Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 211405
FFGMPD
OHZ000-KYZ000-INZ000-MIZ000-ILZ000-211800-

MESOSCALE PRECIPITATION DISCUSSION 0306
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1004 AM EDT THU AUG 21 2014

AREAS AFFECTED...NERN ILLINOIS INTO INDIANA...SWRN OHIO AND NRN
KENTUCKY

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

VALID 211402Z - 211800Z

SUMMARY...PERIODS OF TRAINING CONVECTION ARE EXPECTED TO CONTINUE
THROUGH ROUGHLY 18Z FOR PORTIONS OF THE MIDWEST...CENTERED OVER
INDIANA...WITH POSSIBLE FLASH FLOODING. AS LOW LEVEL FLOW WEAKENS
THIS AFTERNOON...THE FLASH FLOOD THREAT SHOULD TEMPORARILY
DIMINISH ACROSS THE HIGHLIGHTED REGION.

DISCUSSION...RECENT RADAR IMAGERY HAS SHOWN AREAS OF CONVECTION
EXTENDING FROM SERN MINNESOTA / WRN WISCONSIN...SEWD INTO INDIANA
AND WRN OHIO. THIS AXIS HAS BEEN OCCURRING NEAR AND NORTH OF A
SLOW MOVING WARM FRONT WHICH WAS ANALYZED SEWD ACROSS THE MIDWEST
AT 14Z FROM IOWA INTO NRN ILLINOIS. VAD WIND PROFILE WINDS SHOWED
25 TO 35 KTS AT 850 MB FROM THE WEST WITH CLOUD BEARING LAYER MEAN
WINDS ALSO ROUGHLY FROM THE WEST AT 25 TO 35 KTS ALLOWING SOME OF
THE CELLS TO EXHIBIT TRAINING CHARACTERISTICS.

SPC MESOANALYSIS AND RAP DATA INDICATE WEAK ELEVATED INSTABILITY
WAS PRESENT ACROSS THE REGION WHICH IS HELPING TO SUSTAIN NEW
UPDRAFT DEVELOPMENT ACROSS PORTIONS OF THE THREAT AREA WITH
SEVERAL LOCATIONS HAVING RECEIVED UP TO 3 INCHES ACCORDING TO DUAL
POL ESTIMATES FROM KIND. ALTHOUGH GROUND TRUTH HAS BEEN HARD TO
COME BY GIVEN THE SOMEWHAT ISOLATED NATURE OF THE HEAVIER
RAINFALL...THE EXPECTED DURATION OF TRAINING CELLS THROUGH ABOUT
18Z SHOULD CONTINUE A LOW END FLASH FLOOD THREAT. MODEL DATA
INDICATES THAT 850 MB FLOW WILL DIMINISH BY 18Z TO ABOUT 10 TO 15
KTS WHICH SHOULD WEAKEN LIFT ACROSS THE RELATIVELY COOL AIR NORTH
OF THE BOUNDARY...BRINGING A TEMPORARY END TO THE FLASH FLOOD
THREAT. HI-RES MODEL DATA IS MIXED ON THE EVOLUTION AND
AMOUNTS...BUT ROUGHLY HALF OF THE AVAILABLE HI-RES GUIDANCE
SUGGESTS ANOTHER 3-4 INCHES WILL BE POSSIBLE FOR PORTIONS OF THE
THREAT AREA THROUGH 18Z.

OTTO

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

ATTN...WFO...ILN...IWX...GRR...IND...LOT...

ATTN...RFC...NCRFC...OHRFC...

LAT...LON   42468778 42178589 40358374 38818349 38688476 39498612
            41048818 41868844 42468778



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