ACUS11 KWNS 241910
SWOMCD
SPC MCD 241910=20
MIZ000-OHZ000-INZ000-ILZ000-242115-

Mesoscale Discussion 1771
NWS Storm Prediction Center Norman OK
0210 PM CDT Thu Jul 24 2025

Areas affected...portions of northern IL/IN into southern Lower MI

Concerning...Severe potential...Watch possible=20

Valid 241910Z - 242115Z

Probability of Watch Issuance...60 percent

SUMMARY...Isolated strong to severe wind gusts are possible this
afternoon into early evening across portions of northeast Illinois,
northern Indiana, and southern Lower Michigan.

DISCUSSION...Isolated thunderstorms are developing across northeast
IL as of 19z ahead of surface boundary moving slowly southeastward.
Ahead of the boundary and initial thunderstorm development, strong
heating into the low 90s, with dewpoints in the mid/upper 70s, is
resulting in a corridor of moderate/strong instability (MLCAPE up to
3000 J/kg). Deep shear will remain weak across the region, but
effective shear magnitudes around 20-30 kt may be sufficient for a
few organized cells/clusters. Modified RAP forecast soundings show
large instability, with steep low-level lapse rates from 7-8 C/km in
the 0-3 km layer. Given the very moist and strongly unstable
airmass, isolated downbursts producing strong to severe gusts are
possible through the afternoon into early evening.=20

Some uncertainty remains regarding storm coverage, especially given
veering low-level flow, reducing convergence/lift along the surface
boundary. Nevertheless, any storm that does develop could produce
locally damaging gusts. A severe thunderstorm watch may be needed at
some point this afternoon.

..Leitman/Guyer.. 07/24/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_9QGtYDejcpF7tJu0QkexNPsQ76Uv3O9_eucSzJML7IA-HrQWtziHU9CYwBx7pVOl0cTHe4gn= 5ojpbcCPBbhBlvoyBA$ for graphic product...

ATTN...WFO...DTX...IWX...GRR...IND...LOT...ILX...DVN...

LAT...LON 41818422 41428473 40638685 40478776 40568856 40878952
41308972 41558955 42008844 43338482 43328451 43158423
42928408 42298413 41818422=20

MOST PROBABLE PEAK WIND GUST...55-70 MPH


=3D =3D =3D
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