THE POLAR VORTEX has arrived in North America with tens of millions of people in the United States braced today for a deep arctic chill, which authorities say could be life-threatening.

Sub-zero temperatures already blanketing parts of Canada were already sweeping across the US Midwest and towards the East Coast.

The big chill in the Midwest came on the heels of a major storm that dumped up to a foot of snow on the region over the weekend — and reportedly claimed at least two lives so far.

“We need everyone to do your part and make sure you and your families are prepared,” said Illinois Governor JB Pritzker.

Pat Christman via AP Pat Christman via AP

Companies told their workers to stay home. Schools were closed. Hundreds of flights were canceled.

Temperatures in almost a dozen states stretching more than 1,930 kilometres from the Dakotas to Ohio were forecast to be the coldest in a generation, if not on record.

“One of the coldest arctic air mass intrusions in recent memory is surging south into the Upper Midwest before spreading across much of the eastern two-thirds of the country,” the National Weather Service said.

Anthony Wahl via AP Anthony Wahl via AP

“Expect frigid temperatures, bitterly cold and life-threatening wind chills, likely leading to widespread record lows and low maximum temperatures from the Upper Midwest to the Great Lakes and Ohio Valley.”

The culprit? A swirl of arctic air that broke away from the polar vortex that usually encircles the North Pole.

The National Weather Service forecast temperatures between -23 to -40 Celsius by Wednesday across the Midwest, with wind chills making it seem as cold as -53 degrees in one area of Minnesota.

Chicago, America’s third largest city, was expected to be colder than parts of Antarctica.

Authorities in Illinois, Michigan and Wisconsin put emergency measures in place to handle the frigid weather.

Chicago's El trains move along snow-covered tracks AP AP

Frostbite warnings

Americans were asked to stay home if possible tomorrow, when temperatures were expected to be at their coldest.

Scores of schools, businesses and government agencies announced closures in multiple states.

“People exposed to extreme cold are susceptible to frostbite in a matter of minutes,” warned the NWS.

Gary Verstegen clears a sidewalk as a winter storm moves through Wisconsin AP AP

Lawrence Gottlieb of the University of Chicago Medical Center said the threat was significant “when temps fall below zero, especially when there is a strong wind.”

Some 160 warming centers were opened in Chicago, where temperatures could potentially equal or exceed the all-time record of -32 degrees. With the wind chill, it would feel like -40 or -50, officials said.

“They are life-threatening conditions and temperatures,” Chicago Mayor Rahm Emanuel told a news conference.

Cars are covered by snow in Wheeling, Illinois Nam Y. Huh / PA Images Nam Y. Huh / PA Images / PA Images

In Minneapolis, officials allowed residents to stay on public buses and trains for warmth.

Snow storm

In the northeastern and southern United States, snow was falling.

A cold emergency was declared in the US capital Washington, with additional services put on for the homeless.

Pedestrians cross an icy Chicago River on Madison St. near the Civic Opera House Rich Hein via AP Rich Hein via AP

In the southern city of Atlanta, some 300 flights were canceled today, and more than 400 were canceled in Chicago, a major regional hub for US airlines.

In Canada, the icy temperatures — stretching from Manitoba in the western Prairies region to the Atlantic seaboard — prompted a rare “hazardous” cold warning from the government.

Recycling teams collecting trash during a snowstorm in Manitowoc, Wisconsin Joshua Clark via AP Joshua Clark via AP

Environment Canada reported record-breaking snowfall at the Ottawa airport, where some 50 flights were canceled, with an accumulation of nearly a metre.

An additional 200 flights were canceled at Toronto’s airport.

Global warming?

Scientists say climate change is causing more extreme weather, and one theory for polar vortex chills is that arctic air currents usually trapped around the North Pole are weakened and dislodged by a warming climate.

President Donald Trump used the occasion to again voice skepticism about climate change, tweeting: “What the hell is going on with Global Waming? (sic) Please come back fast, we need you!”

But the National Oceanic and Atmospheric Administration, which operates NWS, tweeted, “Winter storms don’t prove that global warming isn’t happening,” with a link to a 2015 explanatory article.

  - © AFP 2019