ACUS11 KWNS 271809
SWOMCD
SPC MCD 271808
INZ000-ILZ000-271945-

Mesoscale Discussion 1764
NWS Storm Prediction Center Norman OK
0108 PM CDT Mon Jul 27 2026

Areas affected...portions of far eastern IL into IN

Concerning...Severe potential...Watch likely

Valid 271808Z - 271945Z

Probability of Watch Issuance...95 percent

SUMMARY...An intense bow echo is developing across northeast IL
south of Chicago. Potential is increasing for a swath of
severe/damaging gusts to develop southeast across parts of far
eastern IL into northern/central IN through early evening. A new
watch is likely downstream from WW 520.

DISCUSSION...A supercell over northeast IL is transitioning toward
an intense bow. This is occurring within a corridor of
strong/extreme instability (3000-4000 J/kg MLCAPE) and 45+ kt
effective shear magnitudes. The downstream airmass into central IN
will support maintenance of this developing bow as convection
develops southeast at around 40-45 kt. KLOT radar indicates 80 kt
winds just a few hundred feet above ground level. Given the
favorable thermodynamic and kinematic environment downstream, a
swath of damaging winds to 80 mph will be possible across western
portions of WW 519 over the next hour. Convection is expected to
continue into central IN this afternoon into early evening. In
addition to intense/damaging wind gusts, isolated large hail and a
tornado or two also are possible. A downstream watch will likely be
needed soon.

..Leitman/Hart.. 07/27/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!5VVaxLx6cHxYLkjHbV647hWz-h5xIj6oPNp3IUo0TqoY1E-jwqL3n2woFxTGvp7pVk7vc0vQ8AjhBTweNVXprqdNZQg$ for graphic product...

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

LAT...LON 41848732 41548667 41078593 40338542 39828524 39458532
39148563 38918604 38768645 38738688 38828748 39208783
39888796 40658810 41218798 41518797 41738785 41848732

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


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--- scorpsmtpd
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