Flash Flood in Winnebago County, Wisconsin

Heavy rainfall, totaling 5.41 inches for the day, over already saturated ground caused widespread flash flooding in the Oshkosh area. Sewage backed up into many basements and the foundations of some homes on the south side of the city crumbled, making them uninhabitable. The flooding destroyed 20 homes, caused major damage to 150, and caused minor damage to over 400 others. Several schools sustained damage, including Lourdes High School and the attached St. John Neumann Middle School, which had extensive water and sewage damage. Water built up in the parking lot and caved in windows on the school's lower level. Flood waters rose over five feet, destroying classrooms, athletic equipment, carpets and computers. Damage to the schools was well over $1 million. The University of Wisconsin-Oshkosh campus also sustained some water damage. High water made 50 to 75 percent of the streets impassible, including parts of U.S. Highways 41 and 45. It also washed out a railroad bridge causing a train to derail and spill diesel fuel into the floodwaters.

Thunderstorms that developed in warm, moist and unstable air ahead of an approaching cold front produced torrential rain that resulted in significant flash flooding, especially in the Oshkosh (Winnebago Co.) area. Heavy rainfall caused street and other nuisance flooding in Waushara Co., Brown Co., Door Co. and Kewaunee Co. The State of Wisconsin suffered over a half billion dollars in damage from this flooding event.

The storms also produced some large hail and wind damage.