Stratosphere and Polar Vortex Watch 2020

[Cheshire Freeze]

On 11/10/2021 at 17:30, Frigid said:

And 2009 predicted a mild winter and we got the coldest winter since 78/79. Not the end..yet

   

 

Temperature anomalies are hardly ever correct with the long rangers. You need to look at the pressure anomalies and extrapolate from there-

 

You can see it predicted extensive N blocking

Edited October 11, 2021 by CreweCold

[damianslaw]

2 hours ago, Don said:

Here we go

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean

I think it predicted a cold winter for 2018/19 which didn't happen.  Not the be all and end all but I would rather it showed a cold outlook than mild!

Can't remember last time any long range forecast went for cold.. default is always mild and I take them with a pinch of salt.

[Frozen Britain]

Just seen this. There is an impressive warming for the stratosphere coming up in the next few weeks: Unusually early Stratospheric Warming event is starting, with more to follow, having a yet unknown effect on the Polar Vortex this upcoming cold season » Severe Weather Europe (severe-weather.eu)

Will it impact our weather here in the UK? Who knows? 

Edited October 11, 2021 by Frozen Britain

[bluearmy]

Latest ec46 shows the upcoming weakening in strat zonal flow flattening out and not making single figures.  A recovery above average through November and then some uncertainty late November. 

[sebastiaan1973]

I see a new warming after 15 november. Russia.  

[Don]

2 hours ago, CreweCold said:

Temperature anomalies are hardly ever correct with the long rangers. You need to look at the pressure anomalies and extrapolate from there-

 

You can see it predicted extensive N blocking

By comparison, here is the pressure anomaly for November, December and January 2022.

Some mid-Atlantic high pressure perhaps ridging perhaps into Greenland at times but I don't like those strong heights over the Mediterranean.

Edited October 11, 2021 by Don

[Don]

55 minutes ago, bluearmy said:

Latest ec46 shows the upcoming weakening in strat zonal flow flattening out and not making single figures.  A recovery above average through November and then some uncertainty late November. 

This seems to have been the trend with these updates during the last couple of weeks?

[damianslaw]

17 minutes ago, Don said:

By comparison, here is the pressure anomaly for November, December and January 2022.

Some mid-Atlantic high pressure perhaps ridging perhaps into Greenland at times but I don't like those strong heights over the Mediterranean.

Heights over Greenland is key though, would set up a deep trough to our NE and going by the anomaly chart above these features would cancel out the med heights. Also the green to the west of Iberia suggests cut off low.. 

[Catacol]

Heart of winter looking grim. We are going to need the SSW wildcard again if this modelling is correct. Note - "if."

[Don]

14 minutes ago, Catacol said:

Heart of winter looking grim. We are going to need the SSW wildcard again if this modelling is correct. Note - "if."

Worth saying these charts were looking pretty grim for last winter, too and it ended up being half decent for some.

[Mike Poole]

50 minutes ago, Catacol said:

Heart of winter looking grim. We are going to need the SSW wildcard again if this modelling is correct. Note - "if."

If that’s correct, there won’t be a SSW!  GloSea5 is supposed to be quite good in the strat.  Some comfort that the NDJ charts look better, though.    I’m never very confident in the October long rangers, and would prefer to wait for the November update to influence my thoughts.  But the trop patterns right now will be influencing the strat vortex in a positive way and won’t be included in this run.  

If all we’re saying with these charts is that GloSea5 is predicting a very mild February, then I have to agree with it.  It fits well with the front loaded winter theory.  There’s plenty more to play for before that.  

Edited October 11, 2021 by Mike Poole

[Griff]

Ecmwf today vs Monday,  

[Don]

2 minutes ago, Griff said:

Ecmwf today vs Monday,  

Better overall I would say.

[Griff]

2 minutes ago, Don said:

Better overall I would say.

Indeed, something to keep an eye on at least. 

