|The 'Four Corners' pattern is showing up on the GEFS Control run.|
Lower height anomalies are shown in darker colors, above normal
height anomalies in warm colors.
This pattern, which I like to refer to as the 'Four Corners' pattern, is showing up in the next 9-10 days on the GEFS control forecast. Before we get into it, let me break down what the Four Corners pattern is.
When you're playing Bingo (or even Tic-Tac-Toe, if that's your strategy), an objective may be to get all four corners covered in order to get an advantage in Tic-Tac-Toe, or to win in Bingo. Much like you receive an advantage from this tactic, North America also receives an advantage from this sort of pattern. In this situation, the GEFS Control is forecasting ridges of high pressure (HP) to set up in four areas: off the Canadian Maritimes, northwest Europe, north Asia, and the Gulf of Alaska. In response to this blockade of HP systems, the polar vortex has to go somewhere, and in this case, North America is the only exit for the Polar Vortex (PV). So, as a direct response to this Four Corners blocking system, the PV will begin sending its energy southward; in this scenario, into North America.
Back to the Day 9 GEFS Control forecast, the forecast does include this Four Corners pattern, and in response, the PV must dip its energy south. Now, while it does not appear that this energy is in the Lower 48 at the moment. However, if you look into northwest Canada, you will see at least one circle of low pressure (LP) in the region. The Gulf of Alaska ridge will force this LP system south into the States.
Let's make the connection between the negative NAO and this strong LP system in the Rockies. This system looks like it will be pushing east- that much is apparent. A negative NAO should try to keep the system south, but notice the HP area in the Southeast. This could pose problems for such a solution, but I will discuss this storm more in depth later on in another post.
-A strong storm system may introduce the new weather pattern.
-There is potential for a positive PNA / negative NAO pattern to set up.
-Watch the Bering Sea / Gulf of Alaska to see if the +PNA can set up.
-This would be December's best chance for a better pattern.