Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 280044
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
842 PM EDT THU APR 27 2017

...VALID 01Z FRI APR 28 2017 - 12Z FRI APR 28 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 NNE ABY 30 NW ABY 20 NNW DHN 15 SSW TOI 25 S OPN MLJ
10 W HQU 30 ESE GRD 20 SW CAE 35 ENE DBN 25 NNE ABY.


0100 UTC UPDATE

REMOVED MARGINAL RISK AREA ACROSS THE CENTRAL/NORTHERN
APPALACHIANS AS CONVECTION AHEAD OF COLD FRONT IS EXPECTED TO
CONTINUE TO WEAKEN THROUGH THE OVERNIGHT HOURS WITH LOSS OF
DAYTIME HEATING/INSTABILITY WHILE LINGERING CELLS REMAIN FAIRLY
PROGRESSIVE LIMITING HEAVIER RAINFALL POTENTIAL.

ACROSS THE SOUTHEAST STATES...LINGERING STRONG CONVECTION REMAINS
FAIRLY SLOW MOVING FROM PARTS OF SE AL INTO CNTL GA WITH STORMS
LINED UP WITH MEAN FLOW ALLOWING FOR SOME TRAINING OF STORMS
THROUGH THE EVENING HOURS.  WOULD EXPECTED SOME ISOLD RUNOFF
THREAT WILL REMAIN INTO THE EARLY OVERNIGHT HERE UNTIL RESIDUAL
INSTABILITY IS WORKED OVER AND DRIER AIR MOVES IN FROM THE WEST.
SULLIVAN

...SOUTHEAST STATES AL/GA/SC...

STEERING FLOW WILL BECOME MORE UNIDIRECTIONAL AT THE BASE OF THE
TROUGH LIFTING THROUGH THE EASTERN STATES THIS MORNING. THIS MAY
ALLOW FOR SOME SW TO NE TRAINING OF CONVECTION AS SIGNALED BY A
FEW HI-RES MODELS IN THEIR HOURLY TO THREE-HOURLY QPFS. MOISTURE
AND INSTABILITY PARAMETERS ARE NOT OVERWHELMING...BUT ARE
RESPECTABLE...AND COULD SUPPORT HOURLY RAIN RATES APPROACHING TWO
INCHES. IN MOST CASES THIS WOULD NOT REACH THE VERY HIGH FLASH
FLOOD GUIDANCE VALUES ACROSS THIS REGION...BUT COULD LEAD TO RAPID
RUNOFF IN POORLY DRAINED OR PARTICULARLY SUSCEPTIBLE AREAS. A
SMALL MARGINAL RISK AREA WAS INTRODUCED WHERE WPC QPF INDICATES
AREAL AVERAGE PRECIPITATION GREATER THAN A HALF INCH AND WHERE
SOME HI-RES RUNS PRODUCE SPOTTY 2 TO 3 INCH AMOUNTS.

BURKE
$$





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