MESOSCALE PRECIPITATION DISCUSSION 0015
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
851 AM EDT THU APR 18 2013
 
AREAS AFFECTED...SOUTHERN AND CENTRAL LOWER MICHIGAN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 181250Z - 181750Z
 
SUMMARY...WARM FRONT AND GREATER INSTABILITY NOSING INTO A REGION
ALREADY INUNDATED BY OVERNIGHT RAINS. ADDITIONAL 1-2 INCH RAINS
WILL COMPOUND ONGOING AREAL FLOODING AND MAY RESULT IN LOCAL FLASH
FLOODING.

DISCUSSION...AN AXIS OF MID LEVEL FRONTOGENESIS...INDICATED BY THE
INVERTED SFC TROUGH ON ASSOCIATED GRAPHIC...HAD YIELDED TRAINING
STORMS OVERNIGHT/THIS MORNING. MONITORING LOCAL STORM REPORTS AND
RAINFALL MEASUREMENTS...THERE APPEARS TO BE SCATTERED TO NUMEROUS
REPORTS OF AREAL FLOODING/INUNDATION OWING TO 2 TO 4 INCHES OF
RAIN IN A REGION WHERE FLASH FLOOD GUIDANCE WAS ALREADY LOW.

THE STAGE IS SET FOR ADDITIONAL RAIN TO COMPOUND THE SITUATION.
TRAINING ECHOES WITH MDT RAIN WILL CONTINUE ALONG THE MID LEVEL
FRONT NEAR/NORTH OF KALAMAZOO TO LANSING TO FLINT...WITH THESE
ECHOES INTERCEPTING THE SOUTHWESTERLY LOW LEVEL JET.
MEANWHILE...WITH SFC WARM FRONT NOSING INTO SOUTHWEST
MICHIGAN...THE NAM SHOWS INSTABILITY INCREASING THROUGH 15 UTC IN
ADVANCE OF PROGRESSIVE SQUALL LINE OVER LAKE MICHIGAN. INCREASED
INSTABILITY ALONG WITH PRECIPITABLE WATER 1.75 INCHES...OR 3
STANDARD DEVIATIONS FROM CLIMATOLOGY... ARGUES FOR A BRIEF BURST
OF HEAVY RAIN WITH THE SQUALL LINE...RESULTING IN ADDITIONAL
RAINFALL 1-2 INCHES ATOP SATURATED GROUND. EVENT SHOULD PROPAGATE
EASTWARD BY MIDDAY.

BURKE


ATTN...WFO...DTX...APX...IWX...GRR...LOT...MKX...

LAT...LON   41728704 41848556 42348443 42838380 43248367 43628376
            43778399 43838477 43578570 42838730 42428794 41798774
            41728704