Stratosphere and Polar Vortex Watch 2020

[Nick_Somerset]

Just read the Sky News weather article...

UK weather: Could another 'Beast from the East' be on the way?

NEWS.SKY.COM

---

About 6-30 miles above the North Pole, there is an event occurring where temperatures may increase by up to 50C over a few days.

...so everyone is getting in on the act now..  

 

Edited January 6, 2021 by Nick_Somerset

[northwestsnow]

12 minutes ago, bluearmy said:

Ed mused this back in December ...... I guess the reply is that with no ssw we could have possibly maintained a decent trop scenario for another couple weeks but later in jan and into feb would likely have gone to mobile. We could now see latter third jan and through feb with downwelling waves ..

Looks like the long game...

No QTR.

[sebastiaan1973]

So the situation today. Chart day 6. We see a displacement and on day an attempt tot split. -13m/s by that time.

 

[sebastiaan1973]

Continuous downwelling. Please notice the strong easterly winds at day 10 higher up in the atmosphere. They should downwell as well day 10+

[daz_4]

1 hour ago, Weather-history said:

Matt Hugo just metioned this in  a tweet and something I have mentioned as well, if you aready in a blocked postion, do you want a SSW event that could disrupt the block? 

While a valid point I don't think the pattern we were in was a winter nirvana or something. While UK and Western Europe was getting below average uppers it was nothing to write home about and rest of the Europe was very warm. So I will take a SSW in this case.

[LRD]

27 minutes ago, northwestsnow said:

Looks like the long game...

No QTR.

Isn't it always. Whatever the main driver(s), it's virtually always the long game... nearly 3 years currently, in fact. And nearly 5 years before that!

I s'pose this is a bit of a chicken and egg question but if the SSW proves to be favourable for us, would the ensembles pick something up before ops? Or would it be the other way round? Or a blend? Where would the first clues be found?

[sebastiaan1973]

15 minutes ago, daz_4 said:

While a valid point I don't think the pattern we were in was a winter nirvana or something. While UK and Western Europe was getting below average uppers it was nothing to write home about and rest of the Europe was very warm. So I will take a SSW in this case.

The pattern delivered nothing substantial. Due to a lack of cold at the Continent. We saw high pressure in the north east of Europe preventing cold air to be pushed to the continent. This disappears due to the SSW.

[Interitus]

On 03/01/2021 at 21:58, ALL ABOARD said:

Hi mate, 

 

Top of your head what's the longest reversal we've ever had in terms of days? 

Obviously excluding final warnings? 

Reversals from MERRA data

Date - days

01/03/84 - 34

24/01/09 - 29

06/01/13 - 22

31/01/87 - 22

26/02/99 - 21

21/01/06 - 19

02/01/19 - 17

12/02/18 - 17

22/03/92 - 15

07/03/89 - 15

11/02/01 - 14

12/03/05 - 12

05/01/04 - 10

27/03/14 - 10

21/02/89 - 9

08/12/87 - 9

22/02/79 - 8

18/03/88 - 7

17/03/80 - 7

22/02/08 - 6

13/03/08 - 6

15/12/98 - 6

23/01/87 - 5

01/01/85 - 5

19/02/10 - 5

24/02/07 - 4

11/02/06 - 4

24/02/84 - 4

30/03/05 - 4

30/12/01 - 4

09/02/10 - 3

29/02/80 - 3

24/03/10 - 3

29/03/08 - 3

20/03/00 - 3

29/03/98 - 3

14/03/88 - 3

05/01/21 - 2

20/01/19 - 2

20/03/18 - 2

25/03/89 - 2

04/12/81 - 2

18/01/03 - 1

29/01/87 - 1

01/02/17 - 1

05/02/95 - 1

25/02/87 - 1

28/03/15 - 1

26/03/05 - 1

04/03/81 - 1

25/03/80 - 1

 

Edited January 6, 2021 by Interitus

[SqueakheartLW]

