ACUS11 KWNS 030041
SWOMCD
SPC MCD 030040=20
INZ000-ILZ000-WIZ000-030245-

Mesoscale Discussion 1456
NWS Storm Prediction Center Norman OK
0740 PM CDT Thu Jul 02 2026

Areas affected...Northeast Illinois

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

Valid 030040Z - 030245Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorms developing across northeast Illinois may
pose a risk of large hail and damaging winds through the late
evening hours. Watch issuance is possible if T-storm
coverage/intensity sufficiently increases.

DISCUSSION...The early stages of thunderstorm development are noted
along a subtle low-level confluence band across northeast IL and
into extreme southeast WI. This confluence band remains just ahead
of a more prominent outflow boundary quickly approaching from the
west. The pre-outflow environment over the greater Chicago area was
recently sampled by an ACARs sounding out of Midway, which depicted
a largely uncapped and buoyant, but only modestly sheared,
environment. However, an upstream 00 UTC RAOB from DVN (taken ahead
of the outflow boundary) sampled stronger (40 knot) mid-level flow
that is likely approaching the region.=20

Based on these observations, there is reason to expect some degree
of storm organization in the coming hours across northeast IL as the
stronger mid-level flow spreads east. Emerging convection will
likely trend towards clusters with time given the orientation of the
zone of initiation with the mean flow, but a supercell or two
appears possible - both ahead of and along/behind the primary
outflow boundary - in the next few hours. Guidance continues to
handle this regime poorly, and it's unclear if convection will
intensify to severe limits before reaching the Lake Michigan shore. Nonetheless, trends will be monitored, and watch issuance is
possible if the severe threat appreciably increases.

..Moore/Guyer.. 07/03/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7qx9YmpDuq2ZccR2CEiEt6LULc9_mln1k-NHVM1e59bILJ5CpzOoNeiu3CDji0B5VZmkLiVh5= QiPZtFl7SJXtzbKeWw$ for graphic product...

ATTN...WFO...LOT...MKX...DVN...

LAT...LON 41398901 41568941 42058951 42418957 42638923 42778849
42798767 42528767 42308771 42118762 41998752 41868746
41768748 41398750 41398901=20

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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* Origin: Capitol City Weather Station (1:2320/127)