Polar Vortex / Stratosphere Watch 2022 / 2023

[bluearmy]

Berlin site usually comes aboard 1 st nov  - could be good timing ….

[bluearmy]

Strat vortex looks to become a little stretched in week 2 

ec op almost splits it from below by day10.  Trop wave 2 could do some early season damage if the scandi and Aleutian/Alaskan ridges verify 

[bluearmy]

On 31/10/2022 at 05:47, bluearmy said:

Berlin site usually comes aboard 1 st nov  - could be good timing ….

Not updated as would usually be the case from beginning nov

shame as there would be some interesting data to view as the vortex looks to be pulled and possibly split from the bottom to 30hpa. (depending on trop modelling verifying) 

[northwestsnow]

 

 

[bluearmy]

It’s certainly better for coldies than to see a strengthening compact SPV but at the moment, the back end of the gfs runs show the zonal flow into the mid thirties at 10hpa 60N

Would want to see more affect on the SPV zonal flow than we currently see late week 2.  How the trop ridges actually verity will dictate 

[bluearmy]

Gfs ops today have been messing about with the spv as week two progresses 

splits and notable slow downs

the ens don’t seem to be so keen however 

[Kirkcaldy Weather]

Does look like a bit of strat related interest going through the latter half of November. I found this tweet from 4 / 5 days ago clearly that run of the ECM favoured a split 

 

 

 

Edited November 9, 2022 by Kirkcaldy Weather

[Kirkcaldy Weather]

Browsing the different levels on stratobserve newest run with 7 splits by November 23rd at 50hpa  

[Kirkcaldy Weather]

 

 

[bluearmy]

6 hours ago, Kirkcaldy Weather said:

 

 

As does gfs 

And gfs goes onto strengthen the spv down to the mid levels thereafter 

Eps strat data is now unavailable on the website - annoying. 

[TSNWK]

14 minutes ago, bluearmy said:

As does gfs 

And gfs goes onto strengthen the spv down to the mid levels thereafter 

Eps strat data is now unavailable on the website - annoying. 

Morning.. so the strat' is showing signs of  coupling? I have this in my mind as a bad thing for coldies? But reading between the lines of your and @Kirkcaldy Weather posts it might nor be? Confused 🙂

[bluearmy]

4 minutes ago, TSNWK said:

Morning.. so the strat' is showing signs of  coupling? I have this in my mind as a bad thing for coldies? But reading between the lines of your and @Kirkcaldy Weather posts it might nor be? Confused 🙂

There seems to be a decent correlation through the atmosphere at the moment. As trop ridges establish, they throw waves up into the upper strat which have interfered with the strengthening spv. As week two progresses, the spv zonal flow seems to be descending through the levels. This wouldn’t generally be considered a good thing for coldies. But that’s a way off. Whilst the trop waves headed up are doing a decent job, it’s tough to get modelling of the mid strat to be solid as it becomes reliant on how good the trop is in the 7/10 day period. And we know that’s not good. 

[frederiksen90]

Vortex is splitting in GFS 30 hPa:

 

https://max.nwstatic.co.uk/gfsimages/gfs.20221113/00/216/npst30.png

[Kirkcaldy Weather]

On 10/11/2022 at 01:40, Kirkcaldy Weather said:

Browsing the different levels on stratobserve newest run with 7 splits by November 23rd at 50hpa  

Now up to 10 splits 

[bluearmy]

6 hours ago, Kirkcaldy Weather said:

Now up to 10 splits 

It does seem that it quickly puts itself back together and strengthens thereafter 

I expect we have to wait to see the effect that any further scandi upper ridging will have weeks 2 into 3 

[phil nw.]

The Strat.polar vortex  at 10hPa is now quite cold and well formed with mean zonal winds forecasted to pick up further by early December.

We can see from the images though that it's a different story lower down.

From mid-level down forecast is  for negative anomalies to continue so for the time being opportunities for further blocking patterns remain until we see a connection with the increasing winds higher up.

[bluearmy]

So we have a weakening of the zonal flow down to 20 m/s around 26th (post transient split). Thereafter a recovery forecast towards 40 m/s. However, it should be noted that this strengthening is accompanied by the spv traversing across to the Asian side which offers support to a flow of some kind from the Arctic into europe as we head into the new month. 
 

it would seem at this stage that this movement of the spv will continue as it then looks to drift back towards the pole. That’s way  into the distance of course but it does look as though we could see a notable warming at the same time in the e Asian sector. 

