Stratosphere and Polar Vortex Watch 2020

[Catacol]

wrong thread....

 

Edited November 1, 2021 by Catacol

[mb018538]

Latest CFS run:



GFS is along the same lines initially, but doesn't weaken as much as the ECM into December:



Best hope the ECM is on to something!

[Premiere Neige]

2 hours ago, mb018538 said:

Latest CFS run:



GFS is along the same lines initially, but doesn't weaken as much as the ECM into December:



Best hope the ECM is on to something!

Is there a particular model that verifies best in terms of forecasting zonal winds?

[SqueakheartLW]

Is that another zonal wind weakening I see there in FI

Looks like GFS is starting to come on board with the ECM in weakening things as we head towards December.

I know it's only one run but it's a start.

[bluearmy]

5 hours ago, SqueakheartLW said:

Is that another zonal wind weakening I see there in FI

Looks like GFS is starting to come on board with the ECM in weakening things as we head towards December.

I know it's only one run but it's a start.

Gfs run only goes to mid month …… quite a distance from December !

And no weakening evident on the 12z run ….. need to see much more consistency 

[Mike Poole]

Latest on GFS from Stratobserve:

I think the coldies on here need to make their minds up now.  Which way to go, there is a chance from the op models now of a cold spell trop led after mid month.  30% chance maybe.  2010 scenario the jackpot there, and it isn’t unreasonable.  But the same trop synoptics won’t necessarily be the ones you’d want if you were just after a SSW, it diverges a bit now.  I’m buying the front loaded winter without help from the strat, and selling the early SSW.  What do others think?

[bluearmy]

2 hours ago, Mike Poole said:

Latest on GFS from Stratobserve:

I think the coldies on here need to make their minds up now.  Which way to go, there is a chance from the op models now of a cold spell trop led after mid month.  30% chance maybe.  2010 scenario the jackpot there, and it isn’t unreasonable.  But the same trop synoptics won’t necessarily be the ones you’d want if you were just after a SSW, it diverges a bit now.  I’m buying the front loaded winter without help from the strat, and selling the early SSW.  What do others think?

Too early to go on the question. I’m edging towards the spv weakening by December on the back of a further scrussian/sceuro upper ridge and Aleutian trough in the trop which could end up displacing the spv back towards Eurasia as we have seen over the past few weeks. 

[Catacol]

2 hours ago, Mike Poole said:

Latest on GFS from Stratobserve:

I think the coldies on here need to make their minds up now.  Which way to go, there is a chance from the op models now of a cold spell trop led after mid month.  30% chance maybe.  2010 scenario the jackpot there, and it isn’t unreasonable.  But the same trop synoptics won’t necessarily be the ones you’d want if you were just after a SSW, it diverges a bit now.  I’m buying the front loaded winter without help from the strat, and selling the early SSW.  What do others think?

I think we will get a SSW, early/mid January. Cold start to December to relax in the second half of the month. Dry first half, wetter second half of the month. How any SSW develops will determine the mid to late sections of winter, and way too early therefore to call the season overall. However broadly speaking ENSO and QBO are favourable for something significant in the strat, and we are on that upwards curve out of solar minimum. Certainly plenty of interest. If the season ends up being reviewed as a front loaded one I’ll be disappointed given this context. 

[Blessed Weather]

8 hours ago, Catacol said:

I think we will get a SSW, early/mid January. Cold start to December to relax in the second half of the month. Dry first half, wetter second half of the month. How any SSW develops will determine the mid to late sections of winter, and way too early therefore to call the season overall. However broadly speaking ENSO and QBO are favourable for something significant in the strat, and we are on that upwards curve out of solar minimum. Certainly plenty of interest. If the season ends up being reviewed as a front loaded one I’ll be disappointed given this context. 

May I wholeheartedly support your post! I too am optimistic about a SSW during January. If I may beg to differ from Dr. Amy Butler, I'm not overly concerned about her statement (in my earlier post) that the eQBO has yet to descend to 50hPa. There's research out there that suggests the 20hPa - 30hPa level is more important for early winter impact and 50hPa more for later winter impact.

Looking at the difference that the elusive combination of eQBO and La Nina make for winter prospects of a SSW, this from the 2014 research paper "Changes in Frequency of Major Stratospheric Sudden Warmings with El Niño/Southern Oscillation and Quasi-Biennial Oscillation" by Masakazu Taguchi. Headline finding and chart:

A characteristic feature is the high MSSW probability for the La Niña and QBO easterly winters, which is consistent with strengthened stationary wave
with zonal wave-number 1 compared to the climatology.

