This cold snap will be relatively short-lived, with a return to more typical winter temperatures likely by late December.
What is a polar vortex? How it affects snow and ice in the United States
A polar vortex is a large region of cold air that circulates over the North Pole. If the wind is strong, the wind will be suppressed, but if the wind weakens, it may sway or stretch.
Are you ready for a serious cold?
Weather Trader meteorologist Ryan Maue said in a Dec. 9 post on X that the most extreme cold air on Earth will roll into the central and eastern United States “like a wrecking ball” this weekend.
Maue called it “a giant chunk of the textbook polar vortex of western Canada’s cold.”
“The coldest to coldest temperatures on the entire planet will blanket the central and eastern United States over the weekend and into early next week,” Judah Cohen, a research scientist and climatologist at the Massachusetts Institute of Technology (MIT), said in an email to USA TODAY.
“It also looks like next week the most widespread and persistent area of below-normal temperatures around the world will extend from Alaska to the eastern United States,” he said.
But, good news for those who hate frigid weather, this cold snap could be relatively short-lived. Forecasts predict a return to more typical winter temperatures later this month and into the new year as the polar vortex retreats north and La Niña conditions become more pronounced once again.
How cold will it get?
In Chicago, for example, wind chills “could reach 20 degrees or below at some point this weekend,” the National Weather Service said. The Dakotas could see even colder winds approaching 45 degrees below zero.
The Bureau of Meteorology says winds this low can cause frostbite on exposed skin within 10 minutes.
According to the Bureau of Meteorology, temperatures in many places will be as much as 30 degrees colder than the seasonal average.
It’s cold because of the polar vortex
The blast of cold air comes from the polar vortex. A polar vortex is a large upper-level low-pressure area or circulation that typically exists above the Arctic Circle. When this storm is strong, it tends to trap the coldest air in the northern hemisphere over the poles.
“However, if the cold air weakens or extends, the frigid air could move southward,” AccuWeather meteorologist Alex Sosnowski said in an online forecast.
A pulse or “lobe” of the polar vortex could wind its way south over the United States, and that’s what will happen this week, Maue said.
AccuWeather meteorologist Paul Pastelok told USA TODAY that this kind of on-off-on-off behavior is not uncommon due to disturbances in the polar vortex, where “waves” or “lobes” swirl and descend on the United States, bringing temporary cold winds.
He said this particular leaf should last until “the 18th or 19th of the month.”
“We think we could see two to three more severe cold snaps across much of the Midwest and East from Dec. 10 to Dec. 19,” Pastelok said. “There is a chance of frost or freezing late next week south of central Florida.”
When will the United States come out of the cold?
Experts predict that the vortex will then retreat towards the North Pole for some time.
“We’re seeing a shift in patterns globally, with some moderation in temperatures in late December and January (in the U.S.),” Pastelok said.
Cohen agreed, saying, “I believe that the entire cycle of weak or turbulent polar vortices that began at the end of November will be over by the end of next week…Clearly the polar vortex is strengthening, and it seems inevitable to me that the weather will be milder for a period of time in the east-central United States.”
“A more normal La Niña pattern”
As the polar vortex recedes later this month, U.S. winter weather will become more dependent on La Niña, a natural climate troublemaker, Pastelok said.
“This should facilitate a return to a more normal La Niña pattern,” he said.
Using La Niña as a key guide, the Climate Prediction Center’s winter forecast says a warmer-than-normal winter is most likely for the southern United States, California, and much of the East Coast and Florida. Colder-than-average conditions are expected across the Pacific Northwest and upper Midwest.