GFS

Yet more evidence of this 3rd warming showing up in the 00z GFS

Parallel

GEFS Legacy

Summary

Both GFS and GEFS Legacy are showing signs of this 3rd warming. GFS and GFS Parallel currently have a stronger signal compared with the GEFS Legacy. All 32 GFS runs and the parallel are now showing a warming of some degree near the back end of their runs and some stronger warmings are now showing up

GEFS Legacy has more hints rather than any stronger warmings at present but if the signal sticks then this model should come more on board in the next few days

GEM

GEM doesn't go out far enough yet to pick up on a possible 3rd warming but it is still really weakening the vortex unlike the GFS and GEFS Legacy models

NASA

NASA similar to GEM but slightly stronger vortex but in similar position

JMA

JMA has a weak strung out vortex at the end of the run but not a good place for UK cold with the core of the cold above Greenland

CMA

The CMA is weakest with the vortex so far and looks like it is getting another major warming going over Siberia too

FIM

The FIM has little of the vortex left at the end of the run and has signs of another warming too

ECM

ECM is clearly having another attempt at splitting the vortex by 240 hours at 10hpa

[Vikos]

2 hours ago, sebastiaan1973 said:

So the situation today. Chart day 6. We see a displacement and on day an attempt tot split. -13m/s by that time.

 

So, now it's even strengething the reversal, also the duration of the reversal. Few days ago, the graph was lightly scratching the 0-Line (10hPa Zonal Wind), now it goes clearly beneath

 

[Battleground Snow]

1 hour ago, SqueakheartLW said:

GFS

Yet more evidence of this 3rd warming showing up in the 00z GFS

Parallel

GEFS Legacy

Summary

Both GFS and GEFS Legacy are showing signs of this 3rd warming. GFS and GFS Parallel currently have a stronger signal compared with the GEFS Legacy. All 32 GFS runs and the parallel are now showing a warming of some degree near the back end of their runs and some stronger warmings are now showing up

GEFS Legacy has more hints rather than any stronger warmings at present but if the signal sticks then this model should come more on board in the next few days

GEM

GEM doesn't go out far enough yet to pick up on a possible 3rd warming but it is still really weakening the vortex unlike the GFS and GEFS Legacy models

NASA

NASA similar to GEM but slightly stronger vortex but in similar position

JMA

JMA has a weak strung out vortex at the end of the run but not a good place for UK cold with the core of the cold above Greenland

CMA

The CMA is weakest with the vortex so far and looks like it is getting another major warming going over Siberia too

FIM

The FIM has little of the vortex left at the end of the run and has signs of another warming too

ECM

ECM is clearly having another attempt at splitting the vortex by 240 hours at 10hpa

Still there on the the 06z, would this the the final blow to the vortex?

 

[SqueakheartLW]

The 06z GFS runs and the 06z parallel have strengthened the 3rd warming signal even further

All runs have a warming yet again and even more warmer ones are showing up now compared with the 00z runs

The counts are below along with the peak warming averages

GFS + Parallel

Peak Warming     06/01 00z     06/01 06z

-28                          2                    1

-24                          5                    5

-20                          5                    5

-16                          7                    6

-12                          9                    7

-8                            3                    2

-4                            1                    2

0                             1                    3

+4                           0                    2

Av Peak              -15.88           -13.45

As can be seen an overall further strengthening of the warming signal

[phil nw.]

 

Not quite seeing a split yet but It's a waiting game now to see if the displacement can work in our favour.

On the ECM data from yesterday at day 10 we see the spv stretched across the Atlantic side with the main lobe over Siberia.The daughter lobe over NA could be the problem in getting heights to develop in our favour currently.

Images below at the different levels.

Looking at the mean zonal wind profile at day 10 we see the reversal filtering down over the polar area but at 60N there is still some residual energy showing which i guess is the northern jet .It looks like it still has enough in it to scupper any Greenland heights  currently.That daughter vortex not helping and needs to disappear and that's why a split would help to give us the pathway we need.

