After a lot of thought and about 150 curls at the gym, I wanted to write about what I think will unfold in the pattern for the next two weeks.  

I’m sure everyone is freaking out about the latest in the crazy guidance seen on the long range GFS and ECMWF guidance.  The big scare is an upper low that forms over Alaska by next week, which in theory would support a flood of Pacific air into the CONUS, support a trough in the West, and a ridge in the East.  Hold your horses guys, and don’t run for the hills.  I’m going to explain exactly what I think will unfold in the pattern.  

When looking for the key indicators of parking an upper low over Alaska, I look for some key indicators to support a sustained upper low developing in this location. One of those factors is SST in the Gulf of Alaska. Overall, SST are running slightly below normal. It was the significantly below normal SST in the Gulf of Alaska that gave some meteorologist support for a “warm” late December to February forecast as the upper low deepens over Alaska, drives Pacific Air into the Western trough and pumps the SE ridge over the East. The following maps are the overall anomalies and the changes in the past 30 days, 14 days, and 7 days. Hat tip to Stormvista and MDA for data.

As you can see, the SST are warming in the Gulf of Alaska, which normally is not supportive of a “sustained” upper low over Alaska. (note: I like these maps because I’m color blind and the other maps used normally are very difficult for me to see, these maps are much clearer). Now I don’t use SST alone, but I incorporate my previous theory on this winter and the 10 to 30 MB stratospheric temperatures and trends when I think about this sustained Alaska upper low idea. Look, the stratosphere just doesn’t support a sustained pattern of this type. The coldest stratospheric anomalies remain over Eurasia or western Asia, which strongly suggest a ridge over central Asia which supports a -EPO pattern. Even the model guidance producing this upper low over Alaska keeps the -EPO block in place though slightly east of a traditional position. So if the SST don’t support a sustained upper low feature and the stratospheric environment doesn’t support it, then what does?

Let me tell you what I think is going on. I think we are entering a period of change in the blocking set up over North America and the North Atlantic. The upper low that has been killing any chance of a TRUE negative NAO over northern Canada is showing signs of dropping south and eventually east. As this process develops, I think the upper low will first slide towards central Canada, which has an influence of lowering heights over western and central Alaska. The model guidance is reading into this lowering as a strong closed upper low. My theory is that a piece of energy or disturbance will break off from the upper low over central Canada and drop through Alaska. It does not remain over Alaska, but in the time it is there for a few days, the results for the eastern US will be “unpleasant” for snow lovers. Yes, a ridge will build along the East coast as the trough axis temporarily moves towards the central Plains. I am very confident of another cold blast (intensity still being debated by me) for the middle of the month for the Plains, which will drive towards Texas. As a result, warm air will get pumped up the coast. However, much like the guidance from a few days ago, the long range guidance will over play the 850 MB warmth. Instead of well above normal temperatures, look for near normal temperatures for a few days followed by a day of above normal temperatures ahead of the cold front.

In the meantime, the upper low over Alaska weakens and becomes a non-issue in the long term. A ridge will reestablish itself as the -EPO signal wins out and remains supported by the changes seen in the SST of the Gulf of Alaska. Think of this as a feed back mechanism. The driving force is the wave patterns in the Stratosphere and the feed back support is the SST. I hope that makes sense. Anyway, the upper low over Canada will be in a much more favorable position to allow for a true negative NAO to form mid month and continue into January. If this upper low slides SE towards Ontario/Quebec, major game on. I’m on a wait and see position on that. So those are my thoughts. Could I be wrong? Sure. It’s called a theory, not law. I don’t have a big enough ego to assume I know everything, but this is what I think will unfold as we go forward.