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000
FOUS30 KWBC 211824
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 PM EDT TUE MAY 21 2013

...VALID 18Z TUE MAY 21 2013 - 00Z THU MAY 23 2013...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 NNE GLH 25 W LLQ 30 WNW ELD OSA 10 NE TRL HQZ DFW AFW LUD
15 NW GLE 15 SE PVJ 15 S SNL 10 NNE FSM 35 NW RUE 35 S FLP
15 WNW BVX 10 SW JBR 20 ESE JBR 20 SSE HKA 20 WNW MKL MKL
30 SSE MKL 45 SSE MKL 30 N TUP 30 WNW TUP 50 SE UTA 40 NNE GLH
30 NNE GLH.


UPDATE

SOUTHERN PLAINS INTO THE LOWER MS VALLEY

THERE WERE ONLY SOME MINOR CHANGES MADE TO THE PREVIOUS EXCESSIVE
RAINFALL POTENTIAL OUTLOOK AREA ASSOCIATED WITH THE ACTIVE
CONVECTION ACROSS THE SOUTHERN PLAINS TOWARD THE LOWER MS VALLEY.
CONVECTION REMAINS ACTIVE ALONG AND NORTH OF THE OUTFLOW BOUNDARY
STRETCHING FROM NORTHEAST TX INTO SOUTHERN AR AND HAS INTENSIFIED
SIGNIFICANTLY LATE MORNING INTO EARLY AFTERNOON ALONG THE UPSTREAM
COLD FRONT AND ASSOCIATED STRONG HEIGHT FALLS MOVING EASTWARD INTO
THE SOUTHERN PLAINS.  CONVECTION REMAINS SLOW MOVING TO THE NORTH
OF THE OUTFLOW BOUNDARY WHERE MOIST SOUTH TO SOUTHWESTERLY LOW
LEVEL INFLOW INTO THE BOUNDARY IS SUPPORTING ADDITIONAL CONVECTIVE
DEVELOPMENT.  HOWEVER---UPSTREAM OF THIS---THE CONVECTION AHEAD OF
THE STRONG SOUTHERN PLAINS HEIGHT FALLS IS MUCH MORE PROGRESSIVE
AND WILL LIKELY REMAIN SO THIS AFTERNOON INTO TONIGHT AS THE
HEIGHT FALLS CONTINUE TO PRESS EASTWARD THROUGH THE SOUTHERN
PLAINS AND THEN EAST NORTHEASTWARD INTO THE LOWER TO MID MS
VALLEY.  THIS PROGRESSIVE NATURE OF THE CONVECTION WILL LEAD TO A
LESSENING OF THE EXCESSIVE RAINFALL POTENTIAL OVERNIGHT AS THE
CONVECTION MOVES SOUTHEAST TOWARD HIGHER FFG VALUES AND THE
TRAINING POTENTIAL DIMINISHES.  UNTIL THIS HAPPENS---HEAVY
RAINFALL AMOUNTS LIKELY ALONG AND NORTH OF THE ABOVE MENTIONED
OUTFLOW BOUNDARY AND AHEAD OF THE UPSTREAM COLD FRONT.  SHORT TERM
PRECIPITATION AMOUNTS TO THE NORTH OF THE OUTFLOW BOUNDARY OF 1-2"
AND .50-1"+ AHEAD OF THE FRONTAL CONVECTION POSSIBLE.  THE
COMBINATION OF THE CONVECTION TO THE NORTH OF OUTFLOW BOUNDARY AND
THE FRONTAL CONVECTION MAY RESULT IN RUNOFF ISSUES FROM FAR
NORTHEAST TX---SOUTHEAST OK---CENTRAL TO SOUTH AR---FAR NORTHWEST
MS AND FAR SOUTHWEST TN.

SOUTHEAST FL

THE CLOSED LOW OVER NORTH FL IS EXPECTED TO MOVE ONLY VERY SLOWLY
EASTWARD THIS PERIOD.  PERSISTENT SOUTHERLY TO SOUTHEASTERLY LOW
LEVEL FLOW TO THE SOUTH AND SOUTHEAST OF THIS UPPER CENTER IN THE
AXIS OF ABOVE AVERAGE PW VALUES STREAMING OFF THE ATLANTIC WILL
MAY FOCUS ISOLATED VERY HEAVY RAINFALL AMOUNTS ALONG THE COASTAL
SOUTHEAST PORTIONS OF FL.  ISOLATED 2-5"+ TOTALS
POSSIBLE---ESPECIALLY IN THE EARLY MORNING HOURS---WITH VERY LOW
CONFIDENCE WITH PLACEMENT. THESE INTENSE RAINFALL RATES AND
AMOUNTS POSE RUNOFF ISSUES---ESPECIALLY OVER URBANIZED AREAS ALONG
THE SOUTHEAST COAST OF FL.

ORAVEC
$$