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About chionomaniac

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    Strat freak

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  1. Liking the fact that the cold air is further south on this latest GFS run. With precipitation around we may see some cold rain or even snow. Blimey
  2. Well that's a dumbed down definition of a SSW if ever I saw one. Well done MO for confusing a definition even more. At what point do scientists ever use the word 'about' in definitions!?
  3. I think that in this case Judah hasn't stated whether there is a major or minor warming and this has led to a lot of people stating that a SSW is occurring (just like David Morse has done) when in fact a SSW as defined by Polvani et al is known as a major one with wind reversal and isn't occurring. Amy Butler confirmed that this still hasn't been agreed yet and will be further considered when SPARC meet later in the year. Calling a SSW a minor one is a bit like using the term mini tornado to me. It's either a tornado or it isn't. Likewise SSW.  
  4. I don't actually understand what Judah is trying to say here? And many have mentioned this as well as Andrej has on twittter. So let's make this absolutely clear, in old money this can be classified as a minor warming or even a minor SSW at a stretch (though personally I can't stand that term). But this graph does not take into account the mean zonal winds and dynamical shape of the vortex because that would show no mean zonal mean wind reversal at 60N and 10hPa and never has, so no SSW as the majority know and define one. Judah has tried to argue on twitter that this will still lead to a blocked trop profile. But when you look at the dynamical positioning and reforming of the vortex after the warming event then it looks pretty obvious that there is no blocking to be had - certainly not in the Atlantic sector. There is a lot more to strat dynamics than one chart showing the temperature rise at the North Pole, and Judah has yet to demonstrate exactly how the displaced vortex will lead to tropospheric impacts other than what the models show currently and @recretos has so ably demonstrated so far.
  5. I think the tweet I posted is for the week after that.   And @Interitus and @bluearmy that 10hPa is a lot larger value than I thought. 
  6. It'll be close. I'm going for +3.5m/s!
  7. I think you highlight the difficulty here in translating how a possible vortex displacement event high up in the stratosphere may affect the troposphere at a later point. Especially if the displacement nudges the vortex off the pole leaving a temporary technical SSW, but the vortex recovers positionally wise - without ever losing enough intensity for long enough to have long lasting and propagating effects tropospherically. And that to me is the big question mark regarding the upcoming warming event. This can be demonstrated using the GFS as it shows what could potentially happen after day 10. So day 10 we see a strong warming with considerable displacement placed on the vortex and the vortex is in some distress However, the warming is not strong enough, and without the back up of a Karate chop wave 2 we see the vortex recover, not totally unscathed, but strong enough probably to still have an impact on the tropospheric vortex especially in the Atlantic sector. Those situated under the stratospheric Aleutian high are probably more likely to see tropospheric blocking with the favoured areas always towards the Pacific sector - the best we can hope for is probably a west based -Ve NAO but probably a pattern more like this as MV highlights from the ECM week 4 ensembles   The East coast of the US wins again.....
  8. The wave 2 event is pretty well established at this point
  9. Hi Chris you are right and wrong here. Firstly, the wrong bit - the second chart is a temperature chart and does not show the position of the polar vortex at 10 hPa - so you should not even make the correlation analogy! The correct bit  ( or partially correct bit) is about the downwelling, or to put it more accurately, the position of the tropospheric vortex in relation to the position of the strat vortex. Yes, this can be well correlated - but not necessarily always ( an example of a disconnect recently was the trop Kara high in early Jan). So when the vortex displaces stratospherically to the Scandi /Siberian sector, then a transfer of the bulk of the tropospheric vortex to this region is quite common. But the best correlation can be seen with a complete split of the vortex from strat to trop. Then we are laughing...
  10. Jan 2009 - the ideal split SSW - was the same. And that had instant trop results from the easterly.  The GFS can overestimate the MT events though as well.
  11. Here is the NW GFS 10hPa chart at day 16.   Technically, this is not a SSW (reversal at 60N and 10hPA) but may lead to one - though caveats that this is again day 16 and the warming is reducing by day 14 so the split may not be strong enough.  A good sign (though we have seen many of them) and backed up by the EPS which show a wave 1 displacement followed by wave 2 split.   So, in short we are seeing another GFS FI chart that could lead to a SSW, but no SSW showing yet. 
  12. No SSW ( using the technical major warming description here) has been forecast yet and as much as the warming around day 10 is quite large, it is not strong enough to reverse the mean zonal flow at 60ºN and 10hPA - with u wind staying above 20m/s at this point. The forecast displacement may have some trop affect with the vortex positioning, and with possible MJO and GWO alignment at the same time,  forecasts like the ECM op have a good chance of occurring. But I would say that this is primarily trop induced with a little help from the strat.  The vortex at 10hPa will still be ripe for further 'attack' but the GFS has suggested that the vortex will quite possibly regain strength. I know that Judah Cohen has been tweeting that he considers a SSW to be on the cards - but not by the definition that currently exists for a major one in my book, so caution should be used when reading these tweets. (Amy Butler has suggested via twitter that the summer meeting of SPARC will reconsider the SSW definition question further)
  13. The problem with displacements is that unless we see a full stratospheric destruction of the PV then we are unlikely to benefit from the slight stratospheric upheaval at the top of the strat. All signs with this displacement at this point are that it will not create a SSW and certainly not a vortex destroying one, and any propagation down to the trop of the displacement is looking stilted to say the least. We are still seeing tropospherically the increased strength vortex that occurs before the displacement, and it may take some time before this washes out of the system. I think the winter will need some tropospheric (GWO) feedback systems in place in the meantime and there is no sign of that help for a little while too! Those relying on the strat to save this winter may be disappointed, as, even if we still get a SSW and even if it does eventually propagate, it is still very uncertain that blocking would appear in the correct place. That was the fear before winter started and it still remains.   There, now I have said what I have been thinking for a while, hopefully I will be proved totally wrong!