Stratosphere and Polar Vortex Watch 2020

[bluearmy]

The 12z gfs shows that the pendulum is still able to swing back but still not as displaced as it was earlier in the week. 

[Don]

3 hours ago, bluearmy said:

The 12z gfs shows that the pendulum is still able to swing back but still not as displaced as it was earlier in the week. 

Bit of a pre-winter roller coaster ride this year?  Don't you just love it?! 

Edited October 8, 2021 by Don

[bluearmy]

8 hours ago, Don said:

Bit of a pre-winter roller coaster ride this year?  Don't you just love it?! 

Well I’m not here cos I love you don! 

[Don]

4 hours ago, bluearmy said:

Well I’m not here cos I love you don! 

Damn you! 

[Griff]

On 07/10/2021 at 21:02, Griff said:

Far too soon to be interesting...

 

On 07/10/2021 at 21:07, Mike Poole said:

On the contrary, if that did happen (a SSW in October as shown by 3 ENS members) it would be very very interesting!  I think a Canadian warming is possible this year (early SSW), displacement of vortex early season away from Canada.  Haven’t had one for ages, I believe it increases chance of UK cold, but as the last one was before my time, someone else could perhaps comment, please?

 

On 07/10/2021 at 21:43, Griff said:

I'm going with a PhD in reverse psychology this year  

Personal preference aside (? ☃ etc), Simon Lee has an interesting take on this. Apologies for posting a tweet here, but it's well worth a read... 

TLDR... Nothing is ever certain! 

 

 

[bluearmy]

1 hour ago, Griff said:

 

 

Personal preference aside (? ☃ etc), Simon Lee has an interesting take on this. Apologies for posting a tweet here, but it's well worth a read... 

TLDR... Nothing is ever certain! 

 

 

He talks about Rossby waves not being able to propagate into easterlies. But there is no sign of a reversal (just a weakened vortex) 

hence I’m not sure about the whole basis of the tweets …have I missed something ? 

[Griff]

43 minutes ago, bluearmy said:

He talks about Rossby waves not being able to propagate into easterlies. But there is no sign of a reversal (just a weakened vortex) 

hence I’m not sure about the whole basis of the tweets …have I missed something ? 

My understanding from the entire thread is that a weakened vortex now doesn't necessarily lead to cold for us in November / December, and could contribute to a stronger than average PV in winter, or did I miss something?  

[Methuselah]

14 minutes ago, Griff said:

My understanding from the entire thread is that a weakened vortex now doesn't necessarily lead to cold for us in November / December, and could contribute to a stronger than average PV in winter, or did I miss something?  

TBH, Griff, I think we are all missing something. And, quite possibly, each missing something different?

Edited October 10, 2021 by Ed Stone

[bluearmy]

43 minutes ago, Griff said:

My understanding from the entire thread is that a weakened vortex now doesn't necessarily lead to cold for us in November / December, and could contribute to a stronger than average PV in winter, or did I miss something?  

He says (I think) that an early reversal will likely mean a stronger vortex in the heart of winter ……. That’s pretty much understood and why some are expecting a front loaded winter.  My query was that we aren’t looking at an early reversal but just a weakened vortex. Surely rossby waves can propagate effectively into a weakened spv ……

the 6 runs of the monthly cfs bias corrected have two with a strong recovery post this weakening, two which stay pretty weak before recovery in  December and two which which go onto a technical reversal end nov before recovery by the new year 

[Catacol]

46 minutes ago, Griff said:

My understanding from the entire thread is that a weakened vortex now doesn't necessarily lead to cold for us in November / December, and could contribute to a stronger than average PV in winter, or did I miss something?  

Agreed - and us mere mortals have seen more than one early "weak" vortex morph into a very strong one by end of December. A canadian warming early November will be interesting to follow but if it lessens the chances of a major reversal in late Dec or into January then it is no friend of mine!

[Griff]

54 minutes ago, Catacol said:

Agreed - and us mere mortals have seen more than one early "weak" vortex morph into a very strong one by end of December. A canadian warming early November will be interesting to follow but if it lessens the chances of a major reversal in late Dec or into January then it is no friend of mine!

