MESOSCALE PRECIPITATION DISCUSSION 0140
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
329 AM EDT MON MAY 14 2018

AREAS AFFECTED...UPPER MIDWEST INTO SOUTHERN GREAT LAKES

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

VALID 140728Z - 141328Z

SUMMARY...THUNDERSTORMS ARE EXPANDING IN COVERAGE AND SHOULD SOON
TRAIN.  HOURLY RAIN TOTALS TO 1.75" WITH LOCAL AMOUNTS TO 3" ARE
POSSIBLE.

DISCUSSION...SATELLITE IMAGERY HAS SHOWN A SLOW RAMP UP OF
CONVECTION WITH COOLING CLOUD TOPS ACROSS EASTERN IA AND SOUTHERN
WI OVER THE PAST FEW HOURS WITHIN AN AREA OF GENTLY CONVERGING 850
HPA WIND FLOW NORTH OF A SLOWLY ADVANCING WARM FRONT.  THIS HAS
OCCURRED AHEAD AND SOUTH OF A SHORTWAVE MOVING EASTWARD ALONG THE
IA/MN BORDER INTO SOUTHERN WI.  PRECIPITABLE WATER VALUES OF
1.3-1.5" LIE ACROSS THIS AREA PER GPS VALUES.  INFLOW AT 850 HPA
IS WEST-SOUTHWEST AT 40 KTS PER VAD WIND PROFILES.  MU CAPE VALUES
ARE ROUGHLY 1000-3000 J/KG IN THIS REGION, WITH EFFECTIVE BULK
SHEAR OF ~25 KTS PER SPC MESOANALYSES.

AS CELL COVERAGE CONTINUES TO INCREASE, TRAINING BECOMES MORE
LIKELY VERY SOON ACROSS EASTERN IA AND SOUTHERN WI.  THE BAND IS
EXPECTED TO SHIFT SOUTHWARD INTO NORTHERN IL WITH TIME.  THIS
ACTIVITY IS EXPECTED TO ADVECT DOWNSTREAM INTO NORTHEAST IN AND
NORTHWEST OH WITH TIME.  FLASH FLOOD GUIDANCE ARE RELATIVELY LOW
DUE TO RECENT RAINS.  GIVEN THE MOISTURE AND INSTABILITY, HOURLY
RAIN TOTALS TO 1.75" ARE ACHIEVABLE SHOULD A LONG ENOUGH BAND
TRAIN.  THIS WOULD BE NECESSARY AS CELL MOTIONS HAVE BEEN EAST AT
30-35 KTS.  THE END OF THE LINE FOR CONVECTION WITH HEAVY RAINFALL
IS EXPECTED TO BE NORTHWEST OH DUE TO LOWER INSTABILITY AND LESS
LOW-LEVEL INFLOW.  MESOSCALE GUIDANCE ADVERTISES LOCAL AMOUNTS IN
THE 2-3" RANGE THROUGH 13Z.

ROTH

ATTN...WFO...ARX...CLE...DMX...DTX...DVN...GRR...IWX...LOT...
MKX...

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

LAT...LON   43208775 42288480 41238371 41008545 41638943
            41819335 42079405 42979218