Quantitative Precipitation Forecast
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FOUS30 KWBC 161328
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
927 AM EDT SAT SEP 16 2017

...VALID 15Z SAT SEP 16 2017 - 12Z SUN SEP 17 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 N CWCJ 10 SSE ARV 20 NNW CDJ 25 SE UKL 15 SSW PNC 25 W END
10 NNE AVK 15 ESE P28 25 W EMP 10 N RDK 20 ESE SPW 10 ENE XVG
15 NE CYXL.




15Z UPDATE...

HAVE EXPANDED THE MARGINAL RISK SLIGHTLY ALONG AND IN ADVANCE OF
COLD FRONT..PRIMARILY ACROSS PORTIONS OF THE CNTL PLAINS BASED
PARTLY ON EARLY MORNING CONVECTIVE TRENDS.  MODELS..INCLUDING MUCH
OF THE OVERNIGHT HI RES GUIDANCE APPEAR TO BE SLOW AND/OR
UNDERDONE WITH CONVECTIVE DVLPMENT IN THE WARM SECTOR FROM PARTS
OF NRN OK THROUGH MUCH OF ERN KS INTO SE NEB THIS MORNING.  RECENT
RAP ANALYSIS INDICATED RELATIVELY BROAD AREA OF 500-1000 J/KG
MLCAPES ACROSS THIS REGION..AND DESPITE DEPICTED CIN..STORMS HAVE
CONTINUED TO SLOWLY EXPAND.  SEVERAL SUBTLE FEATURES WERE NOTED IN
WV IMAGERY THAT MAY HELP SUSTAIN SOME BRIEF ORGANIZED ACTIVITY
THROUGH THE MORNING.  HOWEVER..WITH MAIN HEIGHT FALLS PUSHING OUT
ACRS THE NRN PLAINS/UPPER MS LATER THIS AFTN/EVENING..WE MAY SEE
SLIGHTLY BETTER ORGANIZATION OF CONVECTION ALONG AND AHEAD OF THE
COLD FRONT.  NRN PORTION OF THE FRONT IS EXPECTED TO BE FAIRLY
PROGRESSIVE..WHILE SRN PORTION WILL BE SLOWER TO PUSH EAST AND AS
A RESULT COULD SUPPORT SOME SLOWER MOVING HEAVIER CONVECTIVE
CELLS..ESPECIALLY LATE SAT/SAT NIGHT FROM ERN KS/OK INTO WRN MO.
FLASH FLOOD GUIDANCE ACROSS THE LATTER REGION REMAINS FAIRLY HIGH
SUGGESTING ANY FLASH FLOOD THREAT SHOULD BE FAIRLY ISOLATED.
SULLIVAN    PREVIOUS DISCUSSION FOLLOWS...

...MID-UPPER MS VALLEY TO THE S-CENTRAL PLAINS...

EJECTING WRN US TROUGH ENERGY AND AMPLE ASSOCIATED HEIGHT FALLS
WILL PUNCH NEWD ACROSS THE N-CENTRAL US DAY1. A NARROW BUT DEEP
LEAD MOISTURE AXIS WITH PRECIPITABLE WATER VALUES POOLED IN EXCESS
OF 1.5" WILL CONTINUE TO FEED NEWD TO INTERACT WITH A SURFACE
LOW/FRONTAL SYSTEM. FAVORABLE RIGHT ENTRANCE REGION UPPER JET
STREAK DYNAMICS AND MODEST INSTABILITY WILL ALSO CONTRIBUTE TO
DEVELOPMENT OF SOME HEAVY CONVECTIVE DOWNPOURS FROM THE MID-UPPER
MS VALLEY STATES SWWD TO THE S-CENTRAL PLAINS. MOISTURE
AVAILABILITY SUPPORTS A MARGINAL RISK OF EXCESSIVE RAINFALL WITH
ANY CELLS THAT LINGER/TRAIN OVER THE SAME AREA TO PRODUCE A QUICK
COUPLE INCHES OF RAIN. FFG VALUES ARE RELATIVELY HIGH ACROSS MOST
OF THE BROAD THREAT REGION DEPICTED TO LIMIT RISK...WITH AN
EXCEPTION OVER THE ARROWHEAD OF MN WHERE RECENT HEAVY RAINS HAVE
OCCURRED.

SCHICHTEL



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