000
FOUS30 KWBC 201359
QPFERD

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

...VALID 15Z 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
25 SSE MLC ADM 15 E DUC 10 SSE CHK OKC GOK 15 ESE PNC 15 SE WLD
40 S EMP 20 SSW UKL 20 E UKL 25 SW SZL 25 ESE DMO 35 E JEF
10 NNW FAM 35 SSW FAM 35 W POF 30 SSE FLP 30 SE FSM 25 SSE MLC.


UPDATE

ACROSS PORTIONS OF THE SOUTHERN PLAINS INTO THE MID MS
VALLEY---THE PREVIOUS THREAT REGION WAS DECREASED IN SIZE ON THE
NORTHEASTERN PORTION TO REFLECT BETTER WHERE THE GREATEST HEAVY
RAIN THREAT WILL BE LATER TONIGHT INTO THE EARLY MORNING HOURS OF
TUESDAY.  VERY FAVORABLE RIGHT ENTRANCE REGION JET DYNAMICS
FORECAST IN THE VICINITY OF NORTHEASTERN OK---NORTHWEST AR---FAR
SOUTHEAST KS INTO SOUTHWESTERN MO BEGINNING 0000 UTC
TUE---CONTINUING TO THE END OF THIS FORECAST PERIOD---1200 UTC
TUESDAY. THIS AND STRENGTHENING MOIST SOUTH SOUTHWESTERLY LOW
LEVEL INFLOW AHEAD OF AND INTO THE SLOW MOVING FRONTAL BOUNDARY
PUSHING SOUTHEASTWARD INTO THE CENTRAL TO SOUTHERN PLAINS/MID MS
VALLEY REGION WILL SUPPORT POTENTIAL FOR ACTIVE CONVECTION WITH A
PERIOD OF TRAINING AND OR BACK BUILDING OF CELLS POSSIBLE FROM
NORTHEAST OK---ACROSS NORTHWEST AR INTO SOUTHWEST MO

ACROSS THE NORTHERN PLAINS/UPPER MS VALLEY REGION---THE PREVIOUS
SLIGHT RISK AREA WAS ELIMINATED AS THIS EVENT APPEARS TO BE A
PROLONGED MODERATE PRECIPITATION EVENT.  WITH RAINFALL RATES STILL
BELOW CURRENT 3 AND 6 HOUR FFG VALUES---BELIEVE THE THREAT OF
EXCESSIVE RAINFALL AMOUNTS WILL NOT BE WIDESPREAD AN CONFINED TO
ISOLATED AREAS.

ORAVEC



PREVIOUS DISCUSSION


...NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

STILL SEE A THREAT FOR SOME FLOODING PROBLEMS OVER PORTIONS OF THE
NORTHERN PLAINS (INCLUDING THE HIGH PLAINS OF MT/WY) INTO NORTHERN
MINNESOTA...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
CENTRAL 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
$$