Twenty-six states are in a deep freeze this morning — with temperatures as low as 36-below zero and wind chills as low as 60-below — and a polar vortex is to blame.
Though normally confined to the Arctic, this polar vortex is catching everyone’s attention because it has dipped so low into North America.
According to CNN International senior meteorologist Brandon Miller, a polar vortex is a circulation of strong, upper-level winds that normally surround the northern pole in a counterclockwise direction — a polar low-pressure system.
These winds tend to keep the bitter cold air locked in the Arctic regions of the Northern Hemisphere. It is not a single storm. On occasion, this vortex can become distorted and dip much farther south than you would normally find it, allowing cold air to spill southward.
The polar vortex can lead to major cold air outbreaks in any portion of the Northern Hemisphere — North America, Europe and Asia.
A similar weather phenomenon in 2009 drove temperatures in the Midwest down to 22-below zero.
So why has it traveled so far south?
According to Frank Giannasca, senior meteorologist with The Weather, warmer air builds up over areas such as Greenland or Alaska, and that air forces the colder, denser air southward. Also, weather patterns can create the right conditions for the polar vortex to point south. But in this case, “this very well just may be one of those anomalies where it forces itself southward,” Giannasca said.
The good news? The frigid weather isn’t here to stay. Temperatures are expected to return to normal by the weekend.
How are you braving the cold? Tell us in the comments below!