SIOUX FALLS, S.D. — A winter storm was pounding parts of the Upper Midwest with heavy snow and making travel treacherous Friday.

Blowing and drifting snow and whiteout conditions were expected to move in overnight Friday in the Dakotas, Minnesota and Iowa.

In South Dakota and Minnesota, dozens of schools canceled classes Friday ahead of the snowfall. South Dakota Gov. Kristi Noem ordered state government executive branch offices in 42 counties to close early on Friday.

A winter storm warning across the region was expected to give way to blizzard-like conditions by Saturday with gusty winds of 50 mph whipping up snow and bringing down power lines and tree branches. The University of North Dakota also closed Friday afternoon.

Snow was making driving dangerous in parts of Minnesota. The Minnesota State Patrol urged people not to travel unless they had to. In North Dakota, officials closed Interstate 29 from Fargo to the South Dakota border late Friday afternoon.

Totals of 5 inches (12.7 centimeters) to 9 inches (22.8 centimeters) of snow are expected across much of central and southern Minnesota and western Wisconsin Friday. As of 4 p.m. Friday, the National Weather Service in Sioux Falls, South Dakota, reported more than 6 inches (15 centimeters) of snow.