MESOSCALE PRECIPITATION DISCUSSION 0406
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
813 PM EDT WED JUN 28 2017

AREAS AFFECTED......SOUTHEAST WI AND NORTHERN IL...

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

VALID 290010Z - 290510Z

SUMMARY...CLUSTER OF SHOWERS AND THUNDERSTORMS ACROSS EASTERN IA
AND SOUTHWEST WI ARE EXPECTED TO CROSS SOUTHEAST WI AND NORTHERN
IL THIS EVENING. 1 TO 3 INCHES OF RAIN IS EXPECTED WITH ISOLATED
HIGHER TOTALS LIKELY.

DISCUSSION...A WARM FRONT WAS IN PLACE LATE THIS AFTERNOON AND
EVENING ACROSS SOUTHERN WI AND NORTHERN IL.  THUNDERSTORMS THAT
DEVELOPED IN ADVANCE OF AN APPROACHING COLD FRONT IN IOWA HAVE
PRODUCED WIDESPREAD 1-2 INCHES OF RAIN WITH AN ISOLATED 4 INCH
REPORT IN WEST UNION IA.

THE ACTIVITY IS EXPECTED TO CONTINUE MOVING EAST ACROSS SOUTHEAST
WI AND NORTHERN IL THIS EVENING AS STRONG LOW LEVEL SOUTHWEST FLOW
CONTINUES ADVECTING HIGH MOISTURE INTO THE REGION.  FAVORABLE HIGH
SURFACE DEWPOINTS IN THE LOWER 70S AND MIXED LAYER CAPE VALUES TO
2500 J/KG ALSO AID IN FURTHER DEVELOPMENT.

INFLOW AT 850 HPA IS CONVERGENT AT 40-50 KTS.  PRECIPITABLE WATER
VALUES ARE 1.75-2.0" IN THE 23Z RAP ANALYSIS.

EXPECTATIONS ARE FOR THE CONVECTION TO CONTINUE PROPAGATING
STEADILY EAST NEAR 25-30 KT WITH CELL MERGERS.  OCCASIONALLY
TRAINING BANDS WILL LEAD TO LOCALIZED HEAVY RAIN AND FLOODING OF
LOW LYING AND POORLY DRAINED AREAS. 

THE 20-22Z HIGH RES RAPID REFRESH RUNS HAVE BEEN INDICATING 2 TO 3
INCHES OF RAIN...AS WELL AS THE 12Z HIGH RES WRN NMMB.  THESE
AMOUNTS HAVE GOOD CONTINUITY FROM UPSTREAM REPORTS, SO LOOK
REASONABLE.
HOURLY RAIN RATES TO 2" AND LOCAL AMOUNTS TO 4" ARE POSSIBLE IN
SOUTHEAST WI AND NORTHERN IL.

PETERSEN

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

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

LAT...LON   42948777 42628693 41968721 41788863 41659122
            42339121 42668942