Quantitative Precipitation Forecast
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000
FOUS30 KWBC 172221
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
621 PM EDT SUN SEP 17 2017

...VALID 2221Z SUN SEP 17 2017 - 12Z MON SEP 18 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 SE 4CR 55 WNW CVS 40 S DHT 20 WNW HHF 25 WNW AVK 25 WSW EMP
35 SSW IXD 15 NW AIZ 10 NNW VIH 35 E VIH 25 WSW MVN CIR
15 NW BYH BVX 20 S SLG 20 N MLC 10 N ADH 10 W F05 20 SSE PVW
55 SSE CVS 35 ENE ROW 35 WNW ATS 25 SE 4CR.


...SOUTHERN PLAINS...

EARLY THIS EVENING THUNDERSTORMS WERE ONGOING ALONG A SURFACE
FRONTAL BOUNDARY FROM EASTERN OKLAHOMA INTO NORTH TEXAS. WATER
VAPOR IMAGERY INDICATED A SHORTWAVE TROUGH WASHING OVER THE
CONVECTION FROM SOUTHWEST TO NORTHEAST...ENHANCING DEEP LAYER
ASCENT FOR ANOTHER FEW HOURS. WITH MEAN LAYER STEERING FLOW ONLY
10 KNOTS...AND SOME CONVECTION ALREADY SHOWING A TENDENCY TO
REMAIN ROOTED ALOFT / TRAINING...RATHER THAN FOLLOWING THE SURFACE
OUTFLOW...THERE WILL BE SOME POTENTIAL FOR ISOLATED 2 TO 4 INCH
RAIN AMOUNTS. FLASH FLOOD GUIDANCE VALUES ARE RATHER HIGH...AND
THE THREAT MAY BE SHORT-LIVED...SUCH THAT THE RISK WAS MAINTAINED
AS MARGINAL...BUT EXPANDED TO INCLUDE THIS PORTION OF THE RED
RIVER VALLEY.

FARTHER WEST...SCATTERED CONVECTION WAS ROOTED JUST ABOVE THE
FRONTAL ZONE...WORKING ITS WAY THROUGH THE TEXAS PANHANDLE...AS
LARGER SCALE HEIGHT FALLS BEGAN TO APPROACH FROM THE WEST. THE
ACTIVITY WAS SCATTERED...AND CELLULAR...WITH LITTLE INDICATION OF
UPSCALE GROWTH OR TRAINING. WITH TIME...HOWEVER...DEEP LAYER
ASCENT WILL FAVOR ADDITIONAL POCKETS OF DEEP CONVECTION FORMING UP
THROUGH WESTERN OKLAHOMA AND THE TX PANHANDLE...AND ALSO ROLLING
OFF THE COLORADO HIGH PLAINS AND INCREASING IN COVERAGE THROUGHOUT
WESTERN/CENTRAL KANSAS AND FAR SOUTHERN NEBRASKA OVERNIGHT. WITH
LOW LEVEL INFLOW INCREASING DURING THIS TIME...SOME BETTER
ORGANIZATION OF HEAVY RAIN AREAS MAY OCCUR...WHICH SUPPORTS
MAINTAINING THE MARGINAL RISK...ALTHOUGH WE DID RESHAPE THE RISK
AREA A BIT. PRECIPITABLE WATER VALUES...INFLOW...AND RAINFALL
EFFICIENCY...SHOULD INCREASE WITH TIME DURING THE OVERNIGHT HOURS.

BURKE
$$





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