Severe Thunderstorm Warning in Effect Tonight—Live Radar, Impact Zones & Critical Safety Tips

July 29 2025 – The National Weather Service (NWS) has issued multiple Severe Thunderstorm Warnings stretching from the eastern Dakotas through Minnesota, Iowa, Wisconsin and northern Illinois, with storms expected to race east-southeast at 60-80 mph and produce wind gusts topping 80 mph. Meteorologists warn that today’s setup could evolve into a derecho—a long-lived, fast-moving line of destructive thunderstorms capable of hurricane-force winds—impacting morning and evening commutes for cities such as Minneapolis–St. Paul, Des Moines, Milwaukee, Chicago and Indianapolis. Why today’s threat is unusual • Extreme instability: Afternoon temperatures in the upper 90s and dew points near 80 °F are creating “heat-burst” energy levels rarely seen outside mid-summer heat waves. • Jet-stream support: A 110-kt upper-level jet is diving out of Canada, supplying the shear needed for bow-echo formation and possible embedded tornadoes. • Mesoscale boundaries: Overnight storms left an outflow boundary draped across southern Minnesota; storms tracking along this boundary can intensify suddenly and drop large hail the size of golf balls or larger. Real-time damage reports – Lennox, South Dakota: 79-mph measured gust flipped irrigation pivots and downed power poles before 9 p.m. CDT Monday. – Bloomington, Minnesota: Radar-indicated 90-mph “couplet” prompted immediate shelter-in-place orders; tree damage already confirmed by emergency managers. – Sioux Falls, South Dakota: Quarter-size hail shattered vehicle glass on I-29; travelers forced to seek refuge under overpasses. What a Severe Thunderstorm Warning means When the NWS issues a Severe Thunderstorm Warning, radar or trained spotters have confirmed winds ≥ 58 mph and/or hail ≥ 1 inch in diameter. The warning is an action statement: move to a sturdy building, away from windows, and avoid travel until the storm has passed. Safety checklist for today’s storms (optimized for quick search answers) 1. Charge phones and battery packs before noon. Cell service often fails after 70-mph winds. 2. Secure patio furniture, trampolines and garbage cans—items that become dangerous projectiles in high winds. 3. Plan alternate indoor cooling: 200 million Americans remain under Excessive Heat Warnings. If power fails, relocate to a public cooling center announced by local emergency management. 4. Never shelter in a car or mobile home; relocate to a site-built structure or designated storm shelter. 5. After the warning expires, treat all downed lines as live and report outages to your utility, not 911, unless there is fire or injury. Travel and infrastructure impacts • Air: Minneapolis–St. Paul, Chicago O’Hare and Milwaukee Mitchell airports face ground stops; check airline apps for real-time gate changes. • Road: Expect closures along I-35, I-90 and I-94 due to overturned semis and tree debris. • Rail: Freight carriers have begun staged shutdowns between Sioux Falls and Milwaukee to inspect tracks for wind damage. Looking ahead The Storm Prediction Center’s Day 1 Convective Outlook keeps an Enhanced to Moderate Risk over the Great Lakes through Wednesday morning. As the derecho races into Ohio and western Pennsylvania tonight, a new corridor of damaging winds could redevelop along the Appalachians before sunrise Tuesday. Bottom line If you receive a Wireless Emergency Alert or hear sirens today, act immediately; seconds matter in a Severe Thunderstorm Warning. Keep multiple, redundant ways to get weather information and stay tuned to local NWS offices for updates as this potentially historic wind event unfolds.