MESOSCALE PRECIPITATION DISCUSSION 0118
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1257 AM EDT WED MAY 02 2018

AREAS AFFECTED...ERN MN/IA BORDER INTO S-CNTRL WI

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

VALID 020454Z - 021000Z

SUMMARY...PERIODS OF MODERATE TO HEAVY RAINFALL WILL POSE A FLASH
FLOOD THREAT FROM THE ERN MN/IA BORDER INTO S-CNTRL WI THROUGH
ABOUT 10Z. ADDITIONAL RAINFALL OF 1-3 INCHES IS EXPECTED.

DISCUSSION...A SOMEWHAT DISORGANIZED AREA OF CONVECTION WAS
OBSERVED FROM THE IA/MN BORDER INTO S-CNTRL WI AS OF 0430Z WITH
STEADY OVERALL MOVEMENT OFF TOWARD THE ENE. TWO EMBEDDED MCVS
STOOD OUT WITHIN THIS CLUSTER OF CONVECTION...ONE OVER CNTRL WI
AND THE OTHER OVER NRN IA...WITH SCATTERED POCKETS OF HEAVY
RAINFALL EMBEDDED WITHIN A BROADER REGION OF LARGELY STRATIFORM
RAIN ACROSS THE REGION. OBSERVED RAINFALL RATES HAVE BEEN MAXING
OUT BETWEEN 0.5 AND 1.0 IN/HR...CLOSE TO DUAL POL ESTIMATES FROM
KARX. MUCAPE ACROSS THE REGION IS AT OR ABOUT 500 J/KG PER THE
LATEST SPC MESOANALYSIS PAGE...DOWN APPROXIMATELY 300-600 J/KG
OVER THE LAST 3 HOURS.

MEAN STEERING FLOW PARALLEL TO A QUASI-STATIONARY FRONT...LOCATED
FROM LAKE SUPERIOR TO ERN NE...HAS BEEN ALLOWING FOR BRIEF PERIODS
OF TRAINING OF SOME OF THE HEAVIER CONVECTIVE CORES. WHILE
INSTABILITY  WILL CONTINUE TO WANE OVERNIGHT...ESPECIALLY ACROSS
NRN LOCATIONS...POCKETS OF 500 J/KG ARE EXPECTED TO MAINTAIN OVER
NERN IA INTO SRN WI THROUGH 10Z. THIS ALONG WITH SOME DEGREE OF
UPPER LEVEL JET DIVERGENCE/DIFFLUENCE ARE EXPECTED TO MAINTAIN
PERIODS OF HEAVY RAIN FROM NERN IA INTO SRN WI BETWEEN THE
AFOREMENTIONED MCVS. GIVEN FLASH FLOOD GUIDANCE VALUES OF 1.5
INCHES IN 3 HOURS...ESPECIALLY OVER ERN WI...ADDITIONAL RAINFALL
MAY SUPPORT A FEW AREAS OF FLASH FLOODING OVER THE NEXT FEW
HOURS...BUT ANY PROBLEMS SHOULD REMAIN LOCALIZED.

OTTO

ATTN...WFO...ARX...DMX...DVN...GRB...MKX...MPX...

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

LAT...LON   45038757 44258715 43448741 42908753 42748828
            42699051 42599199 42659332 43389363 43919185
            44648952