ACUS11 KWNS 111401
SWOMCD
SPC MCD 111400
INZ000-ILZ000-WIZ000-IAZ000-111600-

Mesoscale Discussion 1921
NWS Storm Prediction Center Norman OK
0900 AM CDT Tue Aug 11 2026

Areas affected...southern Wisconsin...northern Illinois...and far
northwest Indiana

Concerning...Severe Thunderstorm Watch 563...

Valid 111400Z - 111600Z

The severe weather threat for Severe Thunderstorm Watch 563
continues.

SUMMARY...The potential for significant wind gusts up to 75-85 mph
is expected to persist with an evolving bow echo this morning.

DISCUSSION...An MCS with a history of producing wind gusts of 70-80
mph is currently evolving into a broader bowing configuration over
east-central IA and far northwest IL as of 1355Z. The 12z DVN
sounding is likely a good representation of the ambient inflow
environment, featuring steep mid-level lapse rates and abundant
boundary-layer moisture, yielding MUCAPE of 4500-5000 J/kg. A
largely unidirectional wind profile with around 35 kt of deep-layer
shear (per the 12z DVN sounding and current VWP) in conjunction with
the strongly unstable environment is likely to support further
intensification of the bow echo with an associated risk for
significant wind gusts up to 75-85 mph. Around 30 kt of 0-3 km shear
oriented largely perpendicular to the cold pool may support some
tornado potential, especially where the low-level shear and cold
pool remain in balance.

The bow echo is expected to track along a residual outflow boundary
from a downstream MCS, which extends east-southeast through the
south side of the greater Chicago metropolitan area into far
northwest IN.

..Mead.. 08/11/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!6mCIa_SKgEpJpTyJearH_sc7sYT93mAGdkAvbnsyMAuev4H6LspUaHzmQbw6tGwcfumbcHKhXwrny2efKlRKNiYvdmU$ for graphic product...

ATTN...WFO...LOT...ILX...MKX...DVN...ARX...

LAT...LON 41019100 41759134 42869123 43259046 42988895 42728791
42168727 41348703 40718724 40268791 40358868 41019100

MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


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--- scorpsmtpd
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