Autumn & Winter 2023---2024 Stratospheric Polar Vortex. Events, Analysis, Discussions AND Outlooks

[Andy8472]

Yesterdays ECM & EPS going for a reversal "again" 

[Fiona Robertson]

This morning's eye candy. Set on temp at 10hPa, green circle over pole. Checked through the various hPas. Tilt on the right hand side is less than yesty, tilt on LHS has developed.

Edited January 8 by Fiona Robertson

[Andy8472]

very near wind reversal at 10hpa

[lorenzo]

Heatflux advertising the forecast blocking impacts, nudging their way to 10hPa on the evolution plot.

PV type charts show a 'slider-esque' regime / wave guide.

Thereafter a definitive reduction in strength of the Canadian vs European Vortices.

Decent view up through the layers on the GPH plots also.

Out at day 10 vortex under continued duress

 

 

[bluearmy]

1 hour ago, Andy8472 said:

very near wind reversal at 10hpa

It is a tech ssw reversal andy ?   Negative zonal flow recorded and the blue covering 60N 10hpa on the cross section 

and looks same again on this mornings run 

Edited January 8 by bluearmy

[Andy8472]

12 minutes ago, bluearmy said:

It is a tech ssw reversal andy ?   Negative zonal flow recorded and the blue covering 60N 10hpa on the cross section 

and looks same again on this mornings run 

i would say so "a technical reversal of zonal winds is at 10 hPa 60N" also this mornings 0z GFS was similar although a bit later but no reversal on the 6z 

[Andy8472]

Also shows on this mornings stratobserve zonal mean graph, maybe a close call red herring again or yet again "flip a coin" 

Edited January 8 by Andy8472

[bluearmy]

7 minutes ago, Andy8472 said:

Also shows on this mornings stratobserve zonal mean graph, maybe a close call red herring again or yet again "flip a coin" 

I actually think it’s a bit irrelevant if it’s a displacement ssw 

whether it’s 70N or 60N is not as important as the overall profile of the reversal flow through the strat and the size/duration  of the reversal 

Edited January 8 by bluearmy

[Andy8472]

4 minutes ago, bluearmy said:

I actually think it’s a bit irrelevant if it’s a displacement ssw 

whether it’s 70N or 60N is not as important as the overall profile of the reversal flow through the strat and the size/duration  of the reversal 

Yeah true, IF it happens shame it wasn't a hard hitting split SSW but hey "beggars can't be choosers" 

[Fiona Robertson]

This evening's eye candy 

[bluearmy]

A lot of chat about ssw ref the ec46 00z run and the 12z eps 

the 12z gfs has no tech reversal but cross section shows how reversed the upper strat is forecast to be at days 4 and 8 

  

this follows on from an initial upper strat reversal that began early last week and has ebbed and flowed since then. So the new marked  slow down in zonal winds at 60N 10hpa  is sustaining what we’ve already seen higher up and likely taking it down towards 60N before we see the flow generally regain strength thereafter throughout the upper strat above 60N  (that’s the prediction) 

So the tech aspect of the reversal seems to be not particularly relevant to the overall scenario that is ongoing 

 

[Blessed Weather]

An interesting sPV blog written by Dr. Amy Butler and published yesterday, 8th January, on the NOAA/Climate website. Concluding remarks:

"What’s the atmosphere cooking up next? Forecasts suggest that the polar vortex will continue to stay weak for the next 10-14 days, with some forecast systems even showing another chance at a major stratospheric warming event. Meanwhile the vortex has changed from being displaced towards Europe to becoming more elongated across North America and Scandinavia, with the possibility of the polar vortex splitting into two lobes in the lowermost stratosphere- an indication of how unstable the vortex has become."

Full blog:

Cooking up a stratospheric polar vortex disruption | NOAA Climate.gov

WWW.CLIMATE.GOV

---

Recent atmospheric patterns don't match those that typically precede a sudden stratospheric warming event. But forecasts do suggest the polar vortex might get stretched out of shape in coming weeks.

 

[stodge]

Tonight's GFS 12Z shows the vortex under further assault but this time from a European warming in FI.

I would assume that would clear the way for Scandinavian height rises in early February.

The Siberian wave 1 warmings will send the PV back to Canada and lead to a relaxation of the cold probably from the 22nd-25th onwards for maybe ten days before we see new height rises over Scandinavia in early Feb.

Just my thoughts...

