“The most dangerous period is likely during the late afternoon and evening when strong tornado potential should be maximized,” meteorologists at the Storm Prediction Center in Norman, Oklahoma, wrote.
The National Weather Service in the Twin Cities said Monday afternoon that they had a report of an observed tornado looking west from Fairmont, Minnesota, which is southwest of Minneapolis.
Pea- to marble-sized hail pelted parts of Faribault County in southern Minnesota, and rain was heavy, Sheriff Scott Adams said.
“A heavy downpour -- it became extremely dark out,” he said.
The National Weather Service reported receiving multiple reports of tornadoes near the small town of Winnebago, Minnesota, about 110 miles (177.03 kilometers) southwest of Minneapolis-St. Paul. But Adams said the reports weren’t confirmed and there appeared to be no wind damage as of Monday evening.
Melissa Dye, a meteorologist at the National Weather Service’s office in the Twin Cities, said spotters likely saw “gustnados,” which are small whirlwinds that form during thunderstorms but are not connected to a cloud base, as a tornado. She said they can look like tornadoes because of they kick up dust and debris.
Dye said spotting a tornado would be difficult because they’d be wrapped by the rain.
The Minneapolis-St. Paul area appeared to largely skirt the worst of the weather.
“Any severe threat is pretty much done for the metro area,” she said Monday evening.
She said there is still some storm activity in the Albert Lea area, just north of the Iowa border.
The Storm Prediction Center said a lesser potential for severe weather extended as far south as parts of Texas and Oklahoma.
Monday's first round of storms darkened skies over downtown Minneapolis around 9 a.m. and brought brief heavy rains, but it triggered no weather warnings as it passed through.
The City of Minneapolis closed its public-facing non-emergency city facilities, including its main service center, as of 2 p.m. and activated its emergency operations center.
The Minneapolis, St. Paul and Bloomington school districts were among several in Minnesota that canceled evening activities ahead of the storms. Some Iowa schools also closed early for the day or canceled evening activities.
As severe thunderstorms began popping up in the early afternoon, the National Weather Service reported 2.8-inch (7 centimeters) hail near Beaver Creek in southwestern Minnesota. Forecasters issued tornado watches for almost the entire southern half of Minnesota, plus much of northern Iowa and western Wisconsin, effective until late Tuesday.
On Sunday evening, a tornado derailed an empty BNSF coal train west of Ashby in northwestern Nebraska. Initial reports were that a tornado measuring more than 1 mile (1.6 kilometers) wide derailed many of the approximately 130 cars on the train, toppling several onto their sides. There were no immediate reports of injuries and the locomotive remained upright, the News Channel Nebraska radio group reported. It was one of several tornadoes reported in that part of Nebraska on Sunday evening.
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AP writer John Hanna in Topeka, Kansas, contributed to this story.