The National Weather Service issued a tornado warning at 6:33 p.m. Aug. 18 for portions of Waukesha and Washington counties, telling people in the warned area to take shelter immediately as severe thunderstorms capable of producing a tornado moved southeast across the region.
The warning covered northeastern Waukesha County and southeastern Washington County and was set to remain in effect until 7:15 p.m. The storms were moving at about 35 mph and were expected to be near New Berlin, Brookfield, Menomonee Falls, Mequon, Pewaukee, Sussex, Hartland, Elm Grove, Germantown and Lisbon around 6:40 p.m., with Richfield, Hubertus, Colgate and Chenequa also in the possible path.
For residents in the warning area, the guidance was direct: move immediately to a basement or an interior room on the lowest floor of a sturdy building and stay away from windows. People outdoors, in vehicles or in mobile homes were told to get into the nearest substantial building, while drivers were warned not to try to outrun a tornado, especially on highways.
The danger came from radar-indicated rotation, not a confirmed tornado on the ground, which is why the warning carried such urgent instructions even before any touchdown was reported. The National Weather Service said flying debris could be dangerous and that the storm could damage roofs, windows, vehicles and trees.
The warning followed an earlier tornado warning for southeastern Columbia County, northeastern Dane County and southwestern Dodge County that ended early at 6:30 p.m., underscoring how quickly conditions were changing across southern Wisconsin. A watch means the atmosphere is primed for a tornado; a warning means one is imminent or already has touched down, and on Aug. 18 that meant the safest move was to get below ground or behind as many walls as possible before the storm arrived.