[damianslaw]

1 hour ago, stodge said:

Tonight's GFS 12Z shows the vortex under further assault but this time from a European warming in FI.

I would assume that would clear the way for Scandinavian height rises in early February.

The Siberian wave 1 warmings will send the PV back to Canada and lead to a relaxation of the cold probably from the 22nd-25th onwards for maybe ten days before we see new height rises over Scandinavia in early Feb.

Just my thoughts...

A relaxation of the blocked cold high set up but potentially also with a weak southerly tracking jetstream.

Edited January 9 by damianslaw

[bluearmy]

The 00z ec looks to be the first op run in two days not to be tech displacement reversal 

ec 46 hadn’t gone all in on this so expect it to remain weakly positive.  As discussed before - it’s really only of interest to statisticians. 

[Andy8472]

Dr Butler has posted a informative tweet about the current state of the vortex

https://twitter.com/DrAHButler/status/1744842979188330610

[BLAST FROM THE PAST]

 

the first warming was significant but came from such a low baseline whereby the strat was seriously cold….hence maybe why it didn’t get ‘all the way there’ to a split?  However, look at the forecast for a further warming….this could get very interesting 

 

BFTP

[Andy8472]

Not the most dramatic nor long lasting reversal you'll ever see but the Ecm still going for a technical SSW at 192hr!

[Bricriu]

It seems to me the latest GFS run echoes  the comments of Amy Butler about events in the strat. Let's hope it's not a rogue run and we can build on it.

22 minutes ago, Andy8472 said:

Not the most dramatic nor long lasting reversal you'll ever see but the Ecm still going for a technical SSW at 192hr!

Would you be expecting   a quick tropospheric  response from that given the  strat is in a weak  state already?  Also is there any danger it could flip the pattern to a negative  outcome for us. I am thinking not given the UKMO long range, but who knows?

[Andy8472]

8 minutes ago, Bricriu said:

It seems to me the latest GFS run echoes  the comments of Amy Butler about events in the strat. Let's hope it's not a rogue run and we can build on it.

Would you be expecting   a quick tropospheric  response from that given the  strat is in a weak  state already?  Also is there any danger it could flip the pattern to a negative  outcome for us. I am thinking not given the UKMO long range, but who knows?

i think it's already giving a quick response according to Amy on twitter https://twitter.com/DrAHButler/status/1744842979188330610 

Personally i can't see it being a bad thing at all & can't see it flipping the patten the other way but time will tell as always

Edited January 10 by Andy8472

[Mike Poole]

4 hours ago, Andy8472 said:

i think it's already giving a quick response according to Amy on twitter https://twitter.com/DrAHButler/status/1744842979188330610 

Personally i can't see it being a bad thing at all & can't see it flipping the patten the other way but time will tell as always

Not sure it needs any quick response, the effect looks to me to be from the bottom up - the trop vortex is already marmalised.  

[Duane S.]

The excellent Amy Butler putting out quite a few really interesting tweets right now. Essentially emphasising it’s tropospheric led disruption that is doing the damage to the vortex.

“4/) Practically speaking, what matters for surface impacts/predictability is what happens in the lower stratosphere, where the polar vortex will be fully disrupted. So in that sense this event could still have persistent effects on tropospheric weather patterns”

[stodge]

The GFS 12Z OP fully illustrates how battered the vortex could get:

The predominantely Siberian warming ongoing is going to lead to a relaxation of the cold in our part of the world early in the week of the 22nd but the renewed assaults in that week will I hope (and it is only that, nothing is guaranteed) offer some possibilities in early February. The question then becomes what recovery we will see through February - last year the PV recovered strongly from the warmings in January.

[frederiksen90]

Wind reversal at 10hpa in EC OP and EC ensemble mean in both 12Z and 00Z 16.-17. january

Edited January 12 by frederiksen90

[lorenzo]

@Eagle Eye adding your post here too given the work undertaken and quality of content, this thread slightly more slow moving than the main Model Disco.

Also given your keen insight, and mind miles beyond my own - recommend this paper as one of the best on Stratospheric internal vacillation. This is something we have mentioned a lot in historic stratosphere threads but one that the community is still trying to understand.  Given the fact the paper is now 15 years old probably speaks to the complexity of where some dynamics of our old winter foe the Polar Vortex just remain elusive.. Enjoy https://journals.ametsoc.org/view/journals/clim/22/6/2008jcli2365.1.xml

 

Edited January 12 by lorenzo