So I would argue that we have that elusive combo in place. The eQBO at 30hPa has been strengthening over the last 6 months:

Source: https://acd-ext.gsfc.nasa.gov/Data_services/met/qbo/QBO_Singapore_Uvals_GSFC.txt

And NOAA confirm that La Nina conditions are present both at an oceanic and atmospheric level, with the latest multi-model forecasts showing the majority of members expect conditions to continue through winter 2021/22. NOAA say an 87% probability.

Source: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/

So whilst nothing guaranteed, there are solid reasons to be optimistic.

Edited November 3, 2021 by Blessed Weather
typo

[Mike Poole]

Stratobserve ensembles’ zonal winds for today’s update: 

While an increase up to about the 12th Nov, thereafter flat if not declining…still not seeing any SSW in the foreseeable, and would still like to see the current trop pattern play out, but if it is still declining around the turn of the month, that could lead to interesting times into winter, either the lack of an intense strat vortex for the trop vortex to couple with in December, or a potential SSW a little later, which I think we would need to rescue the second half of winter from Atlantic dross (here in the UK, anyway).  

Edited November 4, 2021 by Mike Poole

[Griff]

Pretty average that, innit! 

[bluearmy]

2 hours ago, Griff said:

Pretty average that, innit! 

No indication of a roaring spv in first half of December but no real sign of a v weak spv either. I suppose you could say that this could leave the trop to rule the roost if it proves to be correct  ……. 

[mb018538]

No real changes in the latest data - Vortex at 10hpa trundling along a fair way above the average, but no vortex-zilla at this stage.



No connect yet down to the lower levels, so we're ok on that front. A blocked NH pattern testament to this.

[Griff]

Roll up, roll up... Well up a bit then down a bit, but is there a strat trop disconnect...  

[Blessed Weather]

Now at T312 this post should be viewed as just for fun at at the moment, but that is quite some Atlantic block setting up on the tonight's GFS 12z around the 21st November. GFS suggesting the Atlantic could stay blocked from the 19th right through to the end of the run on 24th Nov. And research shows a persistent Atlantic block can generate the required planetary Wave No. 1 to potentially cause a displacement of the SPV. More info in the research paper Blocking precursors to stratospheric sudden warming events.

"In this paper, we report that 25 of the 27 events objectively identified in the ERA-40 dataset for the period 1957–2001 are preceded by blocking patterns in the troposphere."

So is tonight's GFS a tease or onto something? Charts for 21st Nov show a sharp up-tick in Wave 1 activity coinciding with the block:

Charts: Meteociel and Weatheriscool

 

 

 

Edited November 8, 2021 by Blessed Weather
tidied up layout and added links

[frederiksen90]

It does not resemble the stronger vortex coupling with the troposphere. There is plenty of blockage in the next 6 weeks in EC46. And this may contribute to a further weakening of the vortex and perhaps SSW during December or January. Maybe eastern QBO along with the sun helps to maintain high pressure block and periodic cold into December?

[damianslaw]

13 minutes ago, frederiksen90 said:

It does not resemble the stronger vortex coupling with the troposphere. There is plenty of blockage in the next 6 weeks in EC46. And this may contribute to a further weakening of the vortex and perhaps SSW during December or January. Maybe eastern QBO along with the sun helps to maintain high pressure block and periodic cold into December?

Years when the PV didn't gain much of a footing on the UK were 1996, 2010, both years brought alot of blocked conditions. 2021 really has seen a very quiet atlantic, barely anything to it all year - its been notable by its absence. No energy in it whatsoever. No storms again this autumn it seems.. last winter was very quiet atlantic wise. 

