ACUS11 KWNS 271725
SWOMCD
SPC MCD 271724
INZ000-ILZ000-271900-

Mesoscale Discussion 1762
NWS Storm Prediction Center Norman OK
1224 PM CDT Mon Jul 27 2026

Areas affected...northeast IL/northwest IN

Concerning...Severe Thunderstorm Watch 520...

Valid 271724Z - 271900Z

The severe weather threat for Severe Thunderstorm Watch 520
continues.

SUMMARY...A favorable environment supporting large to very large
hail and a tornado risk will develop across portions of northeast IL
into northwest IN over the next 1-2 hours.

DISCUSSION...A supercell located over northeast IL will develop
south/southeast across the southern greater Chicago metro vicinity.
The downstream airmass is very moist (mid/upper 70s dewpoints) and
unstable (3000-4000 J/kg MLCAPE). Favorable vertical shear with 50+
kt effective shear magnitudes and 0-1 SRH near 125 m2/s2 is noted
from the KLOT VWP. Effective STP values have increased to 3-5 as
well. This environment will continue to support supercell structures
with a continued risk for very large hail to around 2.5 inches,
strong wind gusts, and possibly a strong tornado over the next 1-2
hours.

..Leitman.. 07/27/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!9hjMMurmuHaBxmZvVkEIp-52r55yL_lvw5gX0au1YU5PAhU0vv9VdZlJuzrgVm7yx1v1-ZY4EtDBBMdaw0jACcKo4ZE$ for graphic product...

ATTN...WFO...LOT...

LAT...LON 42018782 41528726 41138721 40998753 41038799 41228829
41718827 41928825 42058811 42018782

MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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--- scorpsmtpd
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