National Weather Service Raw Text Product

714 
FXUS63 KDVN 230529
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1129 PM CST TUE DEC 22 2015

...AVIATION UPDATE...

.SYNOPSIS...
ISSUED AT 405 PM CST TUE DEC 22 2015

LOW STRATUS ACROSS THE CWA MUCH OF TODAY WAS FINALLY BEING SCOURED
OUT DUE TO STRENGTHENING LOW/MID LEVEL WARM AIR ADVECTION. THIS
TREND HAS REACHED OUR SOUTHWEST CWA AND WILL CONTINUE TO SPREAD TO
THE NORTHEAST. TEMPERATURES HAVE PUSHED INTO THE LOWER 40S WHERE
SOME SUN HAS RETURNED BUT IN AREAS WHERE THE LOW STRATUS REMAINS
READINGS WERE IN THE 30S. 

ELSEWHERE...WARM TEMPERATURES WERE FOUND FROM THE SOUTHERN PLAINS/
LOWER MS VALLEY INTO THE OH VALLEY. READINGS THERE WERE WELL INTO THE
60S AND 70S. IN CONTRAST TEMPERATURES WERE ONLY IN THE 20S WITH
SNOW FALLING ACROSS ND AND NW MN. THIS STRONG THERMAL GRADIENT
WILL HELP SET THE STAGE FOR AN INTENSE STORM SYSTEM ON WEDNESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 405 PM CST TUE DEC 22 2015

FORECAST FOCUS ON INTENSE LATE DECEMBER STORM SYSTEM.

TONIGHT...STRONG LOW AND MID LEVEL WARM/MOIST AIR ADVECTION WILL
BE IN PLACE ACROSS THE CWA. MOISTENING FROM THE TOP DOWN WILL
GRADUALLY LEAD TO RAIN CHANCES AFTER MIDNIGHT MAINLY WEST OF THE
MS RIVER. BY MORNING SATURATION IS COMPLETE IN OUR WESTERN CWA AND
BY THEN LIKELY POPS ARE IN ORDER. DUE TO A STEADY SOUTHEAST TO
SOUTH WIND AND THICKENING MID/HIGH LEVEL CLOUDS TEMPERATURES WILL
ACTUALLY BE RISING ALL NIGHT. BY LATE TONIGHT READINGS SHOULD BE
WELL INTO THE 40S TO AROUND 50 OVER MOST OF THE CWA...IF NOT
SOMEWHAT HIGHER.

WEDNESDAY...STORM SYSTEM TO IMPACT THE MIDWEST AS AN INTENSE
CYCLONE TRACKS FROM THE SOUTHERN PLAINS TO CENTRAL IA BY NOON
(984 MB) AND THEN TO NORTHERN WI BY EVENING (981 MB). THIS WILL
PULL DEEP MOISTURE NORTHWARD ON A 60 KNOT LOW LEVEL JET WITH
PWAT'S INCREASING TO OVER 1 INCH. AHEAD OF THE COLD FRONT VERY
STRONG DEEP LAYER SHEAR WILL EXIST BUT CAPE WILL BE MINIMAL. THE
SEVERE THREAT (INCLUDING TORNADOES...SOME STRONG) LOOKS TO BE
SOUTH AND EAST OF THE DVN CWA WHERE THE AXIS OF THE STRONGEST LOW
LEVEL JET AND HIGHER CAPE WILL BE LOCATED. HOWEVER...IF OUR
EAST/SOUTHEAST CWA CAN GET ENOUGH SUNSHINE DURING THE AFTERNOON
AND A BIT MORE INSTABILITY THEN AT LEAST ISOLATED DAMAGING WIND OR
HAIL IS POSSIBLE...AND A BRIEF TORNADO CAN'T BE RULED OUT. SPC HAS
PULLED THE MARGINAL RISK A BIT FARTHER WEST INTO EXTREME EASTERN
IA. OTHERWISE...MODERATE TO LOCALLY HEAVY RAINFALL IS LIKELY WHICH
WOULD AGGRAVATE THE ALREADY ONGOING RIVER FLOODING SITUATION.
WIDESPREAD RAINFALL AMOUNTS LOOK TO BE ABOUT 1/2 TO 1 INCH...LOCALLY
HIGHER IN THUNDERSTORMS. FOR MORE DETAILS SEE HYDROLOGY SECTION
BELOW. I WILL CONTINUE TO MENTION ISOLATED STORMS IN THE MORNING
THEN SCATTERED COVERAGE IN THE AFTERNOON...IN ADDITION TO THE
WIDESPREAD RAINFALL. POPS WILL BE AT 100 PERCENT. THE 12Z/22 SPC
WRF-NMM DEPICTS A LINE OF POTENTIAL STRONG THUNDERSTORMS DEVELOPING
LATE IN THE AFTERNOON ALONG AND EAST OF THE MS RIVER. THIS WOULD
BE ALONG/AHEAD OF A DRY SLOT ARRIVING FROM THE SOUTHWEST.

