ACUS11 KWNS 111643
SWOMCD
SPC MCD 111642
INZ000-MIZ000-ILZ000-111845-

Mesoscale Discussion 1925
NWS Storm Prediction Center Norman OK
1142 AM CDT Tue Aug 11 2026

Areas affected...northeast Illinois into far southwest lower
Michigan and northern and central Indiana

Concerning...Severe Thunderstorm Watch 563...565...

Valid 111642Z - 111845Z

The severe weather threat for Severe Thunderstorm Watch 563, 565
continues.

SUMMARY...Damaging winds with significant gusts up to 75-85 mph are
expected to continue with the ongoing bow echo. Brief tornadoes are
also possible.

DISCUSSION...An intense bow echo with a history of 85-95+ mph wind
gusts across Chicagoland has shifted into far northwest IN as of
1635Z. System movement is east at 55 to 60 kt. Considerable
downstream convection present from the vicinity of the bow echo to
north of Muncie has hindered daytime heating and resultant air mass destabilization within the inflow region of the bow echo.
Nonetheless, the presence of an organized cold pool with an intense
rear-inflow jet will support the continuation of damaging winds with significant gusts up to 75-85 mph for at least the next hour or two
across portions of northern IN and perhaps far southwest lower MI.
Brief tornadoes are also possible, especially with mesovortices
forming near or north of the apex of the bow.

Some recent CAM guidance suggests that a longer-duration significant
wind threat could materialize within the southern flank of the bow
echo and preceding convective band over central into southeast IN.
That scenario appears plausible given the influx of a strongly
unstable air mass from central IL into the region.

..Mead.. 08/11/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!8ltadmanovdqVyqBnR71RyVpnldY_TvN_OE1HTSDHL3QIL7mQSOR3xjjXGh3sTyBBLXkksmFLFMOgbhIsVBs-e9VWYE$ for graphic product...

ATTN...WFO...IWX...IND...LOT...ILX...

LAT...LON 40898785 41428750 41698735 41848649 41828585 41638518
40958502 40538500 40268510 40088535 39968574 39878640
40358759 40898785

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


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--- scorpsmtpd
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