Great Lakes Hail Supercells, Appalachian Wind Gales Charge East — SevereWX

Great Lakes Hail Supercells, Appalachian Wind Gales Charge East

Afternoon severe thunderstorms are ramping up across a massive swath from the Great Lakes to the Appalachians, with the Storm Prediction Center (SPC) issuing two Mesoscale Discussions signaling watches are likely soon. Hail and supercell risks lead in the Midwest, while damaging winds dominate farther south.

Great Lakes to Midwest Frontal Fury

Along a cold front slicing from southern Michigan into northeast Illinois, northern Indiana, and northwest Ohio, thunderstorms are maturing fast. Diurnal heating is boosting MLCAPE to 2500-3000 J/kg, eroding any cap and fueling deeper updrafts. Strong mid-level winds (35-40 knots) are promoting organized storms, including initial supercells in Michigan. Expect large hail early, transitioning to severe wind gusts as storms cluster into Indiana and Ohio this afternoon. Peak threats: hail to 1.25 inches and winds over 60 mph.

Appalachian Terrain and Confluence Ignition

Meanwhile, scattered storms are exploding over higher terrain in southeastern West Virginia, southern Virginia, western North Carolina, and far northeast Tennessee—plus a key confluence zone from northern Virginia to western North Carolina. Moist low levels and 2000-3000 J/kg MLCAPE overcome weak mid-level lapse rates, with minimal inhibition letting cells surge eastward. Shear of 15-25 knots aids organization, driving damaging downdraft gusts of 55-70 mph. Hail up to 1.25 inches is possible too.

What This Means for You

A Mesoscale Discussion (MCD) is SPC's early alert for rapidly evolving severe weather on a regional scale—think of it as a "watch this space" bulletin. With 60% odds in the Great Lakes area and 80% in Appalachia, severe thunderstorm watches could drop within the hour, covering these zones through late afternoon.

Stay Prepared

Secure outdoors, avoid flooded roads, and have a severe weather plan. Monitor local NWS radars, NOAA Weather Radio, or apps for watch/warning updates. Safety first as these storms pack punch—don't wait for the watch!