CHICAGO — A powerful, gusty storm dumped mounds of snow across the upper Midwest on Sunday, closing major highways in several states, canceling more than 1,600 flights in Chicago and collapsing the roof of the Minnesota Vikings' stadium.

CHICAGO — A powerful, gusty storm dumped mounds of snow across the upper Midwest on Sunday, closing major highways in several states, canceling more than 1,600 flights in Chicago and collapsing the roof of the Minnesota Vikings' stadium.

At least four weather-related deaths were reported as the storm system dropped nearly 2 feet of snow in parts of Minnesota and marched east. A blizzard warning was in effect Sunday for parts of eastern Iowa, southeastern Wisconsin, northwestern Illinois and northern Michigan, according to the National Weather Service. Surrounding areas, including Chicago, were under winter storm warnings. Much of Iowa was under a wind-chill advisory.

In Minneapolis, the heavy snow left the Metrodome decidedly unready for some football. Video inside the stadium aired by Fox Sports showed the inflatable Teflon roof sagging before it tore open, dumping massive amounts of snow across one end of the playing field.

No one was hurt but the Vikings' game against the New York Giants had to be moved to Detroit's Ford Field. The day of the game had already been pushed back from Sunday to Monday because the storm kept the Giants from reaching Minneapolis on time. Stadium officials were trying to repair the roof in time for the Vikings' next home game, Dec. 20 against Chicago.

The wintry weather, with blowing snow that severely limited visibility, wreaked havoc on air and road travel. In the Chicago area, wind gusts of up to 50 mph, temperatures in the teens and wind chills well below zero were expected, along with up to 8 inches of snow.

At least 1,375 flights were canceled at O'Hare International Airport and more than 300 were canceled at Midway International Airport, Chicago aviation officials said.