Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 241834
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EDT SUN AUG 24 2014

...VALID 18Z SUN AUG 24 2014 - 00Z TUE AUG 26 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


...EASTERN MONTANA...

THE EXCESSIVE RAINFALL OUTLOOK WAS UPDATED TO LINGER THE RISK AREA
ACROSS EASTERN PORTIONS OF MT...WHERE DESPITE THE WEAKENING
(LIGHT-MODERATE) RAINFALL RATES...THE VERY LOW FFG (QUARTER INCH
OR LESS in 3/6 HOURS) IS SUPPORTIVE OF THE CONTINUED ENHANCED RISK
INTO THE EVENING. EXPECT CONDITIONS TO IMPROVE MORE RAPIDLY LATER
THIS AFTERNOON AND EVENING AS THE RAINFALL RATES CONTINUE TO
DIMINISH WHILE THE BULK OF THE PRECIPITATION ASSOCIATED WITH THE
TROWAL ZONE LIFTS NORTH INTO SOUTH-CENTRAL CANADA.


...NORTHERN PORTIONS OF THE MID MISSISSIPPI VALLEY INTO THE UPPER
MIDWEST...

THE ELONGATED LOW-LEVEL FRONTAL ZONE EXTENDING WELL SOUTH OF THE
AFOREMENTIONED LOW MOVING INTO CANADA WILL HELP SERVE AS A FOCUS
FOR MAINLY SCATTERED CONVECTION ACROSS THE MIDWEST...THOUGH AREAS
FARTHER NORTH (NORTHERN PTNS OF THE MID MS VLY INTO THE UPPER MS
VLY)...NORTH OF THE MID-LEVEL CAP...WILL LIKELY SEE GREATER AREAL
COVERAGE AND MORE ROBUST RAINFALL RATES EARLY IN THE PERIOD GIVEN
THE DYNAMICAL BOOST VIA A FOCUSED AREA OF UPPER DIVERGENCE AND
LOWER TROPOSPHERIC FRONTOGENESIS WITHIN THE RIGHT ENTRANCE REGION
OF A JET STREAK TO THE N-NE...ALONG WITH A FAVORABLE THERMODYNAMIC
PROFILE WITH PWATS AROUND 1.75 INCHES AND MUCAPES OF 2000-3000+
J/KG THROUGH THIS EVENING. THE S-SW LOW LEVEL JET INCREASING TO
30-40 KTS WHILE BECOMING MORE ALIGNED WITH THE 850-300 MB MEAN
FLOW THIS EVENING...DURING THE WINDOW OF COMBINED FVRBL DYNAMICAL
AND THERMODYNAMICAL CONDITIONS...WOULD LEAD TO A PERIOD OF UPWIND
PROPAGATION AND POTENTIAL FOR BACK-BUILDING/TRAINING OF CELLS
LATER THIS EVENING AND OVERNIGHT. AS A RESULT...PORTIONS OF THE MS
VLY FROM NRN IA INTO ERN MN AND WRN WI COULD SEE LOCALIZED AMOUNTS
AOA 3 INCHES AS PER THE 12Z 4KM NAM CONEST...NSSL WRF...AND
WRF-ARW.

HURLEY
$$





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