At least eight tornadoes touched down across counties just south and west of the Twin Cities metro Wednesday night, but damage was mainly limited to downed trees, the National Weather Service said.
Storms rolling from south to north spawned twisters in Steele, Rice, Sibley and Scott counties, said Caleb Grunzke, a meteorologist with the Weather Service's Chanhassen office.
There had been a slight chance for severe weather on Wednesday, and there was just enough instability in the atmosphere to produce low-topped supercells that led to the season's first big tornado outbreak, Grunzke said.
The first warnings went out in Steele County near Owatonna, where two tornadoes were sighted about 7:25 p.m. Over the next 90 minutes, twisters also touched down near Morristown, Henderson, Dundas and Elko New Market. In total, the Weather Service counted eight tornadoes, Grunzke said.
Authorities in Steele and Rice counties reported no damage to structures, but storm chasers reported downed trees west of Dundas in Rice County and south of Elko New Market in Scott County.
The Weather Service has not determined the strength of the twisters, Grunzke said, but they were believed to have been on the weaker end of the scale in which tornadoes are ranked from EF0 to EF5 based on wind speed.
Unofficial rain totals included 1.27 inches in Maple Grove, 1.64 inches in Victoria, 2.11 inches in Howard Lake and 2.43 inches near Minnetrista. Most places saw less than an inch, the Weather Service reported.
A very small risk of tornadoes, as storms had potential to redevelop, continued Thursday afternoon. The highest chance for tornadoes was over southeastern Minnesota. The rest of the state had a marginal risk for severe weather, with heavy rain, high winds and hail representing the biggest threats, Grunzke said.
Friday was expected to bring a chance of storms and temperatures in the 80s. A burst of heat, humidity and sunshine was predicted to arrive Saturday with a high of 91 degrees in the Twin Cities. Another chance for thunderstorms was in the forecast for Sunday with a high of 80, the Weather Service said.
Tim Harlow • 612-673-7768