I have concluded that a polar vortex collapse and subsequent Arctic Freeze is imminent across the nation in January. I'll explain why.
I want to dig deeper into the time just before that warm air shot into the Arctic Circle. Try and watch for the observation on November 25-27. If you can see it, you can see how the warm air entered east Asia before blowing up and shooting into the Arctic. Looking at the most recent December image, we can see that another small blob of warm air has emerged in central Asia. Judging by the last two or three images, this blob also looks to be entering East Asia, meaning we could see another stratospheric warming if this warm air shoots into the Arctic Circle.
The model forecasts above both show big high pressure centers interrupting the polar vortex and splitting it into two pieces. Such a split exemplifies the traditional weakening of the polar vortex. When that polar vortex is weakened, the cold air locked up in said polar vortex flows south, possibly into North America, maybe into the US. This is a very good sign coming from the models at this point in time to go along with the stratospheric observations.
Take a look at the two ECMWF Forecasts below:
The top image of the 100mb level has the polar vortex centered in East Asia. Note the warming occurring in North America, another sign of cold potential at the surface (more on that later). Now take a glance at the 1mb image. The polar vortex is now shown to be to the east of Greenland. They are pretty far apart! Why does it matter? Take a look at the analogy below.
Think of the game Jenga. You must try to take out pieces of the tower to get as many pieces out, but still have it standing. The more pieces you take out on one side, the more unstable that side becomes, and eventually the tower falls down because of the difference in stability of the tower (a.k.a. where more blocks are placed). In a similar situation, when you have the polar vortex far apart in different levels, like what is forecasted above, the polar vortex becomes more unstable and weakens, possibly to the point of collapse.
One more analogy for you: Think of the polar vortex like a cylinder full of cold air. If you cut the cylinder in half and move one half away from the other, the cold air will sink. That is exactly how the stratosphere. If you have displaced parts of the stratosphere, the cold air that is held in the polar vortex will be released and flow down into lower latitudes. If the PV is displaced enough, it may collapse altogether, leading to an icebox solution over parts of the world.
The GFS model also shows the displacement of the polar vortex at Hour 240:
|Pressure at hour 240 at the 1mb level|
|Pressure at Hour 240 at 100mb level|
Here is what I have gathered:
-Current stratospheric temperatures are at average values.
-A strong warming event looks to occur at the end of December.
-Very elevated EP Flux forecasts enhance such a warming potential.
-The polar vortex will become displaced as a response.
-High pressure forms over the Arctic, further messing up the polar vortex.
-AAM QBO values are already turning positive, increasing the potential for the permanent warming event to switch winter to spring later on in 2013.
All of the factors above combined, severe damage looks to be done to the polar vortex. I can envision a partial collapse of the vortex occurring, which would only lead to enhanced cold outbreaks in the United States. I am not confident on this collapse occurring, but if there is a best time for such a collapse to happen, it could be coming up at the end of this year.
Keep a sharp eye out for prolonged cold weather if these forecasts by the ECMWF and GFS verify.