The weather pattern over North America for the past several weeks has featured troughing across the Western U.S. with southerly flow east of the Rockies. That has sustained ridging but also cut-off moisture flow from the Gulf of Mexico to induce storminess. The result has been extremely dry conditions for the past 30-60 days especially in the Mid-Atlantic and Northeast. Some relief has arrived but will take significant rain/snow to overcome the deep deficits.

GFS 12z this afternoon has something different. We see a lobe of the tropospheric polar vortex able to break out of the Canadian Arctic and blast much colder air pooled over Alaska into the Lower 48. However, abnormal warmth still remains locked over Hudson Bay that must be chilled before we can sustained winter weather e.g. Lake Effect snow and winter storms — since the backside of the low pressure systems actually pulls down rather warm (above freezing) air.