A "polar vortex" is sweeping down from the North Pole into the United States and as far south as the Gulf Coast, swathing much of the nation in an icy blanket that comes complete with life-threatening wind chills as low as minus-70 degrees.
Much of the midwest and New England is still digging out from the deadly snowstorm
that blanketed states with several inches of snow, and left 16 people dead in its wake. But the super-chilled polar air that's set to start driving a wedge into the country on Sunday will put many people who remain snowed in into a deep freeze as well.
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According to NASA research
, a polar vortex is a large cyclone that's located near one or both of the planet's geographical poles, and are low-pressure areas that strengthen in the winter. Normally, they remain circulating around the Arctic or Antarctic circles.
When the polar vortex is weak, its patterns come down to the Earth's surface. NASA researchers and other meteorologists years ago noted a correlation between a weak vortex and deep cold occurring in many cities in the Northern Hemisphere.
In any case, it's rare that the polar vortex pushes the North Pole's cold air into the United States, but on Sunday, it will drive temperatures down below sub-zero levels and make things feel even colder.
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The results could prove deadly, thanks to a "perfect storm" that combines the jet stream, already-cold surface temperatures, and the polar vortex itself, says Weather Bell meteorologist Ryan Maue in Tallahassee, Fla.
"All the ingredients are there for a near-record or historic cold outbreak,” he said. “If you’re under 40 (years old), you’ve not seen this stuff before."
And these promise to be temperatures not often seen beyond places like the North Pole or Siberia.
In Indianapolis and Chicago, temperatures are expected to go as low as minus-15 degrees. In Fargo, N.D., which is used to cold winter weather, the thermometer will plummet to 25 below zero, and in International Falls, Minn., the temperature is expected to go even lower, to 31 below zero.
The wind chill factor will make it feel like it's 50, 60, or even 70 degrees below zero, reports the New York Post
That's kind of cold that can result in frostbite in just a few minutes, and fatal hypothermia not long after that.
The effects will be made even worse than usual because of the snow that's already on the ground, said Maue, which will keep the sun from warming the ground and air.
Also, don't expect the Gulf to send any warming air to break up the cold, because that isn't happening this time around, Maue noted.
As if the polar vortex isn't bad enough, parts of the central Midwest are also expecting up to a foot of snow from a new storm, reports The Weather Channel
The new storm, which brought snow to the Rockies on Saturday, will head east through early Sunday, with low pressure developing over the Southern Plains and heading to the eastern Great Lakes.
This means widespread accumulating snow is coming to Missouri, Illinois, Ohio, and lower Michigan through Sunday, with the National Weather Service issuing winter storm warnings
before the polar vortex is to strike.
People in the south shouldn't feel smug over the north's misfortune, as places like Atlanta are expected to plunge into the mid-20s on Tuesday.
Maue said that such cold waves swoop down once a decade or so, but aren't as bad as other storms that cause long cold spells.
Many cities and states are already making preparations for the cold blast.
In Minnesota, where residents are used to cold weather, school has been cancelled statewide for the first time in 17 years. North Dakota hasn't canceled school, but Gov. Jack Dalrymple urged district superintendents to keep students' safety in mind come Monday.
Meanwhile, football fans in Green Bay who brave Sunday's playoff game pitting the Packers and San Francisco 49ers will be shivering through the excitement of being part of one of the coldest NFL games ever.
The temperature will be at minus 2 at kickoff, and by the time the game is over, it'll be down to minus 7, with wind chills down to a brutal 30 below zero, the National Weather Service says.
The cold spell is expected to last just a few days, but could freeze over the Great Lakes, meaning the country can expect heavy snows and cold temperatures the rest of the winter, said Maue, including for the Super Bowl in February.
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The Associates Press contributed to this report.
Wind chill: http://1.usa.gov/19FjvpT
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