Some forecasters say a complex dance involving the polar vortex could send some of the most extreme cold air on Earth into the United States.
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.
Although meteorologists have not yet issued specific forecasts, there is a growing consensus that some parts of the United States will have a frigid December.
The National Weather Service’s Climate Prediction Center says the northern and northeastern United States are most likely to experience colder-than-normal conditions, but some forecasters say a complex dance involving the polar vortex could bring some of the most extreme cold air on Earth to the United States.
“In my opinion, the cold weather in the first week of December will be the appetizer and the main course will be in mid-December,” climatologist Judah Cohen, a research associate at MIT, said in an email to USA TODAY.
In fact, Cohen’s computer model predicts that “the most likely frigid region on Earth, which we can confidently claim to be the best in the world, will stretch from the Canadian Plains to the East Coast of the United States during the third week of December.”
When it comes to snow, this is still a wild card as the weather systems that produce snow are typically unpredictable more than a few days in advance. Suffice it to say that the presence of cold air is half the battle.
Is the polar vortex on hold?
Weather Trader meteorologist Ryan Maue said in a post on Substack that a major “polar vortex” of very cold air will remain largely confined to Canada for the next seven to 10 days. Maue will continue to monitor the risk of polar vortex penetration at 48 degrees north latitude until December.
In fact, a complex dance of large-scale weather patterns far above our heads, including the infamous polar vortex and a phenomenon known as “sudden stratospheric warming,” will determine the strength and duration of cold air in the United States in December, Cohen said. But, he admitted, “I’m conflicted about what’s going on in the polar vortex.”
How cold will it get?
Although the most extreme cold temperatures won’t arrive until late December, widespread and sustained below-normal temperatures for this time of year are expected across a wide area from the western High Plains to the East Coast, with near-normal conditions in the southeastern states and warmer temperatures in Florida, the National Weather Service said.
The coldest extremes in terms of both highs and lows are expected in the Midwest on Monday, Dec. 1 and Tuesday, Dec. 2, with highs expected to remain in the teens to mid-20s over many of these regions, with lows reaching the 0s as far as northern Missouri and northern Illinois by Monday morning as an arctic air mass establishes over the region.
The National Weather Service said there is a good chance nighttime lows will dip below freezing from eastern Montana to North Dakota.
(This story has been updated to meet our standards.)
