MESOSCALE PRECIPITATION DISCUSSION 0227
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
656 PM EDT WED MAY 17 2017

AREAS AFFECTED...NORTHERN WI...UP OF MI

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

VALID 172300Z - 180400Z

SUMMARY...MULTIPLE ROUNDS OF MODERATE TO HVY SHOWERS WITH EMBEDDED
CONVECTIVE ELEMENTS TRACKING THROUGH AREAS OF SATURATED SOILS FROM
EITHER TODAY OR LAST FEW DAYS POSES A POSSIBLE FLASH FLOODING
THREAT THROUGH EARLY OVERNIGHT HOURS.

DISCUSSION...GOES-E EIR/VIS DEPICTS A CONGEALING CLUSTER OF
MODERATELY COOL CLOUD TOPS WITH EMBEDDED WEAK OVERSHOOTING TOPS
ACROSS THE SOUTHERN UP ALONG THE TRAILING LOW TO MID-LEVEL TROF
EXTENDING FROM MATURE MCV OVER THE NORTH CENTRAL UP.  WHILE FLASH
FLOODING MAY BE POSSIBLE ALONG THE MERGING CONVECTION AND HAVING A
WEAK TRAINING PROFILE; HOWEVER REDUCING INSTABILITY FURTHER
SUPPORTS THE GENERAL WEAKENING TREND NOTED IN RADAR/SATELLITE AS
WELL AS  MOVING TOWARD AREAS OF HIGHER FFG NOT BEING AS AFFECTED
BY PRIOR ROUNDS OF RAINFALL OVER THE LAST FEW NIGHT'S FURTHER WEST
INTO N WI.  STILL A SWATH OF .75-1.5" OF RAINFALL MAKE THE AREA
SUSCEPTIBLE TO FLASH FLOODING WITH ANY ADDITIONAL UPSTREAM BANDS
OF CONVECTION. 

DEEP UPPER LOW AND ASSOCIATED OCCLUDING SURFACE WAVE WILL CONTINUE
TO TRANSLATE NORTHEAST WITH SHORTWAVE TROFS/DPVA BANDS LIFTING
NORTHEAST...THE FIRST IN THE NEXT HOUR OR TWO...THE SECOND
ENTERING THE AREA OF CONCERN AROUND 04-05Z. THESE BANDS HAVE BEEN
FED BY SUFFICIENT INSTABILITY FURTHER SOUTH BUT WITH PROXIMITY TO
STRONGER COLD CONVEYOR BELT ACROSS S ONTARIO/LK SUPERIOR INTO
CENTRAL MN...CONVECTION WILL WEAKEN AND BEGIN TO OVERRUN THE
BOUNDARY PROVIDING MODERATE SHOWERS WITH WEAK REMAINING EMBEDDED
CONVECTIVE ELEMENTS.  THESE BEST LINGERING CONVECTIVE ELEMENTS ARE
MOST LIKELY FURTHER EAST TOWARD NE WI/S UP OF MI GIVEN EXPECTED
SLIGHTLY VEERING 850MB FLOW AFTER 00Z (DUE TO UPSTREAM
FILLING/OCCLUDING OF CYCLONE) WHICH MAY TRACK THROUGH AREAS
AFFECTED BY THE FIRST BATCH. SO WITH AN ADDITIONAL 1-2" OVER
EITHER THE SATURATED SOILS OVER N WI FROM THE LAST FEW NIGHT'S
CONVECTION OR THIS FIRST ROUND MAY BE SUFFICIENT TO EXCEED THE
LOWERED FFG VALUES AND POSE A POSSIBLE FLASH FLOODING SITUATION
LATER THIS EVENING. 

GALLINA

ATTN...WFO...ARX...DLH...GRB...MPX...MQT...

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

LAT...LON   46758610 46038636 44888799 44358990 44829084
            45139200 45619220 45979189 46319130 46569056
            46698891