WAVE TROUGH DEEPENS AND CONVECTIVE
INSTABILITY ACROSS TROPICAL SOUTH AMERICA INTENSIFIES.

DAVISON...WPC (USA)
$$

723 
FXSA20 KWBC 191544
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1143 AM EDT TUE OCT 19 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 19/16UTC: IN A SLOW TO EVOLVE
PATTERN...A BROAD MID/UPPER LEVEL RIDGE REMAINS THE DOMINANT
FEATURE OVER THE SOUTHEAST PACIFIC...WITH AXIS BRANCHING ACROSS
CENTRAL CHILE/THE BUENOS AIRES PROVINCE. EAST OF THIS AXIS...OVER
THE SOUTH ATLANTIC...A LONG WAVE TROUGH EXTENDS TO THE NORTHWEST
ALONG 50S 25W...40S 40W...URUGUAY/RIO GRANDE DO SUL TO NORTHERN
ARGENTINA. AS IT TRAILS OVER THE CONTINENT...THE LONG WAVE TROUGH
IS PRESSING AGAINST A CELL OF THE SUBTROPICAL RIDGE OVER BRASIL.
THE ENSUING GRADIENT FAVORS A TIGHT BELT OF UPPER LEVEL WESTERLIES
ACROSS NORTHERN CHILE/ARGENTINA TO SOUTHERN BRASIL...WITH 250 HPA
WINDS NOW PEAKING AT 90-100KT. AT LOW LEVELS...THE UPPER LEVEL
TROUGH SUPPORTS A SURFACE FRONT THAT EXTENDS FROM THE CENTRAL
SOUTH ATLANTIC TO NORTHERN SAO PAULO/RIO DE JANEIRO IN SOUTHEAST
BRASIL...WITH BOUNDARY TRAILING ACROSS MATO GROSSO DO SUL TO SANTA
CRUZ IN EASTERN BOLIVIA.

THROUGH WEDNESDAY MORNING...WHILE YIELDING TO A HIGH AMPLITUDE
LONG WAVE TROUGH...THE MID/UPPER LEVEL RIDGE WILL RELOCATE ACROSS
THE SOUTHERN CONE TO THE WESTERN ATLANTIC...WITH THE RIDGE TO
CENTER ON A CLOSED HIGH NEAR 48S 52W EARLY ON WEDNESDAY MORNING.
AS THE RIDGE RELOCATES TO THE WESTERN ATLANTIC...IT WILL DISPLACE
THE POLAR TROUGH FARTHER EAST...MEANWHILE SHEARING A SHORT WAVE
VORTEX OFF THE COAST OF URUGUAY/SOUTHERN BRASIL. THIS WILL EVOLVE
INTO A CLOSED LOW TO THE NORTH OF THE MID/UPPER LEVEL RIDGE...WITH
THE CLOSED CIRCULATION CENTERING NEAR 38S 45W. EARLY ON FRIDAY THE
CUT OFF LOW IS TO FILL AND REMAINING SHORT WAVE TROUGH WILL START
TO PULL.  AT LOW LEVELS...THE ASSOCIATED SURFACE FRONT...WHILE
LOSING UPPER LEVEL SUPPORT IS TO FRONTOLIZE AS IT MEANDERS NORTH
ACROSS RIO DE JANEIRO TO ESPIRITO SANTO/BAHIA IN BRASIL.
MEANWHILE...UNDER FAVORABLE UPPER LEVEL JET DYNAMICS...A HEAVY
RAINFALL PRODUCING MCS IS LIKELY TO DEVELOP ACROSS RIO DE JANEIRO
TO SOUTHERN MINAS GERAIS/ESPIRITO SANTO...TO SUSTAIN MAXIMA OF
40-80MM. ON WEDNESDAY TO THURSDAY EXPECTING ADDITIONAL RAINFALL
AMOUNTS OF 25-50MM WHILE CLUSTERING BETWEEN ESPIRITO SANTO AND
EASTERN MINAS GERAIS.

AS THE MID/UPPER LEVEL RIDGE RELOCATES ACROSS THE SOUTHERN CONE TO
THE WESTERN ATLANTIC ON WEDNESDAY...IT WILL YIELD TO A LONG WAVE
TROUGH THAT MOVES ACROSS THE EASTERN PACIFIC EARLY ON WEDNESDAY
MORNING. THROUGH THURSDAY THE TROUGH WILL THEN TAKE A POSITIVE
ORIENTATION WHILE EXTENDING FROM THE DRAKE PASSAGE...ACROSS
PATAGONIA IN ARGENTINA TO 28S 110W. A BUILDING RIDGE TO THE WEST
WILL THEN DISPLACE THE CONTINENTAL TROUGH TO THE EAST ACROSS THE
WESTERN ATLANTIC AND TO THE NORTH INTO CENTRAL ARGENTINA/CHILE. A
SOUTHERN STREAM VORTEX THAT LIFTS ACROSS THE THE DRAKE PASSAGE ON
FRIDAY...IS TO MERGE WITH THE REMNANTS OF THE POLAR TROUGH TO THE
EAST...WHILE SIMULTANEOUSLY A LOW ON THE NORTHERN STREAM GRADUALLY
CLOSED NEAR 27S 90W. AT LOW LEVELS...THIS WILL SUSTAIN A
DEEP/BROAD TROUGH OVER THE SOUTHEAST PACIFIC/BELLINGSHAUSEN SEA
LATER ON TUESDAY. THROUGH WEDNESDAY EVENING...AS A POLAR RIDGE
BUILDS TO THE SOUTH OVER PATAGONIA...THE FRONT WILL MOVE NORTH
ACROSS CENTRAL ARGENTINA...TO THE BUENOS AIRES PROVINCE LATER ON
THURSDAY. THROUGH THE WEEKEND THE FRONT WILL THEN MOVE FARTHER
NORTH INTO SOUTHERN BRASIL WHILE TRAILING ACROSS PARAGUAY/MATO
GROSSO DO SUL IN BRASIL. AS IT ENTERS SOUTHERN CHILE THIS FRONT
WILL SUSTAIN MODERATE RAINFALL AMOUNTS...WITH RAINFALL MAXIMA OF
15-30MM. MODERATE CONVECTION WILL THEN PERSIST THROUGH
WEDNESDAY...DECREASING TO 10-15MM ON WEDNESDAY. OVER SOUTHERN
BUENOS AIRES PROVINCE/SIERRA DE LA VENTANA...THIS WILL SUSTAIN
LIGHT RAINFALL AMOUNTS ON WEDNESDAY EVENING. ON THURSDAY THE
ACTIVITY WILL SPREAD NORTH ACROSS URUGUAY/RIO DE LA PLATA...WITH
RAINFALL AMOUNTS OF 05-10M. ON FRIDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 15-20MM ACROSS THE RIO DE LA PLATA BASIN TO
CENTRAL ARGENTINA...WHILE TO THE NORTH EXPECTING MAXIMA OF
20-40MM. DEEPER MOISTURE OVER PARAGUAY AND MATO GROSSO DO SUL WILL
THEN FEED AN MCS FORMING OVER PARAGUAY/MATO GROSSO DO SUL...WITH
RAINFALL MAXIMA OF 40-80MM.

NORTH OVER THE DOMAIN...AT 250 HPA...A BROAD UPPER LEVEL RIDGE
DOMINATES THE FLOW BETWEEN PARA AND AMAZONAS IN BRASIL. THROUGH
THURSDAY THE RIDGE WILL BUILD SOUTH ACROSS BOLIVIA TO NORTHWEST
ARGENTINA...FAVORING THE NORTHWARD AMPLIFICATION OF A SHORT WAVE
TROUGH OVER SOUTHEAST BRASIL. IN THIS PATTERN...SCATTERED
CONVECTION IS TO CLUSTER ACROSS CENTRAL BRASIL...WITH MAXIMA OF
15-25MM. HIGHER AMOUNTS ARE EXPECTED ACROSS EQUATORIAL SOUTH
AMERICA...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-45MM
AS ENHANCED BY TROPICAL/EASTERLY WAVES STREAMING TO THE NORTH.
THIS TENDS TO BECOME MORE WIDESPREAD AND INTENSE ON
THURSDAY...THEN WEAKEN THROUGH THE WEEKEND.

DAVISON...WPC (USA)
$$

418 
FXSA20 KWBC 181550
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1150 AM EDT MON OCT 18 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 18/16UTC: A BROAD MID/UPPER LEVEL
RIDGE IS INITIALIZED OVER THE EASTERN PACIFIC...WITH AXIS
BRANCHING ACROSS SOUTHERN CHILE/PATAGONIA IN ARGENTINA TO THE
SOUTHWEST ATLANTIC. A LONG WAVE TROUGH TO THE EAST FLANKS THIS
RIDGE...WITH AXIS TO THE NORTHWEST ALONG 50S 40W...45S 50W...THE
BUENOS AIRES PROVINCE TO MENDOZA IN ARGENTINA. AS THE LONG WAVE
TROUGH PRESSES AGAINST A CELL OF THE SUBTROPICAL RIDGE TO THE
NORTH...THIS FAVORS A TIGHT BELT OF UPPER LEVEL WESTERLIES ACROSS
THE CONTINENT BETWEEN 20S-34S...WITH AXIS MANIFESTING AT 250 HPA
AS A 90-110KT SUBTROPICAL JET MAXIMA. AT LOW LEVELS THE UPPER
LEVEL TROUGH SUPPORTS AN ELONGATED FRONT THAT EXTENDS FROM THE
CENTRAL SOUTH ATLANTIC TO SAO PAULO/RIO DE JANEIRO IN SOUTHEAST
BRASIL...WITH BOUNDARY TRAILING ACROSS MATO GROSSO DO SUL TO SANTA
CRUZ IN EASTERN BOLIVIA.

THROUGH WEDNESDAY MORNING THE MID/UPPER LEVEL RIDGE WILL BUILD
ACROSS THE SOUTHERN CONE TO THE WESTERN ATLANTIC...WITH AXIS TO
CENTER ON A WELL ORGANIZED MID LEVEL HIGH NEAR 45S 55W EARLY ON
WEDNESDAY MORNING. AS THE RIDGE BUILDS...THE LONG WAVE POLAR
TROUGH TO THE EAST IS FORECAST TO RELOCATE TO THE SOUTHEAST
ATLANTIC. AS THE TROUGH PULLS AWAY...GRADIENT ACROSS NORTHERN
ARGENTINA-PARAGUAY/SOUTHERN BRASIL IS TO SLACKEN AND THE JET IS TO
WEAKEN THROUGH THURSDAY MORNING. THE SURFACE
FRONT...MEANWHILE...IS TO MEANDER NORTH ALONG THE SOUTHEAST COAST
OF BRASIL...RELOCATING TO ESPIRITO SANTO/MINAS GERAIS ON
WEDNESDAY. BUT AS IT LOSES ITS UPPER LEVEL SUPPORT...THE BOUNDARY
IS TO FRONTOLIZE. MEANWHILE...THE UPPER LEVEL JET WILL VENT
CONVECTION AS THE FRONT MEANDERS NORTH ALONG THE SOUTHEAST COAST
OF BRASIL. THIS WILL FAVOR HEAVY COASTAL CONVECTION DURING THE
NEXT FEW DAYS...WITH MAXIMA OF 40-80MM EXPECTED BETWEEN RIO DE
JANEIRO AND SAO PAULO DURING THE DAY TODAY...AND SOUTHERN
MINAS/ESPIRITO SANTO ON TUESDAY-WEDNESDAY. 

AS THE MID/UPPER LEVEL RIDGE RELOCATES ACROSS THE SOUTHERN CONE TO
THE WESTERN ATLANTIC ON WEDNESDAY...IT WILL MAKE WAY FOR A LONG
WAVE TROUGH THAT MOVES ACROSS THE EASTERN PACIFIC EARLY ON
WEDNESDAY MORNING. THROUGH THURSDAY THE TROUGH WILL TAKE A
POSITIVE ORIENTATION WHILE EXTENDING FROM THE DRAKE
PASSAGE...ACROSS PATAGONIA IN ARGENTINA TO 28S 110W. BUILDING
RIDGE TO THE WEST WILL THEN DRIVE THIS TROUGH NORTH ACROSS THE
BUENOS AIRES PROVINCE TO MENDOZA IN ARGENTINA LATER ON
FRIDAY...WITH AXIS TO THEN AMPLIFY NORTH ALONG 55W TO SOUTHERN
BRASIL DURING THE WEEKEND. AT LOW LEVELS...THIS WILL SUSTAIN A
BROAD TROUGH OVER THE SOUTHEAST PACIFIC/BELLINGSHAUSEN SEA LATER
ON TUESDAY...WITH FRONT TO ADVANCE ACROSS TIERRA DEL
FUEGO/SOUTHERN CHILE TO CENTRAL PATAGONIA ON WEDNESDAY EVENING.
BUILDING POLAR RIDGE...AND ENSUING SOUTHERLY JET...THEN DRIVES THE
FRONT NORTH ACROSS THE BUENOS AIRES PROVINCE ON THURSDAY. AS IT
ENTERS SOUTHERN CHILE THIS FRONT WILL SUSTAIN MODERATE RAINFALL
AMOUNTS...WITH RAINFALL MAXIMA OF 15-30MM. MODERATE CONVECTION
WILL THEN PERSIST THROUGH WEDNESDAY...DECREASING TO 10-15MM ON
WEDNESDAY. OVER SOUTHERN BUENOS AIRES PROVINCE/SIERRA DE LA
VENTANA...THIS WILL SUSTAIN LIGHT RAINFALL AMOUNTS ON WEDNESDAY
EVENING. ON THURSDAY THE ACTIVITY WILL SPREAD NORTH ACROSS
URUGUAY/RIO DE LA PLATA...WITH RAINFALL AMOUNTS OF 05-10M. ON
FRIDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 10-15MM...WHILE TO
THE NORTH OVER CHACO ARGENTINO AND CORRIENTES IT IS TO RESULT IN
RAINFALL AMOUNTS OF 20-45MM IN DEEP/ORGANIZED CONVECTION.

NORTH OVER THE DOMAIN...AT 250 HPA...A BROAD UPPER LEVEL RIDGE
DOMINATES THE FLOW BETWEEN PARA AND AMAZONAS IN BRASIL. THROUGH
THURSDAY THE RIDGE WILL BUILD SOUTH ACROSS BOLIVIA TO NORTHWEST
ARGENTINA...FAVORING THE NORTHWARD AMPLIFICATION OF A SHORT WAVE
TROUGH OVER SOUTHEAST BRASIL. IN THIS PATTERN...MOST ACTIVE
CONVECTION IS TO INITIALLY CLUSTER IN CENTRAL BRASIL BETWEEN MATO
GROSSO AND SOUTHERN PARA...WITH MAXIMA OF 20-45MM/DAY. ON TUESDAY
TO WEDNESDAY FOCUS OF THE ORGANIZED CONVECTION SHIFTS TO AMAZONAS
IN BRASIL...NORTHERN JUNGLE OF PERU TO SOUTHERN AMAZONIA IN
COLOMBIA...BUT THE DAILY MAXIMA DECREASES TO 20-30MM/DAY. THIS
WILL THEN GRADUALLY WEAKEN LATER IN THE WEEK WHILE MOST ACTIVE
SHIFTS NORTH TO EQUATORIAL SOUTH AMERICA.

DAVISON...WPC (USA)
$$

294 
FXSA20 KWBC 151518
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1117 AM EDT FRI OCT 15 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 15/15UTC: AT MID/UPPER LEVELS A LONG
WAVE TROUGH IS INITIALIZED OVER THE CONTINENT WITH AXIS NORTH
BETWEEN 70W-55W TO 20S. A BUILDING RIDGE TO THE WEST WILL DISPLACE
THIS TROUGH EAST INTO THE WESTERN SOUTH ATLANTIC LATER THIS
EVENING...AND THE RIDGE IS TO ALSO STEER A ROBUST SHORT WAVE
PERTURBATIONS IN THE SOUTHERN STREAM ACROSS THE DRAKE PASSAGE AND
TIERRA DEL FUEGO LATER THIS EVENING. AS IT CLEARS THE SOUTHERN
CONE...THE SHORT WAVE PERTURBATION IS TO THEN AMPLIFY OVER THE
WESTERN ATLANTIC. THE INFLOW OF SHORT WAVE ENERGY WILL THEN HELP
REINFORCE THE LONG WAVE TROUGH TO THE EAST. THIS FEATURE IS TO
THEN HOLD THROUGH THE WEEKEND...BUT EARLY NEXT WEEK IT WILL START
TO DAMPEN WHILE SHEARING SHORT WAVE ENERGY TO THE EAST-SOUTHEAST.
OVER THE CONTINENT THE UPPER LEVEL TROUGH WILL PRESS AGAINST A
BROAD CELL OF THE SUBTROPICAL RIDGE TO THE NORTH. THE ENSUING
GRADIENT WILL THEN FAVOR A FAIRLY PERSISTENT SUBTROPICAL/NORTHERN
POLAR JET MAXIMA TO EXTEND ACROSS THE CONTINENT INTO THE ATLANTIC
BETWEEN 20S-34S DURING THE NEXT SEVERAL DAYS. THE JET ALOFT WILL
SUSTAIN AREAS OF UPPER DIVERGENCE THAT ARE TO VENT DEEP CONVECTION
ACROSS MID SECTIONS OF SOUTH AMERICA DURING THE NEXT SEVERAL DAYS.

