What's causing this extreme cold?

Hadas Kuznits
January 31, 2019 - 4:16 pm
Snow Roads

David Madden | KYW Newsradio

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PHILADELPHIA (KYW Newsradio) — Why is the United States facing such a sudden, extreme cold snap?  

Stephen Strader, assistant professor of geography and the environment at Villanova University, says climate is influenced by jet streams. 

"The jet stream separates cold air to the north and warm air to the south, and what it relies upon is a really large temperature difference between the North Pole and the Equator," Strader said.  

READ: Science Says: Get used to polar vortex outbreaks 

But he says the Earth's Arctic regions are warming over time. 

"There's less sea ice than ever before and those regions are much warmer, it causes our jet stream to meander. So that wavy pattern actually causes certain areas to get much warmer than average and certain areas to get much colder than average," he explained. 

Strader adds that "When warm air over the Pacific Ocean and warm air over the Atlantic drives north, it forces that cold air that typically resides in northern parts of Canada near the North Pole in the Arctic regions, it drives that air southward and in this case, over the last few days, that air has been very strongly driven southward and displaced toward much of the Midwest and Northeast." 

And he says while Philadelphia is cold, it could be worse. 

"We're just sort of right on that boundary where it's not quite dipping down from the north just enough," said Strader.