National Weather Service Raw Text Product

000 
AXNT20 KNHC 191735
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 
205 PM EDT SAT 19 APR 2003

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...AND ATLANTIC OCEAN
TO THE AFRICAN COAST FROM THE EQUATOR TO 32N INCLUDING NORTHERN 
SECTIONS OF SOUTH AMERICA. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

SPECIAL FEATURES...
NONE.

TROPICAL WAVES/ITCZ...
AXIS OF ITCZ-RELATED CLOUDS/CONVECTION IS CENTERED ALONG 3N0 
4N20W 5N37W 3N52W. SCATTERED MODERATE CONVECTION FROM EQ-6N 
BETWEEN 3W-8W. WIDELY SCATTERED MODERATE WITHIN 60NM OF THE AXIS 
BETWEEN 18W-35W. WIDELY SCATTERED MODERATE ALONG THE SEA BREEZE 
ON THE BRAZILIAN COAST FROM EQ-4N BETWEEN 50W-53W.

MIDDLE/UPPER LEVEL SYNOPTIC FEATURES...
THE PATTERN FINALLY SEEMS TO BE GETTING A LITTLE MORE 
PROGRESSIVE AS THE MODELS SEEM READY TO NUDGE THE WRN ATLC 
TROUGH TO THE E...ALBEIT A LITTLE TOO LATE FOR RESIDENTS OF 
PUERTO RICO AND THE VIRGIN ISLANDS. ASIDE FROM THIS MAIN WEATHER 
FEATURE...THE REMAINDER OF THE ATLC BASIN REMAINS QUIET WITH 
UPPER LEVEL RIDGING OVER THE GLFMEX AND ERN ATLC.

AN UPPER LEVEL RIDGE CURRENTLY STRETCHES FROM THE ERN PACIFIC 
NWD ACROSS THE GLFMEX INTO THE MISSISSIPPI VALLEY OF THE UNITED 
STATES AND IS PRODUCING RELATIVELY BENIGN WEATHER FROM MEXICO TO 
FLORIDA. THE SUBTRPCL JET HAS BEEN PUSHED TO THE N FROM NRN 
MEXICO INTO TEXAS AND THIS IS GOING TO KEEP THE BEST 
SYNOPTIC-SCALE DYNAMICS N OF THE AREA OVER THE NEXT SEVERAL 
DAYS. ABUNDANT UPPER LEVEL MOISTURE IS STREAMING JUST S OF THE 
MAIN JET CORE OVER NRN MEXICO AND A GOOD CHUNK OF THE GLFMEX BUT 
THIS ONLY PRODUCING SOME HIGH LEVEL CIRRUS OVER THE AREA AS 
STRONG RIDGING REMAINS IN PLACE. A TROUGH OVER THE ROCKY 
MOUNTAIN STATES IS DROPPING SE WITH A DEVELOPING COLD FRONT OVER 
CNTRL TEXAS POISED TO SKIRT THE GULF COAST THROUGH MONDAY AND 
TUESDAY.

AND NOW TO THE MAJOR FEATURE OF THE DAY...A LARGE UPPER LEVEL 
TROUGH COVERS MUCH OF THE WRN ATLC FROM A CYCLONIC CIRCULATION 
NEAR 34N69W SWD TO THE CNTRL CARIBBEAN. DRY UPPER LEVEL AIR 
STRADDLES THE TROUGH AXIS MAINLY TO THE W TOWARDS FLORIDA...BUT 
THIS SYSTEM HAS BEEN ANYTHING BUT DRY OVER THE PAST SEVERAL 
DAYS. A DEEP PLUME OF TRPCL MOISTURE IS MOVING FROM THE AMAZON 
BASIN NWD ACROSS THE ERN CARIBBEAN TO THE E OF THE TROUGH AXIS 
BEFORE TURNING ANTICYCLONICALLY INTO THE CNTRL ATLC. THE TROUGH 
CONTINUES SW ACROSS THE SW CARIBBEAN AS A SHEAR ZONE WHERE 
STRONG SUBSIDENCE IS OCCURRING FROM 7N-14N BETWEEN 
74W-83W...SANDWICHED BETWEEN THE ERN PACIFIC RIDGE AND A TRPCL 
RIDGE TO THE E. THE UKMET SHOWS THAT THE TROUGH IS FINALLY 
BEGINNING TO MOVE EWD WITH THE STRONGEST UPPER LEVEL DIVERGENCE 
MOVING INTO THE CNTRL ATLC. HOWEVER...WEAK DIVERGENCE AND HIGH 
RH VALUES OVER THE GREATER ANTILLES WILL KEEP THE THREAT OF 
SHOWERS AND TSTMS HIGH THROUGH LATE SUNDAY AS THE TAIL END OF 
THE SURFACE TROUGH REMAINS OVER THE AREA. IN ADDITION...THE MAIN 
SURFACE LOW WILL DROP S OF 30N AND IS FORECAST TO MOVE LITTLE 
THROUGH TUESDAY EVENING. THE AREA OF SUBSIDENCE OVER CUBA AND 
THE BAHAMAS WILL SLOWLY INCH EWD TOWARDS HISPANIOLA AND THE 
CNTRL CARIBBEAN WITH DRYING OCCURRING THROUGH THE DAY MONDAY 
INTO TUESDAY FROM WEST TO EAST.

