ACUS11 KWNS 271440
SWOMCD
SPC MCD 271440
MIZ000-INZ000-WIZ000-ILZ000-271715-

Mesoscale Discussion 1760
NWS Storm Prediction Center Norman OK
0940 AM CDT Mon Jul 27 2026

Areas affected...southeast WI...northeast IL...southwest Lower
MI...northeast IN

Concerning...Severe potential...Watch possible

Valid 271440Z - 271715Z

Probability of Watch Issuance...60 percent

SUMMARY...Severe potential will increase into early afternoon across
the Lake Michigan vicinity. Timing and storm evolution is a bit
uncertain, but a severe thunderstorm probably will be needed in the
next few hours.

DISCUSSION...A developing bow is currently moving across northeast
WI. Additional convection is developing ahead of this feature to the
southeast from Green Bay into central Lake Michigan along a moisture
and differential heating band within stronger northwesterly flow
aloft. Further south across parts of southern WI into northern IL,
elevated convection and developing TCU are noted in latest radar and
visible satellite imagery within a corridor of extreme instability.
It is possible that multiple clusters of strong to severe storms
could develop within these two corridors as the furthest north
cluster also continues to intensify and develop southeast.

While its remains unclear exactly how the risk will evolve over the
next few hours, it seems likely that storms will develop within a
very unstable airmass characterized by 2000-4000 J/kg MLCAPE, very
steep midlevel lapse rates, and 50+ kt deep-layer shear. The most
favorable corridor through early afternoon for severe storms
producing swaths of damaging winds and isolated hail will be from
eastern parts of WI into northeast IL, southern/central Lake
Michigan, and southwest Lower MI/northwest IN. Timing of watch
issuance is uncertain, but a severe thunderstorm watch will likely
be needed at some point by midday/early afternoon.

..Leitman/Hart.. 07/27/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!_YP9CMvF-S2366px3tbwkddGocwssdk9D3AR1nGm8GqY-0eatjvgxxQwgrY2t0VfAJp4pYiEAkPAUfEwvC7Wv9nZfIw$ for graphic product...

ATTN...WFO...IWX...GRR...GRB...LOT...MKX...

LAT...LON 44948764 43908676 42968600 42508573 41988565 41148650
41138732 41478805 42108900 42788924 43668913 44568838
44948764

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


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--- scorpsmtpd
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