Stratosphere and Polar Vortex Watch

[Summer Sun]

 

Edited December 30, 2018 by Summer Sun

[sebastiaan1973]

https://www.researchgate.net/publication/329300936_Enhanced_StratosphereTroposphere_Coupling_During_Extreme_Warm_Stratospheric_Events_with_Strong_Polar-Night_Jet_Oscillation

Latest of Karpechko.

Seems to me that this SSW will be a non-PJO. So not enough downwelling. Please see the chart with 1-15 days after CD.

Can anyone -in good English- write him a mail, to ask him what his opinion is about the SSW and the downwelling?

[Interitus]

The vortex ends up splitting but at time of reversal it is a displacement, it's not unusual for this to happen. There is some significance in the distinction because displacement would normally be seen to imply wave 1 forcing, as in this case, with a split being wave 2. Wave 1 tilts more westward with height which may be why any coupling from the 10mb split to our west looks like sending a northerly plunge to our east, compared to a wave 2 split which would have a more direct imprint on the surface.

[sebastiaan1973]

Interitus is there any relationship between the time of the reversal at 10 hPa and downwelling.

So, if the reversal of the winds at the level is longer, than there is more chance for downwelling?

[lorenzo]

Couple of GIFS grabbed from NASA site - more for posterity than anything else..( future re-visits to the thread etc). 

[northwestsnow]

28 minutes ago, sebastiaan1973 said:

Interitus is there any relationship between the time of the reversal at 10 hPa and downwelling.

So, if the reversal of the winds at the level is longer, than there is more chance for downwelling?

You seem very despodent about this SSW Sebastian, much like artur3..

[Catacol]

23 minutes ago, northwestsnow said:

You seem very despodent about this SSW Sebastian, much like artur3..

If it fails to downwell below 50hpa then we will all be despondent. Impact on trop will be negligible and pacific only factors may give us a bit of cold in mid January but nothing spectacular. A long way to go yet, but models seem to be moving towards less impact than hoped. Is this a wQBO effect? Sebastiaan's post several days ago would suggest this is the historical suggestion. Only 2 out of 13 split vortex events in wQBO years have downwelled to the trop.

Edited December 30, 2018 by Catacol

[Summer Sun]

 

[northwestsnow]

Just now, Catacol said:

If it fails to downwell below 50hpa then we will all be despondent. Impact on trop will be negligible and pacific only factors may give us a bit of cold in mid January but nothing spectacular. A long way to go yet, but models seem to be moving towards less impact than hoped. Is this a wQBO effect? Sebastiaan's post several days ago would suggest this is the historical suggestion. Only 2 out of 13 split vortex events in wQBO years have downwelled to the trop.

oh dear..

Guess we will have to wait and see catacol, , did you base your optimistic posts over the recent weeks on this downwelling? 

[northwestsnow]

3 minutes ago, Catacol said:

If it fails to downwell below 50hpa then we will all be despondent. Impact on trop will be negligible and pacific only factors may give us a bit of cold in mid January but nothing spectacular. A long way to go yet, but models seem to be moving towards less impact than hoped. Is this a wQBO effect? Sebastiaan's post several days ago would suggest this is the historical suggestion. Only 2 out of 13 split vortex events in wQBO years have downwelled to the trop.

Well i never knew that!!

6/1 odds of it downwelling then, changes everything really.

[Catacol]

6 minutes ago, northwestsnow said:

oh dear..

Guess we will have to wait and see catacol, , did you base your optimistic posts over the recent weeks on this downwelling? 

I had seen an impact - yes. Perhaps a little slow to appreciate the fact that many split events in wQBO years tend to remain aloft....and Sebastiaan's really useful data from several days ago has given me pause for thought. However 2 more optimistic things to end on - we are still going to see an impact from pacific activity so a change of pattern is coming. Also - what is to stop this from being the 3rd example in 12 of a split in a wQBO year that DOES downwell? Jury out on that. This split looks bigger than most, and if it stays in place for long enough then perhaps it increases the chances of successful downwelling. Sebastiaan has asked this of Inheritus this morning already - 1979 and 2013 downwelled. I wonder how long winds reversed in those 2 cases? I don't have that data.

Edited December 30, 2018 by Catacol

[northwestsnow]

Just now, Catacol said:

I had seen an impact - yes. Perhaps a little slow to appreciate the fact that many split events in wQBO years tend to remain aloft....and Sebastiaan's really useful data from several days ago has given me pause for thought. However 2 more optimistic things to end on - we are still going to see an impact from pacific activity so a change of pattern is coming. Also - what is to stop this from being the 3rd example in 12 of a split in a wQBO year that DOES downwell? Jury out on that. This split looks bigger than most, and if it stays in place for long enough then perhaps it increases the chances of successful downwelling. Sebastiaan has asked this of inheritus this morning already - 1979 and 2013 downwelled. I wonder how long winds reversed in those 2 cases? I don't have that data.

Thanks Catacol.

Guess it really is wait and see, Exeter remain on board for the cold mid month ..

[Catacol]

7 minutes ago, northwestsnow said:

Thanks Catacol.

Guess it really is wait and see, Exeter remain on board for the cold mid month ..

