Om kort door de bocht te gaan, er gebeurd (virtueel) een boel in de hoogste lagen van de stratosfeer. Maar de opwarming daar heeft voorlopig (lees: weken) geen significant effect op de troposfeer. Zie bijv. deze twee bijdrages.
http://forum.netweather.tv/topic/81567-stratosphere-temperature-watch-20142015/page-22#entry3071637
http://forum.netweather.tv/topic/81567-stratosphere-temperature-watch-20142015/page-22#entry3071700
Recretos (een weerliefhebber uit Slovenie!!) en naar mijn idee deskundig brengt het volgende naar voren (samengevat; flink verschil met situatie vorig jaar om deze tijd).
Later on, the main activity will be confined to the more upper layers of the stratosphere, and it really is very decent activity. Still, not much out of it for the troposphere (naturally), but as long as things are stirring up there on the top, the vortex cannot be one large single entity as it wants to be. There is also some slight disconnect between the upper/mid/low strat layers. The reason is that the troposphere is slightly more on the dominant side as far as lower strat goes. So we will need that upper strat activity to start taking over more than just the upper layers, combined with more constant dynamics. Just one wave of activity isnt going to cut it. We need constant battering, to put it that way, and some help from the trop. patterns.
Now for those of you that cant see those "positive points" right away on the graphics above, I have made three new graphics just for you. It is the difference between this year and last year, centred on 27.11 as far as ECM forecasts go and in a relatively good range of skill. It is the difference on this date between this year and last year. Data from this year is based on the Para GFS forecast (it is perhaps a bit different than ECM, but it gives a good general idea nonetheless), and data for last year is based on reanalysis from ECMWF ERA-Interim (accessible from the data portal me and Matt were talking about). It shows nicely just how weaker the mid-upper strat vortex really is, and as far as temperature goes, it has a pretty non-hospitable environment. It looks really cool (no pun intended), at least to me, and its a good indicator how different things are up there. It is interesting to note how the QBO phase also has its own temperature profile.
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