MESOSCALE PRECIPITATION DISCUSSION 0014
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 AM EDT THU APR 18 2013
 
AREAS AFFECTED...NRN MO..SE IA..NRN IL..SRN WI..NRN IN..SRN MI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 180650Z - 181250Z
 
SUMMARY...THE COMBINATION OF REDUCED FLASH FLOOD GUIDANCE VALUES
AND SUSTAINED PERIODS OF MODERATE TO HEAVY RAIN WILL RESULT IN A
CONTINUED THREAT FOR FLASH FLOODING FROM NORTHERN MISSOURI INTO
NORTHERN ILLINOIS AND SOUTHERN MICHIGAN THROUGH 12Z.  

DISCUSSION...AN ELONGATED BAND OF MODERATE TO HEAVY RAINFALL
CONTINUES TO DEVELOP IN VICINITY OF LOW PRESSURE OVER CENTRAL
MISSOURI AND TO THE NORTH OF A WARM FRONT EXTENDING EASTWARD FROM
THE LOW TOWARD PEORIA IL AND LAFAYETTE IN.  THE REGION OF
STRONGEST ASCENT ALSO COINCIDES WITH A COUPLING OF THE ENTRANCE
AND EXIT REGIONS OF SEPARATE JET STRUCTURES. DUE TO THE RAPIDLY
EVOLVING NATURE OF THE EVENT...MESOSCALE GUIDANCE IN GENERAL
OFFERS LIMITED INSIGHT INTO THE RAINFALL'S EVOLUTION. 
HOWEVER...THE WRF-ARW IS CLOSE IN SOME REGARD...INCLUDING MATCHING
THE ANTICIPATED RAINFALL AMOUNTS THROUGH 12Z DERIVED FROM AN
AVERAGE OF HOURLY RAINFALL REPORTS AND RADAR ESTIMATED.  COMBINING
OBSERVED RAINFALL AMOUNTS WITH MODEL GUIDANCE PRODUCES ADDITIONAL
RAINFALL AMOUNTS OF 0.75 TO 1.5 INCHES AHEAD OF THE LOW'S PATH
THROUGH 12Z...WITH LOCAL AMOUNTS OF 2 TO 3 INCHES POSSIBLE.  WITH
3-HOURLY FFG VALUES BELOW 1.5 INCHES IN MANY AREAS...A CONTINUED
THREAT FOR FLASH FLOODING WILL CONTINUE.

JAMES


ATTN...WFO...IWX...GRR...LOT...ILX...MKX...LSX...DVN...SGF...
DMX...EAX...

LAT...LON   39519457 40579389 42119131 42668980 43228788 43498576
            43108470 42538451 41928507 41538686 40449000 38529164
            38049305 38569448 39519457