Flash Flood Guidance
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000
AWUS01 KWNH 281209
FFGMPD
IAZ000-MOZ000-MNZ000-NEZ000-281608-

MESOSCALE PRECIPITATION DISCUSSION 0331
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
808 AM EDT THU AUG 28 2014

AREAS AFFECTED...FAR EASTERN NE/IA/EXTREME NORTHERN MO...

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 281208Z - 281608Z

SUMMARY...AN MCV WHICH DEVELOPED OVERNIGHT ACROSS KS HAS LIFTED
NORTHEASTWARD INTO EASTERN NE/WESTERN IA. THE SYSTEM CONTINUES TO
HAVE ACCESS TO AMPLE MOISTURE CONTENT AND IS UNDER A STRONGLY
DIFFLUENT SECTOR OF THE UPPER JET. FLASH FLOODING WILL BE POSSIBLE
THROUGH ROUGHLY 16Z.

DISCUSSION...WIDESPREAD MODERATE TO HEAVY RAINFALL CONTINUES TO
OCCUR IN ASSOCIATION WITH A MESOSCALE CIRCULATION LIFTING INTO
NORTHEASTERN NE. THERE HAS BEEN A SUBTLE DECREASE IN THE COVERAGE
OF COLDER CLOUD TOPS BUT THE OVERALL STRUCTURE OF THE COMPLEX
STILL LOOKS REASONABLY ORGANIZED. A MODEST 700-MB FLOW IN EXCESS
OF 35 KNOTS BASED ON THE VAD WIND PROFILE WAS OBSERVED WHICH
SHOULD BE SUSTAINED FOR THE NEXT FEW HOURS. THE ONE LIMITING
FACTOR HAS BEEN THE INSTABILITY WITH THE 11Z RAP OBJECTIVE
ANALYSIS SUPPORTING ONLY 250 TO 500 J/KG OF MUCAPE. THE
INSTABILITY PROFILES WERE A LITTLE BETTER UPSTREAM WHICH COULD
EXPLAIN WHY THE COVERAGE OF COLDER TOPS HAS DECREASED IN RECENT
SCANS. HOWEVER...FLASH FLOODING IS STILL POSSIBLE AS THE ONGOING
SHIELD OF PRECIPITATION ENTERS A REGION OF SOMEWHAT LOWERED FFG
VALUES. EXPECT HOURLY RAINFALL RATES OF 1 TO 2 INCHES PER HOUR TO
BE THE NORM GIVEN THE PAST HISTORY OF THIS SYSTEM.

HIGH-RESOLUTION GUIDANCE SHOW A CLEAR SIGNAL OF HEAVY RAINFALL
ACROSS IA THROUGH 18Z. A VAST MAJORITY OF THESE MODELS PAINT A
MAXIMUM IN QPF FROM EASTERN NE INTO MUCH OF CENTRAL IA. THIS
RAISES THE CONFIDENCE IN BELIEVING THIS COMPLEX WILL STAY INTACT
FOR AT LEAST A FEW MORE HOURS. IN SPITE OF THE WEAK
INSTABILITY...THE DYNAMICS FROM THE MCV AND UPPER JET DIFFLUENCE
SHOULD MAKE UP FOR THIS LIMITATION.


RUBIN-OSTER

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DVN...ARX...MPX...DMX...EAX...FSD...OAX...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   43269572 43509396 43399269 42629176 41809157 41179173
            40709235 40529355 40479546 40659608 41249646 42229647
            43269572



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