Source: College of DuPage NEXLAB
Two waves of severe thunderstorms produced swaths of large hail, along with spotty wind damage, and a brief tornado in Minnesota on Monday May 9, 2022. Heavy rains also fell in northwestern Minnesota.
The first wave of thunderstorms plowed into Minnesota during the first 10 hours of Monday, as a fractured arc of intense thunderstorms raced east and northeastward across the state between sunrise and the mid-morning hours. With radar indicating thunderstorm tops reaching almost ten miles high at times, these large storms were able to generate a lot of hail, some of which was capable of extensive damage.
The main swath of large hail was up to 10 miles wide at times, and came from a single, regenerating thunderstorm that tracked east-northeastward from western Yellow Medicine County on the South Dakota border, to Pine and Chisago counties on the Wisconsin border. Another hail core moved northeastward in Otter Tail County. Hail up to two inches in diameter, or roughly the size of large hen eggs, fell in Montevideo and Fergus Falls. Even larger hail, the size of tennis balls and baseballs, (2.5 and 2.75 inches in diameter, respectively) fell at Clarkfield, Boyd, and Blomkest in western Minnesota. Otherwise, the main severe thunderstorm produced half-dollar to golf ball-sized consistently from Canby, to Willmar, to Princeton, to Sturgeon Lake.
The storms also produced spotty wind damage in parts of eastern Minnesota, with trees down in Ramsey, and Stacy, where the winds knocked out power as well.
The second wave of severe thunderstorms formed in a roughly north-to-south line beginning in the late afternoon. Hail began falling near St. Cloud, and then the northern Twin Cities, and eventually extending from the southeastern Twin Cities suburbs southward into Iowa. Hailstones the size of ping pong balls, golf balls, and larger pummeled the northern, southern, and southeastern suburbs of the Twin Cities. These storms all moved northeastward as the axis of storms marched east. Spotters reported a brief tornado near Gilman, just northeast of St. Cloud. The storms produced a 76 mph gust near Stewartville, just south of Rochester.
The tracks of large hail swaths through towns and cites in western and central Minnesota in the morning, and through more densely populated areas in the evening, meant that by day's end, hail had dinged, pocked, or damaged a lot of vehicles, siding, and roofs across many different parts of Minnesota. This active severe weather day in Minnesota ended up making NOAA's list of "Billion-Dollar Weather and Climate Disasters," with total damages estimated at US $2.3 billion as of October 2023.
On the northwest side of the morning activity, the thunderstorms merged with a wide area of heavy rain with embedded thunderstorms that tracked northeastward and northward across the Red River Valley and adjacent portions of Minnesota and North Dakota. Thunderstorms had formed in South Dakota multiple times over the weekend, with some activity making into northwestern Minnesota. Three-day precipitation totals reached 1-2 inches over much of western and northwestern Minnesota, with some totals including 2.16 inches at Red Lake Falls, 2.0 inches at Rothsay, 1.96 inches at St. Cloud, and one inch at Pipestone.
Updated November 29, 2023