46ºF

Polar Vortex back in the headlines, but what is it?

Rounds of Arctic cold to impact Virginia

ROANOKE, Va. – The Polar Vortex has been making its rounds around social media and national news outlets. You may have heard of it, but what is it? It’s not a storm, it’s not made up and there’s not just one. The way it's talked about in times of cold isn't quite scientifically accurate, though. If you want the short version as to how this impacts us, scroll down to the bottom of the page.

The Polar Vortex term became famous in January 2014, after bitter cold gripped the nation. Since then, every time it gets cold it’s assumed it’s the Polar Vortex, which is not the case.

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There are two Polar Vortices...one in the troposphere, the part of the Earth’s atmosphere where humans live that resides way up where jet aircraft fly. This is typically the one that impacts us...the ridges and troughs, the waves of the polar jet stream. The center or centers of the vortex reside over the coldest air on Earth and stays there. However, when the overall pattern is wavy, large ridges and troughs present, a piece of the vortex can break off and drift into the United States sending extreme cold our way.

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The other is in the stratosphere, about 6 miles above our heads. This develops in fall/winter, due to the lack of solar heating in the polar region. Studies show that when this one is disturbed, warming taking place in the stratosphere, it weakens and allows for Arctic air to spill down into the United States.

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In Late December, something known as Sudden Stratospheric Warming occurred. Studies show when this happens and the Stratospheric Polar Vortex is weakened, the potential for bitter cold and snow increase in the eastern third of the country a few weeks later. Well, we have made it to the few weeks later.

The Arctic oscillation (AO) keeps tabs on this Vortex by tracking the variation of pressure and wind in the atmosphere. There is a positive and negative phase to the AO. When the AO goes negative, massive Arctic-air outbreaks are known to occur in parts of the world. Below is a computer forecast of the Arctic Oscillation. The bottom falls out as the AO plummets into the negative phase toward the end of the month.

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GET ON WITH IT ALREADY:

To make a long story short, we’re not being impacted by THE Polar Vortex as you may hear, but just a piece of it. That piece or pieces does bring bone-chilling cold into the lower-48, however. Over the next several days the Arctic Oscillation will crash. That indicates much more cold and potentially snow will follow our short date with the Arctic early next week. The next several weeks look to be quite cold and potentially snowy. The harshest part of this winter is yet come. Stay tuned.


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