AT LOW LEVELS...A POLAR RIDGE BUILDING ACROSS CENTRAL ARGENTINA
SUSTAINS A SOUTHERLY LOW LEVEL JET ACROSS PARAGUAY TO BOLIVIA.
THIS...IN-TURN...DISPLACES THE ASSOCIATED SURFACE FRONT NORTH
ACROSS THE SOUTHERN TO SOUTHEAST STATES OF BRASIL...MATO GROSSO DO
SUL TO NORTHERN BOLIVIA LATER THIS AFTERNOON. ON SATURDAY-MONDAY
THE FRONT IS TO THEN STALL ACROSS NORTHERN SAO PAULO...MATO GROSSO
TO NORTHERN BOLIVIA. EARLY NEXT WEEK...PORTION OF THE FRONT OVER
THE CONTINENT WILL START TO FRONTOLIZE...WHILE REMNANTS OVER THE
ATLANTIC MEANDER NORTH ACROSS ESPIRITO SANTO TO BAHIA. MOST
INTENSE CONVECTION WITH THIS FEATURE IS EXPECTED DURING THE DAY
TODAY...WITH MAXIMA OF 35-70MM ACROSS RIO GRANDE DO SUL...WHILE
OVER SAO PAULO THE ENVIRONMENTAL CONDITIONS WILL BE MORE FAVORABLE
FOR A HEAVY RAINFALL PRODUCING MCS TO FORM EARLY ON SATURDAY
MORNING. IN THIS AREA EXPECTING MAXIMA OF 75-125MM. HEAVY
CONVECTION IS TO ALSO AFFECT CENTRAL PORTIONS OF BOLIVIA AS
ENHANCED BY THE SOUTHERLY LOW LEVEL JET...TO SUSTAIN MAXIMA OF
40-80MM ALONG THE LEE OF THE ANDES. ON SATURDAY ACTIVITY ACROSS
SOUTHEAST BRASIL WEAKENS TO 20-35MM...WITH SIMILAR AMOUNTS ACROSS
THE SOUTHERN TO CENTRAL JUNGLE OF PERU. OTHER CONVECTION IS
EXPECTED NORTH OF THIS FRONT BETWEEN TOCANTINS/GOIAS AND AMAZONAS
IN NORTHWEST BRASIL...WITH RAINFALL AMOUNTS OF 15-25MM/DAY.
THROUGH THE WEEKEND TO EARLY NEXT WEEK ACTIVITY OVER SOUTHEAST
BRASIL WILL SHIFT NORTH TO ESPIRITO SANTO/MINAS GERAIS-RIO DE
JANEIRO...WITH DAILY MAXIMA OF 25-50MM. OVER CENTRAL BRASIL...AS
ENHANCED BY AN UPPER LEVEL TROUGH...ACTIVITY IS TO ALSO INTENSIFY
EARLY NEXT WEEK...WITH MAXIMA OF 20-35MM/DAY.

ON THE SOUTHERN STREAM FLOW...A PROGRESSIVE FRONT LIFTS ACROSS THE
BELLINGSHAUSEN SEA TO THE DRAKE PASSAGE/SOUTHERN CONE LATER TODAY.
THROUGH SATURDAY EVENING THIS EVOLVES INTO A BROAD OCCLUDED TROUGH
BETWEEN THE MALVINAS/FALKLAND ISLANDS AND THE WEDDELL SEA...WHILE
THE FRONT ADVANCES ACROSS PATAGONIA TO LA PAMPA IN ARGENTINA.
MEANWHILE...IN A COLD ADVECTIVE PATTERN...THIS WILL SUSTAIN
SCATTERED SNOW SHOWERS ACROSS TIERRA DEL FUEGO AND EXTREME
SOUTHERN PORTIONS OF CHILE...WITH ACCUMULATION OF 10-15CM. ON
SATURDAY EXPECTING ADDITIONAL SNOWFALL AMOUNTS OF 05-10CM...WITH
WET SNOW AND SLEET EXPECTED LATER IN THE DAY.

EARLY NEXT WEEK...A HIGH AMPLITUDE TROUGH IS TO PROPAGATE ACROSS
THE EASTERN PACIFIC...WITH AXIS TO ENTER THE SOUTHERN CONE ON
TUESDAY TO WEDNESDAY. RIDGE TO THE EAST IS TO THEN RELOCATE ACROSS
THE SOUTHERN CONE TO THE WESTERN ATLANTIC WHILE YIELDING TO THE
ADVANCING LONG WAVE AXIS. AT LOW LEVELS THE TROUGH ALOFT WILL
SUSTAIN A BROAD TROUGH OVER THE SOUTHEAST PACIFIC LATER ON
TUESDAY...WITH AXIS TO ORIGINATE ON A DEEP/VERY INTENSE OCCLUDED
LOW OVER THE BELLINGSHAUSEN SEA. THIS...HOWEVER...TENDS TO WEAKEN
AS IT MOVES ACROSS THE ANTARCTIC PENINSULA TO THE SOUTHWEST
ATLANTIC ON WEDNESDAY. ON TUESDAY THROUGH THURSDAY MORNING THIS IS
TO SUSTAIN MODERATE RAINFALL AMOUNTS ACROSS CHILE TO THE SOUTH OF
ISLA DE CHILOE...WITH RAINFALL AMOUNTS OF 15-20MM/DAY.

UPPER LEVEL PATTERN TO THE NORTH...OVER THE CONTINENT...WILL
REMAIN UNDER THE INFLUENCE OF A BROAD CELL OF THE SUBTROPICAL
RIDGE. AS THE RIDGE RIDGE HOLDS OVER BRASIL AND PERU...IT IS TO
STEER AN AMPLIFYING UPPER LEVEL TROUGH ACROSS THE NORTHEAST STATES
OF BRASIL TO PARA/THE GUIANAS. AS THE COLD CORE TROUGH MOVES
FARTHER INLAND ACROSS BRASIL...IT WILL ENHANCE CONVECTIVE
INSTABILITY. IN RESPONSE...ACTIVITY TO THE NORTH OF 15S IS
EXPECTED TO GRADUALLY INTENSIFY DURING THE WEEKEND TO EARLY NEXT
WEEK. ON MONDAY TO TUESDAY THIS IS TO PEAK AT 20-45MM/DAY...WITH
LOCALLY HIGHER AMOUNTS HIGHLY PROBABLE OVER AMAZONAS IN BRASIL AND
THE NORTHERN JUNGLE OF PERU TO EASTERN ECUADOR.

DAVISON...WPC (USA)
$$

864 
FXSA20 KWBC 141603
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1203 PM EDT THU OCT 14 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 14/16UTC: A BUILDING MID/UPPER LEVEL
RIDGE OVER THE EASTERN PACIFIC IS TO DISPLACE A LONG WAVE TROUGH
ACROSS THE ANDES OF CHILE INTO ARGENTINA LATER THIS
AFTERNOON...WITH AXIS RELOCATING TO THE WESTERN ATLANTIC BY
DAYBREAK ON FRIDAY. AS SHORT WAVE ENERGY SHEARS TO THE
SOUTHEAST...THIS WILL THEN EVOLVE INTO A BROAD TROUGH SPANNING
BETWEEN THE WESTERN ATLANTIC AND MID SECTIONS OF SOUTH AMERICA.
MEANWHILE...AS THE RIDGE HOLDS TO THE WEST...IT IS TO STEER SHORT
WAVE PERTURBATIONS NORTHWARD ACROSS THE BELLINGSHAUSEN SEA TOWARDS
THE DRAKE PASSAGE/SOUTHERN CHILE-TIERRA DEL FUEGO. IN THIS PATTERN
A ROBUST PERTURBATION ENTERS TIERRA DEL FUEGO/SOUTHERN PATAGONIA
LATER ON FRIDAY...WITH AXIS TO INTENSIFY AS IT NEARS THE SOUTH
GEORGIA ISLANDS EARLY ON SUNDAY MORNING. WEAKER PERTURBATIONS ARE
TO THEN FOLLOW...STREAMING ACROSS THE SOUTHERN CONE EARLY NEXT
WEEK. AT 250 HPA...A SUBTROPICAL AND A NORTHERN POLAR JET MAXIMUM
ARE TO STREAM ACROSS MID SECTIONS OF SOUTH AMERICA...WHILE THE
SOUTHERN POLAR FOCUSES ACROSS SOUTHERN CHILE AND PATAGONIA IN
ARGENTINA. THE NORTHERN POLAR AND SUBTROPICAL JETS ARE TO FAVOR A
BROAD AREA OF UPPER DIVERGENCE ACROSS SOUTHEAST
PARAGUAY/URUGUAY-SOUTHERN BRASIL EARLY ON FRIDAY MORNING...WITH
ENVIRONMENTAL CONDITIONS TO LIKELY FAVOR GENERATION OF AN MCS
DURING THIS PERIOD. THROUGH FRIDAY EVENING THE AXIS OF UPPER
DIVERGENCE WILL SHIFT WEST AND NORTH ACROSS MATO GROSSO DO
SUL/MATO GROSSO IN BRASIL...INTO NORTHERN BOLIVIA-SOUTHERN
PERU/ACRE IN BRASIL-SOUTHERN PERU EARLY ON SUNDAY MORNING.

AT LOW LEVELS...A POLAR RIDGE BUILDS ACROSS THE SOUTHERN CONE
EARLY IN THE CYCLE. AS THE GRADIENT TIGHTENS THIS WILL TRIGGER A
SOUTHERLY PAMPERO LOW LEVEL JET ACROSS CENTRAL ARGENTINA THAT
DRIVES A PROGRESSIVE FRONT NORTH ACROSS THE RIO DE LA PLATA
BASIN-CORDOBA LATER TODAY. AS IT SURGES ACROSS ARGENTINA THIS WILL
SUSTAIN A SEVERE WEATHER PRODUCING SQUALL LINE TO THE NORTH. AS
PREVIOUSLY INDICATED THIS WILL EVOLVE INTO AN MCS BETWEEN CHACO
ARGENTINO-SOUTHEAST PARAGUAY AND RIO GRANDE DO SUL IN BRASIL...TO
TRIGGER HEAVY RAINFALL AMOUNTS WITH MAXIMA OF 50-100MM...WHILE
ACROSS PARANA AND SANTA CATARINA IN SOUTHERN BRASIL EXPECTING
MAXIMA OF 20-40MM. ON FRIDAY ACTIVITY INTENSIFIES BETWEEN SAO
PAULO AND MATO GROSSO DO SUL WITH MAXIMA OF 75-125MM...WHILE OVER
RIO GRANDE AND PORTIONS OF PARANA EXPECTING MAXIMA OF 35-70MM.
HEAVY PREFRONTAL/FRONTAL CONVECTION IS TO ALSO BUILD ACROSS
CENTRAL BOLIVIA ON FRIDAY TO SATURDAY AS THE FRONT SURGES ACROSS
SUBTROPICAL TO TROPICAL SOUTH AMERICA...WITH MAXIMA OF 40-80MM. ON
SATURDAY...ACTIVITY WILL THEN BUILD WEST AND NORTH ALONG THE LEE
OF THE ANDES INTO CENTRAL JUNGLE OF PERU...WITH MAXIMA OF 20-35MM.
LATER DURING THE WEEKEND...FOCUS OF THE CONVECTION SHIFTS TO
SOUTHEAST BRASIL AS ENHANCED BY THE MEANDERING UPPER LEVEL
JET...WITH ACTIVITY CLUSTERING BETWEEN RIO DE JANEIRO-NORTHERN SAO
PAULO AND SOUTHERN MINAS GERAIS. IN THIS AREA ACTIVITY SURGES ON
SUNDAY-TUESDAY...WITH MAXIMA OF 30-60MM/DAY. ACROSS SOUTHERN
CHILE...MEANWHILE...INITIALLY EXPECTING MODERATE CONVECTION WITH
MAXIMA OF 10-15MM. ON FRIDAY THIS INCREASES TO 15-30MM WHILE TO
THE SOUTH...OVER TIERRA DEL FUEGO...EXPECTING MODERATE TO HEAVY
SNOWFALL AMOUNTS BETWEEN FRIDAY AND SATURDAY...WITH STORM TOTAL
AMOUNTS OF 15-25CM. 

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE DOMINATES THE FLOW TO THE NORTH OF 20S. EAST OF
THIS AXIS...A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) EXTENDS
OFF THE NORTHEAST COAST OF BRASIL. OVER THE NEXT FEW DAYS THE TUTT
IS TO AMPLIFY TO THE NORTHWEST ACROSS NORTHERN BRASIL TO THE
GUIANAS/NORTHERN PARA IN BRASIL. THIS IS TO FAVOR AN UPPER
CONVERGENT PATTERN OVER NORTHEAST BRASIL...WHILE OVER PARA AND
AMAZONAS IT WILL INTERACT WITH THE SUBTROPICAL RIDGE IN SUPPORT OF
SCATTERED DEEP CONVECTION. THIS IS TO INTENSIFY THROUGH
SUNDAY...WITH DAILY MAXIMA OF 20-45MM. OTHERWISE...MODERATE
AMOUNTS ARE EXPECTED BETWEEN NORTHERN BOLIVIA/ACRE IN BRASIL TO
MATO GROSSO...WITH MAXIMA OF 15-25MM/DAY.

DAVISON...WPC (USA)
$$

742 
FXSA20 KWBC 131545
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1145 AM EDT WED OCT 13 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 13/16UTC: AT MID LEVELS...A SHORT
WAVE TROUGH ON THE NORTHERN STREAM IS INITIALIZED OFF THE
CENTRAL/NORTHERN COAST OF CHILE...WHILE A HIGHER AMPLITUDE LONG
WAVE TROUGH LIES TO THE WEST. UNDER THE INFLUENCE OF THE LATTER
THE SHORT WAVE TROUGH SPILLS ACROSS THE CENTRAL ANDES OF CHILE
INTO ARGENTINA EARLY IN THE CYCLE...AND THROUGH THE DAY IT IS TO
STREAM ACROSS THE MESOPOTAMIA VALLEY IN ARGENTINA TO
URUGUAY/SOUTHERN BRASIL. SIMULTANEOUSLY...A BUILDING RIDGE OVER
THE EASTERN PACIFIC IS TO THEN DISPLACE THE LONG WAVE TROUGH
ACROSS THE SOUTHERN CONE TO THE WESTERN ATLANTIC LATER ON
THURSDAY/EARLY ON FRIDAY MORNING. SHORT WAVE PERTURBATIONS ARE TO
THEN STREAM UNDER THE RIDGE AND FEED INTO THE BROAD TROUGH AS IT
MEANDERS OVER THE WESTERN ATLANTIC. AT 250 HPA...A SUBTROPICAL AND
NORTHERN POLAR JET MAXIMUM ARE TO STREAM ACROSS MID SECTIONS OF
SOUTH AMERICA...WHILE THE SOUTHERN POLAR FOCUSES ACROSS SOUTHERN
CHILE AND PATAGONIA IN ARGENTINA. THE NORTHERN POLAR AND
SUBTROPICAL JETS ARE TO FAVOR A BROAD AREA OF UPPER DIVERGENCE
ACROSS THE BUENOS AIRES PROVINCE/RIO DE LA PLATA BASIN EARLY IN
THE CYCLE AND THE SOUTHERN STATES OF BRASIL LATER TODAY. THE
STRONG UPPER DIVERGENT PATTERN REPEATS AGAIN ON FRIDAY
MORNING...AND AS IT COMBINES WITH INCREASING HELICITY AND MID
LEVEL HEIGHT FALLS WOULD LIKELY TRIGGER SEVERE CONVECTION.

