Major U.S. winter storm cancels flights, closes roads and schools

Brutal winter weather bringing snow, dangerous gusts of wind and bitter cold settled over much of the northern United States on Wednesday, shutting down roadways and businesses and leading to flight cancellations.

FlightAware, a flight tracking service, said carriers had already cancelled some 2,200 flights in the United States by early Wednesday afternoon, as the storm made its way through the western and central states.

About 400 of those cancelled flights were due to arrive or depart from the Minneapolis-St. Paul International Airport.

The Federal Aviation Administration (FAA) said in a tweet on Tuesday that the severe weather could cause flight delays or cancellations this week in Minnesota and other states in the Great Lakes and southern plains.

The U.S. weather system began moving into Canada later Wednesday and will continue into Thursday, with snowfall and freezing rain warnings in place for parts of southern Ontario and southern Quebec.

The departure board for Toronto's Pearson airport showed cancellations on Wednesday morning for Air Canada Jazz flights to Minneapolis. Later in the day, Air Canada and WestJet said blizzard conditions may cause delays to flights into and out of airports in Toronto, Ottawa and Montreal on Wednesday and Thursday.

More than 50 million Americans were under winter weather advisories on Wednesday morning as the storm moved across a wide swath of the western and northern United States and into the east.

The storm has produced a band of freezing rain stretching from central Iowa through Chicago and into southern Michigan, coating many roads, trees and power lines with up to 0.6 centimetres of ice, said forecaster Frank Pereira of the U.S. National Weather Service.

Farther west, a more than 320-kilometre stretch of Interstate 40 from central Arizona to the New Mexico line closed on Wednesday due to snow and wind gusts of up to 129 km/h. Thousands were without power in Arizona.

A rare blizzard warning was issued for the Los Angeles County mountains and California's Ventura County Mountains, effective early Friday, the weather service said.

Powerful winds were the biggest problem in California, toppling trees and power lines. By Wednesday afternoon, more than 91,000 customers in the state were without electricity, according to PowerOutage.us.

A gale warning was to remain in effect for the San Francisco Bay Area until 9 p.m. local time Wednesday. Snow accumulations of up to 15 centimetres are expected by Thursday morning for higher elevations, including the Santa Cruz Mountains just south of San Jose.

"Nearly the entire population of CA will be able to see snow from some vantage point later this week if they look in the right direction (i.e., toward the highest hills in vicinity)," UCLA climate scientist Daniel Swain wrote on Twitter.

Many school classes throughout the Dakotas, Minnesota, Wyoming and Wisconsin were called off for Wednesday, ahead of the storm. Offices closed, and so did the Minnesota Legislature. South Dakota Gov. Kristi Noem shut down state executive branch offices in several parts of the state, and employees were working remotely.

In Wyoming, virtually every road was impacted, and many were closed. Officials warned they may stay that way for days.

Multi-day road closures likely in Wyoming

"Please change travel plans if your are coming towards Wyoming, waiting to go west from Cheyenne or Laramie on I-80, or waiting to go east on I-80 from Rock Springs," the Wyoming Department of Transportation posted on Facebook. "A major winter storm and multi-day closures are likely on Interstates and secondary roads throughout Wyoming!"

Michelle Wilson said business was slow at the Denny's where she works in Fargo, N.D., where the morning temperature was –24 C. Wilson wasn't surprised — people know better than to venture out when the weather turns this dangerous.

"When the wind picks up and you're in a flat land like North Dakota, it's whiteout conditions immediately," Wilson said.

The snowfall could be historic, even in a region accustomed to heavy snow, with the heaviest amounts forecast for east-central Minnesota and west-central Wisconsin, the National Weather Service said. The Minneapolis-St. Paul area could see 61 centimetres of snow or more for the first time in over 30 years.

At C&S Supply, an employee-owned hardware store in Mankato, Minn., manager Corey Kapaun said demand was high for salt and grit, but not for shovels, snow blowers or other equipment. He attributed that to the fact that winter is two-thirds over.

"I think people are either prepared or they're not," Kapaun said. "It's usually the first snowfall of the year that gets a lot of attention. With a storm like this, I expected a little bit more, but we've already had a big year of snow already."

Forecasters at AccuWeather said the same storm system could result in icing across a 2,092-kilometre band from near Omaha, Nebraska, to New Hampshire on Wednesday and Thursday, creating potential travel hazards in or near cities such as Milwaukee, Detroit, Chicago and Boston.

As the northern U.S. deals with a winter blast, record warmth is expected in the mid-Atlantic states and the Southeast. Record highs are expected from Baltimore to New Orleans and in much of Florida, a National Weather Service meteorologist said.

Washington could hit 80 F (27 C) on Thursday, which would top the record of 78 F (25 C) set in 1874.