Winter to the extreme: Two polar vortex invasions and major storm to whip Lower 48

Two pieces of the polar vortex have broken away from the Arctic region and will swirl through Canada, drawing frigid air into the Lower 48.

https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/12/14/winter-to-the-extreme-two-polar-vortex-invasions-and-a-major-storm-to-whip-lower-48/?utm_term=.ca09d0e31160