Stratosphere and Polar Vortex Watch 2020

[Don]

1 hour ago, bluearmy said:

 Not useless at all in October if you’re after trop wave affects on the strat ……

Ok, I best take that back then!

[Mike Poole]

4 hours ago, bluearmy said:

 Not useless at all in October if you’re after trop wave affects on the strat ……

I’m of the persuasion (at the moment) that prospects for cold this winter, will be determined mainly by patterns in the troposphere.  For that to be the case, however, the trop must assist in stopping the strat vortex getting going…so you have that, but the trop patterns that inhibit the strat vortex getting going aren’t necessarily the ones that will generate early winter cold here…the balance can be struck (2009 and 2010) but it is difficult and will need watching right into winter.  

[knocker]

The role of North Atlantic–European weather regimes in the surface impact of sudden stratospheric warming events

Abstract

Sudden stratospheric warming (SSW) events can significantly impact tropospheric weather for a period of several weeks, in particular in the North Atlantic–European (NAE) region. While the stratospheric forcing often projects onto the North Atlantic Oscillation (NAO), the tropospheric response to SSW events, if any, is highly variable, and what determines the existence, location, timing, and strength of the downward impact remains an open question. We here explore how the variable tropospheric response to SSW events in the NAE region can be characterized in terms of a refined set of seven weather regimes and if the tropospheric flow in the North Atlantic region around the onset of SSW events is an indicator of the subsequent downward impact. The weather regime analysis reveals the Greenland blocking (GL) and Atlantic trough (AT) regimes as the most frequent large-scale patterns in the weeks following an SSW. While the GL regime is dominated by high pressure over Greenland, AT is dominated by a southeastward-shifted storm track in the North Atlantic. The flow evolution associated with GL and the associated cold conditions over Europe in the weeks following an SSW occur most frequently if a blocking situation over western Europe and the North Sea (European blocking) prevailed around the SSW onset. In contrast, an AT regime associated with mild conditions over Europe is more likely following the SSW event if GL occurs already around SSW onset. For the remaining tropospheric flow regimes during SSW onset we cannot identify a dominant flow evolution. Although it remains unclear what causes these relationships, the results suggest that specific tropospheric states in the days around the onset of the SSW are an indicator of the subsequent tropospheric flow evolution in the aftermath of an SSW, which could provide crucial guidance for subseasonal prediction

https://wcd.copernicus.org/articles/1/373/2020/

[bluearmy]

Whilst the end of the gfs is certainly not the most reliable output , it predicts the vortex to be coupled from top to bottom on the Asian side 

[Don]

4 hours ago, bluearmy said:

Whilst the end of the gfs is certainly not the most reliable output , it predicts the vortex to be coupled from top to bottom on the Asian side 

What would that potentially mean for us moving forward?

[SqueakheartLW]

Looks like the EQBO is progressing nicely ready for the up coming winter when looking at the latest QBO chart

Seems we have 2 WQBO's and the main EQBO. A what looks like will be the next WQBO is still lingering at 10hpa whilst the remains of the old WQBO are still hanging on lower down. Not yet sure whether having the EQBO up at 10 to 40hpa is better for winter prospects than having the EQBO in the 30 to 100hpa region with WQBO from 10 to 30hpa. Maybe something for me to have a look at since the NASA site has a good QBO dataset that goes right back to 1979 featuring QBO speeds at several levels on a monthly basis.

I put all of this into a spreadsheet and then colour coded all of it based on speed of the QBO and the most recent data is below

Shows up the EQBO and WQBO nicely here. The greens, blues and purples are the EQBO whilst the pink, red and brown are the WQBO. Shows here we have had the strongest part of our current EQBO so far in the September 2021 update.

[Mike Poole]

Here’s tonight’s ECM T192 chart:

Looks weird to me for this time of year, any views?

The colours (500 hPa height) more telling than the contours of surface pressure, wonder how stuff up at that level is influencing the strat?  

Bit of a disconnect between the strat and trop vortices by T204 on GFS 0z (same time as ECM chart).

Edited October 3, 2021 by Mike Poole

[Don]

3 hours ago, SqueakheartLW said:

Looks like the EQBO is progressing nicely ready for the up coming winter 

That’s good after the concerns back in the summer that we could be back in a W-QBO again come winter.

[bluearmy]

8 minutes ago, Mike Poole said:

Here’s tonight’s ECM T192 chart:

Looks weird to me for this time of year, any views?

The colours (500 hPa height) more telling than the contours of surface pressure, wonder how stuff up at that level is influencing the strat?  

Bit of a disconnect between the strat and trop vortices right from the word go.  

Not clear what you’re saying Mike - the tpv and spv are both located approx  in the laptev sea area,through the next week. 

