Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 271853
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 PM EDT MON APR 27 2015

...VALID 18Z MON APR 27 2015 - 00Z WED APR 29 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 SE MCB 20 NW MOB 20 SE DTS 35 ENE AAF 30 WSW CTY 35 SSW CTY
65 SSW CTY 75 ESE KVOA 35 SE KDLP 20 NNE S58 35 S P92 20 WSW PTN
30 ENE ARA 15 E BTR 35 SE MCB.


THE LATEST MODEL SOLUTIONS ARE IN VERY GOOD AGREEMENT MASS
FIELD-WISE IN TAKING THE CLOSED H5 LOW INITIALLY OVER THE SOUTHERN
HIGH PLAINS GENERALLY EASTWARD INTO THE MID/LOWER MS VALLEY BY THE
END OF THE PERIOD..WITH GRADUAL HEIGHT FALLS AHEAD OF AND
ACCOMPANYING THIS FEATURE SPREADING THRU THE LOWER MS VALLEY AND
GULF COAST STATES DURING THIS SAME TIME PERIOD.  ALTHOUGH THE
MODELS ARE SHOWING GOOD AGREEMENT MASS FIELD-WISE..THERE IS LESS
AGREEMENT QPF-WISE..WHICH IS NOT SURPRISING GIVEN THE CONVECTIVE
NATURE OF THE PRECIPITATION ON ITS SOUTH AND EAST SIDE.  EVEN THE
MOST RECENT HIRES GUIDANCE NOT HANDLING THE ONGOING CONVECTION
VERY WELL..SO AFTER CONSIDERING ALL OF THIS..THIS FORECAST IS ONE
SOMEWHAT LOWER CONFIDENCE.  THAT SAID..BELIEVE AN AREA OF HEAVIER
RAIN/CONVECTION IS LIKELY FROM THE LOWER MS VALLEY ALONG THE
NORTHERN GULF COASTAL REGION INTO NORTHERN AND CENTRAL PARTS OF
THE FL PENINSULA.  HERE..SLOWLY PROGRESSIVE AND SUSTAINED H85
INFLOW OF 20+ KTS EARLY IN THE PERIOD..INCREASING TO ABOVE 30KTS
ON TUESDAY ASSOCIATED WITH A DEEPENING LOW LEVEL CENTER..WILL
BRING IN PWS NEAR OR ABOVE 2 INCHES INTO SOUTHEASTERN LA AND THE
GULF COAST REGION..WHICH SHOULD SUPPORT THE MORE ORGANIZED
CONVECTION AIDED BY A BROADLY DIFFLUENT UPPER FLOW PATTERN.
LEANED TOWARDS THE 12Z GFS AND GEM REGIONAL QPFS..AND TO A LESSER
EXTENT THE IN-HOUSE ENSEMBLE QPF BIAS CORRECTED..ALL OF WHICH HAD
A DECENT HANDLE ON THIS SCENARIO.  VERY HIGH MOISTURE WILL LEAD TO
INTENSE RAINFALL RATES AND AT LEAST SOME 1-2+ INCH AREAL AVERAGE
RAINFALL AMOUNTS..WITH ISOLATED TOTALS OF 3+ INCHES
POSSIBLE..ESPECIALLY OVER SOUTHEASTERN LA..EXTREME SOUTHERN MS AND
AL..AND OVER INTO PARTS OF THE CENTRAL FL PENINSULA.  FF GUIDANCE
VALUES GENERALLY HIGH THRU THIS ENTIRE AREA..SO KEPT ANY FLASH
FLOODING RISK TO SLIGHT..WITH THE EXPECTATIONS THAT ANY PROBLEMS
SHOULD BE RATHER ISOLATED.

TERRY
$$





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