MAXIMUM TEMPERATURES SHOULD RANGE FROM THE UPPER 40S AT INDEPENDENCE
TO 63 AT MACOMB. DUE TO THE BRUNT FORCE OF THE WARM/MOIST ADVECTION
AND SUCH AN INTENSE CYCLONE TRACKING TO OUR WEST I WILL BE ASSERTIVE
AND FORECAST A RECORD HIGH TEMPERATURE AT MOLINE. THE CURRENT RECORD
FOR DECEMBER 23 IS 59 SET IN 1982...WHICH HAPPENED TO ALSO BE A STRONG
EL NINO WINTER (1982-83). AT THIS TIME RECORDS ARE NOT EXPECTED AT
THE OTHER MAIN CLIMATE SITES. SEE CLIMATE SECTION BELOW.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 405 PM CST TUE DEC 22 2015

WEDNESDAY NIGHT...SFC COLD WILL MOVE EAST OF THE DVN CWA BETWEEN 6
TO 8 PM CST....TAKING THE SHOWERS AND THUNDERSTORMS WITH IT.
THEREFORE...THE THREAT FOR STRONG OR SEVERE THUNDERSTORMS IS
PRIMARILY WEDNESDAY AFTERNOON INTO THE EVENING...LINGERING THROUGH 6
OR 7 PM CST ACROSS THE EASTERN CWA. POTENTIAL FOR SEVERE WEATHER IS
COVERED IN THE SHORT TERM SECTION OF THIS AFD.

BEHIND THE COLD FRONT EXPECT WESTERLY WIND GUSTS NEAR 30 MPH AS COLD
AIR ADVECTION DROPS TEMPS ROUGHLY 30 DEGREES FROM DAYTIME
HIGHS...REACHING THE LOWER 30S MOST AREAS...AND UPPER 20S FAR NW CWA
BY EARLY THURSDAY MORNING. RAIN SHOWERS WILL DIMINISH THROUGH THE
OVERNIGHT AS FORCING FOR ASCENT ASSOCIATED WITH THE STRENGTHENING
SFC LOW...FORECAST TO REACH CENTRAL ONTARIO BY 06Z/THURSDAY...
RAPIDLY SHIFTS OFF TO THE NORTHEAST. 

THURSDAY...CHRISTMAS EVE DAY...OVERALL LOOKS PLEASANT FOR THIS TIME
OF YEAR. HIGHS ARE FORECAST TO RANGE FROM THE MID 30S NW...LOWER 40S
ALONG I-80...TO MID 40S FAR SOUTH. MENTIONED A SLIGHT CHANCE FOR
RAIN/SNOW SHOWERS OVER NW HALF OF THE FORECAST AREA. MODELS ARE
HINTING AT A WEAK MID-LEVEL FRONTOGENETIC BAND OF FORCING TO MOVE
FROM SW TO NE THROUGH THIS REGION. NO ACCUMULATION IS EXPECTED AT
THIS TIME. 