AT LOW LEVELS...THE SHORT WAVE TROUGH WILL INTERACT WITH THE
TRAILING END OF AN OLD FRONT OVER URUGUAY/NORTHERN ARGENTINA TO
INDUCE A FRONTAL WAVE. THIS WILL THEN TRIGGER MODERATE CONVECTION
ACROSS URUGUAY/ENTRE RIOS IN ARGENTINA WITH MAXIMA OF
20-45MM...WHILE OVER PARAGUAY TO SOUTHERN BRASIL IT IS TO SUSTAIN
RAINFALL MAXIMA OF 40-80MM. SIMULTANEOUSLY A STRONGER FRONTAL
BOUNDARY IS TO SURGE ACROSS THE SOUTHERN CONE LATER TODAY...AND
DRIVEN BY A BUILDING POLAR RIDGE TO THE SOUTH THE FRONT WILL RACE
ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA BASIN ON THURSDAY. AS IT
SURGES ACROSS MID SECTIONS OF SOUTH AMERICA THIS WILL THEN TRIGGER
A SEVERE WEATHER PRODUCING PREFRONTAL SQUALL LINE...WITH RAINFALL
MAXIMA OF 50-100MM EXPECTED ACROSS THE PROVINCES OF
CHACO-CORRIETES IN ARGENTINA TO PARAGUAY EARLY ON FRIDAY MORNING.
THROUGH SATURDAY MORNING THE FRONT SURGES ACROSS PARAGUAY TO
CENTRAL BOLIVIA. HEAVY CONVECTION WILL PERSIST WHILE BUILDING EAST
AND NORTH...WITH MAXIMA OF 75-150MM TO AFFECT SAO PAULO/MATO
GROSSO DO SUL WHILE ACROSS CENTRAL BOLIVIA EXPECTING MAXIMA OF
40-80MM. ACROSS SOUTHERN CHILE THE MOST INTENSE CONVECTION IS
EXPECTED DURING THE DAY TODAY WITH MAXIMA OF 20-45MM. THROUGH
FRIDAY THIS WILL WEAKEN TO 15-30MM...WHILE OVER TIERRA DEL FUEGO
EXPECTING A GRADUAL TRANSITION FROM LIQUID PRECIPITATION TO SOLID
(SONW) ON FRIDAY AND SATURDAY...WITH STORM TOTAL AMOUNTS OF
15-25CM.

NORTH OVER THE CONTINENT...AT 250 HPA...BROAD CELL OF THE
SUBTROPICAL RIDGE IS TO CONFINE TO CONTINENTAL AREA TO THE NORTH
OF 20S. AS THE RIDGE HOLDS TO THE NORTH IT IS TO BLOCK POLAR
PERTURBATIONS STREAMING TO THE SOUTH TO NO FARTHER NORTH THAN 20S.
OVER THE NEXT FEW DAYS THIS WILL GENERALLY FAVOR AN UPPER
CONVERGENT/SUBSIDENT PATTERN THAT WILL INHIBIT ORGANIZED DEEP
CONVECTION ACROSS TROPICAL SOUTH AMERICA...WITH ACCUMULATION OF
15-20MM/DAY BETWEEN BAHIA-MINAS GERAIS AND TOCANTINS/GOIAS. BUT AS
THE FRONT ADVANCES ACROSS SOUTHERN BRASIL AND PARAGUAY ACTIVITY TO
THE NORTH IS TO INTENSIFY AND BECOME MORE WIDESPREAD ACROSS BRASIL
TO PERU. ACROSS SOUTHEAST BRASIL MOST ACTIVE IS EXPECTED ON SUNDAY
WITH MAXIMA OF 30-60MM...WHILE ACROSS AMAZONAS TO THE
NORTH/NORTHWEST THE MAXIMA PEAKS AT 20-45MM.

DAVISON...WPC (USA)
$$

855 
FXSA20 KWBC 061557
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1156 AM EDT WED OCT 06 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 06/16UTC: UNDER THE INFLUENCE OF A
RIDGE TO THE WEST...AT MID/UPPER LEVELS...A POLAR TROUGH IS
LIFTING ACROSS THE SOUTHERN CONE/EASTERN PACIFIC...WITH AXIS
TRAILING ACROSS NORTHERN PATAGONIA/LA PAMPA IN ARGENTINA...TEMUCO
CHILE TO 20S 95W. THROUGH THIS EVENING THE TROUGH SPLITS IN
TWO...WITH THE MODELS FORECASTING THE SOUTHERN HALF OF THE TROUGH
TO GRADUALLY DEEPEN AS IT LIFTS ACROSS THE WESTERN ATLANTIC TO 30W
LATER ON THURSDAY. THE TRAILING NORTHERN STREAM VORTEX...
MEANWHILE...WILL REMAIN OFF THE CENTRAL/NORTHERN COAST OF CHILE
WHILE GRADUALLY EVOLVING INTO A CLOSED LOW WEST OF LA SERENA CHILE
EARLY ON THURSDAY MORNING. THE SHORT WAVE TROUGH/CLOSED LOW IS TO
MEANDER OFF THE CENTRAL COAST OF CHILE THROUGH SATURDAY
MORNING...MEANWHILE SHEARING SHORT WAVE ENERGY ACROSS THE CENTRAL
ANDES INTO ARGENTINA. EARLY ON SUNDAY THE REMNANTS OF THE WANING
TROUGH WILL SPILL ACROSS THE CENTRAL ANDES INTO CENTRAL ARGENTINA
AS A BROAD TROUGH AMPLIFIES OVER THE SOUTH PACIFIC TO THE WEST OF
80W. AT 250 HPA...THE UPPER TROUGH WILL PRESS AGAINST A BROAD CELL
OF THE SUBTROPICAL RIDGE TO THE NORTH...TIGHTENING THE GRADIENT
ACROSS MID SECTIONS OF SOUTH AMERICA. OVER THE NEXT FEW DAYS THIS
WILL HELP SUSTAIN A ROBUST JET MAXIMA THAT IS TO TRAVERSE THE
CONTINENT BETWEEN 20S-33S. THE JET ALOFT WILL HELP SUSTAIN AN
UPPER DIVERGENT PATTERN THAT WILL CONVECTIVE DEVELOPMENT DURING
THE NEXT FEW DAYS...AND IT WILL ALSO CONTRIBUTE TO THE GENERATION
OF LEE SIDE PERTURBATIONS ACROSS NORTHERN ARGENTINA/SOUTHERN
BOLIVIA TO PARAGUAY/SOUTHERN BRASIL.

AT LOW LEVELS...DRIVEN BY A BUILDING POLAR RIDGE TO THE SOUTH...A
SURFACE FRONT SURGES ACROSS URUGUAY TO SOUTHERN BRASIL/NORTHERN
ARGENTINA LATER TODAY...WITH THE SURGING FRONT TO THEN REINFORCE
AN OLD FRONTAL BOUNDARY MEANDERING OVER SAO PAULO TO MATO GROSSO
DO SUL/SOUTHEAST BOLIVIA. THE FRONT WILL THEN REMAIN NEARLY
STATIONARY THROUGH THURSDAY...THEN MEANDER SOUTH AS A FRONTAL
WAVE/LOW FORMS OVER SOUTHEAST PARAGUAY/MISIONES IN ARGENTINA ON
SATURDAY. THROUGH THE WEEKEND/EARLY NEXT WEEK...THIS IS TO
INTENSIFY WHILE MEANDERING SOUTH ACROSS URUGUAY. AS THE FRONTS
INTERACT OVER MID SECTIONS OF SOUTH AMERICA...CONVECTION ACROSS
SOUTHERN BRASIL-MISIONES IN ARGENTINA AND SOUTHEAST PARAGUAY WILL
SURGE EARLY IN THE CYCLE...TO SUSTAIN RAINFALL MAXIMA OF 30-60MM
IN POTENTIALLY SEVERE CONVECTION. ON THURSDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 20-35MM BETWEEN PARAGUAY AND SAO PAULO/RIO DE
JANEIRO. ON SATURDAY THROUGH SUNDAY...AS THE MID LEVEL VORTEX
SPILLS ACROSS THE CENTRAL ANDES OF CHILE AND UNDER FAVORABLE JET
DYNAMICS...THE ENVIRONMENTAL CONDITIONS BETWEEN PARAGUAY AND
SOUTHEAST BRASIL WILL BECOME FAVORABLE FOR A HEAVY RAINFALL
PRODUCING MCS TO DEVELOP ALONG THIS FRONT. ON SUNDAY AND MONDAY
THE MODELS AGREE ON ORGANIZED DEEP CONVECTION TO SUSTAIN RAINFALL
AMOUNTS OF 40-80MM...WITH POTENTIAL FOR LOCALLY HIGHER AMOUNTS AS
ENHANCED BY THE MID LEVEL VORTEX AND STRONG TOPOGRAPHICAL FORCING
OVER SOUTHERN/SOUTHEAST BRASIL.

SIMULTANEOUSLY...A BROAD TROUGH IS TO MOVE TO THE SOUTHEAST
PACIFIC LATER ON THURSDAY...WITH AXIS TO ENVELOP AREA TO THE SOUTH
OF 40S. THROUGH FRIDAY MORNING THE TROUGH WILL EXPAND ACROSS
SOUTHERN CHILE TO PATAGONIA IN ARGENTINA/THE DRAKE PASSAGE TO THE
SOUTHWEST ATLANTIC...WITH AXIS TO DAMPEN ON SATURDAY-SUNDAY AS
ANOTHER TROUGH AMPLIFIES TO THE WEST AND A RIDGE BUILDS ACROSS THE
SOUTHERN CONE. MEANWHILE...AT LOW LEVELS...THIS WILL ALSO REFLECT
AS A BROAD TROUGH OVER THE SOUTHEAST PACIFIC...WITH THE ENSUING
GRADIENT TO FAVOR STRONG BOUNDARY LAYER WINDS ACROSS SOUTHERN
REGIONS OF CHILE/TIERRA DEL FUEGO. THIS WILL PERSIST THROUGH THE
WEEKEND TO EARLY NEXT WEEK...WITH FRONTAL SYSTEMS REVOLVING AROUND
THIS AXIS TO HELP FOCUS SUBTROPICAL MOISTURE ACROSS EXTREME
SOUTHERN PORTIONS OF CHILE/TIERRA DEL FUEGO. THIS WILL HELP
SUSTAIN SEVERAL DAYS OF MODERATE RAINFALL AMOUNTS...WITH
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 30-35MM/DAY. NOTE THAT
STRONG TOPOGRAPHICAL FORCING/FLUX MOISTURE CONVERGENCE WOULD
LIKELY RESULT IN LOCALLY HIGHER RAINFALL AMOUNTS.

AT UPPER LEVELS...A SHORT WAVE RIDGE DOMINATES CONTINENTAL AREA TO
THE NORTH OF 25S AND WEST OF 50W...WHILE TO THE EAST A SHORT WAVE
TROUGH EXTENDS ACROSS THE NORTHEAST STATES OF BRASIL. THROUGH
SATURDAY EVENING THE RIDGE WILL RELOCATE ACROSS PERU TO THE
EASTERN TROPICAL PACIFIC...WHILE THE TROUGH RETROGRESSES ACROSS
PARA TO AMAZONAS IN BRASIL. ON FRIDAY TO SATURDAY THE
RETROGRESSING UPPER LEVEL TROUGH WILL ENHANCE CONVECTIVE
INSTABILITY ACROSS NORTHERN BRASIL...WITH ACTIVITY BETWEEN
PARA/AMAZONAS AND EQUATORIAL SOUTH AMERICA FORECAST TO GRADUALLY
INTENSIFY...INCREASING FROM 10-15MM EARLY IN THE CYCLE TO 20-30MM
IN SCATTERED DEEP CONVECTION ON FRIDAY AND SATURDAY.

DAVISON...WPC (USA)
$$

182 
FXSA20 KWBC 051631
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1231 PM EDT TUE OCT 05 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 05/16UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECAST...A BROAD MID/UPPER LEVEL TROUGH REMAINS THE
DOMINANT FEATURE OVER THE CONTINENT/WESTERN ATLANTIC TO THE SOUTH
OF 20S. UPSTREAM OVER THE EASTERN PACIFIC...A LONG WAVE RIDGE
EXTENDS SOUTH ALONG 90W TO THE POLAR ICE CAP. UNDER THE INFLUENCE
OF THE RIDGE TO THE WEST...A DEEPENING TROUGH IS TO RAPIDLY
AMPLIFY AS IT LIFTS ACROSS THE DRAKE PASSAGE TO PATAGONIA IN
ARGENTINA/SOUTHERN CHILE TO THE ARCHIPELAGO DE JUAN FERNANDEZ
EARLY IN THE CYCLE. THROUGH WEDNESDAY EVENING THE MID/UPPER LEVEL
TROUGH IS FORECAST TO SPLIT IN TWO...WITH ITS SOUTHERN HALF TO
GRADUALLY DEEPEN AS IT LIFTS ACROSS THE WESTERN ATLANTIC TO 30W
LATER ON THURSDAY. THE TRAILING NORTHERN STREAM VORTEX WILL REMAIN
OFF THE CENTRAL/NORTHERN COAST OF CHILE WHILE GRADUALLY EVOLVING
INTO A CLOSED LOW WEST OF LA SERENA CHILE EARLY ON THURSDAY
MORNING. THIS IS TO MEANDER OFF THE CENTRAL COAST OF CHILE THROUGH
SATURDAY MORNING...MEANWHILE SHEARING SHORT WAVE ENERGY ACROSS THE
CENTRAL ANDES INTO ARGENTINA. AT 250 HPA...THESE WILL FOCUS A
POLAR AND A SUBTROPICAL JET MAXIMA ACROSS MID SECTIONS OF SOUTH
AMERICA. THE NORTHERN POLAR IS TO SLOWLY PULL AWAY WHILE THE
SUBTROPICAL JET PERSISTS THROUGH THE END OF THE CYCLE.

AT LOW LEVELS...A PROGRESSIVE FRONT SURGES ACROSS LA PAMPA/BUENOS
AIRES PROVINCE IN ARGENTINA LATER TODAY AS A POLAR RIDGE BUILDS TO
THE SOUTH. THROUGH WEDNESDAY EVENING THE FRONT WILL MOVE NORTH
ACROSS SOUTHERN BRASIL TO NORTHERN ARGENTINA...WHERE IT IS TO
INTERACT WITH AN OLD BOUNDARY TO THE NORTH. THIS WILL STRENGTHEN
THE OLD BAROCLINIC BOUNDARY...WITH A FRONTAL WAVE TO FORM ALONG
THIS BOUNDARY OVER CORRIENTES IN ARGENTINA/SOUTHEAST PARAGUAY ON
SATURDAY. AS THE FRONTS INTERACT...CONVECTION ACROSS SOUTHERN
BRASIL-MISIONES IN ARGENTINA AND SOUTHEAST PARAGUAY WILL SURGE ON
WEDNESDAY...WITH MAXIMA OF 30-60MM IN POTENTIALLY SEVERE
CONVECTION. ON THURSDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-45MM BETWEEN PARAGUAY AND PARANA/SANTA CATARINA IN
BRASIL...WHILE TO THE NORTH OVER SAO PAULO/RIO DE JANEIRO THIS
WILL FAVOR MAXIMA OF 20-30MM. THROUGH SATURDAY CONVECTION SURGES
ACROSS PARAGUAY-SOUTHERN/SOUTHEAST BRASIL AS ENHANCED BY THE MID
LEVEL VORTEX...WITH THE ENVIRONMENTAL CONDITIONS TO BECOME
FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO FORM ON SATURDAY.
DURING THIS PERIOD EXPECTING RAINFALL AMOUNTS OF 40-80MM IN
POTENTIALLY SEVERE CONVECTION.

AS THE WEEK WEARS ON...THE RIDGE OVER THE EASTERN PACIFIC TENDS TO
FLATTEN AS A BROAD TROUGH AMPLIFIES ACROSS THE SOUTHEAST PACIFIC
BETWEEN 120W-70W. THIS REACHES MAXIMUM AMPLITUDE ON FRIDAY TO
SATURDAY WHEN THE TROUGH IS TO BOTTOM OUT ALONG 40S. AS IT PRESSES
AGAINST THE RIDGE TO THE NORTH...AND THE GRADIENT TIGHTENS...THIS
WILL FAVOR STRONG WINDS ACROSS SOUTHERN REGIONS OF CHILE/TIERRA
DEL FUEGO DURING THE NEXT SEVERAL DAYS. PROGRESSIVE PERTURBATIONS
ARE TO EMBED IN THIS FLOW...WITH FRONTAL SYSTEMS TO REVOLVE AROUND
A DEEP/BROAD TROUGH OVER THE SOUTHEAST PACIFIC TO THEN STREAM
ACROSS THE DRAKE PASSAGE/SOUTHERN CHILE FROM TIME TO TIME. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY WITH MAXIMA OF
20-30MM. NOTE THAT STRONG TOPOGRAPHICAL FORCING/FLUX MOISTURE
CONVERGENCE WOULD LIKELY RESULT IN LOCALLY HIGHER RAINFALL
AMOUNTS.

