AWUS01 KWNH 271005
FFGMPD
MIZ000-WIZ000-MNZ000-271500-

Mesoscale Precipitation Discussion 0859
NWS Weather Prediction Center College Park MD
604 AM EDT Mon Jul 27 2026

Areas affected...Upper MS Valley into WI and the western U.P. of MI

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

Valid 271003Z - 271500Z

SUMMARY...Increasing potential for at least brief periods of
training heavy rain will evolve over the next 3-5 hours across
portions of the Upper Midwest. Hourly rainfall of 1 to 2 inches
and flash flooding will be possible.

DISCUSSION...Area radar imagery across the Upper Midwest into
southwestern Ontario showed a broken axis of elevated
thunderstorms stretching from just north of the MN/CN border into
the west-central U.P. of MI and portions of eastern WI. The storms
were located along the northeastern edge of a large mid to
upper-level ridge over the western and central U.S., out ahead of
a shortwave impulse riding around the top of the ridge near the
ND/MN/MB junction. Cells over the southern Arrowhead region of MN
into northern WI have struggled to sustain themselves, perhaps
owing to too much low level convective inhibition. Despite the
recent struggles with sustaining convection over MN/WI, the region
was moist and unstable with 09Z SPC mesoanalysis data showing PWs
ov 1.5 to 1.7 inches and MUCAPE of 1000 to 2000+ J/kg, supportive
of heavy rain production.

There are indications in the short term RAP guidance and ALPW
trends that increasing low level moisture, advecting into WI out
ahead of the aforementioned shortwave and related surface front in
MN, will allow for decreasing CIN across WI through 15Z and
increased convective coverage. While this scenario is far from
certain, should convective coverage increase as forecast,
congealing and clustering of storms could allow for bowing/forward
propagating convective segments to develop and advance toward the
southeast. There will be some potential for short term training
along the western flank of these segments. Within any axes of
training, hourly rainfall of 1 to 2 inches will be possible along
with isolated flash flooding.

It should be noted that confidence in this forecast is lower than
average due to consistently poor model handling of current
activity from earlier runs of the HRRR, RRFS and 00Z HREF.

Otto

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

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

LAT...LON 48089181 48049033 47728969 46708863 45908797
44248769 43278807 42938950 43429088 44389184
45349233 46189265 47459260

$$
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