Stratosphere and Polar Vortex Watch 2020

[summer blizzard]

8 minutes ago, daz_4 said:

Well, compared to 81-10, January was 0,9C above average and February 1,5 below average so it wasn't bad but also pretty unremarkable snow wise if I remember correctly. All the fun happened in December.

That’s interesting. January is remembered poorly here because of the contrast but actually it stayed cool here while Feb was warm.

Edited August 7, 2021 by summer blizzard

[daz_4]

22 minutes ago, summer blizzard said:

That’s interesting. January is remembered poorly here because of the contrast but actually it stayed cool here while Feb was warm.

Yep, the cold air got stuck over Scandinavia and CE in February.

 

[Dunstable Snow]

On 06/08/2021 at 11:33, Catacol said:

Haha it’s August and we are already talking winter

For the U.K., away from continental cold, I tend to feel that 2010 has skewed perceptions. Cold in December here is all too often a slushy, marginal affair. The ground is too warm, the oceans are too warm, and the near continent is usually still cooling down. In 2010 we got a direct northerly hit from a vortex shard that I think (without checking) was unique in the modern record and since then front loaded winters have become a wishbone. Not for me. Winter needs colder air sources than December usually supplies us, and the extra week or 3 of continental cooling is key regardless of solar factors. So…any signal pointing to a +NAO in the second half of winter is a kick in the privates.

But there is soooooooo much time to come yet and early seasonal predictions now are about as much use as a chocolate teapot. Once we get to September the chase can begin in a little more earnest.

Totally agree with this. 2009-10 was much better. Started a week before Christmas and went through the rest winter on and off with the run up to Christmas and early January very snowy- would much rather have that than a front loaded waste of time winter. 

[philglossop]

Sorry apologies for last post was in work in a hurry - yup weak La Niña is the current form card for ENSO this winter. 
 

I think this talk of front loaded - whilst very early doors- may well be correct. More data needed in coming months mind

[damianslaw]

6 hours ago, philglossop said:

Sorry apologies for last post was in work in a hurry - yup weak La Niña is the current form card for ENSO this winter. 
 

I think this talk of front loaded - whilst very early doors- may well be correct. More data needed in coming months mind

Was last winter not a weak la nina as well... 

[Cheshire Freeze]

GLOSEA run out for August- doesn't tell us that much at this point, apart from the fact it's seeing a strong signal for HP to centre to our west. A myriad of synoptic set ups are covered by the averaged anomaly...ranging from murky muck pulling in from round the top of the HP to polar NW'lys

Feels like we've been staring at this same anomaly for months now

Edited August 11, 2021 by CreweCold

[Catacol]

The GLOSEA probability maps haven't been great watching in July or August though. The signal for above average heights over SE Europe is also strong, and that isn't good news. The outer quintile probability for SE Europe being significantly above average pressure is 40-55% currently. 

Plenty of time for these to adjust - and always worth remembering that a cold spell of a week or so can be entirely lost in these averages, but I must admit very year I harbour that faint hope of consistent low pressure over SE Europe and high pressure to our north. We can always dream....even in a CC world where the cold weather bullseye on the weather dartboard is getting smaller and smaller and harder to hit.

Remember this ensemble mean? Battleground Britain. Those were the days back in the 2009-13 period when things almost felt like the 80s could return.

Ah well......

Edited August 11, 2021 by Catacol

[Cheshire Freeze]

On 11/08/2021 at 21:54, Catacol said:

The GLOSEA probability maps haven't been great watching in July or August though. The signal for above average heights over SE Europe is also strong, and that isn't good news. The outer quintile probability for SE Europe being significantly above average pressure is 40-55% currently. 

Plenty of time for these to adjust - and always worth remembering that a cold spell of a week or so can be entirely lost in these averages, but I must admit very year I harbour that faint hope of consistent low pressure over SE Europe and high pressure to our north. We can always dream....even in a CC world where the cold weather bullseye on the weather dartboard is getting smaller and smaller and harder to hit.

Remember this ensemble mean? Battleground Britain. Those were the days back in the 2009-13 period when things almost felt like the 80s could return.

Ah well......

Agree with what you say but there looks to be potential for a trough to drop through the UK at times (a bit like this summer) Doubtful how much cold air there would be to tap into though on the N flank, given those high heights across Europe.

[SqueakheartLW]

Just thought it would be time to do a stratospheric update before silly season begins when the northern vortex comes back to life once more ready for the usual things

• How strong will the vortex be this season?
• Will it be a weak one or another dreaded vortex of doom?
• Will we get a SSW and how big will it be?
• What will the QBO be doing this winter?

