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What Is a Polar Vortex?

How does it affect our weather and why is it such a big deal only in certain years?

The term "polar vortex" has become a viral buzzword again this year after its spotlight back in 2014 – but, what exactly is the polar vortex, how does it affect our weather and why is it such a big deal only in certain years?

The fact is, the polar vortex has been studied in meteorology since the middle 1800s! This swirling mass of cold air and atmospheric energy, historically, meanders fairly close to the North Pole and at high latitudes.

This keeps brutal, arctic air consolidated near the Pole, on the north side of a fairly stable jet stream wind. The jet stream is the fast river of air, high in the sky, that flows along the division of cold air to the north and warmth to the south. This steers storm systems along its corridor of wind.

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From time to time, a shift in the Polar Vortex southward would dislodge some arctic cold air southward. The jet stream would respond by dipping south, but both usually returned close to their normal positions.

In recent years – to some extent due to climate change driving major temperature shifts across the globe – the jet stream winds aloft have become more "wavy." This is when bigger intrusions of warmth northward, and, opposite of that, between the warm surges, bigger intrusions of arctic cold air south.

The result this year, and in several recent years, has been for the singular polar vortex to break apart with some regularity. In other words, what the United States is experiencing now is not the usual polar vortex, but a disjointed piece of the once mighty system now broken into a few, meandering swirls.

This broken polar vortex houses broken but intense chunks of arctic air, forced southward between northward-moving surges of warmth.

We’ve seen that exact pattern play out here at home -- spells of intense, cold, dry air followed by surges of warmth. Our exclusive First Alert 10-Day Forecast shows that playing out yet again this time, with temperatures expected to rise into the 40s and 50s in New England by next week.

The video with this post adds some weather maps that illustrate the phenomenon of the changing Polar Vortex.

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