Shown above is the 10 day forecast from the ECMWF ensemble prediction system, or just the EPS. The ensembles are forecasting 500 millibar height anomalies for this timeframe, where low pressure systems are shown in cool colors and high pressure formations are in warmer colors. The big green spot on the Canada-US border is the polar vortex itself- the low pressure entity which practically drives the Arctic to retain its cold powers. If this thing drops south like it did in 2009, cold to a very similar degree could be observed across parts of the nation.
Also key to this forecast is the presence of high pressure on the west coast of Canada and in the Pacific Northwest into the Southwest US. This is commonly known as the Pacific-North American (PNA) index, and is a driver of storm tracks and cold weather within the United States. When the PNA is in its negative phase, low pressure anomalies begin to build and persist in the West US (negative height anomalies, negative PNA), resulting in high pressure and warm air in the East US. Storms are then diverted into the Plains or way into the South. In the positive PNA, high pressure builds into the West, and low pressure evolves across the East, bringing higher potential for cold and snow to the central and east sections of the States. I find it very possible that the PNA could go positive after its been so negative recently- a huge low pressure system pushing south into the US means physics must respond with above normal height anomalies in the West US, and all of the sudden there's a positive PNA in the area.
The ECMWF Ensembles, despite the fact they are at the top of the most reliable models and ensembles of the world, are still prone to errors that strike the other global models, so do not take this as written in stone. It certainly is a good sign to see the ensembles agreeing on this- you need all the help you can get after last winter (even after last month)!