Supercells Gear Up for Large Hail, Damaging Gusts in Wisconsin to Chicago — SevereWX

Thunderstorms are firing up near the Mississippi River in northwest Wisconsin, poised to spread east-southeast into northern Illinois and northwest Indiana through early evening.

The Storm Prediction Center flags a 60% chance of issuing a severe thunderstorm watch soon for this zone. Strong heating is boosting instability to around 1000 J/kg MLCAPE near a surface low, with boundary-layer moisture in the low 60s dewpoints set to rise amid warm advection. Expect cloudiness and showers over northern Illinois to clear eastward, ramping up the risk.

Shear exceeds 35 knots with straight hodographs favoring supercells or clusters. This setup supports isolated large hail (1-1.75 inches), damaging wind gusts (55-70 mph), and even a tornado or two, especially where low-level shear perks up near lake breezes or heating boundaries.

Peak threats include EF2-intensity tornadoes (up to 90 mph), golfball-sized hail, and gusts capable of snapping tree limbs or downing power lines. Cities like Madison, Milwaukee, Rockford, and Chicago's northern suburbs could see action as storms intensify.

Stay tuned to SPC updates and local NWS offices (GRB, MKX, LOT, IWX). Prepare now: Trim trees, secure outdoor items, have multiple alert sources ready, and know your safe spot indoors away from windows.