Severe Thunderstorm Warning Issued: Timeline, Impact Zones, and Essential Safety Tips

Millions across the Midwest and Great Lakes woke up to an active Severe Thunderstorm Warning as a potent spring system races east, threatening destructive winds, very large hail, flash flooding and a few tornadoes. The National Weather Service (NWS) says the highest risk zone stretches from eastern Texas and the lower Mississippi Valley through Illinois, Indiana, Ohio and into Michigan, placing more than 65 million people in the storm track. Key threats today • Damaging straight-line winds of 60–70 mph capable of toppling trees and power lines. • Hail up to golf-ball size—and locally larger—especially in Michigan and northern Illinois where lingering cold air aloft favors rapid hail growth. • Isolated tornadoes, greatest where discrete supercells develop ahead of the main squall line. • Torrential downpours that may trigger flash-flood advisories in saturated river basins. Timing and regional breakdown • Morning: Storm clusters sweep across eastern Oklahoma and Arkansas, entering the lower Ohio Valley by late morning. • Afternoon: A broken line of severe thunderstorms tracks from St. Louis to Chicago, then races toward Indianapolis, Dayton and Columbus with widespread wind damage potential. • Evening and overnight: The line bows through southeast Michigan, metro Detroit and Toledo between 6 p.m. and midnight. NWS Detroit has already flagged the period as a “First Alert Weather Day,” citing the possibility of 1-inch hail and localized 70 mph gusts. Counties currently under Severe Thunderstorm Warning include parts of Harris (TX), Pulaski (AR), St. Clair (IL), Cook (IL), Marion (IN), Lucas (OH) and Wayne (MI). Additional warnings will be issued on a rolling basis as the line surges east; residents should enable Wireless Emergency Alerts and keep a weather radio nearby. Why the outbreak is dangerous A sharp temperature contrast—mid-70s Gulf moisture surging beneath a pocket of cold upper-level air—has created extreme instability for late March. Strong mid-level winds are adding enough shear to rotate storms, increasing the tornado risk, particularly in southern Illinois and western Kentucky during the early afternoon. Safety checklist during a Severe Thunderstorm Warning 1. Seek sturdy shelter on the lowest floor, away from windows; large hail can shatter glass. 2. Bring pets indoors and secure outdoor furniture that could become projectiles. 3. Charge phones and have flashlights ready for likely power outages. 4. Avoid driving through flooded roads; just 6 inches of water can stall a vehicle. 5. Monitor live radar and official NWS updates as warnings may upgrade to Tornado Warnings with little lead time. Looking ahead The cold front driving today’s outbreak will push into the Appalachians overnight, but residual instability could spark additional strong storms Wednesday along the Mid-Atlantic. Behind the front, sharply cooler air and gusty northwest winds arrive, ending the severe threat but ushering in a late-week chill. Bottom line: If your county is placed under a Severe Thunderstorm Warning today, act immediately—do not wait for tornado sirens. Fast-moving storms will leave little time to seek safety once they arrive.