Mesoscale Precipitation Discussion 0921
NWS Weather Prediction Center College Park MD
446 AM EDT Wed Oct 03 2018

Areas affected...Central/Northern WI...UP Michigan

Concerning...Heavy rainfall...Flash flooding possible

Valid 030846Z - 031300Z

Summary...A few repeating/training showers and thunderstorms this
morning with quick bursts of heavy rain may lead to localized
flash flooding across portions of Wisconsin and UP Michigan.

Discussion...Recent GOES-East water vapor imagery showed a
shortwave tracking across portions of Iowa while at the surface, a
warm front was analyzed across southern Iowa and portions of
Illinois. Strong moisture transport and isentropic lift
overrunning this boundary combined with favorable upper level
support has led to a line of elevated showers/storms from
south-central MN through west-central WI into northern/northeast
WI.

GOES-East IR imagery has shown a steady cooling with cloud tops
over the last hour and recent radar returns from KARX/KGRB/KMPX
show increasing reflectivity with 1-hr estimated rates of
0.5-1.0". Finally, PWATs are very high for the area and time of
year, with a recent mesoanalysis showing around 1.5", or 2-3 SD
above normal.

As the shortwave treks across the Upper Midwest and with some
unidirectional flow, there is the potential for some
repeating/training storms that could produce isolated amounts of 2
to 3 inches and lead to localized flash flooding given 1-hr FFG of
1 to 1.5".

HREF probabilities show the greatest risk area to be across
portions of north-central into northeastern WI and portions of the
UP of MI. The threat should end quickly west to east by 13-14z as
the shortwave quickly moves through the region.

Taylor

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

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

LAT...LON   46768722 45928641 45168719 44288978 44099037
            44389171 44549193 45489189 46588903