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000
FOUS30 KWBC 231902
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 PM EDT THU MAY 23 2013

...VALID 18Z THU MAY 23 2013 - 00Z SAT MAY 25 2013...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 N MSV 30 E BGM 10 NE BGM 20 E ITH 25 SSE SYR 15 S UCA
20 ESE UCA 25 ENE RME 30 SSW SLK 25 WNW SLK 10 E MSS CMBR
10 ESE CMLI CXBO 35 SSE CWNH 35 SW FVE 55 NNW MLT 50 NW MLT
20 NW GNR 35 WSW GNR 40 NNE BML 30 N BML 20 NNW BML 10 S 1V4 VSF
20 E AQW 15 ESE PSF 25 SSW PSF 25 SW PSF 45 N MSV.


NORTH CENTRAL OK AND THE SOUTHERN PLAINS

CONVECTION OVER PORTIONS OF OKLAHOMA REMAIN VERY
RESILIENT---DESPITE MODEL FORECASTS SUGGESTING ITS EMINENT DEMISE.
 WHILE THE ACTIVITY THROUGH THIS MORNING HAS GRADUALLY SHIFTED
NORTHWARD---THE PATTERN OF REDEVELOPMENT ON THE NORTHWESTERN EDGE
AND DOWNSTREAM TRAINING CONTINUES.  VERY LITTLE CONFIDENCE AS TO
WHEN THIS WILL DIMINISH OR RE-DEVELOP FARTHER TO THE SOUTH ACROSS
NORTHWEST TX AS MODELS SEEM TO WANT TO DO.  THE SOUTHWESTERLY LOW
LEVEL FLOW OVERRUNNING THE FRONT OVER NORTH TX IS EXPECTED TO BACK
TO A MORE EASTERLY DIRECTION THIS EVENING---WHICH MAY SUPPORT THE
MODEL WESTWARD TREND WITH CONVECTION---BUT THEN VEER BACK TO A
SOUTHERLY DIRECTION FRIDAY.  WITH PW VALUES EXPECTED TO BE ABOVE
AVERAGE OVER THE SOUTHERN PLAINS THIS PERIOD---CONVECTION WILL
LIKELY BE ACTIVE---BUT CONFIDENCE IS VERY LOW WITH THE
LOCATION---ESPECIALLY GIVEN THE RECENT MODEL PERFORMANCE AND THE
WIDE SPREAD AS TO HOW CURRENT ACTIVITY WILL EVOLVE AND WHERE NEW
ACTIVITY WILL FORM.  FOR THE SHORT TERM---ADDITIONAL SHORT TERM
PRECIPITATION AMOUNTS OF 1-2"+ POSSIBLE IN AREAS OF TRAINING OVER
NORTH CENTRAL OK.   AFTER AND IF THIS AREA OF CONVECTION
DIMINISHES---THERE MAY BE OTHER AREAS OF VERY HEAVY RAINFALL
AMOUNTS BUT CONFIDENCE IS LOW WITH DETAILS.  SEVERAL OF THE
OPERATIONAL MODELS SHOW BULLS EYE PRECIPITATION MAXIMA IN THE
CONVECTION EXPECTED TO DEVELOP SOUTHWESTWARD TOWARD THE BIG
BEND--WITH THIS LEADING TO WHAT IS LIKELY CONVECTIVELY INDUCED MID
LEVEL VORTS ACROSS WEST TX TONIGHT AND CONTINUING INTO
FRIDAY---LEADING TO MORE UNCERTAINTIES WITH THE MODEL QPFS THIS
PERIOD AND BEYOND.  HOWEVER---THE ONE MESSAGE FROM THESE FORECASTS
IS THAT THERE MAY BE ADDITIONAL AREAS OF CONCERN WITH RESPECT TO
VERY HEAVY RAINFALL AMOUNTS.


EASTERN TO NORTHEASTERN NY---PORTIONS OF WESTERN TO NORTHERN NEW
ENGLAND

MODELS ARE SHOWING FAIRLY GOOD AGREEMENT WITH THE AMPLIFICATION OF
STRONG HEIGHT FALLS MOVING SOUTHEASTWARD FROM THE LOWER LAKES AND
INTO A CLOSED LOW OVER THE MID ATLANTIC TONIGHT INTO FRIDAY.  PW
VALUES AHEAD OF THIS AMPLIFYING TROF WILL REMAIN MUCH ABOVE
AVERAGE---2.0-2.5+ STANDARD DEVIATIONS ABOVE THE MEAN FROM
PORTIONS OF THE MID ATLANTIC---EASTERN NY AND INTO NEW ENGLAND.
CONVECTION DEVELOPING THIS AFTERNOON IN SEVERAL LINES AHEAD OF
THIS AMPLIFYING UPPER TROF AND ASSOCIATED FRONTAL BOUNDARY WILL
LIKELY BECOME BETTER ORGANIZED IN A REGION OF STRENGTHENING
FRONTAL CONVERGENCE AND VERY FAVORABLE RIGHT ENTRANCE REGION JET
DYNAMICS---SUPPORTING POTENTIAL FOR FAIRLY WIDESPREAD HEAVY
CONVECTIVE RAINFALL POTENTIAL.  A SLIGHT RISK WAS DEPICTED OVER
AREAS OF RELATIVELY LOW FFG VALUES FROM EASTERN TO NORTHEASTERN
NY---PORTIONS OF WESTERN AND NORTHERN NEW ENGLAND--- FOR THIS
ENHANCING CONVECTION WITH ISOLATED SHORT TERM PRECIPITATION
AMOUNTS OF 1-2"+ POSSIBLE.

WV

CONCERNS FOR POTENTIAL RUNOFF ISSUES CONTINUE OVER PORTIONS OF THE
CENTRAL APPALACHIANS.  WITH FFG VALUES AS LOW AS .50-.75" FOR 1
HOUR AND .75-1"+ FOR THE 3 HOUR PERIOD OVER PORTIONS OF THE
NORTHWESTERN VA/EASTERN WV BORDER AREA AND FARTHER WESTWARD ACROSS
WV---THERE MAY BE LOCALIZED RUNOFF ISSUES WITH THE CONVECTIVE LINE
BEGINNING TO DEVELOP FROM SOUTHWEST PA INTO WESTERN W.V.  THE
THREAT FOR RUNOFF ISSUES ACROSS THIS AREA APPEARS TO BE OVER THE
NEXT FEW HOURS BEFORE THE STRONGEST DYNAMICS PUSH FARTHER TO THE
NORTHEAST INTO EASTERN NY AND NEW ENGLAND THIS EVENING.


ORAVEC
$$