"An unusual event playing out high in the atmosphere above the Arctic Circle is setting the stage for what could be weeks upon weeks of frigid cold across wide swaths of the U.S., having already helped to bring cold and snowy weather to parts of Europe.
This phenomenon, known as a “sudden stratospheric warming event,” started on Jan. 6, but is something that is just beginning to have an effect on weather patterns across North America and Europe.
While the physics behind sudden stratospheric warming events are complicated, their implications are not: such events are often harbingers of colder weather in North America and Eurasia. The ongoing event favors colder and possibly stormier weather for as long as four to eight weeks after the event, meaning that after a mild start to the winter, the rest of this month and February could bring the coldest weather of the winter season to parts of the U.S., along with a heightened chance of snow.
Sudden stratospheric warming events take place in about half of all Northern Hemisphere winters, and they have been occurring with increasing frequency during the past decade, possibly related to the loss of Arctic sea ice due to global warming. Arctic sea ice declined to its smallest extent on record in September 2012."
Note the caveat: Judah Cohen and other researchers have demonstrated skill in predicting winters by predicting the polar vortex, as discussed here a month ago, but have not definitively linked global warming to colder winters. And researchers are just beginning to think about this and the West Coast.