Severe weather in Chicago classifies as ‘derecho’ — here’s what that means

CHICAGO – The severe weather that struck Chicago on Monday night classified as a “derecho.”

You might remember the Southern Great Lakes Derecho in May of 1998. Winds gusted up to 90 mph from Mid-Michigan to Metro Detroit, creating one of the worst windstorms to move through the region in recorded history.

💨 Michigan weather history: The derecho of July 16, 1980

To be defined as a derecho, a storm must cause a wind damage swatch that extends more than 240 miles. It must include wind gusts of at least 58 mph along its length.

The Great Lakes Derecho of 1998 killed four people, injured hundreds, and caused millions of dollars’ worth of damage in Michigan.

In 1980, a derecho that tracked across southern Michigan left severe damage along I-94 and to the south. Wind gusts of more than 100 mph were reported, blowing railroad cars off track and blowing out windows of the Renaissance Center.

Statistically, 70% of derechos happen during the warm season of May through August.