IN THE CNTRL ATLC...RIDGING IS THE RULE WITH ONE AXIS STRETCHING 
FROM 14N50W TO 32N53W AND A SECOND RIDGE AXIS EXTENDING FROM ERN 
PANAMA EWD ACROSS NRN S AMERICA INTO THE TRPCL ATLC. UPPER LEVEL 
MOISTURE FROM NRN S AMERICA HAS ENVELOPED MUCH OF THE CNTRL ATLC 
N OF 17N BUT MODERATE SUBSIDENCE IS LOCATED ALONG THE TRPCL 
RIDGE BETWEEN 4N-17N E OF 61W. THE N/S RIDGE WILL SLOWLY MOVE 
EWD WITH CONVECTION BECOMING MORE NUMEROUS OVER THE AREA THROUGH 
THE REST OF THE WEEKEND.

A TROUGH IS LOCATED OVER THE ERN ATLC WITH THE MAIN AXIS 
EXTENDING FROM 10N40W TO THE CANARY ISLANDS. MODERATE SUBSIDENCE 
IS LOCATED WITHIN 300NM OF THE TROUGH AXIS WITH A SMALL AREA OF 
STRONG SUBSIDENCE DEVELOPING ABOUT 200NM NW OF THE CAPE VERDE 
ISLANDS. A STRONG 90+ KT JET IS LOCATED ON THE ERN SIDE OF THE 
TROUGH FROM THE CAPE VERDE ISLANDS NE INTO MOROCCO AND ALGERIA 
BUT THIS FEATURE WILL QUICKLY EXIT THE REGION LATER TODAY. 
MOISTURE IS LIMITED WITH THE SYSTEM BUT THE CHANCE OF SHOWERS 
AND TSTMS WILL INCREASE THROUGH SUNDAY EVENING NEAR THE CANARY 
ISLANDS AS A SHORTWAVE TROUGH DROPS SE FROM THE N ATLC AND 
INCREASED UPPER LEVEL DIVERGENCE MOVES ONSHORE MOROCCO AND THE 
IBERIAN PENINSULA.
    
SURFACE SYNOPTIC FEATURES...
BROAD LOW PRESSURE OVER NRN AND CNTRL MEXICO EXTENDS INTO THE 
WRN GLFMEX...AHEAD OF A DEVELOPING LOW/FRONT OVER TEXAS.

A RIDGE AXIS EXTENDS FROM THE SE UNITED STATES DOWN THE FLORIDA 
PENINSULA AND INTO THE WRN CARIBBEAN.

1010 MB LOW CENTERED NEAR 34N68W WITH A BROAD TROUGH AXIS 
STRETCHING TO 27N67W TO 21N69W. A SECOND TROUGH AXIS STRETCHES 
FROM 22N65W TO 30N62W...CONTINUING TO THE N AS A WEAK COLD 
FRONT. THIS AXIS ACTUALLY LOOKS MORE LIKE A CONVERGENCE LINE 
BETWEEN STRONG SELY WINDS OVER THE CNTRL ATLC AND WEAK NWLY 
WINDS OVER THE WRN ATLC...WITH CONVECTION FORMING OVER THIS 
AREA. THE SYSTEM HAS AN IMPRESSIVE COMMA SIGNATURE WITH 
RELATIVELY CLEAR SKIES W OF 63W OVER MOST OF THE SW ATLC. WIDELY 
SCATTERED MODERATE CONVECTION BETWEEN 59W-64W N OF 23N.

ELY/SELY FLOW COVERS ALL OF THE CNTRL AND ERN ATLC S OF 30N 
BETWEEN AFRICA AND 60W.

SIGNIFICANT CLOUDS/CONVECTION...
GULF OF MEXICO...
SCATTERED MULTI-LEVEL CLOUDS NW OF A LINE FROM TAMPICO MEXICO TO 
BATON ROUGH LOUISIANA...AHEAD OF A DEVELOPING COLD FRONT. 
ISOLATED SHOWERS POSSIBLE UP TO 100NM OF THE COAST OF 
TEXAS/LOUISIANA.

CARIBBEAN SEA...
ISOLATED SHOWERS AND TSTMS WITHIN 120NM OF LAKE MARACAIBO IN 
VENEZUELA TO PUERTO RICO AND THE VIRGIN ISLANDS. SAN JUAN RADAR 
IMAGERY INDICATES SHOWERS AND TSTMS PRIMARILY TO THE E OF PUERTO 
RICO OVER THE VIRGIN ISLANDS AS WELL AS TO THE SW OF THE ISLAND.

TROPICAL ATLANTIC...
SEE ITCZ.

SUBTROPICAL ATLANTIC...
SEE SURFACE SYNOPTIC FEATURES.

$$
BERG