Winter officially begins on Friday at precisely 5:23 p.m EST.
Yes, winter is coming. But for many, it's already arrived.
North Carolina, which doesn't see much snow, got 20 inches last week, leaving two dead and thousands without power. While the Old Farmer’s Almanac offers some good news in a forecast predicting an El Niño will bring warmer temperatures across most of North America this winter, some scientists are saying just the opposite.
And it all has to do with something that sounds ominous: The polar vortex.
Judah Cohen, a researcher from Atmospheric and Environmental Research, says a polar vortex will blast across the East Coast later this month and into January, bringing lots of snow and bone-chilling temperatures, The Washington Post reported.
A polar vortex happens when the stratosphere, the upper part of Earth's atmosphere, warms up suddenly. That brings strong winds, which then splits the vortex, drawing cold air from the north into the south.
"When the vortex, perched some 60,000 feet high in the atmosphere, is stable, winter conditions over the United States and Europe tend to be rather ordinary. Winter is still winter, with the normal mix of storms, cold snaps and thaws," the Post writes. "But when the vortex is disrupted, an ordinary winter can suddenly turn severe and memorable for an extended duration. '[It] can affect the entire winter,' Cohen said in an interview."
Rewind to February of last year to understand the implications. Up to that point, the vortex had held in its stable state, and the winter was a mild, unremarkable one. But then, abruptly, the vortex split.
The fracture set off a chain reaction, which first unleashed a punishing blast of cold in Europe and Asia. The media dubbed the cold snap the “beast from the east” as frigid Siberian air flooded the continent.
Then, the piercing cold hit the Lower 48 states in March. It triggered four consecutive nor’easters along the East Coast, where the polar air collided with the relatively mild Atlantic waters.
In fact, the polar vortex may split into three this winter, Cohen says.
Cohen also wrote on Twitter that "confidence is growing in a significant polar vortex disruption in the coming weeks. This could be the single most important determinant of the weather this winter across the Northern Hemisphere."