Talking of the polar vortex it seems both the GFS and ECM have the rebirth dates roughly nailed on now and it seems we are headed for an early start to the polar vortex this season

GFS appears to be going for 26/08/2021 on this particular run but it is varying with each run but in general some point in the early to mid 20 something in August appears to be favoured for this year

ECM is going for 23/08/2021 or maybe 24/08/2021 here so even earlier than GFS with the dizzy heights of 10m/s by late September and above average speeds at all times predicted

How is our southern friend doing right now then?

It would seem after running below average for quite some time the southern vortex is now going to switch to above average at the same time as the northern vortex starts early and gets off to a flying start too. So much to the EQBO slowing down the zonal flow.

Talking of the QBO this is the latest QBO chart from the NASA Singapore website

Well and truly into EQBO territory now but the main question here is will we still be EQBO this coming winter and how strong is it going to be.

That troublesome area around 10hpa is still there and the one thing that could spoil things for winter and it can be clearly seen on the ECM zonal wind charts too

Latest

10 days time

Still showing up even 10 days away, just lurking there ready to descend and ruin a positive factor for the winter if you want a colder one.

[northwestsnow]

On 11/08/2021 at 17:32, CreweCold said:

GLOSEA run out for August- doesn't tell us that much at this point, apart from the fact it's seeing a strong signal for HP to centre to our west. A myriad of synoptic set ups are covered by the averaged anomaly...ranging from murky muck pulling in from round the top of the HP to polar NW'lys

Feels like we've been staring at this same anomaly for months now

That's a dreadfully  poor chart for winter lovers .

Nothing positive about that, NAO aside !

[Catacol]

Interesting ensemble forecasts here grabbed off Twitter. Weak vortex. Another ScEuro/Aleutian Low combo through Nov/Dec in a La Nina season once again?

Edited August 13, 2021 by Catacol

[Cheshire Freeze]

On 13/08/2021 at 06:09, northwestsnow said:

That's a dreadfully  poor chart for winter lovers .

Nothing positive about that, NAO aside !

It's not great, but it's not as bad as you make out either. The core of higher heights is to our west meaning we see northwesterly incursions at times...as can be seen in the uppers anomaly

Europe is warm but the UK is average. Poor for S UK but NW areas with elevation would be ok at times.

 

[Catacol]

Quick off the blocks perhaps... 

[blizzard81]

16 hours ago, CreweCold said:

It's not great, but it's not as bad as you make out either. The core of higher heights is to our west meaning we see northwesterly incursions at times...as can be seen in the uppers anomaly

Europe is warm but the UK is average. Poor for S UK but NW areas with elevation would be ok at times.

 

Not too bad at all. I particularly like the projected warmth over the north eastern seaboard of the US. That won't do our cold winter prospects any harm at all . 

[northwestsnow]

2 hours ago, blizzard81 said:

Not too bad at all. I particularly like the projected warmth over the north eastern seaboard of the US. That won't do our cold winter prospects any harm at all . 

Well I'm far from satisfied!

I fully expect September's update to replace the faulty +NAO cutrently on offer.

Hopefully a seasonal December ,I have little interest in North Westerlies anymore, been let down far too many times.Of  course this is just my locality ,nit 200m no longer cuts it for the majority of NW winds ,too much sea moderation nowadays.

The QBO is still unclear ,to me anyway.

An Easterly coupled with a weak Nina would surely lend weight to a weaker vortex...

If we see the eQBO and Niba doesn't get too strong I'm hopeful the next update will be better.

[Cheshire Freeze]

On 14/08/2021 at 21:59, northwestsnow said:

Well I'm far from satisfied!

I fully expect September's update to replace the faulty +NAO cutrently on offer.

Hopefully a seasonal December ,I have little interest in North Westerlies anymore, been let down far too many times.Of  course this is just my locality ,nit 200m no longer cuts it for the majority of NW winds ,too much sea moderation nowadays.

The QBO is still unclear ,to me anyway.

An Easterly coupled with a weak Nina would surely lend weight to a weaker vortex...

If we see the eQBO and Niba doesn't get too strong I'm hopeful the next update will be better.

On the flip side, the averaged CFS anomalies on the NOAA site just got real interesting...

Edited August 15, 2021 by CreweCold

[knocker]

 

[Dorsetbred]

2 hours ago, knocker said:

 

Hmm, interesting, but given the recent form of the surges from the Polar vortex, I fell less inclined to consider a game changer, even whn the forecast suggests it's strength..

