As I have been fearing, the multiple sudden stratospheric warmings are taking their toll on the polar vortex here at the surface. We already had the initial impact of the split polar vortex over Martin Luther King Jr. Day, and now appear to be looking at Round 2. As the 500mb forecast above details, there could be a second, stronger blast of cold air that hits the northern part of the nation. The GFS places this piece of the vortex substantially further south than the previous brush with the vortex; that one went into South Canada.
It does not matter where this piece of the vortex goes, because the ball has already been rolling on what we could face in February. I have been seeing consistent forecasts that detail a full stratospheric polar vortex breakdown, more on that later tonight.