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Stratosphere and Polar Vortex Watch

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Some useful tropospheric developments upcoming which are likely to have stratospheric impacts towards the end of November and more particularly into December. A strong convectively coupled tropic

so after many days the GFS & FNMOC & canadian finally now follow the Euro with 44 out 64 Members with a split at day 9- The ECM is day 8. We will call it - SSW & Split for 1st Ja

For all that watch the zonal winds. Let me urge you to look at the geopotential heights more. At least as far as weakening/strengthening trends go. Because as the polar vortex cries for help, you migh

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It sure is puzzling with respect to GFS & FV3.

I've seen the suggestions that it has both insufficient layer density in the upper stratosphere and a shortfall of observation data on the Ural High, but in that case, how come yesterday it temporarily seemed to latch on to something much closer to the other modelling?

Odds are we're on course for seeing just how tragic GFS is as a model, and sadly how even the new FV3 still manages to fall short. The alternative outcome just doesn't bear thinking about... the reputation of the Euro/UK + Japan models would be left in tatters, and we'd be left waiting for yet more warming events to finish the job - by which time the tropical cycle would probably be less ideally positioned to maximise impacts for the UK.



Too bad the 10 hPa pattern doesn't have the physical capability to translate perfectly downward right now ??.


Really @northwestsnow, it's taken that long to do so? ?

Edited by Singularity
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2 minutes ago, northwestsnow said:

Nope.. parrallel also completely backed off as well..


A little concerning ........ Are we going to now see the ECM back off also?

Edited by Don
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Greetings. This is my first post.

GFS06Z ensemble mean is seeing split vortex in the beginning of january, which is very important. The control one still doesnt see it, but in this kind of events ensembles  are probably the one we need to look at for an accurate forecast. There are 20 ensembles available for us if we look at GFS model, and 50 if we look at EMCWF. I trust the ECMWF much more, that the GFS weather model. it also has a better resolution if  we analyse this two models. I am also very pleased, that there are so many people on this forum, that are monitoring the situation in the stratosfere. Keep on the good work.



Edited by Redbull165
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22 minutes ago, Redbull165 said:

GFS06Z ensemble mean is seeing split vortex in the beginning of january, which is very important. The control one still doesnt see it, but in this kind of events ensembles  are probably the one we need to look at for an accurate forecast. 



Cheers on your first post!

For the record: the GEFS still shows a technical SSW but keeps pushing it back. Meanwhile, the hump in the short term is getting higher and higher (conform the operational runs). 


Edited by Ruben Amsterdam
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From the study I mentioned earlier this day I selected these charts. Predictability of downward propagation of major sudden stratospheric warmings Alexey Yu. Karpechko,et al

Major Sudden Stratospheric warmings (SSW) are striking phenomena of wintertime stratospheric circulation usually defined as a reversal of zonal mean circulation from westerlies to easterlies. SSWs often have significant impacts on tropospheric circulation and cause anomalies in surface climate lasting for up to two months. For this reason, dynamics and predictability of SSW receive considerable attention. It is however well-known that not all SSW cause significant, long-lasting impacts on the troposphere. In order to explain differences in tropospheric impacts following SSWs,
several reasons have been previously proposed, including differences in type of SSW (split or displacement), persistence of stratospheric anomalies, preconditioning of the tropospheric circulation, and whether or not SSW was accompanied by a planetary wave reflection in the stratosphere. Here we address the predictability of tropospheric impacts by SSWs by seeking for early precursors of the impacts. We separate mid-winter SSWs into two groups: those which are followed by significant, long-lasting impacts on the tropospheric circulation (defined in terms of anomalous northern annular mode) and those not followed by significant anomalies in the annular mode. We show that SSWs characterised by a more negative Northern Annular Mode index in the lower stratosphere around 150 hPa and enhanced wave activity propagation to the stratosphere during the first few days following the central date have a larger probability to be followed by
tropospheric impacts, both in reanalyses and in climate model runs. These anomalies play more important role for the subsequent downward propagation of the signal to the troposphere than the type of SSW: whether it is a split or a displacement, or absorptive or reflective SSW. We propose that using these anomalies as precursors of tropospheric impacts of SSW can enhance climate predictability.

Please notice the difference between dSSW and nSSW. With dSSW there is a negative AO around the first day of the SSW. Displacment or split doesn't matter. Tonight's NH-profile shows a positive AO. So according to this study there will be no downwelling to the troposphere.  

lijst avn ssws.PNG

plaatje 1.PNG


Edited by sebastiaan1973
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