The term: Polar Vortex is nothing new to the meteorological community. Science nerds and geeks alike have used the phrase when forecasting winter weather for decades (perhaps longer!), but social media has only now made the term relevant to the general public.
Well, that and -30 to -40° wind chills.
If you're just hearing about it now, here's the deal:
Typically the coldest air is found in and around the Arctic Circle. A large circulation that permanently resides near the north pole will frequently slide farther south, ushering colder air into southern Canadian Provinces and often across the border into the US.
|Typical Polar Vortex near Arctic Circle|
This process happens during all 4 seasons, but is most amplified during the winter.
When the polar jet sinks far enough south, the Polar Vortex follows suit, and will swing south, bringing along with it an Arctic blast of unseasonably cold air.
|Irregular Arctic Blast due to southerly track of Polar Votex|
The most recent outbreak is a great example of the potential within our atmosphere to do great things. In this case, an amplified trough of colder-than-normal air rapidly fired down into the US, thus bringing along some of the coldest air in 30 years.
|Extreme Record-breaking Cold|
This time around, the result was drastic. Overnight lows 10-20 degrees BELOW zero for three nights in a row, coupled with a wind that brought 30-50° subzero wind chills into play.
This was an extraordinary case, but that doesn't mean it couldn't happen again.