Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 271401
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1000 AM EDT WED AUG 27 2014

...VALID 15Z WED AUG 27 2014 - 12Z THU AUG 28 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 N ONL 30 WSW FSD 20 SE FSD 15 SSW SPW 20 ESE SLB 20 ESE CIN
20 W DSM 20 WSW CNC 20 ESE LWD 20 WNW CDJ 10 ENE TOP TOP
25 WNW FOE 10 NNE MHK 25 N MHK 40 SSE BIE 15 W FNB 20 SW AFK
10 S LNK 20 WNW LNK HSI 20 SSE HDE 30 NNW HLC 45 S MCK
30 ENE GLD 40 N GLD 20 WNW IML 45 N OGA 40 NW TIF 20 NNE ANW
50 N ONL.


1400 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO EXPAND THE SLIGHT RISK AREA TO THE SOUTHEAST TO COVER PORTIONS
OF FAR SOUTHEAST NEBRASKA---FAR NORTHEAST KANSAS---FAR SOUTHWEST
IA INTO NORTHWESTERN MISSOURI.  THIS IS FOR CONVECTION THAT HAS
ENHANCED ALONG AND TO THE NORTH OF THE STATIONARY FRONTAL BOUNDARY
CURRENTLY STRETCHING FROM SOUTHERN NEBRASKA---EAST SOUTHEASTWARD
THROUGH NORTHEAST KANSAS AND NORTHERN NEBRASKA.  IT APPEARS THAT
CLOUD TOPS ARE BEGINNING TO WARM WITH THE ACTIVITY OVER NORTHERN
MISSOURI/SOUTHERN IOWA---SIGNALING THE TYPICAL POST 1200 UTC
WEAKENING.  HOWEVER---IN THE SHORT TERM OVER THE NEXT HOUR OR
TWO---SLOW MOVEMENT OF CELLS WILL SUPPORT ISOLATED 1 TO 2"
PRECIPITATION AMOUNTS IN AN HOUR FROM FAR NORTHEAST KS INTO FAR
NORTHWEST MISSOURI---FAR SOUTHWEST IA.    FARTHER TO THE
NORTH--WPC HAS ISSUED A MESOSCALE PRECIPITATION DISCUSSION #326
FOR CONVECTION THAT HAS ENHANCED OVER NORTHEAST NEBRASKA.  THIS
ACTIVITY IS CURRENTLY IN A VERY FAVORABLE RIGHT ENTRANCE REGION OF
THE UPPER JET---HELPING IT TO OVERCOME THE MORE TYPICAL EARLY
MORNING WEAKENING TREND IN ORGANIZED CONVECTION.  IN THE WAKE OF
THIS ACTIVITY---ADDITION ACTIVITY WILL LIKELY FORM LATE AFTERNOON
INTO THE OVERNIGHT HOURS AHEAD OF ADDITIONAL HEIGHT FALLS PUSHING
EASTWARD INTO THE CENTRAL PLAINS.

ORAVEC



PREVIOUS DISCUSSION

THE PROGRESSION OF THE MID/UPPER LEVEL TROF OUT OF THE GREAT BASIN
INTO THE CENTRAL/SOUTHERN ROCKIES WILL SUPPORT THE LIKELIHOOD OF
INCREASINGLY HEAVY RAINS DOWNSTREAM THRU PARTS OF THE CENTRAL
PLAINS INTO THE MIDWEST..ESPECIALLY ON WEDNESDAY NIGHT.  AHEAD OF
THIS H5 TROF..A STRENGTHENING SOUTHERLY LOW LEVEL JET ON WEDNESDAY
NIGHT UP THRU THE PLAINS WILL BRING IN HIGHER MOISTURE AND LEAD TO
POOLING OF PWS TO NEAR OR ABOVE 2 INCHES VICINITY OF THE SURFACE
BOUNDARY.  THIS WILL SET UP AN EXPANDING AND INCREASINGLY HEAVY
OVERRUNNING CONVECTIVE EVENT..WITH THE HEAVIEST RAINFALL AXIS
EXPECTED ACROSS NE AND EVENTUALLY EXTENDING INTO WESTERN IA BY
LATER IN THIS PERIOD.  MODEL QPFS..INCLUDING THE GLOBAL AND
HIRES..WERE IN DECENT AGREEMENT ON THIS HEAVY RAINFALL EVENT..SO
CONFIDENCE IN THIS FORECAST IS RATHER HIGH..WITH AT LEAST AN AXIS
OF 1-2+ INCH AREAL AVERAGE RAINS EXPECTED BUT WITH ISOLATED 3-4+
INCH TOTALS POSSIBLE..WHICH COULD LEAD TO SOME ISOLATED FLOODING
PROBLEMS.

TERRY

$$




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