Polar vortex cold looms as U.S hammered by dangerous winter weather

After a largely mild end to 2023, cold jet stream air from the polar vortex appears set to descend on parts of the U.S. later this week, adding to a chaotic January that saw reports of several deaths, heavy snow and tornadoes Tuesday.

The polar vortex refers to the frigid air that flows counter-clockwise around the North Pole, some 15 to 30 miles above the Earth. While the vortex is always there, it strengthens during the winter.

Sometimes, however, large atmospheric waves or warm temperatures can weaken the polar vortex, upsetting the stable jet stream rotation and pushing icy air southward, while warmer air is drawn up to the Arctic.

“Last week, there was a minor disruption of the polar vortex (the vortex winds didn’t fully reverse direction to make it a “major” event), which may help increase chances for cold air outbreaks over the East Coast of the U.S. and Europe in particular for the next 10-12 days,” Amy Butler, an atmospheric scientist at the National Oceanic and Atmospheric Administration, told Nexstar in a statement.