Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 161407
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1006 AM EDT WED AUG 16 2017

...VALID 15Z WED AUG 16 2017 - 12Z THU AUG 17 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 N DYS 70 SSE CDS 10 W LTS JWG 40 W WLD 15 NW MHK 10 ENE OLU
20 S HON 15 W FSE 30 SE CYHD 25 N GRB 10 NNW MWC C75 20 ENE LWV
15 E MWA 30 WSW POF 30 NNE HOT 10 SSW DEQ 10 WNW DFW 35 SSW RPH
30 N DYS.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WSW GZH 20 SSW BFM 20 SE HSA 20 SSE NBG 15 SE P92 25 WNW 7R4
ACP 15 E ESF 35 NE TVR 20 ESE GWO 20 N NMM 50 W MGM 20 WSW GZH.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 NW AIZ 10 NNE TBN 30 SSE TBN 20 N UNO 10 SW UNO 25 S FLP
30 NW RUE JSV 15 ENE ADM 15 N PVJ 10 N CQB BVO 15 NE UKL
15 NE MKC 25 N SZL 15 NW AIZ.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NNW ADC PKD 10 N FOZ 25 NW ELO 25 NE BFW 20 N HYR 20 S LUM
25 SE LSE MRJ 20 WSW EFT 10 ENE SFY 15 W SFY MXO 10 NNW CID
25 SW VTI 15 SE MIW FOD 25 NE SLB 10 E ORC 25 ESE FSD 20 NNE BKX
10 NNW ADC.


1500 UTC UPDATE

ONLY SOME MINOR CHANGES MADE TO THE PREVIOUS EXCESSIVE RAINFALL
POTENTIAL OUTLOOK.  THE SLIGHT RISK AREA WAS EXTENDED SLIGHTLY
SOUTHWARD INTO NORTHWEST IA TO COVER THE LOWER FFG AREAS AHEAD OF
THE ONGOING CONVECTION MOVING NORTHWARD ACROSS THIS AREA.

ORAVEC


INITIAL DISCUSSION


...ERN PLAINS/MS VALLEY STATES...

MID-UPPER LEVEL TROUGH ENERGY/HEIGHT FALLS IN SEVERAL STREAMS WILL
BE EJECTING EAST NORTHEASTWARD OVER THE CENTRAL AND NRN PLAINS AND
INTO THE MID-UPPER MS VALLEY DAY1. INSTABILITY/THETAE ADVECTION
INCREASES WITH PW VALUES AHEAD OF THESE HEIGHT FALLS POOL UPWARDS
TO 2 STANDARD DEVIATIONS ABOVE THE MEAN ALONG/AROUND A DEVELOPING
SURFACE LOW AND ASSOCIATED FRONTAL SYSTEM. THIS COMBINED WITH WELL
DEFINED UPPER DIFFLUENCE AHEAD OF THE EJECTING HEIGHT FALLS WILL
SUPPORT POTENTIAL FOR CONVECTIVE FOCUS WITH WIDESPREAD MODERATE TO
HEAVY PRECIP TOTALS/MAXIMA SPREAD WITH FRONTAL SYSTEM PROGRESSION
DOWN TROUGH THE SRN PLAINS/MID-UPPER MS VALLEY...AS WELL IN ERNEST
BACK AROUND THE LOW WRAPPING FURTHER UP ACROSS THE UPPER MIDWEST
WITH MAX POTENTIAL PIVOT POINT CENTERED OVER MN. THERE REMAINS A
TYPICAL AMOUNT OF SPREAD WITH CONVECTIVE PRECIP DETAILS LEADING TO
AVERAGE (LOW) CONFIDENCE WITH THE DETAILS. HOWEVER...MODEL
CONSENSUS IS QUITE SUPPORTIVE OVERALL FOR WIDESPREAD MODERATE TO
HEAVY TOTALS STRETCHING ACROSS LARGE PORTIONS OF THE ERN PLAINS
AND ACROSS THE MID AND UPPER MS VALLEY WITH THE ARW AND TO A
LESSER EXTENT THE LIGHTER NBM PROBABLY MORE IN LINE WITH ONGOING
ACTIVITY AND WPC CONTINUITY.

ACCORDINGLY...ISSUED SLIGHT EXCESSIVE RAINFALL THREAT AREAS OVER
THE COMMA HEAD CENTERED OVER MN/NRN IA/WRN WI WITH CONSOLIDATED
ACTIVITY AND FROM E-CENTRAL OK/SE KS TO NW AR/SW-CENTRAL MO WHERE
THERE IS A THREAT FOR TRAILING/TRAINING HEAVY CONVECTION. THESE
BOTH ARE WITHIN A BROADER MARGINAL AREA.

...LOWER MS/CENTRAL COAST STATES...

PW VALUES REMAIN UPWARDS OF 2"+ FOR THE UPCOMING DAY 1 TIME PERIOD
AND THIS MAY SUPPORT ANOTHER ROUND OF WIDESPREAD SCATTERED SLOW
MOVING CONVECTION ACROSS THESE AREAS. LOW CONFIDENCE ON QPF
DETAILS...BUT AVAILABLE MOISTURE WOULD FUEL POTENTIAL FOR LOCALLY
HEAVY DOWNPOURS. THE LOWER MS VALLEY/CENTRAL GULF COAST MAY OFFER
THE MOST POTENTIAL WITHIN THIS BROAD AREA AS PER INCREASED GULF
INFLOW/INSTABILITY SO ISSUED A MARGINAL RISK AREA THERE.

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

SCHICHTEL
$$




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