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000
FOUS30 KWBC 200958
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
557 AM EDT MON MAY 20 2013

...VALID 12Z MON MAY 20 2013 - 12Z TUE MAY 21 2013...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 ENE BIL 55 SW MLS 35 SSW MLS 15 NE MLS 35 NNW GDV 30 WNW ISN
10 SSW KD50 15 WNW CWEI 15 N CWPO 20 NNE CWGN 25 ENE HCO
20 SSW FSE 30 SSW FAR 35 E K46D 10 NNW K46D 40 SSW K5H4
20 SW KY19 35 S HEI 20 N CUT 15 W IKA 20 NW DHS 30 WSW PIN
15 NNE GEY 40 S BIL 30 ENE BIL.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 W PNT 10 SSW TAZ 30 S UNO 30 SE FSM 10 E ADM 20 NNE DUC
15 NW PWA 15 NW PPF 25 WSW EOK 30 NW C75 20 W PNT.


...NORTHERN PLAINS...

STILL SEE A THREAT FOR SOME FLOODING PROBLEMS OVER PORTIONS OF THE
NORTHERN PLAINS (INCLUDING THE HIGH PLAINS OF MT/WY)...ESPECIALLY
WHERE FLASH FLOOD GUIDANCE VALUES ARE QUITE LOW IN ND AND
SOUTH-CENTRAL MT (MOST NOTABLY OVER THE BURN SCAR AREAS IN MT).
MOIST INFLOW WILL CONTINUE TO FUEL DEFORMATION/DYNAMIC COOLING
RAINS ON THE BACKSIDE OF THE FAIRLY INTENSE AND SLOW MOVING CLOSED
H5 LOW OVER THE NORTHERN HI PLAINS AT THIS TIME.  THE REALLY HIGH
PW`S WILL LIKELY REMAIN WELL TO THE SOUTH AND EAST WITH THE
EXPECTED CONVECTIVE DEVELOPMENT OVER THE MIDWEST AND UPPER MS
VALLEY....BUT LONG DURATION OF THE EVENT COULD POSE THE BIGGER
CONCERN.  EXPECT SOME 0.50-1.00 INCH RAINFALL AMOUNTS IN A 3-6
HOUR PERIOD..BUT WITH SOME 1-2 INCH TOTALS POSSIBLE THIS ENTIRE
PERIOD.


...SOUTHERN PLAINS INTO THE LOWER AND MID MISSISSIPPI VALLEY...

THE EXCESSIVE RAINFALL RISK AREA (SLIGHT) SHIFTED A LITTLE FARTHER
TO THE EAST FROM THE PREVIOUS FCST PACKAGE.  MULTI-CELLULAR
CONVECTION OVERNIGHT SUN INTO EARLY MON WILL CONTINUE TO MOISTEN
THE SOILS SOMEWHAT OVER A FAIRLY LARGE SWATH AND LIKELY LEAD TO
LOWERING FFG LATER MON INTO MON NIGHT. BOTH THE GLOBAL AND HIGH
RES MODELS CLUSTER FAIRLY WELL WITH RESPECT TO THE ADVERTISEMENT
OF ANOTHER MCS MON NIGHT INTO EARLY TUE...WITH THE HIGHEST
AREAL-AVG DETERMINISTIC QPF AND ENSEMBLE PROBABILITIES OF AMOUNTS
EXCEEDING 3-5 INCHES ACROSS SE KANSAS...ERN OKLAHOMA...SW AND CEN
MISSOURI...AND NW ARKANSAS.  OVER THIS REGION...A VEERING (S-SW)
40-50 KT LLJ IS EXPECTED TO DEVELOP OVERNIGHT...AND IS EXPECTED TO
FEED OFF OF A MOISTURE-RICH AIRMASS (PW`S ~1.75" AND K INDICES IN
THE MID TO UPPER 30S) TO GENERATE A FAIRLY ROBUST AREA OF LLVL
MOISTURE TRANSPORT AND FLUX CONVERGENCE.  DYNAMICALLY...THE BROAD
AREA OF UPPER LEVEL AGEOS DIVERGENCE/DEEP LAYER QS CONVERGENCE
OVER THIS REGION WILL GET ENHANCED BY THE LEFT EXIT/RIGHT ENTRANCE
REGION OF THE SRN JET STREAK EMERGING OUT OF THE TROUGH BASE AND
THE NRN JET STREAK ACROSS THE UPPER MIDWEST RESPECTIVELY.
MEANWHILE...THE STRENGTHENING (AND VEERING) LLJ JET WILL LEAD TO
AN INCREASED SOUTHERLY PROPAGATION OVERNIGHT AND PSBL TRAINING
CELLS GIVEN A SLOWER...MORE SOUTHWESTWARD ORIENTED CORFIDI OR MBE
VECTOR.

HURLEY
$$