Edited November 8, 2021 by damianslaw

[frederiksen90]

And when you then see such a 500 hpa anomaly from GFS-ENS for the last third of November, then it really starts to look interesting. Blockage is perfectly located across the Atlantic with troughs over Northern and Central Europe:

 

https://wxcharts.com/charts/gefs/polar/charts/gph500_anom_20211108_12_336.jpg?fbclid=IwAR2-Z7jQvl3LUhOYn9O8JzNZQjE7Vm3maaOb54H7PpI1I1Eupe9FfRsKoVU

[northwestsnow]

9 minutes ago, frederiksen90 said:

And when you then see such a 500 hpa anomaly from GFS-ENS for the last third of November, then it really starts to look interesting. Blockage is perfectly located across the Atlantic with troughs over Northern and Central Europe:

 

https://wxcharts.com/charts/gefs/polar/charts/gph500_anom_20211108_12_336.jpg?fbclid=IwAR2-Z7jQvl3LUhOYn9O8JzNZQjE7Vm3maaOb54H7PpI1I1Eupe9FfRsKoVU

Looks a really cold pattern for much of Europe - Baltic might freeze .

 

[Catacol]

59 minutes ago, Blessed Weather said:

Now at T312 this post should be viewed as just for fun at at the moment, but that is quite some Atlantic block setting up on the tonight's GFS 12z around the 21st November. GFS suggesting the Atlantic could stay blocked from the 19th right through to the end of the run on 24th Nov. And research shows a persistent Atlantic block can generate the required planetary Wave No. 1 to potentially cause a displacement of the SPV. More info in the research paper Blocking precursors to stratospheric sudden warming events.

"In this paper, we report that 25 of the 27 events objectively identified in the ERA-40 dataset for the period 1957–2001 are preceded by blocking patterns in the troposphere."

So is tonight's GFS a tease or onto something? Charts for 21st Nov show a sharp up-tick in Wave 1 activity coinciding with the block:

Charts: Meteociel and Weatheriscool

 

 

 

Certainly a strong possibility. I reckon the signal will prove to be hasty, and the ridge will end up pushed back a bit in the calendar - maybe 4 or 5 days later? -  but it aligns with the likely MJO blocking phases as well as the seasonal Nina signal. The beginning of what we hope will be a trop led assault on the vortex.... this the first attack, followed by a waning of the ridge, and then a renewed surge around New Year. Let the fun begin! It would certainly be a good start to the season if that ridge can embed far enough north in the area around Greenland to give us a stiff northerly.

[Catacol]

Do we have any ozone grogs on here who can interpret this much better than me? MIA over on the snow and ice thread has produced an ozone chart showing high concentrations currently over the NH. Most recent image is here

My question is - how uncommon is it to see concentrations like this, towards the top end of the scale, at this stage in autumn? I work a lot through observation but must admit that following ozone trends has not really been an area of focus. The link between ozone and warming in the stratosphere I understand - the mechanisms of the Brewer-Dobson circulation and what constitutes a "normal" season is not an area of any expertise.

Any thoughts? Is this image unusual? 

[chionomaniac]

2 hours ago, Catacol said:

Do we have any ozone grogs on here who can interpret this much better than me? MIA over on the snow and ice thread has produced an ozone chart showing high concentrations currently over the NH. Most recent image is here

My question is - how uncommon is it to see concentrations like this, towards the top end of the scale, at this stage in autumn? I work a lot through observation but must admit that following ozone trends has not really been an area of focus. The link between ozone and warming in the stratosphere I understand - the mechanisms of the Brewer-Dobson circulation and what constitutes a "normal" season is not an area of any expertise.

Any thoughts? Is this image unusual? 

HI C -

I don't know how long you have  got but historical ozone records can be found here https://www.cpc.ncep.noaa.gov/products/stratosphere/omps/archive/nh/

[chionomaniac]

or here https://www.cpc.ncep.noaa.gov/products/stratosphere/sbuv2to/archive/nh/

[knocker]

or here

https://ozonewatch.gsfc.nasa.gov/monthly/NH.html

[Faronstream]

2 hours ago, Catacol said:

Do we have any ozone grogs on here who can interpret this much better than me? MIA over on the snow and ice thread has produced an ozone chart showing high concentrations currently over the NH. Most recent image is here

My question is - how uncommon is it to see concentrations like this, towards the top end of the scale, at this stage in autumn? I work a lot through observation but must admit that following ozone trends has not really been an area of focus. The link between ozone and warming in the stratosphere I understand - the mechanisms of the Brewer-Dobson circulation and what constitutes a "normal" season is not an area of any expertise.

Any thoughts? Is this image unusual? 

Ozone depletion is linked to a stronger polar vortex and therefore a higher possibilty of mild  winter weather in C/N europe, while normal or high amounts of ozone is linked to a weak polar vortex with the opposite effects.