I would usually say that the ec46 zonal chart is anticipated but after it’s recent poor performance picking up this slow down late November I’m not waiting with baited breath ……

[Mattias]

As I tweeted a couple of days ago (from our newly created weatheriscool account, https://twitter.com/wxiscool/status/1592979954874331138) I believe that downward wave coupling/reflection from the stratosphere might be involved in the interesting and complex evolution forecasted ahead.

There is an area with negative vertical windshear present in the upper stratosphere which is known to be able to act as a reflective surface. In addition, the EP-flux charts show episodes of downward directed EP-flux and in high latitudes there is (in the blocked runs) forecasted an easterly phase tilt of the eddy geopotential heights (which indicate downward wave propagation). Usually reflective events are associated with NAO going positive, however that is generally when the original upward wave activity pulse comes from the climatological wave number one pattern in midlatitudes (which is then later reflected back downward in high latitudes, with decreasing geopotential heights around Greenland and rising heights on the opposite side of the pole), see Shaw and Perlwitz (2013), https://academiccommons.columbia.edu/doi/10.7916/D8N58X9W/download.

However, the initial wave pulse at the moment is not from the climatological zonal wave 1 and a possible upcoming downward reflection event rather seems to act to reinforce the Scandi block and might also support a retrogression of the blocking pattern towards the North Atlantic. If downward wave reflection takes place, as I believe it does in several of the recent model runs, it is not surprising to see a strengthening SPV at the same time as the tropospheric high latitude blocking pattern strengthens. That would be consistent with the recovery of the SPV and the positive u-mean anomalies forecasted in the stratosphere and the negative u-wind anomalies forecasted in the troposphere. Also, to relate back to the previous post, the shift in position of the main SPV can be related to the downward directed EP-flux, because when the main SPV moves from North America/Greenland, towards the pole and the Asian side, it temporarily brings cold air northwards which thus leads to a negative northward heat flux, consistent with the downward directed EP-flux vectors.

There is still a large uncertainty in the forecasts, but it will be interesting to see how it plays out.

[bluearmy]

Having looked like the relocation of the spv to the Asian side had run out of steam on the modelling, we have reverted back on gfs and now the eps mean charts are showing again, we can see the mean below for day 15. The gefs similar locale 

Fwiw, the 46 also has the mean spv at 10 hpa in the Svalbard/n russia area through dec  

[lorenzo]

Interesting times for the vortex, and as Blue states above the FWIW leaves the lower reaches open for interest.

Couple of flat NASA plots to contextualise  the impacts of the Scandi regime on the vortex, quite significant. Merra put the Momentum Flux into the record books in the 00z forecast run this morning, the much maligned CFS u product has caught a glimpse of SSW leanings before, and we now have reversal pixels into the New Year at the edge of the range, one to watch.

 

 

Finally an animation from 84/85 which I can see from H5 reanalysis posted on Twitter has been a pretty solid analog across Nov, and it's a good vid !

https://www.meteo.physik.uni-muenchen.de/~Thomas.Birner/SSW-animations/anim-PV/1984-1985_530K/loop.html

Best modelling watch for many a year..

[bluearmy]

Updated eps 10hpa at day 14.5 ….. steady on the heights but a slight down tick on the warming 
   

 

 

Edited November 24, 2022 by bluearmy

[bluearmy]

 

mean eps at T318 showing a small area of -20/-24c. Spv firmly on the Asian side too at this time in contrast to the current surf of warmth around -28c with the spv in Canada 

[Gowon]

You can see a patch of -15c if you go onto here.

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[bluearmy]

Split spv leads to a reversal down to approx 70N by day 10/11 on gfs
 

    

[bluearmy]

18 hours ago, bluearmy said:

Split spv leads to a reversal down to approx 70N by day 10/11 on gfs
 

    

Which hasn’t shown any sign of repeating btw

The max warming on the Asian side enlarging on the eps mean (as expected) and still around dec 8th/9th

whilst these warmings don’t seem to show any likelihood of leading to an ssw, they should hopefully keep the spv on its toes and prevent it from settling over Canada/Greenland and winding up further. At the moment we don’t see any strength high up looking likely to downwell as far as the trop