Iowa Supercells Set to Explode with 2.5-Inch Hail, Tornado Threat into Illinois, Wisconsin — SevereWX

Iowa Supercells Set to Explode with 2.5-Inch Hail, Tornado Threat into Illinois, Wisconsin

A volatile setup is brewing across south-central and eastern Iowa, northern Illinois, and southern Wisconsin as clusters of towering cumulus clouds repeatedly attempt to ignite thunderstorms this afternoon.

The Storm Prediction Center highlights a cluster over northeast Iowa struggling against lingering inhibition, but persistent boundary-layer heating and expansive cumulus fields point to imminent storm development. Expect supercells to root and intensify into the evening, fueled by 50+ knot mid-level winds and a strengthening low-level jet. This storm mode sets the stage for large hail (1.5-2.5 inches), damaging wind gusts (65-80 mph), and a tornado threat (85-110 mph peak intensity), especially if low-level shear aligns with any lingering boundaries from prior convection.

Storms should spread eastward from central and south-central Iowa, potentially reaching northern Illinois and southern Wisconsin by evening. SPC pegs the odds of a tornado watch at 80%, likely issuing soon if initiation succeeds—otherwise, hold tight for later this afternoon.

Peak Threats:

This MD (1421) runs through 9:30 PM CDT. Track updates via SPC.

Stay prepared: Monitor radar closely, secure outdoor items, and have a severe weather plan ready. Know your safe spot and receive alerts via NOAA Weather Radio or apps.