MILWAUKEE — Unrelenting winter weather again made travel difficult in the Upper Midwest Tuesday, causing highway spinouts, hundreds of school closings and some grounded flights. At least one death was linked to the frigid weather.

The latest winter storm was stressing already weary plow drivers who worked to keep up with the accumulating snow. Up to a foot of new snow was expected in Wisconsin, where a winter storm warning was posted for most of the state.

Schools across the state canceled classes, including the districts of Milwaukee, La Crosse, Wausau, Madison and Waukesha. For some districts, it was the fifth day in two weeks that classes were canceled because of the snow or dangerously cold temperatures.

The snow grounded at least 10 flights Tuesday morning at Dane County Regional Airport.

In Sioux Falls, South Dakotas, a man found dead under a downtown bridge may have died from the frigid weather, police said. The man was discovered just before 7 a.m. Tuesday, police spokesman Officer Sam Clemens said. The National Weather Service says the temperature in Sioux Falls was 12 degrees (minus 11 Celsius) around the time the man was found.

The National Weather Service says wind gusts of up to 30 mph reduced visibility and created dangerous travel conditions for motorist who decided to venture out.

In North Dakota, 16 head of cattle were killed when a semi driver hauling the livestock was blinded by blowing snow from a passing truck, hit an embankment and rolled over Monday afternoon. The Highway Patrol said the driver suffered minor injuries. About five dozen head of cattle survived.

The Minnesota State Patrol was dealing with numerous crashes and spinout around the state. Patrol Sgt. Jesse Grabow three children were in a minivan that rollover on Interstate 94 near Rothsay Tuesday. Grabow says the children were properly restrained and were not hurt.

A winter storm warning was also posted for southeastern Minnesota until midnight. Rochester schools were among districts that canceled classes Tuesday. St. Paul public schools canceled most after-school activities. Both Minneapolis and St. Paul declared snow emergencies beginning at 9 p.m., triggering parking restrictions.