Snowstorm gone, 'polar vortex' brings deep, deep chill to US

With winter storm Hercules all cleared out – the storm left 16 dead, creating deep drifts across northern reaches of the country – a nose-freezing cold front has begun to dominate the mainland US, as Arctic air plunges temperatures to dozens of degrees below normal in places like Atlanta, Fargo, N.D., and even legendary ice box Green Bay, Wisconsin

The deep freeze could break decades-old records in some parts of the country, meaning that many Americans below middle age may never have witnessed, or stood in, such cold.

"All the ingredients are there for a near-record or historic cold outbreak,” Weather Bell meteorologist Ryan Maue told the Associated Press. "If you're under 40 [years old], you've not seen this stuff before."

Chicago is expecting the kind of low temperatures the city hasn’t seen in decades, raising hypothermia fears. The charge of cold air will reach south as far as north Florida, and Atlanta highs will likely freeze stuck at 25 degrees on Tuesday. Even New Englanders used to bundling up are feeling their eyelashes start to freeze. Some parts of the country could see wind chills well south of minus-50 degrees Fahrenheit.

After making news for barely selling out its playoff game against the San Francisco 49ers, the Green Bay Packers are all set to host a home game played at a projected minus-8 degrees Fahrenheit, an estimated point at which beards freeze.

Until now, the coldest NFL game ever played also happened at Lambeau, in 1967, in the so-called “Ice Bowl” playoff game between the Packers and the Dallas Cowboys. (Packers won.)

The culprit, meteorologists say, is a rare polar vortex – a counter-clockwise wind pattern that, in essence, amasses cold air at the North Pole, then releases super-chilled air masses to pour molasses-like down onto North America. That effect is contributing to other cold-favorable conditions, including the location of the jet stream and already chilly ground temperatures.

Most of the Great Lakes are expected to freeze in the next few days, which usually ensures a long cold winter at least for those in that part of the country.

The historic chill comes in the same week that a large group of climate researchers looking for signs of climate change around the South Pole got stuck for days in unusually thick Antarctic ice, only to be rescued by helicopter after a rescue ship also got stuck. Indeed, it turns out the Antarctic annual summer ice melt has been the smallest ever recorded.

Winnipeg, Canada, already got a taste of the deep chill, as thermometers this week dipped into the kind of mercury readings usually found on Mars. This week’s NHL Winter Classic, played in Ann Arbor, Mich., set the tone as snow and wind chill pulled on nostalgic memories of what winter used to look and feel like.

A French and Australian study published this week in the journal Nature, meanwhile, suggests that the Earth’s climate is more sensitive to man-made carbon dioxide emissions than previously believed, meaning that the Earth’s temperature could rise by 4 degree Celsius by 2,100.

Studying how carbon dioxide affects cloud formations, researchers Steven Sherwood, Sandrine Bony, and Jean-Louis Dufresne wrote that “real world observations” suggested that regularly cited climate models are low-balling predictions of future global warming.

To be sure, some of the warmest years on record also had extreme cold spells, suggesting that regional and yearly weather and temperature variations don’t necessarily undermine the widely-accepted man-made climate change theory.

For instance, the Twin Cities may see 20-below temperatures on Sunday, but it was only around this time in early 2009, which followed the hottest year on record, where Minnesota temperatures dipped equally low, if not colder.

Just for context, the US record low of minus-79.8 Fahrenheit was recorded on Jan 23, 1971, at the Prospect Creek Camp in northern Alaska. The coldest temperature ever recorded in the contiguous United States, minus-69.7 Fahrenheit, was found at Rogers Pass, Mont., on Jan. 20, 1954.