UPPER FLOW PATTERN TO THE NORTH REMAINS UNDER THE INFLUENCE OF A
SHORT WAVE RIDGE EXTENDING ACROSS PERU TO WESTERN BRASIL/NORTHERN
BOLIVIA...WHILE A SHORT WAVE TROUGH TO THE EAST MEANDERS OVER
NORTHEAST BRASIL. THROUGH FRIDAY MORNING THE RIDGE TENDS TO BUILDS
SOUTH ACROSS BOLIVIA TO PARAGUAY...WHILE THE TROUGH TO THE EAST
DEEPENS/BECOME BETTER ORGANIZED. BY THE END OF THE WEEK THIS WILL
CENTER ON A CLOSED LOW OVER PARA IN BRASIL. INITIALLY...THE MOST
ACTIVE CONVECTION IS EXPECTED BETWEEN AMAZONAS IN BRASIL AND
NORTHERN JUNGLE OF PERU/EASTERN ECUADOR...WITH MAXIMA OF 25-50MM.
THIS WEAKENS ON WEDNESDAY TO MAXIMA OF 15-20MM/DAY. ON THURSDAY
AND ONWARD...UNDER INFLUENCE OF EASTERLY WAVES STREAMING ACROSS
TROPICAL SOUTH AMERICA...THE DIURNAL CONVECTION OS TO ALSO
INTENSIFY...WITH MAXIMA SURGING TO 20-35MM ON FRIDAY TO SATURDAY.


DAVISON...WPC (USA)
$$

886 
FXSA20 KWBC 051621
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1220 PM EDT TUE OCT 05 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 05/16UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECAST...A BROAD MID/UPPER LEVEL TROUGH REMAINS THE
DOMINANT FEATURE OVER THE CONTINENT/WESTERN ATLANTIC TO THE SOUTH
OF 20S. UPSTREAM OVER THE EASTERN PACIFIC...A LONG WAVE RIDGE
EXTENDS SOUTH ALONG 90W TO THE POLAR ICE CAP. UNDER THE INFLUENCE
OF THE RIDGE TO THE WEST...A DEEPENING TROUGH IS TO RAPIDLY
AMPLIFY AS IT LIFTS ACROSS THE DRAKE PASSAGE TO PATAGONIA IN
ARGENTINA/SOUTHERN CHILE TO THE ARCHIPELAGO DE JUAN FERNANDEZ
EARLY IN THE CYCLE. THROUGH WEDNESDAY EVENING THE MID/UPPER LEVEL
TROUGH IS FORECAST TO SPLIT IN TWO...WITH ITS SOUTHERN HALF TO
GRADUALLY DEEPEN AS IT LIFTS ACROSS THE WESTERN ATLANTIC TO 30W
LATER ON THURSDAY. THE TRAILING NORTHERN STREAM VORTEX WILL REMAIN
OFF THE CENTRAL/NORTHERN COAST OF CHILE WHILE GRADUALLY EVOLVING
INTO A CLOSED LOW WEST OF LA SERENA CHILE EARLY ON THURSDAY
MORNING. THIS IS TO MEANDER OFF THE CENTRAL COAST OF CHILE THROUGH
SATURDAY MORNING...MEANWHILE SHEARING SHORT WAVE ENERGY ACROSS THE
CENTRAL ANDES INTO ARGENTINA. AT 250 HPA...THESE WILL FOCUS A
POLAR AND A SUBTROPICAL JET MAXIMA ACROSS MID SECTIONS OF SOUTH
AMERICA. THE NORTHERN POLAR IS TO SLOWLY PULL AWAY WHILE THE
SUBTROPICAL JET PERSISTS THROUGH THE END OF THE CYCLE.

AT LOW LEVELS...A PROGRESSIVE FRONT SURGES ACROSS LA PAMPA/BUENOS
AIRES PROVINCE IN ARGENTINA LATER TODAY AS A POLAR RIDGE BUILDS TO
THE SOUTH. THROUGH WEDNESDAY EVENING THE FRONT WILL MOVE NORTH
ACROSS SOUTHERN BRASIL TO NORTHERN ARGENTINA...WHERE IT IS TO
INTERACT WITH AN OLD BOUNDARY TO THE NORTH. THIS WILL STRENGTHEN
THE OLD BAROCLINIC BOUNDARY...WITH A FRONTAL WAVE TO FORM ALONG
THIS BOUNDARY OVER CORRIENTES IN ARGENTINA/SOUTHEAST PARAGUAY ON
SATURDAY. AS THE FRONTS INTERACT...CONVECTION ACROSS SOUTHERN
BRASIL-MISIONES IN ARGENTINA AND SOUTHEAST PARAGUAY WILL SURGE ON
WEDNESDAY...WITH MAXIMA OF 30-60MM IN POTENTIALLY SEVERE
CONVECTION. ON THURSDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-45MM BETWEEN PARAGUAY AND PARANA/SANTA CATARINA IN
BRASIL...WHILE TO THE NORTH OVER SAO PAULO/RIO DE JANEIRO THIS
WILL FAVOR MAXIMA OF 20-30MM. THROUGH SATURDAY CONVECTION SURGES
ACROSS PARAGUAY-SOUTHERN/SOUTHEAST BRASIL AS ENHANCED BY THE MID
LEVEL VORTEX...WITH THE ENVIRONMENTAL CONDITIONS TO BECOME
FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO FORM ON SATURDAY.
DURING THIS PERIOD EXPECTING RAINFALL AMOUNTS OF 40-80MM IN
POTENTIALLY SEVERE CONVECTION.

AS THE WEEK WEARS ON...THE RIDGE OVER THE EASTERN PACIFIC TENDS TO
FLATTEN AS A BROAD TROUGH AMPLIFIES ACROSS THE SOUTHEAST PACIFIC
BETWEEN 120W-70W. THIS REACHES MAXIMUM AMPLITUDE ON FRIDAY TO
SATURDAY WHEN THE TROUGH IS TO BOTTOM OUT ALONG 40S. AS IT PRESSES
AGAINST THE RIDGE TO THE NORTH...AND THE GRADIENT TIGHTENS...THIS
WILL FAVOR STRONG WINDS ACROSS SOUTHERN REGIONS OF CHILE/TIERRA
DEL FUEGO DURING THE NEXT SEVERAL DAYS. PROGRESSIVE PERTURBATIONS
ARE TO EMBED IN THIS FLOW...WITH FRONTAL SYSTEMS TO REVOLVE AROUND
A DEEP/BROAD TROUGH OVER THE SOUTHEAST PACIFIC TO THEN STREAM
ACROSS THE DRAKE PASSAGE/SOUTHERN CHILE FROM TIME TO TIME. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY WITH MAXIMA OF
20-30MM. NOTE THAT STRONG TOPOGRAPHICAL FORCING/FLUX MOISTURE
CONVERGENCE WOULD LIKELY RESULT IN LOCALLY HIGHER RAINFALL
AMOUNTS.

UPPER FLOW PATTERN TO THE NORTH REMAINS UNDER THE INFLUENCE OF A
SHORT WAVE RIDGE EXTENDING ACROSS PERU TO WESTERN BRASIL/NORTHERN
BOLIVIA...WHILE A SHORT WAVE TROUGH TO THE EAST MEANDERS OVER
NORTHEAST BRASIL. THROUGH FRIDAY MORNING THE RIDGE TENDS TO BUILDS
SOUTH ACROSS BOLIVIA TO PARAGUAY...WHILE THE TROUGH TO THE EAST
DEEPENS/BECOME BETTER ORGANIZED. BY THE END OF THE WEEK THIS WILL
CENTER ON A CLOSED LOW OVER PARA IN BRASIL. INITIALLY...THE MOST
ACTIVE CONVECTION IS EXPECTED BETWEEN AMAZONAS IN BRASIL AND
NORTHERN JUNGLE OF PERU/EASTERN ECUADOR...WITH MAXIMA OF 25-50MM.
THIS WEAKENS ON WEDNESDAY TO MAXIMA OF 15-20MM/DAY. ON THURSDAY
AND ONWARD...UNDER INFLUENCE OF EASTERLY WAVES STREAMING ACROSS
TROPICAL SOUTH AMERICA...THE DIURNAL CONVECTION OS TO ALSO
INTENSIFY...WITH MAXIMA SURGING TO 20-35MM ON FRIDAY TO SATURDAY.


DAVISON...WPC (USA)
$$

991 
FXSA20 KWBC 051551
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1149 AM EDT TUE OCT 05 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 05/16UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECAST...A BROAD MID/UPPER LEVEL TROUGH REMAINS THE
DOMINANT FEATURE OVER THE CONTINENT/WESTERN ATLANTIC TO THE SOUTH
OF 20S. UPSTREAM OVER THE EASTERN PACIFIC...A LONG WAVE RIDGE
EXTENDS SOUTH ALONG 90W TO THE POLAR ICE CAP. UNDER THE INFLUENCE
OF THE RIDGE TO THE WEST...A DEEPENING TROUGH IS TO RAPIDLY
AMPLIFY AS IT LIFTS ACROSS THE DRAKE PASSAGE TO PATAGONIA IN
ARGENTINA/SOUTHERN CHILE TO THE ARCHIPELAGO DE JUAN FERNANDEZ
EARLY IN THE CYCLE. THROUGH WEDNESDAY EVENING THE MID/UPPER LEVEL
TROUGH IS FORECAST TO SPLIT IN TWO...WITH ITS SOUTHERN HALF TO
GRADUALLY DEEPEN AS IT LIFTS ACROSS THE WESTERN ATLANTIC TO 30W
LATER ON THURSDAY. THE TRAILING NORTHERN STREAM VORTEX WILL REMAIN
OFF THE CENTRAL/NORTHERN COAST OF CHILE WHILE GRADUALLY EVOLVING
INTO A CLOSED LOW WEST OF LA SERENA CHILE EARLY ON THURSDAY
MORNING. THIS IS TO MEANDER OFF THE CENTRAL COAST OF CHILE THROUGH
SATURDAY MORNING...MEANWHILE SHEARING SHORT WAVE ENERGY ACROSS THE
CENTRAL ANDES INTO ARGENTINA. AT 250 HPA...THESE WILL FOCUS A
POLAR AND A SUBTROPICAL JET MAXIMA ACROSS MID SECTIONS OF SOUTH
AMERICA. THE NORTHERN POLAR IS TO SLOWLY PULL AWAY WHILE THE
SUBTROPICAL JET PERSISTS THROUGH THE END OF THE CYCLE.

AT LOW LEVELS...A PROGRESSIVE FRONT SURGES ACROSS LA PAMPA/BUENOS
AIRES PROVINCE IN ARGENTINA LATER TODAY AS A POLAR RIDGE BUILDS TO
THE SOUTH. THROUGH WEDNESDAY EVENING THE FRONT WILL MOVE NORTH
ACROSS SOUTHERN BRASIL TO NORTHERN ARGENTINA...WHERE IT IS TO
INTERACT WITH AN OLD BOUNDARY TO THE NORTH. THIS WILL STRENGTHEN
THE OLD BAROCLINIC BOUNDARY...WITH A FRONTAL WAVE TO FORM ALONG
THIS BOUNDARY OVER CORRIENTES IN ARGENTINA/SOUTHEAST PARAGUAY ON
SATURDAY. AS THE FRONTS INTERACT...CONVECTION ACROSS SOUTHERN
BRASIL-MISIONES IN ARGENTINA AND SOUTHEAST PARAGUAY WILL SURGE ON
WEDNESDAY...WITH MAXIMA OF 30-60MM IN POTENTIALLY SEVERE
CONVECTION. ON THURSDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-45MM BETWEEN PARAGUAY AND PARANA/SANTA CATARINA IN
BRASIL...WHILE TO THE NORTH OVER SAO PAULO/RIO DE JANEIRO THIS
WILL FAVOR MAXIMA OF 20-30MM. THROUGH SATURDAY CONVECTION SURGES
ACROSS PARAGUAY-SOUTHERN/SOUTHEAST BRASIL AS ENHANCED BY THE MID
LEVEL VORTEX...WITH THE ENVIRONMENTAL CONDITIONS TO BECOME
FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO FORM ON SATURDAY.
DURING THIS PERIOD EXPECTING RAINFALL AMOUNTS OF 40-80MM IN
POTENTIALLY SEVERE CONVECTION.

AS THE WEEK WEARS ON...THE RIDGE OVER THE EASTERN PACIFIC TENDS TO
FLATTEN AS A BROAD TROUGH AMPLIFIES ACROSS THE SOUTHEAST PACIFIC
BETWEEN 120W-70W. THIS REACHES MAXIMUM AMPLITUDE ON FRIDAY TO
SATURDAY WHEN THE TROUGH IS TO BOTTOM OUT ALONG 40S. AS IT PRESSES
AGAINST THE RIDGE TO THE NORTH...AND THE GRADIENT TIGHTENS...THIS
WILL FAVOR STRONG WINDS ACROSS SOUTHERN REGIONS OF CHILE/TIERRA
DEL FUEGO DURING THE NEXT SEVERAL DAYS. PROGRESSIVE PERTURBATIONS
ARE TO EMBED IN THIS FLOW...WITH FRONTAL SYSTEMS TO REVOLVE AROUND
A DEEP/BROAD TROUGH OVER THE SOUTHEAST PACIFIC TO THEN STREAM
ACROSS THE DRAKE PASSAGE/SOUTHERN CHILE FROM TIME TO TIME. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY WITH MAXIMA OF
20-30MM. NOTE THAT STRONG TOPOGRAPHICAL FORCING/FLUX MOISTURE
CONVERGENCE WOULD LIKELY RESULT IN LOCALLY HIGHER RAINFALL
AMOUNTS.

UPPER FLOW PATTERN TO THE NORTH REMAINS UNDER THE INFLUENCE OF A
SHORT WAVE RIDGE EXTENDING ACROSS PERU TO WESTERN BRASIL/NORTHERN
BOLIVIA...WHILE A SHORT WAVE TROUGH TO THE EAST MEANDERS OVER
NORTHEAST BRASIL. THROUGH FRIDAY MORNING THE RIDGE TENDS TO BUILDS
SOUTH ACROSS BOLIVIA TO PARAGUAY...WHILE THE TROUGH TO THE EAST
DEEPENS/BECOME BETTER ORGANIZED. BY THE END OF THE WEEK THIS WILL
CENTER ON A CLOSED LOW OVER PARA IN BRASIL. INITIALLY...THE MOST
ACTIVE CONVECTION IS EXPECTED BETWEEN AMAZONAS IN BRASIL AND
NORTHERN JUNGLE OF PERU/EASTERN ECUADOR...WITH MAXIMA OF 25-50MM.
THIS WEAKENS ON WEDNESDAY TO MAXIMA OF 15-20MM/DAY. ON THURSDAY
AND ONWARD...UNDER INFLUENCE OF EASTERLY WAVES STREAMING ACROSS
TROPICAL SOUTH AMERICA...THE DIURNAL CONVECTION OS TO ALSO
INTENSIFY...WITH MAXIMA SURGING TO 20-35MM ON FRIDAY TO SATURDAY.


DAVISON...WPC (USA)
$$

489 
FXSA20 KWBC 051550
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1148 AM EDT TUE OCT 05 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 05/16UTC: CONSISTENT WITH PREVIOUS
ANALYSIS AND FORECAST...A BROAD MID/UPPER LEVEL TROUGH REMAINS THE
DOMINANT FEATURE OVER THE CONTINENT/WESTERN ATLANTIC TO THE SOUTH
OF 20S. UPSTREAM OVER THE EASTERN PACIFIC...A LONG WAVE RIDGE
EXTENDS SOUTH ALONG 90W TO THE POLAR ICE CAP. UNDER THE INFLUENCE
OF THE RIDGE TO THE WEST...A DEEPENING TROUGH IS TO RAPIDLY
AMPLIFY AS IT LIFTS ACROSS THE DRAKE PASSAGE TO PATAGONIA IN
ARGENTINA/SOUTHERN CHILE TO THE ARCHIPELAGO DE JUAN FERNANDEZ
EARLY IN THE CYCLE. THROUGH WEDNESDAY EVENING THE MID/UPPER LEVEL
TROUGH IS FORECAST TO SPLIT IN TWO...WITH ITS SOUTHERN HALF TO
GRADUALLY DEEPEN AS IT LIFTS ACROSS THE WESTERN ATLANTIC TO 30W
LATER ON THURSDAY. THE TRAILING NORTHERN STREAM VORTEX WILL REMAIN
OFF THE CENTRAL/NORTHERN COAST OF CHILE WHILE GRADUALLY EVOLVING
INTO A CLOSED LOW WEST OF LA SERENA CHILE EARLY ON THURSDAY
MORNING. THIS IS TO MEANDER OFF THE CENTRAL COAST OF CHILE THROUGH
SATURDAY MORNING...MEANWHILE SHEARING SHORT WAVE ENERGY ACROSS THE
CENTRAL ANDES INTO ARGENTINA. AT 250 HPA...THESE WILL FOCUS A
POLAR AND A SUBTROPICAL JET MAXIMA ACROSS MID SECTIONS OF SOUTH
AMERICA. THE NORTHERN POLAR IS TO SLOWLY PULL AWAY WHILE THE
SUBTROPICAL JET PERSISTS THROUGH THE END OF THE CYCLE.

