Flash Flood — Winona, Minnesota

2007-08-18 to 2007-08-19 · near Lewiston, Winona, Minnesota

Event narrative

Flash flooding and mudslides were common from the Elba area through Whitewater State Park and into the Lewiston area. Numerous mudslides occurred with many roads closed. Debris slid down hills and blocked drainage areas making flooding worse in many areas. A car was stuck in high water on County Highway 29 at some point.

Highway 74 in Whitewater State Park completely washed out. About 500 campers were evacuated that evening, but about a dozen campers were stranded at a primitive campsite overnight. They were rescued the following morning. The state park lost 3 bridges and there was extreme damage to campgrounds, rest rooms, a group dining hall, and the septic and water systems totaling at least one million dollars. The flood system installed at the park did activate that evening.

Many area creeks and trout streams were heavily damaged.

Wider weather episode

A warm front lifting northward into Iowa triggered round after round of thunderstorms with excessive rainfall across southeast Minnesota during the evening and overnight hours of August 18-19. This was after rain had fallen earlier in the day. Total rainfall amounts of 10 to 15 inches were common, which produced widespread and significant flash flooding. An official rainfall total of 15.1 inches near Hokah (Houston County) established an all-time 24 hour rainfall record for the state of Minnesota. Other rainfall totals, which were unofficial readings, included 17.00 and 14.00 inches respectively in Witoka and Utica (Winona County). Numerous roads and bridges were washed out, houses collapsed due to mudslides and hundreds of homes had flooded basements. Law enforcement and fire department officials reported rescuing people from their vehicles, as well as from house tops. There were seven fatalities reported, five in Winona County and two in Houston County. Damage attributed to the heavy rainfall and subsequent flooding was estimated to be in the millions of dollars. Fillmore, Houston, Olmsted, Wabasha and Winona counties were declared federal disaster areas.

View location on OpenStreetMap → (43.9604, -91.8687)

Source: NOAA Storm Events Database, event_id 50190. Narrative written by the NWS forecast office that issued the report.