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

[bluearmy]

12 minutes ago, Bricriu said:

But that's the key with a major ssw like we saw in 2018 there is more likely to be proper downwelling that propagates. Although the irony is that might have been too good as we ended  up with a west based nao in the end, but alot of Irish People didn't  mind as there was a historic Snowstorm out of it. An event  that probably won't be seen again in our lifetime 

Yep

at least with the strong reversal below 60N, you’re more likely to get the swipe of cold far enough south to engulf the whole country.  It’s frustrating to watch it head across to our north into the north Atlantic basin 

[Mattias]

20 hours ago, Mike Poole said:

There’s a question mark in my mind over how this SSW will affect things going forward.  I think there are two things with an SSW.  In an energetic split vortex SSW, where the zonal wind doesn’t just touch 0 at 60N 10hPa but goes substantially negative and remains easterly for some time, that can downwell and affect the trop weather at our latitude over the next couple of months, maybe eked out in discrete stages.  That’s not really on the table with this one, which brings me to the other thing, which is the lack of the strat vortex westerlies driving the trop pattern - it seems to me that’s largely been the case since the Canadian warming, and should continue.

Which means, for me, it is up to the trop to drive the pattern it wants, unfettered from above.  In which case, it is good that rising AAM and a favourable MJO phase might be driving the pattern into February in the direction of a -AO/-NAO, i.e. in a couple of weeks.  But if that does happen, I wonder how much of that will be attributed directly to the effects of the SSW, and whether or not that would be correct…

I actually do believe that the SSW might significantly influence the tropospheric circulation in the near future, but not in the way we usually expect. The rapid recovery of the vortex, the fast transition to NAO+, downward directed EP-flux, eastward phase tilt with height and the predicted vertical wave structure of the zonal wave number 1 component are all ingridients that together indicates that  downward wave reflection from the stratosphere might be involved in the transition to NAO+ in the next couple of days. However, the time scales of downward reflection events are much shorter compared to the usual SSW-effects related to  downward propagation of zonal mean zonal winds. Thus, I agree  that there should be good  possibilities for another regime shift in the end of January or more likely in February, related to MJO and AAM forcings.

 

[Don]

7 hours ago, bluearmy said:

hence my earlier comment about feb possible being a v frustrating month, 

Which would round off a very frustrating winter! 

[Summer Sun]

The SSW may not have taken place

 

[winterof79]

The polar vortex is acting up | NOAA Climate.gov

WWW.CLIMATE.GOV

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The latest forecast says a major disruption of the polar vortex is on its way, but the stratosphere has been acting up for a while. Our...

 

[WinterOf47]

1 hour ago, winterof79 said:

The polar vortex is acting up | NOAA Climate.gov

WWW.CLIMATE.GOV

---

The latest forecast says a major disruption of the polar vortex is on its way, but the stratosphere has been acting up for a while. Our...

 

So they are saying an SSW was due to occur yesterday, but this has not yet been confirmed from what I am reading in other posts. Given the lack of signposting wouldn’t this be an SSSW a super sudden SW! Could be good news for early to mid Feb.

[Fiona Robertson]

This morning's eye candy, temps at 10 hPa

[sebastiaan1973]

19 hours ago, Mattias said:

I actually do believe that the SSW might significantly influence the tropospheric circulation in the near future, but not in the way we usually expect. The rapid recovery of the vortex, the fast transition to NAO+, downward directed EP-flux, eastward phase tilt with height and the predicted vertical wave structure of the zonal wave number 1 component are all ingridients that together indicates that  downward wave reflection from the stratosphere might be involved in the transition to NAO+ in the next couple of days. However, the time scales of downward reflection events are much shorter compared to the usual SSW-effects related to  downward propagation of zonal mean zonal winds. Thus, I agree  that there should be good  possibilities for another regime shift in the end of January or more likely in February, related to MJO and AAM forcings.

 

Intresting. 

