ACUS11 KWNS 100353
SWOMCD
SPC MCD 100353
INZ000-ILZ000-IAZ000-100600-

Mesoscale Discussion 1890
NWS Storm Prediction Center Norman OK
1053 PM CDT Sun Aug 09 2026

Areas affected...northern Illinois

Concerning...Severe Thunderstorm Watch 550...

Valid 100353Z - 100600Z

The severe weather threat for Severe Thunderstorm Watch 550
continues.

SUMMARY...Severe potential continues within WW550.

DISCUSSION...Supercells and supercell hybrid clusters continue
across portions of northern Illinois. As the low-level jet has
strengthened, a few low topped supercells have shown weak rotation.
One supercell in Lee County near the warm front/outflow boundary
across northern Illinois approached 60 kft with more pronounced and
long lived rotation and reports of a tornado. VAD profiles from KLOT
are sampling 0-3 km SRH around 350-400 m2/s2, with weakening flow
above 3 km. Given the favorable low-level shear, transient weak
rotation will likely continue with low topped cells south of the
boundary. Any storm that can anchor to the boundary may have
potential for a tornado in the short term. Mode is becoming more
clustered through time, with increasing damaging wind potential
later into the overnight.

..Thornton.. 08/10/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!8dHprsUHApAfiHM7YoOSVNgYAS9fC3GPHhVmDUo33i8vagdVWy6h2a5DNxfU3dZco3FyCGpqEDtr5LNkTGqm-YMgCT0$ for graphic product...

ATTN...WFO...LOT...ILX...DVN...

LAT...LON 41999078 42238963 42288892 42228818 42088774 41878733
41458738 40908815 40758899 40748977 40889035 41209084
41579095 41999078

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 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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