Why Is The Polar Vortex Important

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You've likely heard the term "polar vortex" virtually every winter since it first entered into popular culture during a bitterly cold January a decade ago.

The polar vortex is a whirling cone of low pressure over the poles that's strongest in the winter months due to the increased temperature contrast between the polar regions and the mid-latitudes, such as the United States and Europe.

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This isn't like a storm you might think of in the lower atmosphere, with cold and warm fronts producing rain or snow. Instead, the polar vortex occurs primarily in the stratosphere, a layer of the atmosphere about 6 to 30 miles above the ground – above most of the weather with which you're familiar occurs (known as the troposphere).

T​he polar vortex works counterintuitively to what you might expect – the stronger it is, the less impactful it is.

When the polar vortex is strong, cold air is less likely to plunge deep into North America or Europe. Picture this strong vortex fencing off the coldest air from the U.S. and Europe.

Occasionally, though, the polar vortex is disrupted and weakens. This happens when the stratosphere warms.

NASA's Goddard Space Flight Center has a more technical explanation for these sudden stratospheric warming events.

When the polar vortex is weakened, a piece of it can surge farther south, setting up weather patterns that usher arctic cold into portions of North America and/or Europe.

Now let's get to some polar vortex myth-busting:

-​ Not a storm: The polar vortex is not a storm, like a winter storm or blizzard; instead, it's a standard feature of the Earth's atmosphere.

-​ It's not new: It has been around likely as long as there has been weather on Earth and has been mentioned in history for centuries.

-​ It doesn't go away: While the polar vortex is weaker in the summer months and strongest in the winter months, it doesn't go away completely.

-​ There are two: There is a vortex centered over each of the poles.

-​ The polar vortex doesn't always mean snow: Temperatures on the ground still have to be cold enough for snow production. If the atmosphere is too dry or too warm, you'll miss out on the snow.

-​ The polar vortex shouldn't be feared: In the majority of cases, intrusions of the polar vortex won't be disruptive. However, there have been some notable cold air outbreaks and winter storms associated with weak polar vortex events, such as Winter Storm Uri and the Texas extreme cold outbreak in 2021.

Jonathan Belles has been a graphics meteorologist and writer for weather.com for 8 years and also assists in the production of videos for The Weather Channel en español. His favorite weather is tropical weather, but also enjoys covering high-impact weather and news stories and winter storms. He's a two-time graduate of Florida State University and a proud graduate of St. Petersburg College.