Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 220807
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
406 AM EDT SAT AUG 22 2015

...VALID 12Z SAT AUG 22 2015 - 12Z SUN AUG 23 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 N CWPO 25 NE CXWN 40 ESE CWEA 15 SE CYQK 35 NNE ORB
20 SW RPD 15 N ALO 35 NNE CDJ 20 SSE OJC 10 SW EMP 15 NW MHK
15 N MLE SHL 20 SSE DTL 20 SE DVL 15 SE K06D 25 N CWPO.


THE MOISTURE RETURN ACROSS THE PLAINS WHICH WAS ADVERTISED BY THE
MODELS OVER THE PAST COUPLE OF DAYS HAS BEGUN...WITH WIND SPEEDS
ON THE ORDER OF 35 KTS AS SHOWN BY AREA VAD WIND PROFILES.  IN DUE
TIME...PRECIPITABLE WATER VALUES RISE INTO THE 1.25 TO 1.5 INCH
RANGE ACROSS PARTS OF THE UPPER MIDWEST AND IN EXCESS OF 1.5
INCHES ACROSS PARTS OF THE CENTRAL PLAINS.  BETWEEN HIGHLY
DIFLUENT FLOW AND THE EVENTUAL FORMATION OF A DEFORMATION ZONE
ACROSS THE NORTHERN TIER OF STATES FROM THE NORTHERN ROCKIES TO
THE UPPER MIDWEST...THE MODELS HAVE GENERALLY BEEN IN GOOD
AGREEMENT THAT 1 TO 2 INCHES OF RAIN...WITH LOCALLY HIGHER
AMOUNTS...ARE POSSIBLE.   FLASH FLOOD GUIDANCE VALUES ARE PRETTY
HIGH...SUGGESTING THAT ONLY IN AREAS OF PROLONGED MESOSCALE
ENHANCEMENT WILL EXPERIENCE MORE THAN SOME MINOR PROBLEMS DUE TO
RUN OFF.  THE SLIGHT RISK WAS EXTENDED SOUTH INTO THE NATIONS
MIDSECTION...WITH THE RISK OF EXCESSIVE RAINFALL COMING FROM
CONVECTION THAT FORMS AHEAD OF A COLD FRONT ASSOCIATED WITH THE
CYCLONE UP NORTH.  MOISTURE WILL BE DEEPER HERE AND THE MOISTURE
TRANSPORT INTO THE REGION WILL BE ABLE TO FEED THE CONVECTION
AHEAD OF THE FRONT.  WHILE PCPN AMOUNTS FROM THE GLOBAL MODELS
WERE SAFELY BELOW FFG VALUES...THE CONVECTIVE ALLOWING/HI RES RUNS
POINT TO THE POTENTIAL FOR THESE STORMS TO PRODUCE RAINFALL
AMOUNTS WHICH APPROACH OR EXCEED FLASH FLOOD GUIDANCE.

BANN
$$




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