Thunderstorm Wind in Yellow Medicine County, Minnesota

Widespread wind damage occurred around the city of Granite Falls. Numerous trees, power lines and structural damage occurred in the city with the Yellow Medicine East School District main building sustaining major damage. The winds tore off the heating and ventilation systems on the roofs, opening the duct work to the rain. Water poured through the ventilation system and directly into classrooms, hallways and on equipment. On the south side of the Minnesota River, the Granite Run golf course suffered significant damage to trees and their local restaurant.

A small complex of storms that moved out of northeast South Dakota late Saturday morning caused a concentrated area of straight-line wind damage. The Canby, Minnesota airport measured a wind gust of 72 mph. These type of wind speeds continued across portions of Yellow Medicine and Lac Qui Parle counties where hundreds of trees and power lines were blown down. There was another wind gust of 68 mph at the Department of Transportation road sensor (Near Hanley Falls, MN) that went offline as the gust was recorded.

The worst area occurred in the city of Granite Falls where winds tore open two roofs and allowed water to pour through ventilation ducts into classrooms and hallways, causing hundreds of thousands of dollars in damage to the Yellow Medicine East School District building. The Granite Fun restaurant and golf course also sustained damage with 55 to 60 trees blown down. Due to the extensive damage, the city of Granite Falls declared a state of emergency.

Although wind damage occurred east of Granite Falls, mainly between Sacred Heart to Renville, this storm weakened as it moved eastward toward the western part of the Twin Cities.

A secondary area of storms developed across south central Minnesota during the mid-late afternoon near New Ulm, and produced another area of significant wind damage eastward toward Cannon Falls, and Red Wing. There was a swath of tree damage around Cannon Falls where one house lost its roof, with other having minor roof damage.