052
AWUS01 KWNH 210441
FFGMPD
MIZ000-210740-

Mesoscale Precipitation Discussion 0800
NWS Weather Prediction Center College Park MD
1240 AM EDT Tue Jul 21 2026

Areas affected...portions of lower Michigan

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

Valid 210440Z - 210740Z

Summary...Backbuilding/training convection poses a flash flood
risk across portions of Lower Michigan tonight.

Discussion...A fairly focused axis of strong convection was
located near Traverse City and adjacent areas of northern Lake
Michigan over the past hour.  The storms were being forced
partially by ascent associated with stout mid-level troughing over
Lake Superior and adjacent southern Canada along with a
moist/unstable axis extending from northern Illinois into western
Lower Michigan (1000-2000 J/kg MLCAPE, 1.5+ inch PW values).  The
orientation of storms relative to westerly low-level flow and the
primary moist/unstable axis upstream suggests potential for
backbuilding to continue for at least a couple more hours across
northwestern Lower Michigan with a gradual southward shift in
heavy rainfall over the next couple hours.  The backbuilding and
available moisture has contributed to around 1-2 inch/hr rain
rates at times, and 1+ inch/hr rain rates should continue to be
associated with the band during its existence. These rain rates
will fall on areas of 1-2 inch/hr FFG, suggestive of an isolated
flash flood threat.

Longevity of this band of backbuilding convection is in question,
although it appears likely that storms will persist slightly
longer than CAMs are suggesting.  Flash flood potential will exist
through at least 0630/07Z while gradually becoming more
conditional thereafter.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...APX...DTX...GRR...

ATTN...RFC...MSR...NWC...

LAT...LON   44968630 44948482 44498411 43578407 43178602
            44068686