Ready for some serious cold?
The planet's most extreme cold air will be barreling into the central and eastern United States this coming weekend "like a wrecking ball," saidWeather Trader meteorologist Ryan Maue in a post on Xon Dec. 9.
Maue called it a "textbook 'Polar Vortex' mega-dump of western Canadian cold."
"Some of the coldest, if not the coldest, temperatures across the entire globe will cover the central and eastern U.S. over the weekend and into early next week," saidclimatologist Judah Cohen, a research scientist at MIT, in an email to USA TODAY.
"It also seems that the most expansive and continuous area of below normal temperatures across the globe will extend from Alaska to the eastern U.S. this upcoming week," he said.
But in a shred of good news for those who hate the frigid weather, this cold blast could be relatively short-lived. Forecasts expect a return to more typical wintry temperatures by later in the month and into the new year as the polar vortex retreats back to the north – and La Niña returns to prominence.
How cold will it get?
In Chicago, for instance, wind chills could "make a run at 20 below at some point this coming weekend," theNational Weather Servicesaid. Even colder wind chills approaching 45 below are possible in the Dakotas.
Wind chills that low can cause frostbite to exposed skin within 10 minutes, the weather service said.
Temperatures will dip to as much as30 degrees below the seasonal averagein many locations, according to the weather service.
Polar vortex: The North Pole is sending a visitor and it isn't Santa
Cold courtesy of the polar vortex
The blast of cold will come from the polar vortex, which is a large upper-level, low-pressure area or circulation that typically resides above the Arctic Circle. When this storm is strong, it tends to keep the coldest air in the Northern Hemisphere locked up over the pole.
"However, when it weakens or stretches, frigid air can move south," said AccuWeather meteorologist Alex Sosnowski in anonline forecast.
Pulses or "lobes" of the polar vortex can pinwheel south over the U.S., which is what will happen this week, according to Maue.
This type of on-again-off-again behavior from a disrupted polar vortex – with "waves" or "lobes" spinning off down into the U.S., bringing transient cold blasts – isn't unusual, AccuWeather meteorologist Paul Pastelok told USA TODAY.
He said this particular lobe should persist up until "the 18th or 19th of the month."
"We believe that two to three more rounds of intense cold are possible from the Midwest to much of the East, spanning Dec. 10 to 19," Pastelok said. "There is a chance for a frost or freeze late next week as far south as central Florida."
When will the US get relief from the cold?
After that, the vortex should retreat back toward the North Pole for the immediate future, experts predict.
"There's a change in the pattern globally, with some moderation in temperatures (for the U.S.) later in December and into January," Pastelok said.
Cohen agreed, saying, "I believe that the entire cycle of a weak or disrupted polar vortex that began at the end of November is coming to its conclusion by the end of next week... Clearly, the polar vortex is strengthening and some period of milder weather in the central and eastern U.S. looks inevitable to me."
'More normal pattern of La Niña'
With the polar vortex in retreat later this month, U.S. winter weather will be guided more by natural climate troublemaker La Niña, Pastelok said.
"This should favor a return to the more normal pattern of La Niña," he said.
According tothe Climate Prediction Center's winter forecast, which used La Niña as a primary guide, a warmer-than-average winter is most likely across the southern tier of the nation, as well as in California and along much of the East Coast and Florida. Colder-than-normal conditions are expected in the Pacific Northwest and across the upper Midwest.
This article originally appeared on USA TODAY:Polar vortex forecast says some of Earth's coldest air headed to US
