The Arctic polar vortex is collapsing in an early polar vortex disruption that may be the earliest recorded of its kind. That puts a normally deep-winter atmospheric event ahead of schedule and raises the chance of colder air shifting toward North America and Europe.
Judah Cohen, a climatologist at Massachusetts Institute of Technology, called the event unprecedented and said, “As a weather fan, this is a big event because it’s so unprecedented.” He also said, “It’s a lot of excitement. Everybody’s hair is on fire in the climate or meteorologist community.”
North Pole and the stratosphere
The polar vortex is a spinning mass of air high above the North Pole, and it strengthens in the stratosphere every winter. That layer stretches from about 10 to 30 miles above Earth’s surface. Rossby waves can nudge the vortex off balance, making it wobble and weaken until a larger disruption develops.
When that disruption becomes a sudden stratospheric warming, the vortex can drift, stretch, split into multiple swirls, or change direction. The earliest recorded sudden stratospheric warming before this event came on November 28, 1968.
Andrea Lopez Lang on the setup
Andrea Lopez Lang, an associate professor of atmospheric and oceanic sciences at the University of Wisconsin–Madison, said, “It looks like we’re going to have a disruption,” and added, “Where everything sets up is still in question.” That leaves the broad signal intact while the local outcome stays unsettled.
Meteorologists had expected relatively mild winter weather in North America because it is an El Niño year, but this disruption could alter that setup. The polar vortex can influence the polar jet stream in the troposphere, which is one reason a change high above the Arctic can matter farther south.
North America and Europe
The practical issue now is location, timing, and strength. A disruption can push colder air toward North America and Europe, but the forecast impact in the U.S. has not been pinned down in the available details. For now, the big development is the pace: a winter mechanism that usually shows up later is already breaking down at what may be a record-early point in the season.