Current ecm wave action forecasts out to day 10 shows an easing off so a little lull in the coming period which allows the zonal wind flow at the top to level off although still well below normal.As posted earlier a short reversal at both 10 and 30 hPa shows up on the graph.

Hopefully more warming showing up on later GFS outputs verifies and further weakens the vortex.At the moment we are in a wait and see period.

Edited January 6, 2021 by phil nw.

[bluearmy]

Gfs 06z op is a bit different later on so wouldn’t over analyse that run.

but there has been a general theme on gfs of another reversal wave in a couple, weeks time at the top of the strat 

[Bricriu]

2 hours ago, phil nw. said:

 

Not quite seeing a split yet but It's a waiting game now to see if the displacement can work in our favour.

On the ECM data from yesterday at day 10 we see the spv stretched across the Atlantic side with the main lobe over Siberia.The daughter lobe over NA could be the problem in getting heights to develop in our favour currently.

Images below at the different levels.

Looking at the mean zonal wind profile at day 10 we see the reversal filtering down over the polar area but at 60N there is still some residual energy showing which i guess is the northern jet .It looks like it still has enough in it to scupper any Greenland heights  currently.That daughter vortex not helping and needs to disappear and that's why a split would help to give us the pathway we need.

Current ecm wave action forecasts out to day 10 shows an easing off so a little lull in the coming period which allows the zonal wind flow at the top to level off although still well below normal.As posted earlier a short reversal at both 10 and 30 hPa shows up on the graph.

Hopefully more warming showing up on later GFS outputs verifies and further weakens the vortex.At the moment we are in a wait and see period.

I just wonder if a lobe of vortex ends up in the north Atlantic as per the ECM, is this actually the thinking behind the UK Met Office long range too?If so It seems to me Ireland and perhaps Western England could well be under the influence of milder Atlantic air, while eastern England maybe in a colder contintental Airmass or on the boundary of it. As long as it all moves west eventually, but could the leveling off you speak scupper that happening?

Edited January 6, 2021 by Bricriu

[phil nw.]

9 minutes ago, Bricriu said:

I just wonder if a lobe of vortex ends up in the north Atlantic as per the ECM, is this actually the thinking behind the UK Met Office long range too?If so It seems to me Ireland and perhaps Western England could well be under the influence of milder Atlantic air, while eastern England maybe in a colder contintental Airmass or on the boundary of it. As long as it all moves west eventually, but could the leveling off you speak scupper that happening?

Bear in mind my summary only covers the next 10 days on the ecm outputs so later warmings can change the position of the spv. 

A clean split with separate lobes does give a better chance of polar blocking building to our north pushing the jet to the south. 

[Don]

1 hour ago, Bricriu said:

I just wonder if a lobe of vortex ends up in the north Atlantic as per the ECM, is this actually the thinking behind the UK Met Office long range too?If so It seems to me Ireland and perhaps Western England could well be under the influence of milder Atlantic air, while eastern England maybe in a colder contintental Airmass or on the boundary of it. As long as it all moves west eventually, but could the leveling off you speak scupper that happening?

This sounds a little like what happened during the first half of February 2012 in terms of eastern areas being cold and western areas including Ireland milder?

Edited January 6, 2021 by Don

[ALL ABOARD]

Not another one...  

[Cymro]

1 hour ago, Bricriu said:

I just wonder if a lobe of vortex ends up in the north Atlantic as per the ECM, is this actually the thinking behind the UK Met Office long range too?If so It seems to me Ireland and perhaps Western England could well be under the influence of milder Atlantic air, while eastern England maybe in a colder contintental Airmass or on the boundary of it. As long as it all moves west eventually, but could the leveling off you speak scupper that happening?

Western England and Wales perhaps or has the SSW removed us from the British Isles? 

[TSNWK]

11 minutes ago, Cymro said:

Western England and Wales perhaps or has the SSW removed us from the British Isles? 

Not this time we only appear to have a displaced vortex and the MJO is not helping

[SqueakheartLW]

12z GFS runs and parallel showing more evidence of this 3rd warming. I'm sure Brenda from Bristol won't be very happy about yet another warming this month.

