National Weather Service United States Department of Commerce

Strong, Severe Storms Possible This Afternoon/Evening

After a few non-severe storms this morning, another round of storms is expected to fire over southern Minnesota a northern Iowa by mid afternoon. Some could become severe as they track east with a large hail and damaging wind threat. A tornado is possible. The storms will gradually exit east and weaken by late evening. Read More >

Overview

A fairly localized cluster of thunderstorms developed over northeast Iowa and southwest Wisconsin Monday evening, July 11th 2017. The storms developed rapidly, becoming strong to severe. Large hail and damaging winds accompanied a few of the storms early, but the main threat quickly moved to heavy rainfall and flash flooding.

Flash flooding occurred across parts of southeast Clayton county Iowa and into Grant county Wisconsin where over 5-8 inches of rain was measured in local rain gages. Social media reports of 4" of rain in one hour were seen, but not confirmed. Voluntary evacuations occurred along the Turkey River and Mill Creek south of Osterdock IA. Washouts occurred on many driveways and roads in both counties, with mudslides also reported in Grant county Wisconsin. 

Some of the higher rainfall totals:

4 miles west of North Buena Vista, Iowa 8.25"
Osterdock, Iowa 8.20"
Guttenberg, Iowa 5.57"
Garber, Iowa 5.39"

 

rainfall
12 hour rainfall radar estimates, ending 7 am July 12, 2017