Quantitative Precipitation Forecast
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FOUS30 KWBC 301400
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
958 AM EDT SAT MAY 30 2015

...VALID 15Z SAT MAY 30 2015 - 12Z SUN MAY 31 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 SSW AOH 15 S IND 10 WNW AJG 10 WSW FWC 20 SW MVN 25 W MDH
20 NNE FAM SUS IJX 15 NNW PNT LWA 15 N RNP 20 ESE CFS 25 NE CTZR
CWSN 35 S CWSN 25 SE CWAJ 35 NNW MFD 15 SSW AOH.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 ENE TYR 10 NNE LNC GPM 10 WNW AFW 15 NW DTO 15 SSE DUA
35 NNE PRX 25 NW MWT 20 NE RUE 30 SSE UNO 10 E ARG 30 W M97 LLQ
20 SSE ELD 10 WNW SHV 10 ENE TYR.


...MID MS VALLEY/MIDWEST INTO THE LOWER GREAT LAKES...

THE MAIN WEATHER MAKER THIS PERIOD..AT LEAST FROM THE MID MS
VALLEY AND MIDWEST INTO THE LOWER GREAT LAKES..WILL BE THE WELL
DEFINED MCV NOW LIFTING NORTHEASTWARD THRU WESTERN AR.  THIS
SYSTEM WILL CONTINUE TO MOVE NORTHEASTWARD INTO THE LOWER GREAT
LAKES BY SUNDAY MORNING..AHEAD OF A PROGRESSIVE/GENERALLY EASTWARD
MOVING H5 TROF NOW SITUATED OVER THE CENTRAL PLAINS.  IN ADVANCE
OF THIS MCV..A MODEST SOUTHERLY LOW LEVEL JET WILL BRING
INCREASING MOISTURE NORTHWARD..WITH PWS FORECAST TO INCREASE TO
GREATER THAN 1.75 INCHES UP THRU THE OH VALLEY..MIDWEST AND INTO
THE LOWER GREAT LAKES.  LARGE SCALE LIFT WITH THIS MCV ALONG WITH
THE DEEP MOISTURE WILL SUPPORT ORGANIZED AND HEAVY
CONVECTION/RAINS THRU THE MID MS VALLEY AND MIDWEST..AND
ESPECIALLY SO FROM PARTS OF THE MIDWEST INTO THE LOWER GREAT
LAKES..WHERE THE MCV AND MOISTURE WILL INTERACT WITH THE FRONTAL
BOUNDARY PUSHING THRU.  FOR THE MOST PART THE LATEST MODEL RUNS
ARE IN DECENT AGREEMENT IN THEIR HANDLING OF THE MCV..ALTHOUGH IT
APPEARS THE GFS MAY BE SUFFERING A BIT FROM FEEDBACK
PROBLEMS..RESULTING IN A HEAVIER AND SLIGHTLY FARTHER NORTH QPF AS
COMPARED TO THE REMAINDER OF THE GUIDANCE.  WILL STRAY AWAY FROM
THE GFS AT THIS TIME.  STILL..EXPECT AT LEAST SOME WIDESPREAD 1-2+
INCH RAINFALL AMOUNTS WITH THIS MCV AND SOME 2-3+ INCH TOTALS
WHERE IT INTERACTS WITH THE FRONTAL BOUNDARY..WITH EVEN SOME
ISOLATED HIGHER AMOUNTS POSSIBLE.  FF GUIDANCE VALUES GENERALLY ON
THE HIGHER SIDE HERE..SO KEPT THE FLOODING THREAT IN THE SLIGHT
RISK CATEGORY.

...EAST TEXAS/LOWER MS VALLEY...

12Z ANALYSIS AND THE LATEST RAP FORECASTS INDICATE A STRONGER AND
DEEPER MCV OVER NORTH CENTRAL TEXAS THAN DEPICTED BY ALL 00-06Z
GUIDANCE.  USING THE RAP AS A GUIDE...THE MCV SHOULD MAINTAIN
SUFFICIENT STRENGTH THROUGH TONIGHT AS IT ROUNDS THE BASE OF THE
LONGWAVE TROUGH OVER TEXAS AND LIFTS SLOWLY NORTHEASTWARD ACROSS
ARKANSAS...RESULTING IN A NARROW BUT POSSIBLY HEAVY AXIS OF HEAVY
RAINFALL ALONG ITS PATH.  FFG VALUES ARE SOMEWHAT LOW ACROSS
WESTERN AND CENTRAL ARKANSAS...AND HIGHER ACROSS EASTERN
ARKANSAS...WHILE MANY RIVERS STATEWIDE REMAIN IN FLOOD.  FARTHER
TO THE SOUTH...LOWER LEVEL CONVERGENCE IN ASSOCIATION WITH THE
SURFACE REFLECTION OF THE MCV SHOULD INTERACT WITH DIFFERENTIAL
HEATING ZONES ALONG THE TEXAS COAST TO CONTRIBUTE TO LOCALLY HEAVY
RAINFALL THIS AFTERNOON AND EVENING WITH SLOW CELL MOTIONS.  THE
MORE SCATTERED NATURE OF THE CONVECTION SUPPORTS A MORE ISOLATED
RISK OF FLASH FLOODING VERSUS A SLIGHT RISK OF FLASH FLOODING.

TERRY/JAMES


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