Signs Appearing On the Horizon
Let me make clear that I’m not at all ready to predict anything. We have been here before in the last few weeks. While it seems that the upper pattern is locked in place forever we know that is not going to be the case. However some chatter and some signs have begun to appear among long range followers as well as those who have a handle on this sort of thing that there are changes going on in the highest levels of the atmosphere that will cause a pattern change. Now what the change (if it happens) means I’m entirely unsure but let us examine a few things that are starting to show up. Now this is going to be a little complex but I’m learning as well here so one step at a time.
The map above is the upper flow at the very top of the atmosphere or 10 mb. We are talking the stratosphere here. Basically we are talking above 33,000 feet where jets fly. You will notice right away that the flow here is dominated by only a few features which is unlike the lower levels where you have more numerous lows and highs, troughs and so on. The map is the current look and you can see where the vortex is sitting. Now one of the arguments or predictions for a change is for that vortex to eventually stretch and split which would creating rising pressures across the pole and displace cold air southward in the lower atmosphere. Now there is a time lag from when it happens up there and when it translates down here. Models have been hinting at such and event and the last several runs seem to be on a trend.
Signs begin to appear inside the 10 day GFS today both on the operational run as well as the ensemble runs so that is a good sign. The map above is day 10 and you can see that the upper low at the poles is beginning to migrate and stretch. That trend continues out to day 16 which is another sign that the top of the atmosphere is changing. The picture below is day 16 which is January 1st
You can really see the elongation and stretching of the upper low on the ensembles here below
Now some notes of caution. This could look split and then wind up reverting back to the original look above in which case it would mean more of the same (for the most part). There are other indicators and index that are pointing to strong warming going on in the stratosphere when looking both current and model data around the Arctic. Obviously that trend needs to continue for any meaningful pattern change to develop. Should this actually happen it would take a couple of weeks for the pattern change to play itself out at the lower levels. From here we will see where this all takes us. Again these are just signs that are appearing in the horizon and those signs could just be mirages. We will just continue to move along and watch how this all plays out. The video below is last night’s GFS model analysis in case you haven’t seen it.
Shorter term the models seem on course for a blow torch. Last night’s long range models have backed off a bit from the absolute blast furnace for Christmas Eve but I don’t think that idea is entirely off the table right now. The European is not as extreme as the GFS but it still brings 60s up the coast to Southern New England. A lot will depend on how the cold front and warm front set up over us. Will there be an onshore flow before the warm sector takes over and the cold front approaches? I think that will be the biggest question. I will have a more extensive view of this evening.