MESOSCALE PRECIPITATION DISCUSSION 0516
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
526 AM EDT THU JUL 20 2017

AREAS AFFECTED...SRN WI/NRN IL

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

VALID 200925Z - 201330Z

SUMMARY...TRAINING RAINFALL WITH RATES OF 1-2 IN/HR SHOULD SLOWLY
ADVANCE FROM SRN WI INTO NRN IL THROUGH 12Z. AN ADDITIONAL 2-4
INCHES WILL BE POSSIBLE THROUGH 14Z ALONG WITH POSSIBLE FLASH
FLOODING.

DISCUSSION...09Z RADAR IMAGERY SHOWED SEVERAL SMALLER CORES OF
CONVECTION CONTAINING 1-2 IN/HR RAIN RATES EMBEDDED WITHIN A
LARGER SWATH OF PRECIPITATION EXTENDING FROM THE SRN MN/WI BORDER
TO NRN IL. THIS REGION OF ELEVATED CONVECTION CONTINUES TO BE
ROOTED BETWEEN 700-800 MB...OCCURRING 50-100 MILES NORTHEAST OF A
SLOW MOVING SURFACE WARM FRONT ANALYZED NW TO SE THROUGH ERN IA
INTO CNTRL IL AT 09Z. RECENT VAD WIND PLOTS FROM KMPX AND KARX
SHOWED WLY 700 MB FLOW OF 40-50 KT WHICH CONTINUED TO SUPPLY AMPLE
MOISTURE AND INSTABILITY INTO THE CONVECTIVE COMPLEX. EXPERIMENTAL
GOES 16 INFRARED IMAGERY OVER THE PAST FEW HOURS HAS SHOWN BURSTS
OF COLDER CLOUD TOPS ORIGINATING NEAR THE SRN MN/WI BORDER AND
PROPAGATING SEWD INTO SRN WI AND RECENTLY INTO NRN IL. GAUGE AND
RADAR ESTIMATES HAVE PLACED 4-7 INCHES OF RAIN OVER THE PAST 12
HOURS ALONG AND JUST EAST OF THE MISSISSIPPI RIVER INTO WRN WI.

THE ENTIRE COMPLEX OF RAIN HAS BEEN TRANSLATING SEWD AHEAD OF AN
850 MB COLD FRONT WHICH EXTENDED FROM THE CNTRL U.P. OF MICHIGAN
INTO SRN MN BASED ON VAD WIND PLOTS AND RAP ANALYSES AT 09Z.
RAINFALL WILL END FROM NW TO SE AHEAD OF THIS STEADILY MOVING
BOUNDARY INTO THE REMAINDER OF THE MORNING. MID-UPPER LEVEL
DIFFLUENT FLOW WILL REMAIN IN PLACE OVER FAR SRN WI AND NRN IL
HELPING TO SUPPORT VERTICAL MOTIONS IN THE PRESENCE OF
PRECIPITABLE WATER VALUES NEARING 2 INCHES ALONG THE IA/WI BORDER.
WITH LOW LEVEL INFLOW REMAINING STEADY-STATE AND AN ESTIMATED
500-1000 J/KG MUCAPE AVAILABLE FROM WRN WI INTO NRN IL...PER 08Z
SPC MESOANALYSIS PAGE...1-2 IN/HR RAINFALL RATES APPEAR LIKELY TO
CONTINUE OVER THE NEXT 2-4 HOURS ALONG WITH POSSIBLE FLASH
FLOODING.

OTTO

ATTN...WFO...ARX...DVN...LOT...MKX...

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

LAT...LON   44159131 44159052 43458913 42728767 41488713
            41148795 41578951 42009027 42559076 43499165
            43799159