After a one-day break, thunderstorms resumed with a vengeance on Wednesday May 11, 2022. Isolated to scattered thunderstorms produced large hail and heavy rain from the morning into the afternoon across parts of southern Minnesota, before a large complex of storms spread from southwest to northeast across southern and central portions of the state during the evening. The storms produced wind damage and power outages, along with additional heavy rains.
The morning storms formed on the cooler and less humid side of a warm front that had been bottling up an extremely humid air mass in Iowa. These storms drew their energy from unstable conditions 1-4 miles above the ground, and were able to grow 9-10 miles high at times. Large hail fell from several of the cells, with hail reported to the size of tennis balls near Oronoco and Plainview, with golfball-sized hail reported at new Prague, Potsdam, and Pine Island. The storms also closed roads near Owatonna after over 3 inches of rain fell.
Other thunderstorms lifted northward from the Minnesota River in western Minnesota in the early afternoon, eventually turning more to the east. These storms also produced heavy rains and hail, with ping pong ball and golf ball sized hail reported near Zimmerman, Big Lake, and Orrock.
The main event developed during the evening, as intensifying thunderstorms pinwheeled northeastward out of southwestern Minnesota. Between 5 PM and 10PM, the storms tracked across southern, central, and eastern Minnesota, blowing down power lines, knocking down trees, dropping occasionally large wind-driven hail, and producing nearly constant lightning. The storms produced several tornado reports in southwestern Minnesota, with thunderstorm wind gusts above 75 mph reported in Windom, Shakopee. and Morristown. Tree damage was limited throughout the area by the delayed leaf-out of many hardwood trees, though some areas, including the St. Paul campus of the university of Minnesota received extensive tree damage.
Rainfall totals from all of the day's storms (and lasting into the early morning of Thursday May 12th) ranged from 3-5 inches from near Marshall, to Granite Falls, to Willmar, and into southern Stearns County. Volunteer observers with the CoCoRaHS network measured 5.16 inches in southwestern Kandiyohi and northeastern Lyon counties, and 4.99 inches near Danube in Renville County. One to three inch rainfall amounts were common across southern and central Minnesota.
May 12, 2022