High winds and fresh snowfall across Minnesota and the Dakotas on Thursday combined for blizzard conditions that closed schools and created hazardous driving conditions.

Dozens of schools across the region closed early Thursday to avoid sending children home in blizzard conditions. The National Weather Service measured sustained winds up to 40 mph in much of the region, with gusts topping 60 mph in some areas.

Snow totals were not expected to be the main hazard — southern Minnesota and western Wisconsin were forecast to receive 3 to 4 inches maximum — but the fresh accumulation can compound already poor conditions.

“We’re looking at 1 to 2 inches in most areas,” said Dan Luna, weather office manager at the Twin Cities National Weather Service office in Chanhassen. “But fresh snow blows around much, much more easily than old snow. So, the question we always ask in advanced is ‘How much new snow will we have?’ When it’s more than we have forecasted, things get worse quickly.”

Luna said conditions will be worse farther west in western Minnesota, North Dakota and South Dakota, where the terrain doesn’t break the wind as it does near the Minnesota-Wisconsin border.

Travel conditions were treacherous Thursday afternoon, with whiteout conditions and several snow-covered highways. Much of eastern North Dakota and South Dakota was under no travel advisories by each state’s department of transportation, including large portions of Interstates 29, 90 and 94.

The Minnesota Department of Transportation said Interstate 90 remained open.

MnDOT advised no travel in southwestern or southeastern Minnesota. No unnecessary travel was advised in northwestern Minnesota due to whiteout conditions and blowing snow.

Snow also was making roads slippery in the Twin Cities. Statewide, the State Patrol reported more than 650 crashes during the day. There were 87 cases of injuries, though none was serious or fatal.

The National Weather Service extended a blizzard warning from west-central and south-central Minnesota north into central Minnesota until 3 a.m. Friday.

Minnesota remained in the deep freeze Thursday with morning temperatures below zero and wind-chill readings in the negative double digits.

Luna also said conditions should clear up in time for the weekend.

“Once we get past Friday, things will be much more typical of January,” Luna said. “It will be warmer, less windy and the snow should stop.”