A sudden stratospheric warming event has pushed the polar vortex off the North Pole, sending Arctic air on the move

By Andrew FreedmanJan. 5, 2021 at 7:00 a.m. CST

A dramatic spike in temperatures is occurring at high altitudes above the North Pole, where the air is thin and typically frigid. Known as a sudden stratospheric warming event, experts say it’s likely to have potentially significant repercussions for winter weather across the Northern Hemisphere for weeks to possibly months.Support our journalism. Subscribe today.

This unusually strong event may have profound influences on the weather in the United States and Europe, possibly increasing the potential for paralyzing snowstorms and punishing blasts of Arctic air, with the odds of the most severe cold outbreaks highest in Northern Europe. The United States is slightly more of a winter wild card for now, experts say, with individual winter storms tough to predict beyond a few days in advance.

While occurring about 18 miles high in the sky and disconnected from the weather on the ground, stratospheric warming events can affect the polar vortex, which is a circulation of air around low pressure that acts as a repository for some of the coldest air on the planet.

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If the polar vortex is strong and stable, as it was last winter, that cold air will stay bottled up over the Arctic, and snow chances may be few and far between for regions such as the Mid-Atlantic and Northeast.