US weather forecast: Record low temperatures caused by polar vortex ‘threaten 110 million Americans’

The polar vortex striking the United States is attributed to a sudden warming far above the North Pole

Life-threatening temperatures across the United States and a polar vortex in the Midwest is set to impact nearly 110 million Americans this week.

The extreme cold and record-breaking temperatures are blasting a swathe of states spanning from North Dakota to Missouri and into Ohio after a powerful snowstorm pounded the region earlier this week.

The unusually frigid weather is attributed to a sudden warming far above the North Pole. A blast of warm air from misplaced Moroccan heat last month made the normally super chilly air temperatures above the region rapidly increase. That split the polar vortex into pieces, which then started to wander, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research.

One of those polar vortex pieces is responsible for the subzero temperatures across the Midwest this week.

Cold weather advisories are in effect across a broad swath of the central US, from North Dakota to Missouri and spanning into Ohio. Temperatures will be as many as 20 degrees below average in parts of the Upper Great Lakes region and Upper Mississippi Valley, according to the National Weather Service. “You’re talking about frostbite and hypothermia issues very quickly, like in a matter of minutes, maybe seconds,” said Brian Hurley, a meteorologist with the Weather Prediction Centre.

Meanwhile, homeless shelters across the country are preparing for the onslaught of cold. Chicago Mayor Rahm Emanuel said city agencies are making sure homeless people are in shelters or offered space in warming buses. He also urged residents to check on their neighbors and take safety precautions. More than a thousand flights had been cancelled across the city's major airports by Tuesday afternoon, including 300 in Atlanta.

In Minneapolis, charitable groups that operate warming places and shelters were expanding hours and capacity “as they do whenever dangerous extreme temperature events occur,” said Hennepin County Emergency Management Director Eric Waage. He said ambulance crews were handling all outside response incidents as being potentially life-threatening.

The Milwaukee Rescue Mission’s call volume was “unusually high,” but officials said there should still be enough beds for those who need them.

The potentially record-breaking low temperature forecast in Milwaukee is negative 28 degrees Fahrenheit (negative 33 degrees Celsius), with a wind chill as low as negative 50 degrees Fahrenheit (negative 45 degrees Celsius). The current record of minus 26 degrees Fahrenheit (negative 32 degrees Celsius) was set in 1996.

Subzero temperatures hit some states Tuesday, but Wednesday is expected to be the worst. Wind chills in northern Illinois could fall to negative 55 degrees Fahrenheit (negative 48 degrees Celsius), which the National Weather Service called “possibly life threatening.”

Additional reporting by AP