[sebastiaan1973]

Once again a warming at the Russian side of the Arctic after 15th of november.

https://apps.ecmwf.int/webapps/opencharts/products/extended-anomaly-10t?base_time=202110140000&projection=opencharts_arctic&valid_time=202111290000

[frederiksen90]

As I interpret it, we see the effect of the Canadian warming in the stratosphere by shifting the vortex to Europe, which provides increasing low-pressure activity over Scandinavia and the opportunity for short-term cool elements from the northwest in the next 2-3 weeks. Then it is clear that the low pressure trend disappears again - all the while the zonal winds of 10 hPa try to normalize. The effect of the Canadian warming disappears at the surface and the signal to go back towards more high pressure over Europe / Scandinavia as well as the Urals in the 3rd and 4th week is quite clear. This may be a precursor to a new and perhaps even more powerful weakening of the vortex. It is also seen that the heat rises in 10 hPa over Siberia in the same period. And once the vortex has weakened sharply once, is there more often a tendency for a warm-up or possibly a split on another attempt? It looks very interesting, because we do not go into a totally dynamic westerly current, but back to strong positive height anomalies, which contribute to planetary wave motion from the troposphere

[jules216]

This type of warming is in my view the worst outcome, it once again prevents the typical La Nina shot of early cold in November and once again puts in place the SE Europe Western Russian/Ural high in place that will prevent any meaningful cold in November, this west based NAO on models while tropospheric vortex moved over northern Euroasia is as ugly as it gets,because the secondary warming in Urals will shift the vortex in to places that puts northern America in for a shot for cold while us in Europe will be again hoping for a 2 week cold spell  in February. for once I was looking for a typical La Nina autumn where in Novembers like 1989,1995,1998,1999,2005,2007,2011 or 2016 we had plenty on snow even in low elevations. If I go by EC monthly this is like 2020 dejavu. I guess the Hadley cell exapansion and abnormal heat in North Africa is creating too inflated subtropical high pressure areas that augment what once were typical La Nina patterns. The cold is shifted ever so northward while us in central/southern Europe feel more effects of subtropical highs. If we get second mild November in a row during moderate La Nina this will be for me the final proof,that analog based forecast using years before 2015 is obsolete.

[sebastiaan1973]

1 hour ago, jules216 said:

This type of warming is in my view the worst outcome, it once again prevents the typical La Nina shot of early cold in November and once again puts in place the SE Europe Western Russian/Ural high in place that will prevent any meaningful cold in November, this west based NAO on models while tropospheric vortex moved over northern Euroasia is as ugly as it gets,because the secondary warming in Urals will shift the vortex in to places that puts northern America in for a shot for cold while us in Europe will be again hoping for a 2 week cold spell  in February. for once I was looking for a typical La Nina autumn where in Novembers like 1989,1995,1998,1999,2005,2007,2011 or 2016 we had plenty on snow even in low elevations. If I go by EC monthly this is like 2020 dejavu. I guess the Hadley cell exapansion and abnormal heat in North Africa is creating too inflated subtropical high pressure areas that augment what once were typical La Nina patterns. The cold is shifted ever so northward while us in central/southern Europe feel more effects of subtropical highs. If we get second mild November in a row during moderate La Nina this will be for me the final proof,that analog based forecast using years before 2015 is obsolete.

In my opinion the warm water of the Northern Pacific plays an important role. 

[jules216]

9 minutes ago, sebastiaan1973 said:

In my opinion the warm water of the Northern Pacific plays an important role. 

See my post in winter thread for explanation.

[Dorsetbred]

On 11/10/2021 at 23:11, Don said:

Worth saying these charts were looking pretty grim for last winter, too and it ended up being half decent for some.

Still feel this is heading more towards the "new norm"...

[Don]

3 minutes ago, Dorsetbred said:

Still feel this is heading more towards the "new norm"...

Are you referring to the 'new norm' being what these charts are showing for winter, i.e. a typical winter pattern moving forward?

Edited October 15, 2021 by Don

[bluearmy]

Quite a strange 12z gfs op run (from top to bottom) 

I doubt we’ll see it repeat …..

[SqueakheartLW]

Do I see another sign of a slowdown in zonal winds again here

Another new region of negative anomalies has started to show its face on the right of the chart along with the nearer one that also made its first appearance a week or so ago

Looks like the vortex is about to get hammered a bit if this comes off

[bluearmy]

13 minutes ago, SqueakheartLW said:

Do I see another sign of a slowdown in zonal winds again here

Another new region of negative anomalies has started to show its face on the right of the chart along with the nearer one that also made its first appearance a week or so ago

Looks like the vortex is about to get hammered a bit if this comes off

I’d caution a watching brief for the time being - the last slowdown in zonal flow was overdone by the week 2 modelling and this particular gfs op is isolated with the level of displacement and stretching of the spv ….

[Howie]

https://twitter.com/judah47/status/1449735532716691457?t=rTQUPEalSQiQMs9Y2paX0A&s=19 interesting