ACUS11 KWNS 131906
SWOMCD
SPC MCD 131906=20
OHZ000-MIZ000-INZ000-ILZ000-131930-

Mesoscale Discussion 0397
NWS Storm Prediction Center Norman OK
0206 PM CDT Mon Apr 13 2026

Areas affected...portions of northeastern Illinois into northern
Indiana and extreme southern Lower Michigan

Concerning...Severe potential...Watch needed soon=20

Valid 131906Z - 131930Z

Probability of Watch Issuance...95 percent

SUMMARY...The severe threat is increasing, with a WW issuance
impending. Severe hail appears to be the main threat, though a
couple of damaging gusts are also possible.

DISCUSSION...Elevated convection, which has been oscillating in
intensity within a low-level WAA advection regime, has recently
shown an uptick in intensity, with 1 inch diameter hail recently
reported. These storms are moving over a heated airmass, with
surface temperatures warming into the 80s F. Given boundary layer
growth, these storms are likely rooting into the boundary layer,
where 1500 J/kg MLCAPE is present. Given 30+ kts of effective bulk
shear, surface-based supercell development is likely underway. The
strongest storms will support a severe hail threat over the next few
hours, though a damaging gust or two is possible. A tornado cannot
be completely ruled out. Given the recent uptick in storm intensity,
a Severe Thunderstorm Watch will be issued momentarily.

..Squitieri/Hart.. 04/13/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9NJixF7R6ho658OBKPepLeBbvreCtfao6p7ocCtVx_hXgdYDJ6uBxMoqwuP_8wNSXIdHtbU2T= HkgSZM2c7wzUzusVMo$ for graphic product...

ATTN...WFO...IWX...IND...LOT...

LAT...LON 41448883 41908707 42028574 41938492 41618460 41168467
40798527 40668612 40608701 40608766 40738846 41448883=20

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


=3D =3D =3D
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