A police officer and another motorist try to help stranded drivers on an icy Interstate 30 in Fort Worth, Texas. (Paul Moseley/Fort Worth Star-Telegram/Associated Press)

A massive winter storm some are dubbing "Snowpocalypse" is unleashing a hodgepodge of brutal weather — sleet, ice, wind and loads of snow — on the U.S. Midwest as it moves across the country to the Northeast and Canada later Tuesday night.

Before it's over, the storm is expected to affect 100 million people in the U.S. over a 3,200-kilometre stretch from New Mexico to Maine. "This is a life-threatening storm," warned the National Weather Service.

"Snowpocalypse" was among the hottest trending topics on Twitter on Tuesday.

By Tuesday afternoon, snow began to fall in Chicago as the city was buffeted by wind gusts of 80 km/h, and residents were bracing for a near-record snowfall of 60 centimetres.

The National Weather Service warned that high winds with gusts of up to 97 km/h could produce waves on Lake Michigan of more than eight metres leading to considerable coastal flooding and freezing spray, particularly along the main city thoroughfare of Lake Shore Drive.

A lot of people were heading to grocery stores to stock up on supplies and hunker down at home, Andy Roesgen of NBC News told CBC News in an interview from Chicago.

Chicago's Midway Airport was shut down, while 1,300 flights were cancelled at O'Hare International Airport.

Earlier Tuesday, eight states had blizzard conditions, with Texas, Missouri and Oklahoma the hardest hit. There are warnings, watches and advisories in another 30 states.

"The centre of the storm is in Texas right now," CBC meteorologist Johanna Wagstaffe said in an interview Tuesday morning. "We've already seen 30 centimetres of snow in Oklahoma City, making it the snowiest February day on record there, and it's still falling."

Kansas, Oklahoma, Missouri and Illinois declared emergencies. National Guard troops were called in Missouri. Whiteouts paralyzed Oklahoma City and the Tulsa area, where snowpack caused the partial collapse of a roof at the Hard Rock Casino.

Airline cancellations in the storm zone topped 7,700 through to Wednesday and Dallas-Fort Worth International Airport was closed due to an ice storm. In Canada, Toronto's Pearson airport cancelled more than 200 flights to the U.S.

School districts, universities and legislatures were also closed in many states.

Snow moving to N.Y., New England

Snowplows work to remove ice from Interstate 55 Tuesday in St. Louis, Mo. A blizzard warning is in effect for the St. Louis area. (Tom Gannam/Associated Press)

"Tomorrow the heavy snow will move to New York and the New England states," said Wagstaffe.

When the snow finally ends, bitter cold will set in. Temperatures in some parts of the Midwest will dip well below –17 C. Gusty winds will blow all of that snow. Visibility will be virtually zero at times.

Forecasters are also predicting a band of ice running from Ohio to the northern plains, including Arizona, Montana and Illinois, meaning those states might receive a thick coating that could cause power outages as well as treacherous driving conditions.

There may be a silver lining to the storm however, forecasters said.

Thanks to all the snow and cloud cover, the groundhogs, Phil in the U.S. and Willy in Canada, most likely won't see their shadows Wednesday on Groundhog Day. That means that we should get an early start to spring according to groundhog legend.