[northwestsnow]

Is there a link between Global warming and SSW's in winter ?

Only if you subscribe to GW I  guess, but they seem to be more common nowadays SSW's in winter...

[jules216]

I posted my analogs on twitter for next few months - 1989,1995,1998,2005 and 2020. Criteria used -IOD,-QBO, -PDO, La Nina and solar flux below 90. A good bet is tropical forcing to be in around phases 4-7 with ideal timing to be at the start of November for seasonal wavelenghts timing with -NAO correlation. -IOD will be around -0.8 which is lowest since 2016 autumn, that also correlated with waek early season vortex.

 

 

[mb018538]

On 16/08/2021 at 09:28, jules216 said:

I posted my analogs on twitter for next few months - 1989,1995,1998,2005 and 2020. Criteria used -IOD,-QBO, -PDO, La Nina and solar flux below 90. A good bet is tropical forcing to be in around phases 4-7 with ideal timing to be at the start of November for seasonal wavelenghts timing with -NAO correlation. -IOD will be around -0.8 which is lowest since 2016 autumn, that also correlated with waek early season vortex.

 

 

Thanks for the detailed thoughts and forecast Jules. Do you foresee that extent of northern blocking? High pressure over the Aleutians and Iceland is very uncommon!

[sebastiaan1973]

Ben Noll op Twitter: "How many ensemble members are indicating the potential for a weaker polar vortex? Answer: a majority. The UKMET, for example, targets mid-November through mid-December for a slowing of the typical westerly winds at 10 hPa. Impacts on our weather, if any, may lag somewhat. https://t.co/1GyhzN62Iz" / Twitter

Edited August 16, 2021 by sebastiaan1973

[jules216]

57 minutes ago, mb018538 said:

Thanks for the detailed thoughts and forecast Jules. Do you foresee that extent of northern blocking? High pressure over the Aleutians and Iceland is very uncommon!

I think its all about timing, i have learned that over last few seasons, even strong correlation with certain drivers may need a permition of atmospheric base state. The Rossby wave train that may setup up meridinal flow in the north Atlantic may still mean nothing if a massive NE Euro high or Western Russia high pressure is present,that may ne unmovable and we end up with faux cold or only very high ground snow. Example of april this year had a record long phase 7 MjO which aided Rossby wave train that kept locking us in cold, similar phase 7 happened in 2018 yet it was the warmest April on record, totaly different oucome as be base state was different. Need to keep an eye on max 30day time frame and where we are at the begining of various high frequency forcing start periods, otherwise I think these seasonal long range maps/products are only showing potential, no more

[Uncertainty]

3 hours ago, jules216 said:

I posted my analogs on twitter for next few months - 1989,1995,1998,2005 and 2020. Criteria used -IOD,-QBO, -PDO, La Nina and solar flux below 90. A good bet is tropical forcing to be in around phases 4-7 with ideal timing to be at the start of November for seasonal wavelenghts timing with -NAO correlation. -IOD will be around -0.8 which is lowest since 2016 autumn, that also correlated with waek early season vortex.

 

 

Well you did a great job with your summer analogues Jules. I would say the seasonals are not dissimilar to your anomalies, though a weaker signal obviously at this way out.

Compare this to 2019’s equivalent 

This was a good forecast, perhaps even an underestimation of the +++ Nao

We are most certainly ‘in with a chance’ of AR or -NAO patterns later this year, possibly the best for many years. I too would like to see a big block on Glosea before getting really excited, I was underwhelmed by the August update and EC, CFS, Meteofrance are all far more interesting. 

 

[jules216]

7 minutes ago, Uncertainy said:

Well you did a great job with your summer analogues Jules. I would say the seasonals are not dissimilar to your anomalies, though a weaker signal obviously at this way out.

Compare this to 2019’s equivalent 

This was a good forecast, perhaps even an underestimation of the +++ Nao

We are most certainly ‘in with a chance’ of AR or -NAO patterns later this year, possibly the best for many years. I too would like to see a big block on Glosea before getting really excited, I was underwhelmed by the August update and EC, CFS, Meteofrance are all far more interesting. 

 

Thanks, my summer analogs were quite different years to this winter analogs funnily enough, I did use a lot of years which had cold May in Slovakia which went well. I know exactly one thing this year,that if cold early doesnt come it wont be because of strong zonality, but by a legacy high pressure in NE or E Europe as it has been an eternity since we got lucky there with a trigger shortwave that can lock us all in cold akin to likes of February 2012. Every early cold last decade if came early came from a -NAO and that can still be a achieved but with bad configuration to the east of Europe.