ACUS11 KWNS 152149
SWOMCD
SPC MCD 152149=20
ILZ000-WIZ000-IAZ000-152315-

Mesoscale Discussion 0454
NWS Storm Prediction Center Norman OK
0449 PM CDT Wed Apr 15 2026

Areas affected...portions of northern Illinois and southern
Wisconsin

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

Valid 152149Z - 152315Z

Probability of Watch Issuance...40 percent

SUMMARY...Some severe risk may develop along and north of a warm
front this afternoon/evening. There remains uncertainty about the coverage/intensity of severe storms. A WW is possible.

DISCUSSION...As of 2145 UTC, regional mesoanalysis showed a warm
front was slowly lifting northward across northern IL and southern
WI. To the south of the front, temperatures have warmed into the mid
70s with lower 60s F dewpoints supporting moderate destabilization.
While thus far to the north of the front, instability has been more
limited, area RAP soundings and subtle warming/moistening is likely
supporting 500-1000 J/kg of MLCAPE, that will gradually expand
northward with time.

Deep-layer shear (40-50 kt EBWD) over much of the western Great
Lakes region will remain supportive of organized convective modes
with line segments and supercells possible. Damaging gust and hail
could be possible with any stronger storms. While low-level moisture
is somewhat limited, it should increase with time as the front lifts
slowly north. Low-level shear is also fairly robust and expected to
intensify this evening. This could support a risk for a couple
tornadoes with any stronger line segment mesovorticies or with any
supercells able to remain semi-discrete.

With adequate destabilization taking place, ongoing storms over
northeast IA will likely continue eastward. These storms have shown
some organization into linear segments and at least weak storm scale
rotation already. Additional storm development (possibly more
discrete) is likely ongoing across northern IL. With storm coverage
expected to increase with time, a severe risk appears plausible. A
WW may be needed.

..Lyons/Hart.. 04/15/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7TJhj4m0NCjPYLV88Vn75MkzNLblEeJnuugveQD-RKsfE9qGiUR6O2A8p-RXxAYPf494rf655= 6Eme9ZyyFTyUJiatO8$ for graphic product...

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

LAT...LON 43318786 42608769 42168774 41988808 42028914 42189048
42359104 42629125 43159105 43409053 43608924 43588856
43498812 43318786=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


=3D =3D =3D
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