AT LOW LEVELS...A PROGRESSIVE FRONT SURGES ACROSS LA PAMPA/BUENOS
AIRES PROVINCE IN ARGENTINA LATER TODAY AS A POLAR RIDGE BUILDS TO
THE SOUTH. THROUGH WEDNESDAY EVENING THE FRONT WILL MOVE NORTH
ACROSS SOUTHERN BRASIL TO NORTHERN ARGENTINA...WHERE IT IS TO
INTERACT WITH AN OLD BOUNDARY TO THE NORTH. THIS WILL STRENGTHEN
THE OLD BAROCLINIC BOUNDARY...WITH A FRONTAL WAVE TO FORM ALONG
THIS BOUNDARY OVER CORRIENTES IN ARGENTINA/SOUTHEAST PARAGUAY ON
SATURDAY. AS THE FRONTS INTERACT...CONVECTION ACROSS SOUTHERN
BRASIL-MISIONES IN ARGENTINA AND SOUTHEAST PARAGUAY WILL SURGE ON
WEDNESDAY...WITH MAXIMA OF 30-60MM IN POTENTIALLY SEVERE
CONVECTION. ON THURSDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
20-45MM BETWEEN PARAGUAY AND PARANA/SANTA CATARINA IN
BRASIL...WHILE TO THE NORTH OVER SAO PAULO/RIO DE JANEIRO THIS
WILL FAVOR MAXIMA OF 20-30MM. THROUGH SATURDAY CONVECTION SURGES
ACROSS PARAGUAY-SOUTHERN/SOUTHEAST BRASIL AS ENHANCED BY THE MID
LEVEL VORTEX...WITH THE ENVIRONMENTAL CONDITIONS TO BECOME
FAVORABLE FOR A HEAVY RAINFALL PRODUCING MCS TO FORM ON SATURDAY.
DURING THIS PERIOD EXPECTING RAINFALL AMOUNTS OF 40-80MM IN
POTENTIALLY SEVERE CONVECTION.

AS THE WEEK WEARS ON...THE RIDGE OVER THE EASTERN PACIFIC TENDS TO
FLATTEN AS A BROAD TROUGH AMPLIFIES ACROSS THE SOUTHEAST PACIFIC
BETWEEN 120W-70W. THIS REACHES MAXIMUM AMPLITUDE ON FRIDAY TO
SATURDAY WHEN THE TROUGH IS TO BOTTOM OUT ALONG 40S. AS IT PRESSES
AGAINST THE RIDGE TO THE NORTH...AND THE GRADIENT TIGHTENS...THIS
WILL FAVOR STRONG WINDS ACROSS SOUTHERN REGIONS OF CHILE/TIERRA
DEL FUEGO DURING THE NEXT SEVERAL DAYS. PROGRESSIVE PERTURBATIONS
ARE TO EMBED IN THIS FLOW...WITH FRONTAL SYSTEMS TO REVOLVE AROUND
A DEEP/BROAD TROUGH OVER THE SOUTHEAST PACIFIC TO THEN STREAM
ACROSS THE DRAKE PASSAGE/SOUTHERN CHILE FROM TIME TO TIME. IN THIS
AREA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY WITH MAXIMA OF
20-30MM. NOTE THAT STRONG TOPOGRAPHICAL FORCING/FLUX MOISTURE
CONVERGENCE WOULD LIKELY RESULT IN LOCALLY HIGHER RAINFALL
AMOUNTS.

UPPER FLOW PATTERN TO THE NORTH REMAINS UNDER THE INFLUENCE OF A
SHORT WAVE RIDGE EXTENDING ACROSS PERU TO WESTERN BRASIL/NORTHERN
BOLIVIA...WHILE A SHORT WAVE TROUGH TO THE EAST MEANDERS OVER
NORTHEAST BRASIL. THROUGH FRIDAY MORNING THE RIDGE TENDS TO BUILDS
SOUTH ACROSS BOLIVIA TO PARAGUAY...WHILE THE TROUGH TO THE EAST
DEEPENS/BECOME BETTER ORGANIZED. BY THE END OF THE WEEK THIS WILL
CENTER ON A CLOSED LOW OVER PARA IN BRASIL. INITIALLY...THE MOST
ACTIVE CONVECTION IS EXPECTED BETWEEN AMAZONAS IN BRASIL AND
NORTHERN JUNGLE OF PERU/EASTERN ECUADOR...WITH MAXIMA OF 25-50MM.
THIS WEAKENS ON WEDNESDAY TO MAXIMA OF 15-20MM/DAY. ON THURSDAY
AND ONWARD...UNDER INFLUENCE OF EASTERLY WAVES STREAMING ACROSS
TROPICAL SOUTH AMERICA...THE DIURNAL CONVECTION OS TO ALSO
INTENSIFY...WITH MAXIMA SURGING TO 20-35MM ON FRIDAY TO SATURDAY.


DAVISON...WPC (USA)
$$

566 
FXSA20 KWBC 041602
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1201 PM EDT MON OCT 04 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 04/16UTC: A BROAD MID/UPPER LEVEL
TROUGH IS THE DOMINANT FEATURE OVER THE CONTINENT TO THE SOUTH OF
20S. A RIDGE TO THE WEST...WITH AXIS SOUTH BETWEEN 120W-95W TO THE
POLAR ICE CAP...IS STEERING SOUTHERN STREAM PERTURBATIONS NORTH
ACROSS THE BELLINGSHAUSEN SEA. THESE THEN REVOLVE AROUND THE LONG
WAVE WHILE AMPLIFYING ACROSS THE SOUTHERN CONE. IN THIS
PATTERN...A ROBUST TROUGH LIFTS ACROSS TIERRA DEL FUEGO TO
PATAGONIA IN ARGENTINA LATER TODAY...WITH AXIS TO STRETCH ACROSS
THE SOUTHERN CONE AND THE ARCHIPELAGO OF JUAN FERNANDEZ EARLY ON
TUESDAY MORNING. THROUGH WEDNESDAY THE TROUGH SPLITS IN TWO...WITH
ITS SOUTHERN HALF LIFTING ACROSS THE WESTERN ATLANTIC WHILE THE
REMAINING NORTHERN STREAM VORTEX EVOLVES INTO A CLOSED LOW OVER
THE EASTERN PACIFIC. THE FORMER IS TO THEN INTENSIFY THROUGH
THURSDAY MORNING...WHILE THE LATTER IS TO MEANDER OFF THE
CENTRAL/NORTHERN COAST OF CHILE THROUGH THE END OF THE WEEK.

AT LOW LEVELS...AN ELONGATED FRONT EXTENDS TO THE NORTH-NORTHWEST
FROM THE WESTERN SOUTH ATLANTIC INTO THE SOUTHEAST STATES OF
BRASIL TO NORTHERN BOLIVIA LATER TODAY. LOSING UPPER LEVEL
SUPPORT...THE FRONT RETROGRESSES TO PARAGUAY ON TUESDAY. ON
WEDNESDAY THE PORTION OVER THE ATLANTIC PERSISTS...WHILE TRAILING
END OVER MATO GROSSO DO SUL/PARAGUAY IS EXPECTED TO FRONTOLIZE.
OVER SOUTHEAST BRASIL THE MOST ACTIVE CONVECTION WITH THIS FRONT
IS EXPECTED EARLY IN THE CYCLE...WITH MAXIMA OF 20-45MM. HIGHER
AMOUNTS ARE EXPECTED TO THE NORTH ACROSS CENTRAL BOLIVIA...WHERE
THE FRONTAL CONVECTION WILL COMBINE WITH TOPOGRAPHICALLY INDUCED
PRECIPITATION TO SUSTAIN RAINFALL MAXIMA OD 30-60MM. THIS RAPIDLY
WEAKENS ON TUESDAY TO WEDNESDAY AS THE FRONT WEAKENS WHILE
RETROGRESSING TO PARAGUAY.

SIMULTANEOUSLY...A SURGING FRONT LIFTS ACROSS PATAGONIA/SOUTHERN
CHILE THIS AFTERNOON...REACHING THE RIO DE LA PLATA BASIN/CORDOBA
IN ARGENTINA LATER ON TUESDAY. BUILDING POLAR RIDGE TO THE SOUTH
WILL THEN DRIVE THE FRONT NORTH TO SOUTHERN
BRASIL/PARAGUAY-BOLIVIA ON WEDNESDAY...WHERE THE FRONT IS EXPECTED
TO STALL. OVER TIERRA DEL FUEGO...IN A COLD ADVECTIVE
PATTERN...THIS WILL SUSTAIN MODERATE SNOWFALL AMOUNTS WITH
ACCUMULATION OF 10-15CM...WHILE OVER SOUTHERN CHILE LIQUID
PRECIPITATION IS TO RESULT IN RAINFALL AMOUNTS OF 15-20MM. THROUGH
WEDNESDAY...AS THE FRONT RACES ACROSS ARGENTINA...FOCUS OF THE
ORGANIZED CONVECTION WILL SHIFT TO MID SECTIONS OF SOUTH
AMERICA...WITH MAXIMA OF 30-60MM ACROSS SOUTHERN BRASIL TO
SOUTHEAST PARAGUAY...WHILE OVER CHACO PARAGUAYO-SANTA CRUZ BOLIVIA
EXPECTING MAXIMA OF 20-30MM. ON THURSDAY...UNDER INFLUENCE OF THE
MID LEVEL TROUGH AND AN UPPER LEVEL SUBTROPICAL JET...ACTIVITY
ACROSS PARAGUAY/SOUTHERN BRASIL IS TO INTENSIFY...WITH MAXIMA OF
40-80MM. PREFRONTAL CONVECTION OVER CENTRAL BOLIVIA WILL THEN
RESULT IN RAINFALL AMOUNTS OF 20-45MM. ON FRIDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 15-25MM ON THE SOUTHEAST STATES OF
BRASIL...TO CLUSTER BETWEEN RIO DE JANEIRO AND SAO PAULO...WHILE
OVER PARAGUAY THE MAXIMA IS TO PEAK AT 20-45MM.

NORTH OVER THE CONTINENT...AT 250 HPA...A BROAD/LOW AMPLITUDE
RIDGE IS INITIALIZED OVER THE CONTINENT TO THE NORTH OF 20S...WITH
A SHORT WAVE TROUGH/ILL ORGANIZED LOW CENTERING OVER NORTHEAST
BRASIL. THROUGH THURSDAY THE RIDGE IS FORECAST TO BUILD SOUTH
ACROSS BOLIIVA/PARAGUAY TO JUJUY/SALTA IN NORTHWEST
ARGENTINA...WITH AXIS TO THEN CENTER ON A CLOSED HIGH OVER
RONDONIA/NORTHERN BOLIVIA. AS THE RIDGE STRENGTHENS TO THE WEST
AND SOUTH...THE TROUGH TO THE EAST IS TO THEN DEEPEN/BECOME BETTER
ORGANIZED. INITIALLY...THE MOST ACTIVE CONVECTION IS EXPECTED
ACROSS AMAZONAS IN BRASIL TO SOUTHERN COLOMBIA/NORTHERN JUNGLE OF
PERU...WITH MAXIMA OF 20-45MM IN SCATTERED DEEP CONVECTION. ON
TUESDAY THIS INCREASES TO 25-50MM WHILE BUILDING WEST ACROSS ACRE
IN BRASIL TO THE CENTRAL JUNGLE OF PERU. BUT AS THE UPPER LEVEL
TROUGH DEEPENS...AND THE RIDGE BUILDS TO THE WEST...CONVECTION
ACROSS AMAZONAS IN BRASIL IS EXPECTED TO WEAKEN WHILE DIURNAL
CONVECTION BETWEEN RORAIMA AND PARA TO THE NORTH AND EAST
GRADUALLY INTENSIFIES IN RESPONSE TO THE EVOLVING PATTERN ALOFT.

DAVISON...WPC (USA)
$$

917 
FXSA20 KWBC 041526
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1125 AM EDT MON OCT 04 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 01/14UTC: THERE IS GOOD CONTINUITY
WITH THE PREVIOUS FORECAST CYCLE...WITH GLOBAL MODELS AGREEING ON
THE NORTHWARD AMPLIFICATION OF A LONG WAVE TROUGH ACROSS THE
SOUTHEAST PACIFIC EARLY IN THE FORECAST CYCLE. THROUGH THIS
EVENING THE SLOW TO EVOLVE/PROPAGATE PERTURBATION WILL MOVE ACROSS
THE ANTARCTIC PENINSULA/DRAKE PASSAGE WHILE TRAILING ACROSS
PATAGONIA IN ARGENTINA TO CENTRAL CHILE. ON SATURDAY THE TROUGH IS
TO SLOWLY MOVE ACROSS THE SOUTHERN CONE...WITH ITS BOTTOM HALF TO
ACCELERATE ACROSS THE SOUTH ATLANTIC WHILE SHEARING A SHORT WAVE
OVER CENTRAL ARGENTINA. THROUGH SUNDAY MORNING THIS WILL EVOLVE
INTO A CLOSED LOW JUST EAST OF THE BUENOS AIRES PROVINCE. IN A
LIGHT STEERING FLOW...THIS IS TO THEN MEANDER TO THE
EAST-SOUTHEAST THROUGH MONDAY EVENING.

AT LOW LEVELS THE LOW/TROUGH ALOFT WILL SUSTAIN A SURFACE FRONT
THAT LIFTS ACROSS THE SOUTHERN CONE LATER TODAY...MEANWHILE
TRIGGERING MODERATE RAINFALL AMOUNTS ACROSS SOUTHERN CHILE WITH
MAXIMA OF 15-20MM. IN A COLD ADVECTIVE PATTERN THIS IS TO ALSO
TRIGGER HEAVY SNOWFALL AMOUNTS ACROSS THE SOUTHERN ANDES WITH
ACCUMULATION OF 10-15CM...WHILE ACROSS TIERRA DEL FUEGO IT WILL
SUSTAIN SNOWFALL AMOUNTS OF 05-10CM. ON SATURDAY TO SUNDAY THE
FRONTAL LOW IS TO GRADUALLY OCCLUDE AS IT MEANDERS TO THE
SOUTH/SOUTHEAST OF THE BUENOS AIRES PROVINCE. THIS COMBINES WITH A
BUILDING POLAR RIDGE TO THE WEST TO SUSTAIN A PAMPERO (SOUTHERLY)
LOW LEVEL JET THAT THEN DRIVES THE FRONT NORTH ACROSS
URUGUAY-CORDOBA IN ARGENTINA. THE SURGING FRONT IS TO THEN TRIGGER
A PREFRONTAL SQUALL LINE ACROSS SOUTHERN BRASIL/NORTHERN ARGENTINA
TO PARAGUAY LATER ON SATURDAY AFTERNOON. THE MCS/SEVERE WEATHER
PRODUCING SQUALL LINE IS TO TRIGGER HEAVY RAINFALL AMOUNTS ACROSS
SOUTHERN/SOUTHEAST BRASIL TO PARAGUAY...WITH MAXIMA OF 75-125MM
EXPECTED BETWEEN SATURDAY AND SUNDAY. LESSER AMOUNTS ARE EXPECTED
ACROSS CHACO ARGENTINO TO CENTRAL PARAGUAY...WITH MAXIMA OF
15-30MM. ON SUNDAY...UNDER INFLUENCE OF THE SOUTHERLY JET...THE
FRONT WILL MOVE FARTHER NORTH ACROSS SOUTHEAST BRASIL-PARAGUAY TO
CENTRAL BOLIVIA...FAVORING ADDITIONAL RAINFALL AMOUNTS OF 35-70MM
OVER SOUTHEAST BRASIL. ACROSS CENTRAL BOLIVIA THE MAXIMA INCREASES
FROM 20-45MM IN PREFRONTAL CONVECTION ON SUNDAY TO 30-60MM ON
MONDAY. ACROSS CENTRAL BOLIVIA THIS WOULD LIKELY RESULT IN STORM
TOTAL AMOUNTS OF 50-100MM.

