Quantitative Precipitation Forecast
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282
FOUS30 KWBC 180114
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
914 PM EDT SUN MAY 17 2015

...VALID 01Z MON MAY 18 2015 - 12Z MON MAY 18 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
MSL 35 SE MLU 25 NE UTS 40 NE LHB 10 SSW 3T1 20 NE MWT
10 SW MWA 25 WNW BWG MSL.



...MID MS/OH VALLEY CONFLUENCE SOUTHWESTWARD INTO EASTERN TX...

HAVE SCALED BACK THE EXCESSIVE OUTLOOK AREA A BIT IN TX AND
LA...WITH THE CURRENT VERSION VALID FROM 01-12Z NOW ENCOMPASSING
NORTHERN LA AND A SMALL PORTION OF EASTERN TX.

THE COMBINATION OF AIRMASS MODIFICATION WITHIN THE BOUNDARY LAYER
WITH THE LINGERING COLD POOLS AND WHAT APPEARS TO BE RIGHT EXIT
REGION FORCING (UPPER LEVEL CONVERGENCE) FROM THE SUBTROPICAL JET
STREAK PER THE LATEST WATER VAPOR LOOPS CONTINUES TO SHUT OFF NEW
CONVECTION ACROSS TX. THE CONCERN FOR THE OVERNIGHT PERIOD IS THAT
THE BEST UPPER LEVEL SUPPORT (UPPER DIVERGENCE ENHANCED FROM THE
RIGHT ENTRANCE REGION OF THE JET STREAK ACROSS THE MID MS VLY)
WILL SHIFT FARTHER EAST INTO THE LOWER-MID MS VALLEY...AS
SUPPORTED BY THE MOST RECENT HRRR AND RAP TRENDS WHICH FINALLY
APPEAR TO HAVE A HANDLE ON THE CONVECTIVE TRENDS.

THERMODYNAMIC PROFILES OVERNIGHT WILL REMAIN FAVORABLE ACROSS THE
OUTLOOK AREA...WITH PWATS OF 1.75 TO 2.00 INCHES (2+ STANDARD
DEVIATIONS ABOVE NORMAL FOR MID MAY)...WHILE MUCAPES RANGE FROM
1000-2000 J/KG. MODEST LOW-LEVEL INFLOW OVERNIGHT INTO THE OUTLOOK
AREA (~30 KTS) WILL ORIENT NEARLY PARALLEL AND CLOSE TO THE SAME
MAGNITUDE OF THE MEAN WIND...WHICH WILL LEAD TO INCREASED UPWIND
PROPAGATION AND TRAINING OF CELLS. THUS EVEN WITHOUT THE BENEFIT
OF A ROBUST LLJ...EXPECT CELL TRAINING TO RESULT IN LOCALLY
EXCESSIVE SHORT-TERM RAINFALL RATES.

HURLEY
$$





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