[Mike Poole]

34 minutes ago, bluearmy said:

Not clear what you’re saying Mike - the tpv and spv are both located approx  in the laptev sea area,through the next week. 

That’s not how I interpret the Stratobserve plot at T204, (I may be wrong - always!), there looks to be a disconnect by that time.  Edit, clarified earlier post as to time. At 1 hPa the centre is towards Greenland. 

Edited October 3, 2021 by Mike Poole

[bluearmy]

1 hour ago, Mike Poole said:

That’s not how I interpret the Stratobserve plot at T204, (I may be wrong - always!), there looks to be a disconnect by that time.  Edit, clarified earlier post as to time. At 1 hPa the centre is towards Greenland. 

      
 

the tpv at 500hps and the spv at 10hpa are totally coupled (GFS 00z run T204)

looking at the 12z run, I agree that the 1hpa spv is likely more towards e Greenland closer to the pole 

Edited October 3, 2021 by bluearmy

[sebastiaan1973]

Quite an impressive warming. 

[sebastiaan1973]

Zonal winds less than normal for six weeks ahead. https://apps.ecmwf.int/webapps/opencharts/products/extended-zonal-mean-zonal-wind?area=nh&base_time=202110040000

Edited October 4, 2021 by sebastiaan1973

[Uncertainty]

Hot off the press NDJ pressure anomaly from Meteofrance.

 

[northwestsnow]

15 minutes ago, Uncertainy said:

Hot off the press NDJ pressure anomaly from Meteofrance.

 

Like

Really like .. 

Hoping EC is simar ,although I doubt it will be as promising.

 

[bluearmy]

the 00z gfs shows an impressive displacement of the spv end week 2. The Canadian warming pushes the spv to nw Russia coast with the top of the vortex ne of Iceland. 

the ec46 shows the warming has gone by week 6 but perhaps a sign of a renewed effort building in W Russia 

certainly a different start to this strat season high up ….
 

 

Edited October 5, 2021 by bluearmy

[sebastiaan1973]

This was meteo france in september. We see a large improvement. 

[bluearmy]

3 hours ago, sebastiaan1973 said:

This was meteo france in september. We see a large improvement. 

Apples and oranges ?

the updated chart posted today was SLP anoms for NDJ.  That was the previous Z500 anoms for DJF.  I’m not a fan of three monthly means because they likely hide a multitude of things.  However, I agree that the updated chart is an improvement on a coldie level from the chart you post.

 

i see in the winter thread that you’ve broken out the monthly charts and November looks the best for a wintry set up.  Ah well ……. All is not lost though 

Edited October 5, 2021 by bluearmy

[mountain shadow]

2 hours ago, bluearmy said:

.  I’m not a fan of three monthly means because they likely hide a multitude of things.  

Me neither.

They can lead folk up the garden path, thinking that there will be huge Greenland Highs or something. All it could mean, is that rather than average pressure around 990mb it is actually 1000mb, which could still leave us in a Westerly airstream.

[bluearmy]

16 minutes ago, mountain shadow said:

Me neither.

They can lead folk up the garden path, thinking that there will be huge Greenland Highs or something. All it could mean, is that rather than average pressure around 990mb it is actually 1000mb, which could still leave us in a Westerly airstream.

For an average to be higher than normal, it would be very strange if there wasn’t at least one spell where it was significantly higher - but then patterns elsewhere need to play ball at the same time !

[Methuselah]

23 minutes ago, mountain shadow said:

Me neither.

They can lead folk up the garden path, thinking that there will be huge Greenland Highs or something. All it could mean, is that rather than average pressure around 990mb it is actually 1000mb, which could still leave us in a Westerly airstream.

Or some folks want weather type a,b or c with such a passion, they sometimes ascribe too much importance to the wittering of certain so-called 'experienced, knowledgeable' posters and lead themselves (or we lead ourselves?) up the garden path?

I've been here for eighteen years BTW!

[mountain shadow]

2 hours ago, bluearmy said:

For an average to be higher than normal, it would be very strange if there wasn’t at least one spell where it was significantly higher - but then patterns elsewhere need to play ball at the same time !

True, but in my experience,  the only anomalies that count are the black hole ones, that are off the scale.

[bluearmy]

the takeaway from the ec seasonal for NDJ on a NH level is the large Aleutian surface ridge which is likely to dominate.

[Methuselah]

28 minutes ago, bluearmy said:

the takeaway from the ec seasonal for NDJ on a NH level is the large Aleutian surface ridge which is likely to dominate.

I think I'll stick with the Chicken Chow Mein, BA; I can enjoy that before it disappears!

[bluearmy]

Whilst it’s extremely unlikely to pan out quite like this, the 12z gfs op reverses down to approx 75N at the end of the run.  Displacement. Note the neg AO in the trop reflected on this zonal flow chart bottom right 

Edited October 5, 2021 by bluearmy