ON THE SOUTHERN STREAM...AT 500 HPA...A PROGRESSIVE CLIPPER LOW
WILL LIFT ACROSS THE SOUTHEAST PACIFIC WHILE ROUNDING THE SOUTHERN
FRINGES OF THE SUBTROPICAL RIDGE. ON SUNDAY IT WILL LIFT ACROSS
THE DRAKE PASSAGE WHILE EXTENDING A SHORT WAVE TROUGH ACROSS
PATAGONIA IN ARGENTINA. EARLY NEXT WEEK THE LOW/TROUGH IS FORECAST
TO STALL NEAR THE SOUTH GEORGIA ISLANDS AS IT INTERACTS WITH A
DEEPENING TROUGH OVER THE WESTERN ATLANTIC. AT LOW LEVELS THIS
WILL SUSTAIN A DEEP OCCLUDED LOW OVER THE DRAKE PASSAGE LATER ON
SUNDAY EVENING...THAT IS TO SUSTAIN STRONG BOUNDARY LAYER WINDS
AND A PROGRESSIVE FRONT ACROSS PATAGONIA/SOUTHERN CHILE. ACROSS
SOUTHERN CHILE THIS WILL SUSTAIN MODERATE RAINFALL AMOUNTS ON
SUNDAY TO MONDAY...WITH MAXIMA OF 15-30MM. OVER TIERRA DEL FUEGO
INITIALLY EXPECTING RAINFALL AMOUNTS OF 10-15MM...CHANGING TO SNOW
ON MONDAY WHEN IT WILL SUSTAIN SNOWFALL AMOUNTS OF 05-10CM.

NORTH OVER THE CONTINENT...AT 250 HPA...AN ILL ORGANIZED CELL OF
THE SUBTROPICAL RIDGE WILL SPAN BETWEEN THE EASTERN TROPICAL
PACIFIC AND NORTHWEST SOUTH AMERICA. EAST OF THIS AXIS...A NARROW
TROUGH/SHEAR AXIS IS TO MEANDER OVER BRASIL ALONG 10S. IN THIS
PATTERN...MODELS FORECAST DIURNAL CONVECTION BUILDING ACROSS
NORTHERN SOUTH AMERICA TO CLUSTER TO THE NORTH OF 10S...WITH THE
ACTIVITY SPANNING BETWEEN THE NORTHERN JUNGLE OF PERU AND NORTHERN
BRASIL. IN THIS AREA...PERTURBATIONS IN THE EASTERLY TRADES WILL
HELP ENHANCE LOW LEVEL MOISTURE CONVERGENCE AND ARE LIKELY TO
TRIGGER MODERATE/LOCALLY HEAVY RAINFALL AMOUNTS. AS A
RESULT...OVER THE NEXT FEW DAYS EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY WITH MAXIMA OF 20-30MM CLUSTERING BETWEEN PARA AND
AMAZONAS IN BRASIL. FROM TIME-TO-TIME ACTIVITY IS TO ALSO SPREAD
ACROSS SOUTHERN AMAZONIA IN COLOMBIA TO THE NORTHERN JUNGLE OF
PERU/EASTERN ECUADOR.

DAVISON...WPC (USA)
$$

140 
FXSA20 KWBC 011419
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1018 AM EDT FRI OCT 01 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM OCT 01/14UTC: THERE IS GOOD CONTINUITY
WITH THE PREVIOUS FORECAST CYCLE...WITH GLOBAL MODELS AGREEING ON
THE NORTHWARD AMPLIFICATION OF A LONG WAVE TROUGH ACROSS THE
SOUTHEAST PACIFIC EARLY IN THE FORECAST CYCLE. THROUGH THIS
EVENING THE SLOW TO EVOLVE/PROPAGATE PERTURBATION WILL MOVE ACROSS
THE ANTARCTIC PENINSULA/DRAKE PASSAGE WHILE TRAILING ACROSS
PATAGONIA IN ARGENTINA TO CENTRAL CHILE. ON SATURDAY THE TROUGH IS
TO SLOWLY MOVE ACROSS THE SOUTHERN CONE...WITH ITS BOTTOM HALF TO
ACCELERATE ACROSS THE SOUTH ATLANTIC WHILE SHEARING A SHORT WAVE
OVER CENTRAL ARGENTINA. THROUGH SUNDAY MORNING THIS WILL EVOLVE
INTO A CLOSED LOW JUST EAST OF THE BUENOS AIRES PROVINCE. IN A
LIGHT STEERING FLOW...THIS IS TO THEN MEANDER TO THE
EAST-SOUTHEAST THROUGH MONDAY EVENING.

AT LOW LEVELS THE LOW/TROUGH ALOFT WILL SUSTAIN A SURFACE FRONT
THAT LIFTS ACROSS THE SOUTHERN CONE LATER TODAY...MEANWHILE
TRIGGERING MODERATE RAINFALL AMOUNTS ACROSS SOUTHERN CHILE WITH
MAXIMA OF 15-20MM. IN A COLD ADVECTIVE PATTERN THIS IS TO ALSO
TRIGGER HEAVY SNOWFALL AMOUNTS ACROSS THE SOUTHERN ANDES WITH
ACCUMULATION OF 10-15CM...WHILE ACROSS TIERRA DEL FUEGO IT WILL
SUSTAIN SNOWFALL AMOUNTS OF 05-10CM. ON SATURDAY TO SUNDAY THE
FRONTAL LOW IS TO GRADUALLY OCCLUDE AS IT MEANDERS TO THE
SOUTH/SOUTHEAST OF THE BUENOS AIRES PROVINCE. THIS COMBINES WITH A
BUILDING POLAR RIDGE TO THE WEST TO SUSTAIN A PAMPERO (SOUTHERLY)
LOW LEVEL JET THAT THEN DRIVES THE FRONT NORTH ACROSS
URUGUAY-CORDOBA IN ARGENTINA. THE SURGING FRONT IS TO THEN TRIGGER
A PREFRONTAL SQUALL LINE ACROSS SOUTHERN BRASIL/NORTHERN ARGENTINA
TO PARAGUAY LATER ON SATURDAY AFTERNOON. THE MCS/SEVERE WEATHER
PRODUCING SQUALL LINE IS TO TRIGGER HEAVY RAINFALL AMOUNTS ACROSS
SOUTHERN/SOUTHEAST BRASIL TO PARAGUAY...WITH MAXIMA OF 75-125MM
EXPECTED BETWEEN SATURDAY AND SUNDAY. LESSER AMOUNTS ARE EXPECTED
ACROSS CHACO ARGENTINO TO CENTRAL PARAGUAY...WITH MAXIMA OF
15-30MM. ON SUNDAY...UNDER INFLUENCE OF THE SOUTHERLY JET...THE
FRONT WILL MOVE FARTHER NORTH ACROSS SOUTHEAST BRASIL-PARAGUAY TO
CENTRAL BOLIVIA...FAVORING ADDITIONAL RAINFALL AMOUNTS OF 35-70MM
OVER SOUTHEAST BRASIL. ACROSS CENTRAL BOLIVIA THE MAXIMA INCREASES
FROM 20-45MM IN PREFRONTAL CONVECTION ON SUNDAY TO 30-60MM ON
MONDAY. ACROSS CENTRAL BOLIVIA THIS WOULD LIKELY RESULT IN STORM
TOTAL AMOUNTS OF 50-100MM.

ON THE SOUTHERN STREAM...AT 500 HPA...A PROGRESSIVE CLIPPER LOW
WILL LIFT ACROSS THE SOUTHEAST PACIFIC WHILE ROUNDING THE SOUTHERN
FRINGES OF THE SUBTROPICAL RIDGE. ON SUNDAY IT WILL LIFT ACROSS
THE DRAKE PASSAGE WHILE EXTENDING A SHORT WAVE TROUGH ACROSS
PATAGONIA IN ARGENTINA. EARLY NEXT WEEK THE LOW/TROUGH IS FORECAST
TO STALL NEAR THE SOUTH GEORGIA ISLANDS AS IT INTERACTS WITH A
DEEPENING TROUGH OVER THE WESTERN ATLANTIC. AT LOW LEVELS THIS
WILL SUSTAIN A DEEP OCCLUDED LOW OVER THE DRAKE PASSAGE LATER ON
SUNDAY EVENING...THAT IS TO SUSTAIN STRONG BOUNDARY LAYER WINDS
AND A PROGRESSIVE FRONT ACROSS PATAGONIA/SOUTHERN CHILE. ACROSS
SOUTHERN CHILE THIS WILL SUSTAIN MODERATE RAINFALL AMOUNTS ON
SUNDAY TO MONDAY...WITH MAXIMA OF 15-30MM. OVER TIERRA DEL FUEGO
INITIALLY EXPECTING RAINFALL AMOUNTS OF 10-15MM...CHANGING TO SNOW
ON MONDAY WHEN IT WILL SUSTAIN SNOWFALL AMOUNTS OF 05-10CM.

NORTH OVER THE CONTINENT...AT 250 HPA...AN ILL ORGANIZED CELL OF
THE SUBTROPICAL RIDGE WILL SPAN BETWEEN THE EASTERN TROPICAL
PACIFIC AND NORTHWEST SOUTH AMERICA. EAST OF THIS AXIS...A NARROW
TROUGH/SHEAR AXIS IS TO MEANDER OVER BRASIL ALONG 10S. IN THIS
PATTERN...MODELS FORECAST DIURNAL CONVECTION BUILDING ACROSS
NORTHERN SOUTH AMERICA TO CLUSTER TO THE NORTH OF 10S...WITH THE
ACTIVITY SPANNING BETWEEN THE NORTHERN JUNGLE OF PERU AND NORTHERN
BRASIL. IN THIS AREA...PERTURBATIONS IN THE EASTERLY TRADES WILL
HELP ENHANCE LOW LEVEL MOISTURE CONVERGENCE AND ARE LIKELY TO
TRIGGER MODERATE/LOCALLY HEAVY RAINFALL AMOUNTS. AS A
RESULT...OVER THE NEXT FEW DAYS EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY WITH MAXIMA OF 20-30MM CLUSTERING BETWEEN PARA AND
AMAZONAS IN BRASIL. FROM TIME-TO-TIME ACTIVITY IS TO ALSO SPREAD
ACROSS SOUTHERN AMAZONIA IN COLOMBIA TO THE NORTHERN JUNGLE OF
PERU/EASTERN ECUADOR.

DAVISON...WPC (USA)
$$

196 
FXSA20 KWBC 301614
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1214 PM EDT THU SEP 30 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 30/16UTC: CONSISTENT WITH PREVIOUS
FORECAST...A PROGRESSIVE MID/UPPER LEVEL SHORT WAVE TROUGH IS TO
STREAM ACROSS THE DRAKE PASSAGE/SOUTHERN CONE EARLY IN THE CYCLE.
AS IT ENTERS THE CONTINENT THIS WILL PHASE WITH A SHORT WAVE
TROUGH TO THE NORTH...AS THE LATER SPILLS ACROSS THE CENTRAL ANDES
OF CHILE INTO CENTRAL ARGENTINA. AT LOW LEVELS...DRIVEN BY A POLAR
RIDGE OVER THE SOUTHERN CONE AND A SOUTHERLY PAMPERO LOW LEVEL
JET...A SURFACE FRONT RACES ACROSS CENTRAL ARGENTINA/RIO DE LA
PLATA BASIN DURING THE DAY TODAY. AS IT SURGES ACROSS CENTRAL TO
NORTHERN ARGENTINA...THIS BOUNDARY WILL THEN INTERACT WITH AN OLD
FRONT TO THE NORTH...AS THE LATTER TRAILS ACROSS THE WESTERN SOUTH
ATLANTIC TO SOUTHEAST BRASIL-PARAGUAY/NORTHERN ARGENTINA. AS THEY
INTERACT...IT WILL TRIGGER A HEAVY RAINFALL PRODUCING MCS BETWEEN
THE SOUTHERN STATES OF BRASIL AND CORRIENTES/MISIONES IN
ARGENTINA...WITH RAINFALL MAXIMA OF 35-70MM IN POTENTIALLY SEVERE
CONVECTION. ON FRIDAY THIS WILL SPREAD WEST ACROSS PARAGUAY TO
SUSTAIN ADDITIONAL RAINFALL AMOUNTS OF 30-60MM.

A BUILDING MID/UPPER LEVEL RIDGE TO THE WEST WILL THEN FAVOR THE
NORTHWARD AMPLIFICATION OF A LONG WAVE TROUGH ACROSS THE SOUTHEAST
PACIFIC. THROUGH FRIDAY AFTERNOON THE SLOW TO EVOLVE PERTURBATION
WILL MOVE ACROSS THE ANTARCTIC PENINSULA/DRAKE PASSAGE WHILE
TRAILING ACROSS PATAGONIA IN ARGENTINA TO CENTRAL ARGENTINA.
THROUGH SATURDAY MORNING THE TROUGH IS TO SLOWLY MOVE ACROSS THE
SOUTHERN CONE TO THE WESTERN ATLANTIC...WITH AXIS TO THEN SPLIT IN
TWO LATER IN THE DAY. THE REMAINING NORTHERN PORTION WILL THEN
EVOLVE INTO A DEEP CLOSED LOW TO THE SOUTH-SOUTHEAST OF BUENOS
AIRES PROVINCE LATER IN THE DAY. THE LOW IS TO THEN EXTEND A SHORT
WAVE TROUGH TO THE NORTHWEST ACROSS THE RIO DE LA PLATA BASIN TO
NORTHERN ARGENTINA DURING THE WEEKEND. THE TROUGH WILL SUSTAIN A
SURFACE FRONT THAT LIFTS ACROSS THE SOUTHERN CONE LATER ON
FRIDAY...MEANWHILE TRIGGERING MODERATE RAINFALL AMOUNTS ACROSS
SOUTHERN CHILE WITH MAXIMA OF 15-20MM...AND HEAVY SNOWFALL AMOUNTS
ACROSS THE SOUTHERN ANDES WITH ACCUMULATION OF 10-15CM. ON
SATURDAY THE FRONTAL LOW IS TO RAPIDLY OCCLUDE AS IT MEANDERS TO
THE SOUTH OF BUENOS AIRES PROVINCE. THIS WILL COMBINE WITH A
BUILDING RIDGE TO THE WEST TO SUSTAIN A PAMPERO LOW LEVEL JET THAT
DRIVES THE FRONT NORTH ACROSS URUGUAY-CORDOBA IN ARGENTINA. THE
SURGING FRONT IS TO THEN TRIGGER A PREFRONTAL SQUALL LINE TO THE
NORTH. THE SEVERE WEATHER PRODUCING SQUALL LINE IS TO DUMP HEAVY
RAINFALL AMOUNTS ACROSS SOUTHERN/SOUTHEAST BRASIL TO
PARAGUAY...WITH MAXIMA OF 75-125MM EXPECTED BETWEEN SATURDAY AND
SUNDAY...WHILE OVER NORTHWEST ARGENTINA EXPECTING MAXIMA OF
20-35MM. ON SUNDAY THE FRONT MOVES FARTHER NORTH ACROSS SOUTHEAST
BRASIL TO CENTRAL BOLIVIA...FAVORING ADDITIONAL RAINFALL AMOUNTS
OF 20-45MM OVER SOUTHEAST BRASIL WHILE ACROSS CENTRAL BOLIVIA THE
MAXIMA INCREASES FROM 20-45MM ON SUNDAY TO 30-60MM ON MONDAY...FOR
STORM TOTAL AMOUNTS OF 50-100MM.

ON THE SOUTHERN STREAM...A PROGRESSIVE CLIPPER LOW WILL ROUND THE
SOUTHERN FRINGES OF THE SOUTHEAST PACIFIC RIDGE...WITH VORTEX
LIFTING ACROSS THE BELLINGSHAUSEN SEA/SOUTHEAST PACIFIC LATER ON
SUNDAY EVENING/EARLY MONDAY MORNING. AT LOW LEVELS THIS WILL
SUSTAIN A DEEP OCCLUDED LOW OVER TIERRA DEL FUEGO/SOUTHERN
PATAGONIA LATER ON SUNDAY EVENING...WITH THE ASSOCIATED FRONTAL
BOUNDARY BOTTOMING OUT OVER NORTHERN PATAGONIA/LA PAMPA EARLY NEXT
WEEK. ACROSS SOUTHERN CHILE THIS WILL SUSTAIN ANOTHER ROUND OF
MODERATE RAINFALL AMOUNTS WITH MAXIMA OF 15-30MM LATER ON SUNDAY.
IN A COLD ADVECTIVE PATTERN THIS TRANSITIONS TO SOLID
PRECIPITATION ON MONDAY...TO RESULT IN SNOWFALL AMOUNTS OF 05-10CM.

