Here's an article I found interesting that is about the areas affected, as well as the cause of it.
https://www.washingtonpost.com/weather/ ... ed-states/
The pattern as a whole is a symptom of a chain-reaction atmospheric shuffle stemming from an early-January disruption of the polar vortex. Hannah Attard, a professor of atmospheric sciences at Embry-Riddle Aeronautical University, noted in an email that it’s “what I would expect to see” after a sudden warming in the upper atmosphere over the North Pole.
That abrupt warming dislodged colder air ordinarily contained in the polar vortex to the mid-latitudes
That abrupt warming dislodged colder air ordinarily contained in the polar vortex to the mid-latitudes. Atmospheric scientists refer to an index known as the Arctic Oscillation, or AO, as an indicator of how bottled-up that cold air is. When the AO swings negative, big outbreaks of cold over North America, Europe and Asia are possible.
