The National Weather Service in Grand Forks now says an EF-4 tornado impacted portions of Grant and Otter Tail counties, both in Minnesota, on Wednesday evening.
A rapidly developing supercell thunderstorm produced a long lived and deadly tornado that originally touched down in far northern Grant County as a weak tornado (EF-0 to EF-1), but then quickly intensified into a strong to violent tornado as it crossed into southern Otter Tail County, near milepost 70 on Interstate 94. The tornado intensified to a strong tornado (EF-2 to EF-3) as it moved northeastward through southwestern St. Olaf Township and crossed Beebe Lake.
It likely reached maximum EF-4 intensity after it crossed Highway 82 and destroyed a machine shop and yard on the downwind side. It then continued in a northeast direction and reached both maximum width and intensity as it moved into and across a rural homestead along 120th Street and into Blacken Lake. The tornado continued in a northeast direction producing mainly tree and cropland damages as it crossed CR117, north of Kvam Church. Video imagery and deep ground scour indicate that the tornado maintained its intensity as a strong to violent tornado even as it narrowed and eventually began to rope out near 325th Avenue, between 145th Street and CR12.
The storm that produced this tornado continued eastward across southern Otter Tail County and may have produced one or more additional, but brief, tornadoes along its path.
The tornado reached peak winds of 170 miles per hour, covered a nine-mile path, was approximately 650 yards, and resulted in two injuries and one death.