ACUS11 KWNS 180002
SWOMCD
SPC MCD 180002
MIZ000-WIZ000-MNZ000-180230-

Mesoscale Discussion 1643
NWS Storm Prediction Center Norman OK
0702 PM CDT Fri Jul 17 2026

Areas affected...Parts of Upper Michigan...northern Wisconsin...and
far east-central Minnesota

Concerning...Severe potential...Watch unlikely

Valid 180002Z - 180230Z

Probability of Watch Issuance...20 percent

SUMMARY...Severe risk will continue spreading east-southeastward
into tonight. The primary concern will be damaging wind gusts.

DISCUSSION...An east/west-oriented cluster of thunderstorms is
tracking southeastward across far northwestern WI, generally focused
along a cold front and associated surface wind shift. A deeply mixed
PBL downstream may continue to promote outflow dominant storm
structure, with the primary risk being locally damaging wind gusts.
However, around 30-40 kt of line-orthogonal effective shear could
support embedded supercell structures capable of severe gusts and
isolated large hail as well.

Over Upper MI, around 1500 J/kg MLCAPE and stronger deep-layer shear
(around 50 kt of effective shear) will conditionally support
supercell structures with any storms that spread/develop across the
area tonight amid a gradually strengthening warm-advection plume.
Additionally, the latest surface analysis shows a warm front draped
across the area, and the MQT VWP is sampling a related
clockwise-curved low-level hodograph. This boundary and related
enhancement to the low-level shear/streamwise vorticity could
provide a locally favorable corridor for storm organization and the
potential for damaging winds, hail, and a brief tornado tonight.

Current thinking is that the overall severe threat will remain too
marginal and/or localized for a watch, though convective trends are
being monitored -- especially over Upper MI where a locally greater
severe risk is possible.

..Weinman/Hart.. 07/18/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!6NKrxkGDuYObid511Kcjkpa4YN8zUzjdaKR8NHxbuBSZqw91977GWX5Lmb6j1-DJBNZLmUmBburMQAIpy22OUpMQlk8$ for graphic product...

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

LAT...LON 46589032 47048911 47128849 47048791 46878753 46648707
46568667 46688626 46598601 46278596 46128661 46028788
45918889 45279164 45199250 45299311 45659339 45969323
46369254 46469192 46589032

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


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--- scorpsmtpd
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