August 21, 2007: Straight-line wind in Columbia, Dane and Sauk Counties

Short lines of severe thunderstorms moved east-northeast through south-central and southeast Wisconsin during the overnight hours. Some cell movement exceeded 43 kts (50 mph) to the east. Powerful downburst winds reached hurricane-force at 64 knots or higher (74 mph+), resulting in considerable tree and power-line damage. Synoptically, a stationary front stretched from northern Iowa to northern Illinois. Warm, moist, unstable air flowed north over the front in association with an upper-level short-wave trough, resulting in thunderstorm generation.