MESOSCALE PRECIPITATION DISCUSSION 0320
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1109 AM EDT TUE AUG 26 2014
 
AREAS AFFECTED...SERN WI...NERN IL...NWRN IN...EXTREME SWRN MI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 261507Z - 261807Z
 
SUMMARY...AXIS OF MOISTURE AND INSTABILITY IN PLACE ALONG/AHEAD OF
NEARLY STATIONARY SFC FRONT WILL LEAD TO THE POTENTIAL FOR
CONVECTION REPEATEDLY DEVELOPING ACROSS THE SAME AREAS THROUGH
EARLY AFTERNOON. HOURLY RAINFALL RATES OF 1-2 INCHES ARE POSSIBLE.

DISCUSSION...A VERY MOIST AND UNSTABLE AIR MASS IS IN PLACE
ALONG/AHEAD OF SFC FRONT...WHICH WAS ANALYZED AT 14Z GENERALLY
ALONG A LINE FROM BRL TO UGN TO MKG. SPC MESOANALYSIS INDICATES
VERY HIGH 850 HPA DEWPOINTS OF +16 TO +18 DEG C IN PLACE ACROSS
NRN IL...AS WELL AS MUCAPE VALUES IN EXCESS OF 3000 J/KG.
ADDITIONALLY...VERY HIGH SFC DEWPOINTS OF 72 TO 75 DEG F WERE
NOTED AT 14Z ACROSS CENTRAL IL...ADVECTING NORTHWARD INTO THE
OUTLINED AREA ON 5-10KT SOUTHERLY FLOW. VIS SATELLITE INDICATES
SOME NEW CONVECTIVE DEVELOPMENT OCCURRING ACROSS NERN IL/NWRN IN
IN THE VICINITY OF THIS MOISTURE/INSTABILITY MAXIMUM.

AS OUTFLOW ASSOCIATED WITH THE REMAINS OF WEAKENING CONVECTIVE
COMPLEX TO THE WEST OF THE OUTLINED AREA OVERNIGHT APPROACHES...IT
IS SHOWING SIGNS OF INCREASED CONVECTION ALONG THE BOUNDARY. 13Z
HRRR DEPICTS THIS NEW CONVECTIVE DEVELOPMENT AND SHOWS IT
CONTINUING TO INCREASE IN COVERAGE/INTENSITY THROUGH LATE MORNING.
GIVEN THE AVAILABILITY OF MOISTURE/INSTABILITY...AS WELL AS THE
SLOW-MOVING OR NEARLY STATIONARY FRNTL BNDRY OVER THE REGION
THROUGH EARLY AFTERNOON...THE HRRR SEEMS REASONABLE. THIS SOLUTION
WOULD GIVE SOME AREAS 2 TO 3 INCHES OF RAINFALL OVER THE NEXT FEW
HOURS...WITH HOURLY RAINFALL RATES OF 1 TO 2 INCHES POSSIBLE GIVEN
1 HR FFG VALUES IN THIS AREA ARE IN THE 1 TO 2 INCH RANGE...FLASH
FLOODING IS POSSIBLE.

RYAN

ATTN...WFO...IWX...GRR...LOT...MKX...

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

LAT...LON   42518645 41768562 40908622 40758723 40818831 41388901
            42018934 42488916 42888857 42988770 42518645