THE 12KM NAM SHOWS A SLIGHTLY STRONGER BAND OF PRECIP THAN THE OTHER
MODELS BUT HAS A MORE NW PLACEMENT OVER WESTERN AND NORTH-CENTRAL
IOWA...WEST OF THE DVN CWA. THIS SCENARIO PROBABLY WOULD SUPPORT A
NARROW BAND OF MINOR SNOW ACCUMULATIONS IN THE AFOREMENTIONED AREA.
WHAT WE WILL HAVE TO WATCH FOR IS SHIFTS IN MODEL PLACEMENT OF THE
BAND OVER THE NEXT FEW MODEL RUNS.

FRIDAY...CHRISTMAS DAY...MILD AND QUIET...HIGHS IN THE UPPER 30S TO
MID 40S. A SFC HIGH IS FORECAST TO CROSS THE WESTERN GREAT LAKES
WITH ANOTHER LEE-SIDE LOW DEVELOPING EAST OF THE FOUR CORNERS. WARM
AIR ADVECTION DOWNSTREAM OF THE LEE-SIDE LOW SHOULD LEAD TO
INCREASING MOISTURE/CLOUDS THROUGH THE DAY AND A CHANCE FOR LIGHT
RAIN SHOWERS AT NIGHT.

SATURDAY AND SATURDAY NIGHT...MODEL CONSENSUS IS FOR A WIDE RANGE IN
PRECIP CHANCES ACROSS THE DVN CWA. HAVE SLIGHT CHANCES ACROSS THE
FAR NW...NEAR 40-50 POPS ALONG I-80...TO 60-70 POPS OVER THE
SOUTHERN TIER OR TWO OF COUNTIES/ALONG AND SOUTH OF HIGHWAY 34. THE
RIGHT ENTRANCE REGION OF A 300MB JET STREAK IS PROJECTED TO SLIDE
ACROSS THE UPPER MISSISSIPPI VALLEY DURING THIS TIME...WHILE 850MB
WAA INCREASES AND WV TRANSPORT VECTORS BECOME ORIENTED PERPENDICULAR
TO THE UPPER-LEVEL JET AXIS. AS PRECIP ENDS...COLD AIR ADVECTION
DOES WARRANT AT LEAST A MENTION OF A RAIN/SNOW MIX LATE SATURDAY
NIGHT MOSTLY NORTH OF I-80...CHANCES FOR ANY ACCUMULATIONS OF SNOW
AT THIS TIME ARE VERY LOW.

SUNDAY...IMMEDIATELY BEHIND THE SATURDAY/SATURDAY NIGHT JET STREAK
UPPER-LEVEL RIDING AND A COLD POOL OF SFC-850MB AIR SUPPORTS THE
FORMATION OF A MODERATELY STRONG SFC HIGH OVER THE UPPER MIDWEST AND
SOUTH-CENTRAL CANADA. GFS/ECMWF/CANADIAN ARE IN BETTER AGREEMENT
WITH DRY AIR ADVECTION ON SUNDAY VIA NE SFC WINDS...HOLDING MOST IF
NOT ALL OF THE PRECIP TO THE SOUTH OF THE FORECAST AREA. FORECAST
HIGHS RANGE FROM LOWER 30S NW TO LOWER 40S SE.