Absolutely. Most of the more prominent voices have been quiet in recent days - and for good reason. Noone can make a cast iron forecast on what may come in mid to late Jan and on into Feb until we see how this very significant warming impacts on the strat, and to what extent it couples with the trop via downwelling. I posted a few days ago we need to hold our breath - and it may be a fairly long hold.....

But - high risk and potentially high gain. If the split does manage to downwell then a significant wintry spell of some decent duration looks likely. If it doesn't then we get more of a coldish snap and far less good prospects heading into February as the timing then would be wrong in terms of the declining pacific wave. Our next pacific led hope with possible positioning of trop blocks for impact on the vortex would be roughly the same time as the Beast of Feb/March 2018 - but this time with the wQBO well established. Not so good. Prospects for a really significant cold spell I think really do sit with this ongoing warming that is happening as I type, and the extent to which it impacts. Fail - and winter 2018/19 will not go down in the history books - and historic events I think is what many of us are looking for in winter.

Winter 2019/20.....likely eQBO and definite solar minimum...…..

Edited December 30, 2018 by Catacol

[phil nw.]

Yes i, like many, have been monitoring the Berlin site almost daily and last week i started to get concerns on the possible effectiveness of this SSW on the trop.

We started to see the warming itself being put back  and now recent outputs have suggested reversals at lower levels are in doubt.

A look at the latest zw charts comparing days 5/10.They show at 60N the downwelling seems to hold at around 20hPa 

we can see by day 10 at 50 hPa we have some displacements into 3 daughter segments 

which essentially reflects the ens means at 500 hPa.The concern is will this damn ridge ever move and the pattern regress enough to get the northerly.

Having said that and if we fail to see a notable cold outbreak in the UK i still find following these events fascinating and the fact that now the weather community is building more knowledge with each event. 

Edited December 30, 2018 by phil nw.

[Bullseye]

35 minutes ago, northwestsnow said:

Well i never knew that!!

6/1 odds of it downwelling then, changes everything really.

I would suggest checking out @Bring Back1962-63 post over on 33andrain which is quite brilliant imo; who is still quite bullish on downwelling effects. He also adds why each event is quite unique, as some studies on SSW events can maybe not factor in other background signals. I do agree with yourself that this is interesting upcoming period as we have many knowledgeable people on this subject throwing in their views - some differ to others! 

[ArHu3]

28 minutes ago, Catacol said:

Winter 2019/20.....likely eQBO and definite solar minimum...…..

wqbo usually lasts longer than a year, like 14-15 months, right. So next winter still wqo and maybe 2020-21 will see eQBO, if I'm calculating this correctly 

[Badgers01]

fascinating reading as ever - 6/1 odds of downwelling are a sobering fact that maybe should be made more available!!!

[Singularity]

In order to construct useful probabilities, we need to know how size and duration of reversal factor in when looking at wQBO winters, along with how descending wQBO i.e. westerly shear winters compare with the rest.

Using wQBO or eQBO as the only factor is insufficient.

 

Next winter is most likely going to be more or less opposite to this one - easterly shear (descending easterly QBO) but with the shear level higher up than this winter is seeing.

[lassie23]

I think this SSW will be a damp squib

[matty40s]

12 minutes ago, lassie23 said:

I think this SSW will be a damp squib

...your reasoning, what backs that up, go on, enlighten us...

Currently showing a rise of over 60 deg c from its normal average temp is no damp squib, it's almost BbQ time at the North Pole uppers. 

[lassie23]

Just now, matty40s said:

...your reasoning, what backs that up, go on, enlighten us...

Currently showing a rise of over 60 deg c from its normal average temp is no damp squib, it's almost BbQ time at the North Pole uppers. 

i meant for cold in the UK, see iapenells posts

[ArHu3]

19 minutes ago, lassie23 said:

I think this SSW will be a damp squib

Contrary to what @northwestsnowthinks I still think that what the models are showing is not necessarily what we'll end up having, not from any particular knowledge but the last 3 weeks I have seen the Strat forecast going all places in the models, including the EC 

I think with this split we'll have the best chance of anything decent since 2013

Edited December 30, 2018 by ArHu3

[northwestsnow]

7 minutes ago, ArHu3 said:

Contrary to what @northwestsnowthinks I still think that what the models are showing is not necessarily what we'll end up having, not from any particular knowledge but the last 3 weeks I have seen the Strat forecast going all places in the models, including the EC 

I think with this split we'll have the best chance of anything decent since 2013

No problem Artur, i got the impression you were feeling a bit despondent- guess we will see how things unfold in the coming few weeks, i suspect your location will be very cold next week ..

 

Edited December 30, 2018 by northwestsnow

[Weather-history]

16 minutes ago, lassie23 said:

i meant for cold in the UK, see iapenells posts

iapenell didn't expect much of an early summer 2018 neither, nobody is full proof. We can only respect opinions and then judge after the event. 

Edited December 30, 2018 by Weather-history

[Chesil View]

At the moment when it comes to the strat and the effects of the current SSW ,writing off any wintry effects on the UK is incredibly premature.  One could make equally strong argument for saying that due to its timing it will induce another winter like 1947. But that would be premature as well. Only time will tell. The weather will do what it does.