NORTH OVER THE CONTINENT...AT 250 HPA...THE MODELS CONTINUE TO
FORECAST A LOW AMPLITUDE CELL OF THE SUBTROPICAL RIDGE TO CONFINE
BETWEEN THE EASTERN TROPICAL PACIFIC AND NORTHWEST SOUTH
AMERICA...WHILE A SHORT WAVE TROUGH TO THE EAST MEANDERS OVER
NORTHEAST STATES OF BRASIL. IN THIS PATTERN...DIURNAL CONVECTION
OVER NORTHERN SOUTH AMERICA WILL CLUSTER TO THE NORTH OF
10S...WITH ACTIVITY SPANNING BETWEEN THE NORTHERN JUNGLE OF PERU
AND NORTHERN BRASIL. IN THIS AREA...PERTURBATIONS IN THE EASTERLY
TRADES WILL HELP ENHANCE LOW LEVEL MOISTURE CONVERGENCE AND ARE
LIKELY TO TRIGGER MODERATE/LOCALLY HEAVY RAINFALL AMOUNTS. AS A
RESULT...OVER THE NEXT FEW DAYS EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY WITH MAXIMA OF 20-30MM CLUSTERING BETWEEN PARA AND
AMAZONAS IN BRASIL. FROM TIME-TO-TIME ACTIVITY IS TO ALSO SPREAD
ACROSS SOUTHERN AMAZONIA IN COLOMBIA TO THE NORTHERN JUNGLE OF
PERU/EASTERN ECUADOR.

DAVISON...WPC (USA)
$$

971 
FXSA20 KWBC 291601
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1201 PM EDT WED SEP 29 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 29/16UTC: PROGRESSIVE MID/UPPER LEVEL
PERTURBATIONS ARE TO DOMINATE THE FLOW PATTERN DURING THE NEXT
SEVERAL DAYS. THE FIRST ENTERS SOUTHERN CHILE EARLY ON THURSDAY
MORNING...AND AS IT STREAMS ACROSS THE SOUTHERN CONE IT IS TO THEN
PHASE WITH A NORTHERN STREAM PERTURBATION SPILLING ACROSS THE
CENTRAL ANDES OF CHILE INTO ARGENTINA. THE NEXT REACHES SOUTHERN
CHILE EARLY ON FRIDAY MORNING. UNDER THE INFLUENCE OF A BUILDING
RIDGE TO THE WEST...THE TROUGH IS THEN FORECAST TO RAPIDLY AMPLIFY
ACROSS PATAGONIA/LA PAMPA INTO THE CENTRAL PROVINCES IN ARGENTINA
ON SATURDAY...WITH AXIS TO MEANDER ACROSS MID SECTIONS OF SOUTH
AMERICA THROUGH THE WEEKEND.

AT LOW LEVELS...A PROGRESSIVE FRONT SURGES ACROSS PATAGONIA TO LA
PAMPA/SOUTHERN BUENOS AIRES PROVINCE LATER TODAY. ON
THURSDAY...DRIVEN BY A POLAR RIDGE AND A SOUTHERLY PAMPERO LOW
LEVEL JET...THE FRONT RACES ACROSS CENTRAL ARGENTINA/RIO DE LA
PLATA BASIN. AS IT SURGES ACROSS ARGENTINA...THIS WILL INTERACT
WITH AN OLD FRONT MEANDERING TO THE NORTH...AS THE LATTER TRAILS
ACROSS THE WESTERN SOUTH ATLANTIC TO SOUTHEAST
BRASIL-PARAGUAY/NORTHERN ARGENTINA. OVER SOUTHERN CHILE THIS IS TO
FAVOR MODERATE RAINFALL AMOUNTS EARLY IN THE CYCLE...WITH
ACCUMULATION OF 20-35MM...WHILE ON THE CENTRAL ANDES EXPECTING
SNOWFALL AMOUNTS OF 05-10CM. OVER ARGENTINA THIS IS TO SUSTAIN A
ROUND OF MODERATE/POTENTIALLY SEVERE CONVECTION...WITH ACTIVITY
OVER LA PAMPA/BUENOS AIRES TO SUSTAIN ACCUMULATION OF 20-35MM
LATER THIS AFTERNOON. HIGHER AMOUNTS ARE EXPECTED TO THE NORTH IN
INTERACTION WITH THE OLD FRONTAL BOUNDARY...WITH MAXIMA OF 35-70MM
ACROSS SOUTHERN BRASIL-CORRIENTES/MISIONES IN ARGENTINA TO
SOUTHEAST PARAGUAY ON THURSDAY TO FRIDAY.

ANOTHER FRONT WILL FOLLOW...WITH BOUNDARY LIFTING ACROSS PATAGONIA
TO LA PAMPA ON FRIDAY. A BUILDING POLAR RIDGE AND A SOUTHERLY
PAMPERO LOW LEVEL JET ARE TO ALSO DISPLACE THIS BOUNDARY NORTH
ACROSS THE CONTINENT. ON SATURDAY...AS THE FRONT MOVES ACROSS
URUGUAY TO SOUTHERN BRASIL/PARAGUAY IT IS TO TRIGGER A PREFRONTAL
SQUALL LINE. THE SQUALL LINE WILL BE THE FOCUS OF
ORGANIZED/POTENTIALLY SEVERE CONVECTION ACROSS SOUTHERN BRASIL TO
SOUTHEAST PARAGUAY...TRIGGERING RAINFALL MAXIMA OF 75-125MM. OTHER
CONVECTION ACROSS NORTHWEST ARGENTINA IS TO SUSTAIN RAINFALL
AMOUNTS OF 20-35MM IN POTENTIALLY SEVERE CONVECTION. ON SUNDAY THE
FRONT MOVES FARTHER NORTH ACROSS SAO PAULO TO MATO GROSSO DO
SUL-RONDONIA IN BRASIL. LOSING UPPER LEVEL SUPPORT...MAXIMA OVER
SOUTHEAST BRASIL DECREASES TO 20-45MM...WHILE ACROSS CENTRAL TO
NORTHERN BOLIVIA IT WILL SUSTAIN MAXIMA OF 20-35MM.

NORTH OVER THE DOMAIN...AT 250 HPA...A WANING RIDGE EXTENDS FROM
THE EASTERN TROPICAL PACIFIC TO NORTHWEST SOUTH AMERICA. UNDER
PRESSURE FROM POLAR PERTURBATIONS STREAMING TO THE SOUTH THIS
RIDGE IS TO NEARLY COLLAPSE DURING THE WEEKEND...WHILE A LOW
AMPLITUDE/SHORT WAVE TROUGH SETTLES OVER SOUTHEAST-CENTRAL BRASIL.
IN THIS PATTERN...DIURNAL CONVECTION OVER NORTHERN SOUTH AMERICA
WILL CLUSTER TO THE NORTH OF 10S...BETWEEN THE NORTHERN JUNGLE OF
PERU AND NORTHERN BRASIL. IN THIS AREA...PERTURBATIONS IN THE
EASTERLY TRADES WILL HELP ENHANCE LOW LEVEL MOISTURE CONVERGENCE
AND ARE LIKELY TO TRIGGER MODERATE/LOCALLY HEAVY RAINFALL AMOUNTS.
AS A RESULT...OVER THE NEXT FEW DAYS EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY WITH MAXIMA OF 20-30MM CLUSTERING BETWEEN PARA AND
AMAZONAS IN BRASIL.

DAVISON...WPC (USA)
$$

588 
FXSA20 KWBC 281607
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1206 PM EDT TUE SEP 28 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 28/16UTC: MODELS ONCE AGAIN
INITIALIZE A BROAD MID/UPPER LEVEL TROUGH OVER THE SOUTHWEST
ATLANTIC WITH AXIS CENTERING ON A CLOSED LOW NEAR 50S 40W.
TRAILING THIS VORTEX...A PROGRESSIVE TROUGH IS STREAMING ACROSS
THE DRAKE PASSAGE/TIERRA DEL FUEGO. AS IT ENTERS THE WESTERN
ATLANTIC...THIS VORTEX IS TO INTERACT WITH THE BROAD TROUGH TO THE
EAST...SUSTAINING/INDUCING A SHORT WAVE TROUGH ON THE NORTHERN
STREAM ALONG 50W TO 30S. THIS IS TO THEN SLOWLY PULL ACROSS 30W
WHILE GRADUALLY BECOMING BETTER ORGANIZED EARLY ON FRIDAY MORNING.
AT LOW LEVELS...THIS SUSTAIN AN ELONGATED FRONT ACROSS THE SOUTH
ATLANTIC TO SOUTHERN BRASIL/NORTHERN ARGENTINA-PARAGUAY. ON
WEDNESDAY THE FRONT MEANDERS NORTH ACROSS SOUTHEAST BRASIL WHILE
TRAILING TO PARAGUAY/NORTHERN ARGENTINA. EARLY IN THE CYCLE THIS
WILL SUSTAIN MODERATE RAINFALL AMOUNTS ACROSS MISIONES/CORRIENTES
IN ARGENTINA-SOUTHEAST PARAGUAY...WITH MAXIMA OF 20-45MM...WHILE
ACROSS SOUTHERN BRASIL EXPECTING ACCUMULATION OF 20-30MM. ON
WEDNESDAY ACTIVITY WEAKENS WHILE BUILDING EAST AND NORTH ACROSS
SOUTHEAST BRASIL...WITH ACCUMULATION OF 00-05MM/DAY.

SIMULTANEOUSLY...A PROGRESSIVE TROUGH ON THE SOUTHERN STREAM RACES
ACROSS THE SOUTHEAST PACIFIC TO SOUTHERN CHILE EARLY ON WEDNESDAY
MORNING...WITH AXIS SUPPORTING A PROGRESSIVE FRONT THAT RACES
ACROSS PATAGONIA TO CENTRAL ARGENTINA LATER IN THE DAY. THROUGH
THURSDAY EVENING...DRIVEN BY A PAMPERO LOW LEVEL JET...THE FRONT
WILL ACCELERATE ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA BASIN.
THIS WILL THEN INTERACT WITH/REINFORCE THE OLD BOUNDARY TO THE
NORTH. OVER SOUTHERN CHILE THIS WILL RESULT IN MODERATE RAINFALL
AMOUNTS WITH ACCUMULATION OF 20-35MM ON WEDNESDAY...WITH SIMILAR
AMOUNTS IN POTENTIALLY SEVERE CONVECTION ACROSS NORTHERN PATAGONIA
TO LA PAMPA IN ARGENTINA ON WEDNESDAY TO THURSDAY MORNING. ON
THURSDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF 15-20MM AS IT
SURGES ACROSS THE BUENOS AIRES PROVINCE TO CENTRAL ARGENTINA.

ON THE NORTHERN STREAM...AT MID LEVELS...A SHORT WAVE TROUGH IS TO
THEN STREAM ACROSS CENTRAL CHILE TO ARGENTINA EARLY ON THURSDAY
MORNING. AT 250 HPA A SUBTROPICAL JET MAXIMA IS TO ACCOMPANY THIS
PERTURBATION AS IT MAKES LANDFALL OVER CHILE...WITH UPPER LEVEL
JET MAXIMA TO THEN SUSTAIN A DIVERGENT PATTERN ALOFT AS IT STREAM
ACROSS CENTRAL ARGENTINA ON THURSDAY. THE MID LEVEL ENERGY AND
FAVORABLE UPPER LEVEL JET DYNAMICS WILL INCITE ORGANIZED DEEP
CONVECTION ALONG THE MEANDERING FRONT OVER SOUTHERN
BRASIL/NORTHERN ARGENTINA...WITH MAXIMA OF 35-70MM IN POTENTIALLY
SEVERE CONVECTION. ON FRIDAY-SATURDAY THE ENVIRONMENTAL CONDITIONS
BECOME FAVORABLE FOR AN MCS TO FORM OVER NORTHERN
ARGENTINA/SOUTHEAST PARAGUAY-SOUTHERN BRASIL...WITH MAXIMA IN THIS
AREA INCREASING TO 40-80MM. THIS WILL PERSIST THROUGH SATURDAY
WHILE BUILDING NORTH ACROSS PARANA/SANTA CATARINA TO SAO PAULO.

NORTH OVER THE DOMAIN...AT 250 HPA...A CLOSED HIGH TO THE
SOUTHWEST OF THE GALAPAGOS EXTENDS A RIDGE TO THE SOUTHEAST ACROSS
NORTHERN CHILE TO BOLIVIA/NORTHERN ARGENTINA/PARAGUAY...WHILE A
TROUGH TO THE EAST EXTENDS ACROSS SOUTHEAST BRASIL. THE
AFOREMENTIONED MID/UPPER LEVEL PERTURBATIONS STREAMING ACROSS THE
CONTINENT ARE TO PRESS AGAINST THE RIDGE TO THE NORTH...LEADING TO
ITS GRADUAL EROSION/DEMISE. IN RESPONSE...THE TROUGH TO THE EAST
IS EXPECTED TO PULL WHILE MEANDERING EAST ACROSS SOUTHEAST BRASIL
TO THE WESTERN ATLANTIC. DIURNAL CONVECTION OVER NORTHERN SOUTH
AMERICA WILL CONFINE TO AREA TO THE NORTH OF 10S...WITH MOST
ACTIVE OVER EQUATORIAL SOUTH AMERICA. IN THIS AREA EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY WITH MAXIMA OF 15-30MM IN
ASSOCIATION WITH EASTERLY WAVES PROPAGATING ACROSS NORTHERN SOUTH
AMERICA.

DAVISON...WPC (USA)
$$

062 
FXSA20 KWBC 271617
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1216 PM EDT MON SEP 27 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 27/16UTC: A BROAD MID/UPPER LEVEL
TROUGH IS INITIALIZED OVER THE SOUTHWEST ATLANTIC WITH AXIS
CENTERING ON A CLOSED LOW NEAR 50S 48W EARLY THIS MORNING. A
PROGRESSIVE TROUGH IN THE SOUTHERN STREAM CLOSELY FOLLOWS THIS
VORTEX...STREAMING ACROSS THE DRAKE PASSAGE/SOUTHERN CONE LATER
THIS EVENING. THROUGH TUESDAY AFTERNOON THIS WILL THEN INTERACT
WITH THE VORTEX TO THE EAST...FAVORING THE GENERATION OF A SHORT
WAVE TROUGH OFF THE COAST OF URUGUAY/SOUTHERN BRASIL. THE NORTHERN
STREAM PERTURBATION IS TO THEN MEANDER EAST ACROSS 40W WHILE
BOTTOMING OUT TO THE SOUTH OF 23S ON WEDNESDAY EVENING. THIS IS TO
THEN ORGANIZE INTO A CLOSED LOW NEAR 40S 30W LATER ON THURSDAY. 
AT LOW LEVELS...AN OCCLUDING LOW TO THE NORTH-NORTHWEST OF THE
SOUTH GEORGIA ISLANDS IS TO EXTEND A FRONT ACROSS THE WESTERN
ATLANTIC TO URUGUAY/CENTRAL ARGENTINA LATER THIS EVENING. ON
TUESDAY THE FRONT MEANDERS NORTH INTO SOUTHERN BRASIL WHILE
TRAILING ACROSS NORTHERN ARGENTINA. THE BOUNDARY IS TO BRIEFLY
STALL IN THIS AREA THROUGH WEDNESDAY EVENING. ACROSS CENTRAL
ARGENTINA THE FRONT IS TO INITIALLY FAVOR LIGHT CONVECTION...BUT
AS IT PUSHES NORTH INTO SOUTHERN BRASIL/NORTHERN ARGENTINA THE
BOUNDARY INTENSIFIES. ON THE SOUTHERN STATES OF BRASIL THIS WILL
SUSTAIN RAINFALL AMOUNTS OF 20-30MM ON TUESDAY...WHILE ON
WEDNESDAY IT WEAKENS TO 00-05MM/DAY. HIGHER AMOUNTS ARE EXPECTED
ACROSS CORRIENTES IN ARGENTINA...WHERE THIS WILL SUSTAIN RAINFALL
MAXIMA OF 20-45MM. ACTIVITY ALONG THIS BOUNDARY WEAKENS ON
WEDNESDAY...WHEN IT IS TO SUSTAIN LIGHT RAINFALL AMOUNTS OF
00-05MM/DAY.

SIMULTANEOUSLY...A PROGRESSIVE TROUGH ON THE SOUTHERN STREAM RACES
ACROSS THE SOUTHEAST PACIFIC TO SOUTHERN CHILE EARLY ON WEDNESDAY
MORNING. THIS IS TO THEN PULL AS IT ENTERS THE DRAKE
PASSAGE/PATAGONIA IN ARGENTINA AND CENTRAL REGIONS IN ARGENTINA ON
THURSDAY. AT LOW LEVELS THIS SUSTAINS A PROGRESSIVE FRONT ACROSS
SOUTHERN CHILE TO PATAGONIA IN ARGENTINA ON WEDNESDAY
MORNING...WITH BOUNDARY REACHING LA PAMPA/CENTRAL CHILE LATER IN
THE DAY AS A DEEPER PERTURBATION/STRONGER FRONT MAKES LANDFALL TO
THE SOUTH. THESE THEN COMBINE IN SUPPORT OF A PROGRESSIVE FRONT
THAT RACES ACROSS CENTRAL ARGENTINA/RIO DE LA PLATA BASIN LATER ON
THURSDAY...WITH BOUNDARY TO THEN INTERACT/REINFORCE THE
AFOREMENTIONED FRONT MEANDERING TO THE NORTH. OVER SOUTHERN CHILE
INITIALLY EXPECTING RAINFALL AMOUNTS OF 20-35MM...DECREASING TO
05-10MM ON TUESDAY. ON WEDNESDAY THIS SURGES AGAIN TO 20-35MM AS
THE STRONGER/DEEPER PERTURBATION MAKES LANDFALL OVER SOUTHERN
CHILE. OVER LA PAMPA/CENTRAL ARGENTINA THIS IS TO THEN SUSTAIN A
ROUND OF MODERATE/POTENTIALLY SEVERE CONVECTION ON WEDNESDAY
AFTERNOON...WITH MAXIMA OF 20-35MM. ON THURSDAY EXPECTING
ADDITIONAL RAINFALL AMOUNTS OF 15-20MM AS IT SURGES ACROSS THE
BUENOS AIRES PROVINCE TO CENTRAL ARGENTINA.