An even stronger signal yet again compared with the 00z and 06z runs earlier today. When updating my table from earlier we see the following

GFS + Parallel

Peak Warming     06/01 00z     06/01 06z     06/01 12z

-28                          2                    1                    2

-24                          5                    5                    1

-20                          5                    5                    1

-16                          7                    6                    7

-12                          9                    7                    7

-8                            3                    2                    5

-4                            1                    2                    3

0                             1                    3                    5

+4                           0                    2                    2

Av Peak           -15.88            -13.45           -10.30

As can be seen above we have seen a further shift towards a warmer peak to the warmings showing so overall a strengthening of the warming signal

[Singularity]

12z ECM looked to be applying a bit more pressure from above than the 00z did in the 6-10 day range. Forced a couple of trough disruptions but it still wan't enough in the face of what became an onslaught.

I'm a bit suspicious of so much Atlantic thrust though; we're only going into a weakly negative AAM (La Nina-like) regime and zonal flow aloft doesn't look to be any greater than average.

So, I can see where calls for the UK to be right on the edge come from - including Tamara in her very insightful update on the MOD thread. It's all so finely balanced, leaving us to try and second-guess modelling errors which themselves are amplified in this setup. Tends not to work out reliably in my experience! Keeping an open mind very much the healthiest way to proceed.

Those who propose that the SSW could work against us for cold weather need to consider that without the SSW, we'd still have this shift to a more La Nina-like regime, but with stronger zonal flow and high pressure less able to ridge northward through the UK. Those seeking cold, snowy weather would be having to look toward late Jan / early Feb MJO-related possibilities and not just for the tropospheric response but also a means to assault the polar vortex and perhaps initiate a SSW to help with proceedings, albeit at the risk of a much delayed spring, which tends not to be to so many people's taste.

Speaking of the MJO, there are indeed hints that it might start up a cycle by late this month, raising AAM and reducing hostility to HLB patterns aided by any further waves of SSW-induced reversal that make their way down. That's a very interesting prospect, but as usual, predictions of the tropical cycle are fraught with uncertainty, so we can only wait and wonder on that, for now.

With that in mind, we'd be in a better position if there was a wide split of the polar vortex in the modelling rather than a mostly displacement event, as the reversal waves tend to keep coming for 2-3 weeks longer in the wide split case. On the other hand, the displacement dominance lowers the risk of a delayed spring, which during these extra-challenging times, may be most unwelcome for many (at least when looking beyond NetWeather forum members!).

[Don]

4 hours ago, ALL ABOARD said:

Not another one...  

The more the better.  Just need the bl**dy thing to split!!

[chionomaniac]

Hopefully will have time to have a good look at all the strat runs tomorrow and work out where we are heading. Initial thoughts are for another wave 1 warming. With the strat vortex already weakened and trying to recover, this is not a bad thing for the continuance of winter. Anyone who suggests that the trop vortex is likely to recover and regain strength are standing on thin ice.

Best wait til it thickens.  Last third of Jan looks very promising. We have already had a synoptic wish list ticked off this winter, but without the expected linked T850’s. Luckily we still have time for that to change with the strat pv heading for another kicking.

[ALL ABOARD]

25 minutes ago, chionomaniac said:

Hopefully will have time to have a good look at all the strat runs tomorrow and work out where we are heading. Initial thoughts are for another wave 1 warming. With the strat vortex already weakened and trying to recover, this is not a bad thing for the continuance of winter. Anyone who suggests that the trop vortex is likely to recover and regain strength are standing on thin ice.

Best wait til it thickens.  Last third of Jan looks very promising. We have already had a synoptic wish list ticked off this winter, but without the expected linked T850’s. Luckily we still have time for that to change with the strat pv heading for another kicking.

Madness with the GFS now counting down on a third warming and this one looks substantial again... 

Very rare occurrence?? 

 

GFS and GFSP