This is the article Simon Lee writes about. If we have a reflective type of SSW (Judah Cohen states the same), this leads to a Pacific blocking and westerlies over the N-A

Abstract

Sudden stratospheric warming (SSW) events have received increased attention since their impacts on the troposphere became evident recently. Studies of SSW usually focus on polar stratospheric conditions; however, understanding the global impact of these events requires studying them from a wider perspective. Case studies are used to clarify the characteristics of the stratosphere-troposphere dynamical coupling, and the meridional extent of the phenomena associated with SSW. Results show that differences in the recovery phase can be used to classify SSW events into two types. The first is the absorbing type of SSW, which has a longer timescale as well as a larger meridional extent due to the persistent incoming planetary waves from the troposphere. The absorbing type of SSW is related to the annular mode on the surface through poleward and downward migration of the deceleration region of the polar night jet. The other is the reflecting type. This is characterized by a quick termination of the warming episode due to the reflection of planetary waves in the stratosphere, which leads to an amplification of tropospheric planetary waves inducing strong westerlies over the North Atlantic and blocking over the North Pacific sector. Differences in the tropospheric impact of the absorbing and reflecting SSWs are also confirmed with composite analysis of 22 major SSWs.

Key Points

New classification of sudden stratospheric warming during the recovery phase

Absorbing type warming events induce Arctic Oscillation on the surface

Reflecting-type warming events produce a Pacific blocking

[bluearmy]

3 hours ago, WinterOf47 said:

So they are saying an SSW was due to occur yesterday, but this has not yet been confirmed from what I am reading in other posts. Given the lack of signposting wouldn’t this be an SSSW a super sudden SW! Could be good news for early to mid Feb.

Its all semantics 

the ssw is weak and brief. if it isn’t at 60N then it’s at 61N. If it isn’t at 10hpa then it’s at 9hpa. There’s no practical difference. 

the warmings of the past three weeks have been notable and left their signature through the strat at high latitudes 

the recent gfs ops have caught my eye as they are showing some stretching of the spv later week 2. The 06z gfs op also began to show a bottom up split that we’ve just seen play out.  more uncertainty then if the trop is to continue to lead the dance. 

[Summer Sun]

 

[Bricriu]

1 hour ago, Summer Sun said:

 

I presume there will be a lag time with this. If not we can forget about an Easterly 

Edited January 18 by Bricriu

[Don]

2 hours ago, Bricriu said:

I presume there will be a lag time with this. If not we can forget about an Easterly 

It would also depend on if the stratosphere and troposphere couple up?

[Jo Farrow]

Nick's update from yesterday 

A Sudden Stratospheric Warming took place this week, but will it impact our weather?

WWW.NETWEATHER.TV

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A Sudden Stratospheric Warming (SSW) took place on Wednesday, with a reversal of zonal winds at 10 hPa 60N, but it was a brief reversal and zonal winds look to return in the polar stratosphere, marking its recovery. So...

 

[lorenzo]

Ridge solution

This view vs nwp - take a different look... February aint in GH anymore, just got some 5 day regime T.rash to wander through..

Edited January 20 by lorenzo

[Metwatch]

Any impacts of the brief and marginal SSW quickly fading away...

Edited January 20 by Metwatch

[summer blizzard]

As we are a week on, do we have another stratospheric update.

[stodge]

All I can offer is the 12Z GFS OP seems to be building another strong warming, first from Europe then migrating to Siberia.

I don't like these unless they can knock the PV far enough over to central and western Canada to enable heights to build over Scandinavia - one or two little hints at that in the middle of next month.

[bluearmy]

Ec46 moving towards another reversal ???

[SqueakheartLW]

Just when it looked like the stratosphere front had gone back to normal zonality and boring again suddenly warmings start to appear at the end of both GFS and GEM models. The warmest ones are below and every single member that goes out to +384h has some degree of warming at the end

GFS

GEM

Can we get these down to T+0 and will it finally remove the vortex for us and with a very quick response can we just about squeeze out another BFTE 2018 repeat?

[bluearmy]

Could be that we are looking at a tech reversal around 18/20th feb via a stretch and split 

 

[SqueakheartLW]

GFS 12z has a reversal showing up at 10hpa

The reversal is even stronger at 1hpa

Edited January 31 by SqueakheartLW

[bluearmy]

Gfs 06z and 12z have shown tech reversals via displacements 

ec46 doesn’t really look like it’s got enough momentum to go full blown tech ssw reversal based on that past few runs. You’d expect more members to be going negative imo 

[stodge]

Once again the vortex at 10 HPA this evening looks like a boxer up against the ropes but by T+384 it's got a new opponent raining in punches with a European warming building strongly.

By then, on the 500 HPA chart, the core of the vortex is at the Bering Strait which does nothing to hinder Greenland height rises.

 

[Bricriu]

A cold March,  perhaps? Let's hope we don't get a repeat of what happened in January anyway.

Edited February 4 by Bricriu

[robert]

 

Just a snowy video from here in the outer hebrides on my croft. Stay safe and warm everyone