ON THE NORTHERN STREAM...AT MID LEVELS...A SHORT WAVE TROUGH IS TO
THEN STREAM ACROSS CENTRAL CHILE TO ARGENTINA EARLY ON THURSDAY
MORNING. AT 250 HPA A SUBTROPICAL JET MAXIMA IS TO ACCOMPANY THIS
PERTURBATION AS IT MAKES LANDFALL OVER CHILE...WITH UPPER LEVEL
JET MAXIMA TO THEN SUSTAIN A DIVERGENT PATTERN ALOFT AS IT STREAM
ACROSS CENTRAL ARGENTINA ON THURSDAY. THE MID LEVEL ENERGY AND
FAVORABLE UPPER LEVEL JET DYNAMICS WILL INCITE ORGANIZED DEEP
CONVECTION ALONG THE MEANDERING FRONT OVER SOUTHERN
BRASIL/NORTHERN ARGENTINA...WITH MAXIMA OF 35-70MM IN POTENTIALLY
SEVERE CONVECTION. ON FRIDAY-SATURDAY EXPECTING ADDITIONAL
RAINFALL AMOUNTS OF 25-50MM ALONG THIS BOUNDARY.

NORTH OVER THE DOMAIN...AN UPPER LEVEL HIGH TO THE SOUTH OF THE
GALAPAGOS ISLANDS EXTENDS A RIDGE TO THE SOUTHEAST ACROSS NORTHERN
CHILE TO BOLIVIA/NORTHERN ARGENTINA/PARAGUAY. UNDER THE INFLUENCE
OF THIS RIDGE A TROUGH IS TO THEN AMPLIFY ACROSS SOUTHEAST TO
CENTRAL BRASIL EARLY IN THE CYCLE. THROUGH THURSDAY...AS THE
AFOREMENTIONED PERTURBATIONS STREAM TO THE SOUTH...THE RIDGE IS
EXPECTED TO FLATTEN. IN RESPONSE TO THIS CHANGE THE TROUGH IS TO
THEN PULL WHILE MEANDERING EAST ACROSS SOUTHEAST BRASIL TO THE
WESTERN ATLANTIC. MEANWHILE...UNDER THE INFLUENCE OF THIS
TROUGH...SCATTERED DEEP CONVECTION WILL BUILD ACROSS CENTRAL TO
NORTHWEST BRASIL...WITH CONVECTION ACROSS TOCANTINS/GOIAS TO PARA
TO SUSTAIN RAINFALL AMOUNTS OF 15-20MM/DAY. OVER AMAZONAS TO THE
NORTHWEST INTO NORTHERN JUNGLE OF PERU/EASTERN ECUADOR THIS WILL
FAVOR RAINFALL MAXIMA OF 20-35MM. BUT AS THE TROUGH PULLS...THIS
WILL GRADUALLY WEAKEN TO 15-20MM/DAY LATER IN THE WEEK.

DAVISON...WPC (USA)
$$

028 
FXSA20 KWBC 171836
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 PM EDT FRI SEP 17 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 17/13UTC: PRODUCT NOT ISSUED

DAVISON...WPC (USA)
$$

030 
FXSA20 KWBC 171308
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
908 AM EDT FRI SEP 17 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 17/13UTC: PRODUCT NOT ISSUED

DAVISON...WPC (USA)
$$

647 
FXSA20 KWBC 161359
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
958 AM EDT THU SEP 16 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 16/15UTC: NORTHERN SOUTH AMERICA
REMAINS UNDER THE INFLUENCE OF A BROAD CELL OF THE SUBTROPICAL
RIDGE...WITH AXIS ENVELOPING CONTINENTAL AREA TO THE NORTH OF 20S.
DURING THE NEXT FOUR TO FIVE DAYS THE RIDGE IS EXPECTED TO BUILD
SOUTH ACROSS PARAGUAY TO NORTHERN PROVINCES IN ARGENTINA/RIO DE LA
PLATA BASIN. EARLY IN THE CYCLE THIS IS TO ANCHOR ON A CLOSED HIGH
OVER NORTHERN BOLIVIA...BUT AS THE RIDGE BUILDS DURING THE WEEKEND
THE HIGH WILL RELOCATE TO THE EAST-SOUTHEAST TO MATO GROSSO DO SUL
IN BRASIL. AT 250 HPA A SUBTROPICAL JET BOUNDS THE SOUTHERN
FRINGES OF THE CONTINENTAL RIDGE...WITH JET AXIS STRETCHING ACROSS
NORTHERN CHILE/ARGENTINA-SOUTHERN BRASIL/URUGUAY. BUT AS THE RIDGE
BUILDS DURING THE WEEKEND...IT WILL DISPLACE THE JET SOUTH ACROSS
CENTRAL CHILE/ARGENTINA. AT LOW LEVELS...THE JET ALOFT HELPS
SUSTAIN AN ELONGATED FRONT THAT TRAILS ACROSS THE CENTRAL
ATLANTIC-SOUTHEAST BRASIL TO CENTRAL BOLIVIA. THROUGH SATURDAY
MORNING...THE BOUNDARY IS FORECAST TO RETROGRESS ACROSS PARAGUAY
TO SOUTHERN BRASIL/NORTHERN ARGENTINA...WHERE IT WILL REMAIN
THROUGH SUNDAY AFTERNOON. EARLY NEXT WEEK...UNDER THE INFLUENCE OF
A MID LEVEL VORTEX TO THE SOUTH...A FRONTAL WAVE FORMS ALONG THE
BORDER OF URUGUAY/BRASIL. THIS IS FORECAST TO THEN DEEPEN WHILE
MEANDERING EAST INTO THE WESTERN ATLANTIC. AS THE FRONT MEANDERS
SOUTH ACROSS PARAGUAY/MISIONES IN ARGENTINA TO SOUTHERN
BRASIL...ENVIRONMENTAL CONDITIONS ARE TO BECOME FAVORABLE FOR AN
MCS TO DEVELOP ALONG THIS BOUNDARY. EARLY ON FRIDAY THIS WILL LEAD
TO RAINFALL MAXIMA OF 20-45MM...WHILE ON FRIDAY TO SATURDAY IT
INCREASES TO 35-70MM IN ORGANIZED DEEP CONVECTION. ON SUNDAY...AS
THE FRONTAL LOW FORMS OVER SOUTHERN BRASIL...MAXIMA SURGES AGAIN
TO 40-80MM...WITH LOCALLY HIGHER AMOUNTS HIGHLY LIKELY AS ENHANCED
BY THE UPPER LEVEL JET MAXIMA.

IN A SPLIT FLOW PATTERN TO THE SOUTH...WITH THE FLOW DIVIDING
BETWEEN A RIDGE OVER THE SOUTHEAST PACIFIC AND A SHORT WAVE TROUGH
OFF THE SOUTH COAST OF CHILE...THE PERTURBATION OFF THE SOUTH
COAST OF CHILE IS EXPECTED TO MEANDER EAST ACROSS THE SOUTHERN
CONE...WHILE SIMULTANEOUSLY SHEARING A SHORT WAVE TROUGH THAT
LIFTS NORTH ALONG THE SOUTHERN TO CENTRAL COAST OF CHILE ON
SUNDAY. BLOCKED BY THE ANDES...THE DEEP SHORT WAVE TROUGH IS TO
THEN REMAIN OFF THE CENTRAL COAST OF CHILE THROUGH EARLY NEXT
WEEK. AT LOW LEVELS...THIS WILL SUSTAIN A BROAD FRONTAL TROUGH
OVER SOUTHERN CHILE/PATAGONIA IN ARGENTINA LATER TODAY...WITH AXIS
TO SLOWLY FILL WHILE MEANDERING OVER THE SOUTHERN CONE THROUGH
SATURDAY. AS IT WEAKENS...ASSOCIATED SURFACE FRONT IS NOW EXPECTED
TO STALL OVER LA PAMPA IN ARGENTINA. MOST ACTIVE CONVECTION WITH
THIS SYSTEM IS EXPECTED EARLY IN THE CYCLE AS IT MAKES LANDFALL
OVER THE SOUTHERN REGIONS OF CHILE...WITH RAINFALL MAXIMA OF
20-45MM. ON FRIDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS OF
15-25MM TO CLUSTER TO THE SOUTH OF TEMUCO/PUERTO MONTT. AS THE
FRONT MEANDERS NORTH ACROSS PATAGONIA TO LA PAMPA ON SATURDAY...IT
WILL RESULT IN RAINFALL AMOUNTS OF 05-10MM. THIS INCREASES TO
15-20MM ON SUNDAY WHILE BUILDING NORTH ACROSS CENTRAL ARGENTINA.

OVER NORTHERN SOUTH AMERICA...MEANWHILE...EASTERLY WAVES
PROPAGATING TO THE NORTH ARE TO ENHANCE DEVELOPMENT ACROSS
EQUATORIAL SOUTH AMERICA. INITIALLY THE MOST ACTIVE IS EXPECTED
ACROSS NORTHWEST BRASIL WITH MAXIMA OF 20-35MM. BUT AS MJO PATTERN
TRANSITIONS TO ITS CONVERGENT PHASE...ENVIRONMENTAL CONDITIONS ARE
TO BECOME MORE HOSTILE TO DEVELOPMENT. AS A RESULT...ACTIVITY
ACROSS NORTHERN BRASIL/PERU-EASTERN ECUADOR WILL TEND TO WEAKEN
DURING THE WEEKEND/EARLY NEXT WEEK.

DAVISON...WPC (USA)
$$

835 
FXSA20 KWBC 151535
PMDSA 

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1134 AM EDT WED SEP 15 2021

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

FORECAST DISCUSSION FROM SEP 15/16UTC: THE UPPER LEVELS FLOW OVER
NORTHERN SOUTH AMERICA REMAINS UNDER THE INFLUENCE OF A STRONGER
THAN NORMAL CELL OF THE SUBTROPICAL RIDGE. THE RIDGE ALOFT
DOMINATES THE FLOW OVER THE CONTINENT TO THE NORTH OF 20S...WITH
MODELS TENDING IN FAVOR OF A STRONGER RIDGE TOWARDS THE END OF THE
FORECAST CYCLE. EARLY IN THE CYCLE THE RIDGE IS TO CENTER ON A
MEANDERING CLOSED HIGH OVER MATO GROSSO IN BRASIL. THROUGH FRIDAY
EVENING THE HIGH IS TO MEANDER WESTWARD ACROSS SANTA CRUZ TO
CENTRAL BOLIVIA. BUT AS IT BUILDS LATER DURING THE WEEKEND...THE
HIGH IS TO ONCE AGAIN MEANDER BACK TO MATO GROSSO IN BRASIL. AT
250 HPA...AN ANTICYCLONICALLY CURVED SUBTROPICAL JET MAXIMA BOUNDS
THE SOUTHERN FRINGES OF THIS RIDGE...WITH AXIS EXTENDING ACROSS
NORTHERN CHILE/ARGENTINA-URUGUAY/SOUTHERN BRASIL. AT LOW LEVELS
THE PERSISTENT UPPER LEVEL JET IS TO HELP SUSTAIN A SURFACE FRONT
THAT MEANDERS ACROSS NORTHERN SAO PAULO-MATO GROSSO DO SUL TO
CENTRAL BOLIVIA. THROUGH THE END OF THE WEEK THE FRONT IS TO
RETROGRESS TO PARAGUAY/SOUTHERN BRASIL...WITH A FRONTAL LOW
FORMING OVER RIO GRANDE DO SUL ON SATURDAY. OVER SOUTHERN SAO
PAULO-SANTA CATARINA THE FRONT IS TO FAVOR SCATTERED CONVECTION
WITH ACCUMULATION OF 20-35MM DURING THE DAY TODAY. ON
THURSDAY...AS THE FRONT STARTS TO RETROGRESS...THE FOCUS OF THE
ACTIVITY SHIFTS TO PARANA/SANTA CATARINA WITH MAXIMA OF 15-30MM.
SHORT WAVE VORTICES ON THE NORTHERN STREAM WILL THEN HELP SUSTAIN
A SURGE IN CONVECTION AND POTENTIALLY FORMATION OF AN MCS ACROSS
SOUTHERN BRASIL-MISIONES ARGENTINA TO SOUTHEAST PARAGUAY ON FRIDAY
TO SATURDAY...WHERE IT IS TO FAVOR MAXIMA OF 35-70MM.

SIMULTANEOUSLY...A BROAD POLAR TROUGH IN THE SOUTHERN STREAM IS TO
AMPLIFY BETWEEN THE WEDDELL SEA-THE MALVINAS/FALKLAND ISLANDS
EARLY IN THE CYCLE...WITH AXIS REACHING MAXIMUM AMPLITUDE ON
THURSDAY-FRIDAY WHILE MEANDERING EAST ACROSS THE SOUTH GEORGIA
ISLANDS. A SLOWER SHORT WAVE TROUGH IS TO FOLLOW...REACHING THE
SOUTHERN CONE LATER ON THURSDAY. THIS IS TO SLOWLY PUSH EAST
ACROSS THE SOUTHERN CONE DURING THE WEEKEND WHILE PRESSING AGAINST
A RIDGE TO THE EAST. AT LOW LEVELS...A BROAD POLAR TROUGH IS TO
EXTEND OVER THE SOUTH ATLANTIC AND TO THE EAST OF 60W DURING THE
NEXT COUPLE OF DAYS...WHILE A TRAILING FRONTAL TROUGH REACHES THE
SOUTH COAST OF CHILE EARLY ON THURSDAY MORNING. THROUGH FRIDAY
EVENING THIS IS TO THEN SLOWLY MOVE ACROSS THE SOUTHERN CONE TO
THE WESTERN ATLANTIC. DURING THE WEEKEND A BUILDING POLAR RIDGE TO
THE SOUTH IS TO THEN DISPLACE THE ASSOCIATED FRONT NORTH ACROSS
CENTRAL TO NORTHERN ARGENTINA. OVER SOUTHERN CHILE THE DEEPENING
FRONTAL LOW WILL SUSTAIN MODERATE RAINFALL AMOUNTS EARLY IN THE
CYCLE...WITH ACCUMULATION OF 20-35MM. ON THURSDAY THIS INCREASES
TO 20-45MM...WHILE ON FRIDAY EXPECTING ADDITIONAL RAINFALL AMOUNTS
OF 15-25MM. AS THE FRONT SURGES ACROSS CENTRAL ARGENTINA ON
SATURDAY IT IS TO TRIGGER MODERATE CONVECTION OVER CORDOBA WITH
MAXIMA OF 15-20MM. HIGHER AMOUNTS ARE EXPECTED TO THE NORTH ACROSS
RIO GRANDE DO SUL-CORRIENTES IN ARGENTINA...WHERE CONDITIONS ARE
TO ONCE AGAIN BECOME FAVORABLE FOR AN MCS TO DEVELOP AS DEEP
SUBTROPICAL MOISTURE POOLS ALONG THE SURFACE FRONT. ON SUNDAY TO
MONDAY THIS IS TO THEN SUSTAIN RAINFALL MAXIMA OF 40-80MM.

OTHER CONVECTION IS EXPECTED TO THE NORTH OVER THE
CONTINENT...WITH THE BROAD UPPER LEVEL CELL OF THE SUBTROPICAL
RIDGE OVER BRASIL VENTING DIURNAL AND EASTERLY WAVE RELATED
CONVECTION OVER EQUATORIAL SOUTH AMERICA. MOST ACTIVE IS TO
INITIALLY CLUSTER BETWEEN ACRE/RONDONIA-AMAZONA IN BRASIL WITH
MAXIMA OF 20-35MM IN SCATTERED CONVECTION. ON THURSDAY THIS SHIFTS
WEST AND NORTH ACROSS THE PERUVIAN JUNGLE TO EASTERN
ECUADOR...FLARING UP ACROSS NORTHERN AMAZONIA-SOUTHERN COLOMBIA ON
FRIDAY-SATURDAY.

DAVISON...WPC (USA)
$$