Moving To Colder After Thanksgiving Turkey & Stuffing Leftovers
Over the last few weeks we have been following the process of seeing if and when the weather pattern of the last several weeks is going to change or if it will change at all. We have seen a few things happen regarding some of the longer term technical signals. If these signals are correct than a shift is coming probably beginning over Thanksgiving Weekend while you are still eating leftover turkey and stuffing.
We have been looking at the North Atlantic Oscillation and the Atlantic Oscillation and others. Some of you may be under the impression that the North Atlantic Oscillation and the Atlantic Oscillation have to be in a “negative” phase in order for it to snow in the northeast. This is absolutely untrue. As proof just simply look back at the last 2 winters where the NAO and the AO were not only complete non factors but they are about as wrong as you could get at times in terms of the phases they were in. There are other things we look at that trump the NAO and the AO. I have been occasionally referencing the PNA or Pacific North America Pattern and now we will add the EPO to the list which is the East Pacific Oscillation. This is what the Weatherbell Glossary says about the EPO
EPO: Eastern Pacific Oscillation – A dipole pattern similar to the NAO in the Atlantic, but located in the eastern Pacific. There is a tendency for heights/pressures/temperatures to be higher to the north and lower to the south in the negative phase and lower to the north and higher to the south in the positive phase. The negative phase corresponds to widespread cooling over central and eastern North America and the positive phase to warming
Last winter the EPO was negative and the PNA was positive. This was the primary driver of the winter trend for 2013-2014 and for 2014-2015. Well guess what? The EPO is going negative and the PNA is going positive..both with positive (no blocking) NAO & AO. EPO and PNA always trump the NAO and AO.
Now here is the biggest difference between those winters and this one. Those 2 winters did not have a strong El Nino and this one does. Now take all this and lets get a glimpse of the three models today and what they did in the longer range. I went out to day 10 because all three models show a large degree of similarity.
What is very interesting is that all three models but particularly the European shows what appears to be a strengthening subtropical jet. The model differences lie in how strong each model handles the northern stream with the Canadian and the GFS cold and the European less cold but still colder than what we have seen recently. The actual details of the surface maps to me are not as important as the overall look. If the split flow develops the impact will then depend on, among other things, which jet dominates. Too much north and you get suppressed systems to the south. Not enough north and you get southern systems that wind up tracking west where it generally warms up and rains especially along the coast. Even this is probably way to early to ponder.
Another player in all of this is Typhoon In Fa in the Pacific which some models re-curve and serve to energize the low in the Gulf of Alaska which in turn opens up the passageway for arctic air. Not all models re-curve the typhoon. In fact some weather forecasting models weaken the typhoon over time where it is a non factor. We will just treat this as a sort of wild card going forward.
One thing for sure is that this coming week will be fairly quiet through Thanksgiving with temperatures a little colder than normal for the first part of the week and a little warmer than normal for the late week before the next cold front comes through. After that..well..we have the next run to take us down on this road..or perhaps a slightly different road.