MONDAY...PLENTY OF TIME FOR THIS FORECAST TO CHANGE BUT CURRENT
TREND IS FOR A LOWER HEAVY RAIN THREAT AND INCREASED POTENTIAL FOR
AT LEAST SOME FROZEN PRECIP. ECMWF TRACKS THE LOW FURTHER TO THE NW
ACROSS CENTRAL IOWA COMPARED TO THE GFS WHICH IS ACROSS E IOWA. THUS
THE ECMWF HAS WARMER THERMAL PROFILES AND MAINLY RAIN. GFS MAY BE
SHOWING A GREATER EFFECT FROM EVAPORATIVE COOLING...GIVING MOST OF
THE DVN CWA A PERIOD OF SLEET OR SNOW AS THE PRECIP MOVES IN BEFORE
CHANGING TO RAIN. 12Z/12.22 DETERMINISTIC GFS WAS IN FAIRLY GOOD
AGREEMENT WITH THE GFS ENSEMBLE MEAN REGARDING THE TRACK OF THE SFC
LOW. THE HEAVIEST RAIN ASSOCIATED WITH THE WAA/WARM FRONT MAY MISS
THE LOCAL AREA TO THE EAST...FOCUSING OVER THE OHIO VALLEY
WHICH WOULD BE GOOD FOR LOCAL RIVER LEVELS. STAY TUNED. UTTECH

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1122 PM CST TUE DEC 22 2015

GENERALLY CLOUDY SKIES WITH IFR TO LOWER END MVFR CONDITIONS AT ALL
THE TERMINALS THE NEXT 18 TO POSSIBLY 24 HOURS. A FAST MOVING DISTURBANCE
FROM TEXAS WILL MOVE ACROSS THE AREA OVERNIGHT AND WEDNESDAY. LOW
CLOUDS WILL PERSIST OVER THE NEXT 18 HOURS WITH SPOTTY LIGHT FOG
TONIGHT AND INTO WEDNESDAY MORNING. AREAS OF LIGHT TO BRIEFLY MODERATE
RAIN WILL OVERSPREAD THE REGION BETWEEN 23/07Z AND 23/13Z EARLY WEDNESDAY
AND POSSIBLY WITH ISOLATED EMBEDDED STORMS NEAR MLI/BRL TERMINALS IN
THE AFTERNOON HOURS. THE COVERAGE OF PM PRECIPITATION COVERAGE
WARRANTS A PROB30 GROUPING AT BEST. SOUTHERLY WINDS OF 10 TO 20
KTS WILL SHIFT LATE PM TO THE WEST AT 15 TO 30 KTS WITH CLEARING
ARRIVING AROUND 4/06Z OR A BIT LATER.

&&

.HYDROLOGY...
ISSUED AT 405 PM CST TUE DEC 22 2015

HYDROLOGY...RAINFALL AMOUNTS OF A QUARTER INCH TO THREE QUARTERS OF
AN INCH FELL OVER THE PAST 48 HOURS GENERALLY SOUTH OF A LINE FROM
MARENGO TO BELLEVUE. WITH SATURATED GROUND...NEARLY ALL OF THIS
RAINFALL WILL BECOME RUNOFF LEADING TO THE CONTINUED THREAT FOR
MINOR TO MODERATE RIVER FLOODING...AND RECORD HIGH RIVER LEVELS BY
DECEMBER STANDARDS.

ALONG THE MISSISSIPPI...MOST SITES WILL EXPERIENCE RISES THROUGH
THIS WEEK WITH THE PROBABILITY FOR MINOR FLOODING INCREASING BY
THURSDAY.

A ROUND OF MODERATE RAIN IS LIKELY ON WEDNESDAY. ADDITIONAL RAIN
IS FORECAST FOR SATURDAY BUT SHOULD BE MAINLY LIGHT. YET ANOTHER
PRECIPITATION EVENT IS POSSIBLE SUNDAY NIGHT AND MONDAY. THUS...THERE
IS POTENTIAL FOR RIVER FLOODING THROUGH THE CHRISTMAS HOLIDAY
WEEKEND AND INTO NEXT WEEK.

&&

.CLIMATE...
ISSUED AT 405 PM CST TUE DEC 22 2015

RECORD HIGHS FOR DECEMBER 23...

MOLINE.........59 IN 1982
CEDAR RAPIDS...56 IN 1965
DUBUQUE........58 IN 1888
BURLINGTON.....64 IN 1933

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...UTTECH
AVIATION...NICHOLS
HYDROLOGY...UTTECH
CLIMATE...HAASE