Great Lakes Frontal Storms Build Supercell, Hail Threats Afternoon — SevereWX

Great Lakes Frontal Storms Build Supercell, Hail Threats Afternoon

Thunderstorms firing along a southeastward-moving cold front across southern Michigan are gaining strength, with deeper updrafts signaling a shift to severe weather through the afternoon.

SPC's Mesoscale Discussion 1647 flags intensifying convection spreading into northeast Illinois, northern Indiana, and northwest Ohio. Diurnal heating is boosting MLCAPE to 2500-3000 J/kg in a moist boundary layer, while 35-40 knot mid-level winds support organized storm modes. Expect initial supercells in Michigan—packing up to 1.25-inch hail and 90 mph tornado potential—before clustering increases downstream, favoring damaging winds of 55-70 mph.

Watch issuance odds sit at 60%, possibly within the hour as coverage expands. Peak threats: hail to 1.25 inches, gusts to 70 mph, isolated EF1-2 tornadoes.

Stay prepared: Monitor local warnings, secure outdoor items, and have a severe weather plan ready. Check SPC for updates.