Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 250655
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 AM EDT SAT APR 25 2015

...VALID 06Z SAT APR 25 2015 - 12Z SUN APR 26 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 ENE DNV 35 SE ILN 20 NNW HSP 20 NE ROA 10 WSW UKF 40 E TYS
25 NNE CSV 20 S CUL 20 WNW SET 25 SSW MQB 15 ENE DNV.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NNE DQH 15 N MXF 25 NE NMM 10 WNW TVR 30 ENE BQP 35 SE UTA
20 WSW CHA 15 NW GRD 45 E CHS 40 SE HXD 10 NNE DQH.


...LOWER MS AND TN VALLEYS INTO THE SOUTHEAST...

AN UPPER TROUGH CURRENTLY ACROSS THE CENTRAL/SOUTHERN PLAINS WILL
CONTINUE TO SHEAR OUT A BIT UPON LIFTING NORTHEAST INTO THE
SHORTWAVE RIDGE...THEN BECOME ABSORBED BY THE BROAD TROUGH ACROSS
THE NORTHEAST CONUS BY 12Z SUN AS ADDITIONAL SHORTWAVE ENERGY ON
THE BACKSIDE DROPS SOUTH ACROSS THE GREAT LAKES REGION TONIGHT.
WITH THE TROUGH/HEIGHT FALLS FLATTENING OUT SOMEWHAT ACROSS THE
SOUTHERN TIER...FORCING WILL BECOME MORE FRONTOGENETIC (STRAIGHT
UPPER JET FORCING) AS THE LOW-LEVEL INFLOW VEERS MORE WESTERLY
THIS AFTERNOON. DESPITE THE SHIFT IN THE LOW LEVEL
INFLOW...ANOMALOUS PW AND 805-700 MB MOISTURE FLUX AND DEEP LAYER
INSTBY WILL PERSIST ALONG THE FLATTENING SUBTROPICAL JET SOUTH OF
THE SURFACE FRONT. MOREOVER...AS THE LOW LEVEL INFLOW VEERS
WESTERLY AND BECOMES NEARLY PARALLEL TO THE 850-300 MB MEAN
FLOW...W-E CELL TRAINING WILL BECOME MORE OF A CONCERN. AREAL
AVERAGE RAINFALL AMOUNTS ARE EXPECTED TO RANGE BTWN 1-1.5 INCHES
OVER THE OUTLOOK AREA...HOWEVER PER THE HIGH RES GUIDANCE
LOCALIZED AMOUNTS OF 3-5+ INCHES WITHIN A 3-6 HOUR PERIOD COULD
LEAD TO SOME FLASH FLOODING.


...MID MS VALLEY INTO THE LOWER OH VALLEY AND SOUTHERN/CENTRAL
APPALACHIANS...

A MORE PROLONGED PERIOD OF DEEP LAYER FORCING WILL EXIST OVER MUCH
OF THE DAY 1 PERIOD...THOUGH PW AND MOISTURE FLUX ANOMALIES WILL
NOT BE AS ROBUST OVER THESE AREAS COMPARED TO FARTHER SOUTH.
NEITHER WILL THE INSTABILITY...AS MUCAPES REMAIN BELOW 1000 J/KG
THROUGH THE PERIOD (ESPECIALLY NORTHERN PORTION OF THE OUTLOOK
AREA). AT THE SAME TIME...A FAIRLY WIDESPREAD SWATH OF 1-1.5 INCH
RAINFALL AMOUNTS...ALONG WITH LOCALIZED 2-3 INCH AMOUNTS PER THE
HIGH RES GUIDANCE OVER AREAS WHERE CURRENT FFG IS RELATIVELY LOW
(AND WILL LIKELY LOWER WITH TIME) WILL LIKELY LEAD TO ISOLATED
AREAS OF FLASH FLOODING...PARTICULARLY IN AREAS OF STEEPER
TERRAIN.

HURLEY
$$




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