A Derecho Crossed Chicago With a 99-MPH Gust and Knocked Out Power to Nearly a Million Customers in Four States

A fast-moving line of thunderstorms swept across the Midwest on Tuesday and cut power to nearly a million customers, with the National Weather Service later confirming the system met the criteria for a derecho — a long-lived windstorm defined by a continuous swath of straight-line damage rather than by any single tornado.

As of Tuesday evening, more than 991,000 customers were without power across Illinois, Indiana, Ohio and Kentucky, according to the utility tracker PowerOutage.us. ComEd reported outages affecting more than 234,000 of its 4.1 million customers in northern Illinois. In northwest Indiana the damage was proportionally far worse: NIPSCO reported more than 300,000 customers out of roughly 500,000 in the dark by 5 p.m. The strongest gust measured in the region hit 99 mph in Gary, Indiana, with 97 mph recorded in Sugar Grove, Illinois, and 96 mph in Shorewood. Numerous personal weather stations logged gusts above 80 mph.

Tornado sirens sounded in Aurora and Plainfield around 10:15 a.m. and in the city of Chicago by 10:45 a.m. The weather service has since confirmed at least two tornadoes in the south suburbs — one in eastern Will County near Monee and Crete with damage consistent with an EF-1, and another in southern Cook County near southern Oak Forest and Flossmoor with damage consistent with an EF-1 or stronger. That second tornado was rain-wrapped and effectively invisible to anyone on the ground. Ground stops halted all departures at O'Hare and Midway; FlightAware recorded 45 percent of O'Hare flights delayed and 10 percent canceled.

At least two deaths have been reported. In Roseville, Ohio, a resident died during a medical emergency when first responders could not reach the address because of flooded roads. In Portage, Indiana, a home exploded during the storm and killed at least one person; officials have not said whether the explosion was caused by the weather. On the Indiana Toll Road, a stretch at mile marker 17.5 closed in both directions after power lines came down across the roadway, and state police said multiple semi trucks rolled over on southbound I-65 at U.S. 30 after pulling onto the shoulder to wait out the wind.

The damage reports came in faster than crews could respond. In Tinley Park, the roof of the Credit Union 1 Amphitheater was torn and debris was scattered across the field where concertgoers camp. Kerry Hourigan, standing outside the home she has lived in for 25 years, described what she found: "Total devastation. No roof." In Flossmoor, Gilbert Casillas said the noise arrived before the visibility went. "Wind started blowing, and you can hear debris hitting all sides of the house at the same time. I couldn't see more than 2 feet from outside the window," he said. Javid Jenkins, 54, of Homewood, spent the evening hunting for gas to run a generator and save the food in his refrigerator. "We're built for snow. We're built for cold," he said. "We're not built for this."

National Weather Service meteorologist Scott Baker said the Midwest was sitting on the outer edge of a "ring of fire" — a large zone of high atmospheric pressure that pumps moisture and instability along its rim and fires off waves of storms. Earlier in the day the weather service had dropped the hedging language entirely and warned simply: "These are dangerous storms!" The fifth day of the 10-day Lake County, Indiana, Fair was canceled.