Above we have the initial 500mb heights analysis from the latest 0z ECMWF. We see the tight polar vortex of low atmospheric pressures encircled in the black area. This polar vortex is what supports the +AO/+NAO regime. That said, if there were high pressure systems over the same black area, we would be seeing some sort of -AO/-NAO. Let's jump ahead into the ECMWF's forecast.
Hour 192 of 0Z ECMWF
At hour 192 we're seeing the Polar Vortex break apart as a ridge forces itself into the vortex from Asia. This in turn forces a low pressure system towards Greenland, making for a West Based +NAO. While we aren't showing it, this ridge does break down at the end of the ECMWF forecast timeframe. It does show that there is potential for a ridge to break in and possibly bring in some colder weather for the US.
This is another view of the top 2 images, with the analysis period at the top and the hour 192 image on the bottom of these latest 2 images.