CHICAGO (AP) — Successive punches of snow and wind were impacting the eastern half of the United States on Monday as severe weather swept across much of the nation, making roads impassable in the Upper Midwest and canceling more than 2,000 flights nationwide.

Forecasters said mid-Atlantic states and Washington, D.C., were at greatest risk for high winds and tornadoes. The cold front was expected to move off the East Coast by Tuesday, bringing sharply colder weather in its wake, forecasters said.

By Tuesday morning, wind chills below freezing were expected to reach the Gulf Coast and the Florida Panhandle with freeze warnings in effect in parts of the Southeast and parts of Arkansas, Oklahoma, Louisiana, and Texas, forecasters warned. To the north, rain was expected to change over to snow behind the cold front with accumulations of more than 6 inches (15 centimeters) possible in the central Appalachians of West Virginia.

The late winter blast comes as Hawaii continued to be affected by a separate storm system that caused severe flooding over the weekend.

Forecasters warn about line of storms, tornadoes

The National Weather Service that warned a line of severe storms with damaging winds would cross much of the Eastern U.S. After firing up Sunday, the storms were crossing the Mississippi, Tennessee and Ohio valleys. The storm threat was expected to enter the Appalachians, then move toward the East Coast, where “severe thunderstorms with widespread damaging winds and several tornadoes” were expected, the service said.

A stretch from parts of South Carolina to Maryland appeared most likely to experience the greatest damaging winds Monday afternoon, the weather service said. That could include Raleigh, North Carolina; Richmond, Virginia; and the nation’s capital.

Many schools in North Carolina, South Carolina and Virginia were closed Monday. North Carolina Gov. Josh Stein urged residents to enable emergency alerts on their phones ahead of expected wind gusts of 74 mph (119 kph). In Maryland, many school systems planned to dismiss students early on Monday.

Beyond the threat to lives and property, “whether it’s wind gusts from a squall line, blizzard or snow, or just wind because of the storm, you’re looking at several major airports being impacted,“ said AccuWeather senior meteorologist Tyler Roys.

Big snows in Minnesota, Wisconsin, Michigan

Blizzard conditions persisted Monday in parts of Wisconsin and Michigan, where the storm brought as much as 2 feet (61 centimeters) of snow by morning. It was still snowing in the region. Additional snowfall of a foot (30 centimeters) to 20 inches (51 centimeters) of snow can be expected in upper Michigan, along with gusty winds, on Monday, the National Weather Service said. Schools were closed in a number of communities Monday in both states, including Milwaukee and Marquette, Michigan.

Lower snow accumulations in places such as Chicago and Milwaukee were expected to create trouble for commuters on Monday, Roys said.

Jim Allen, 45, who lives on the Upper Peninsula, said his family stocked up on necessities and he was ready to clear snow several times Sunday with a shovel and snowblower.

“We’re basically prepared to just kind of hunker down for a few days if we need to,” Allen said.

The thousands of flights canceled nationwide early Monday included more than 350 at Chicago O’Hare International and another 200 at Atlanta’s Hartsfield-Jackson International, according to FlightAware, which tracks flight disruptions. More than 2,500 more flights were delayed nationwide early Monday. Those disruptions came a day after more than 3,200 cancellations and 10,200 delays nationwide on Sunday.

Power outages remain, some from earlier high winds

More than 250,000 utility customers in six Great Lakes states were without electricity early Monday, according to PowerOutage.us. Some originated on Friday when gusts in the region reached 85 mph (137 kph). Another half-million customers were in the dark from Texas to Kentucky.

In Nebraska, about 30 National Guard members were deployed to combat multiple wildfires across a broad swath of range and grassland, state officials said. One fire-related fatality was reported.

Landslides, rescues, collapsed home on Maui

Rain continued falling on Sunday in Hawaii, where acres of farmland and homes have been flooded, roads have been closed and shelters opened. Some areas of Maui received more than 20 inches (51 centimeters) of rain, Maui County Mayor Richard Bissen said in a social media post.

Maui County later on Sunday downgraded an evacuation notice and said crews were pumping water from retentions basins to keep them at safe levels.

Resident and real estate broker Jesse Wald, who recorded video of a coastal road’s collapse Saturday, said other parts of the road were flooded out by mud and sediment.

“In the 20 years I’ve been here I’ve never seen this much rain,” he said.

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Robertson reported from Raleigh, North Carolina. Associated Press writers Julie Walker in New York and Matthew Brown in Billings, Montana, also contributed to this report.