Exactly this

[Mike Poole]

Well looking at Stratobserve from yesterday’s 0z runs, one cheeky member of the GEM ensembles fancies a SSW at T360:

[Mike Poole]

7 hours ago, Catacol said:

Agreed - and us mere mortals have seen more than one early "weak" vortex morph into a very strong one by end of December. A canadian warming early November will be interesting to follow but if it lessens the chances of a major reversal in late Dec or into January then it is no friend of mine!

Think I’m going the other way on this.  I’d take the Canadian warming for the chance to see something genuinely different play out this winter.  It is not as though normal fayre has delivered any notable winters recently, is it?  

[Allseasons-Si]

On 10/10/2021 at 17:38, Mike Poole said:

Well looking at Stratobserve from yesterday’s 0z runs, one cheeky member of the GEM ensembles fancies a SSW at T360:

It looks like most of the SPV is located on the Siberian side looking at those Mike,...or am i totally wrong,...i think i am right

Edited October 10, 2021 by Allseasons-si
typo

[Mike Poole]

2 minutes ago, Allseasons-si said:

It looks like most of the SPV is located on the Siberian side looking at those Mike,...or am i totally wrong,...i think i am right

Yes, the vortex will be well away from its usual home over Greenland and Canada, early on, I think that is clear, which is what gives the window for the front loaded winter, the question is how long that situation will last for.  I think any trop setup that suppresses the zonal mean zonal wind early on will delay the inevitable coupling of the SPV and TPV, for a front loaded winter to deliver anything, we really have to push that point into January at least.  But from where we are now, I’d rather go down that route than hope for a SSW mid winter, and hope the pieces land favourably for cold later.  

[MP-R]

On 10/10/2021 at 18:23, Mike Poole said:

Yes, the vortex will be well away from its usual home over Greenland and Canada, early on, I think that is clear, which is what gives the window for the front loaded winter, the question is how long that situation will last for.  I think any trop setup that suppresses the zonal mean zonal wind early on will delay the inevitable coupling of the SPV and TPV, for a front loaded winter to deliver anything, we really have to push that point into January at least.  But from where we are now, I’d rather go down that route than hope for a SSW mid winter, and hope the pieces land favourably for cold later.  

Not that we have any control over it and this is purely personal preference, but if we can bag a decent December and January like winter 96/97, that would be grand. Then if the Atlantic wants its turn, it can do it to the north of the UK in Feb so we avoid a washout. Traditionally, the PV starts its wind down through January and especially by February so hopefully any Atlantic onslaught later in the season won't pack the same punch it might in November and December.

[Catacol]

4 hours ago, Mike Poole said:

Think I’m going the other way on this.  I’d take the Canadian warming for the chance to see something genuinely different play out this winter.  It is not as though normal fayre has delivered any notable winters recently, is it?  

Perhaps. I think notable winters in the UK require a SSW (especially given CC) and I think I'm right in saying that an early season CW is yet to produce a reversal. If I'm wrong on that I'm sure someone will point it out. Therefore it may be interesting to see what happens if the vortex is displaced over to the Asian side early in the season with the potential for a northerly - but these days there is so little cold to tap into pre January I'm not sure it would produce the goods. We all know that 2010 was an extraordinary event, ranking alongside the 2018 Beast for the most notable synoptics for wintry heaven to hit parts of the UK in the last 20 years at least, and I guess what happened once can in broad terms happen again - but my fear is that early season weak vortex events often bounce back to produce robust vortex formations in mid winter.

We are getting very close now to the point where some sense of the winter coming can be gleaned, and there are certainly some broad factors in our favour this time around. If you want to cherry pick outrageously then line up your CW with a potentially weak Nina bottoming out in November with an eQBO and go check 1962/63. Solar isn't a match, but the rest isn't miles out. We come back year after year because of the outside chances of a significant winter event and we know it is always possible. We will be disappointed more than excited, and as CC gathers pace the frequency of UK cold looks very likely to decline - but at the same time the potential for events to be extreme is rising even while the frequency is set to fall.....so sometime in the next few decades (and hopefully while I'm still around to see it) we have a chance to see a winter extreme or two....

[Richard Fisher]

Don’t worry folks the Daily Star has this nailed
 

 

[bluearmy]

20 hours ago, bluearmy said:

He says (I think) that an early reversal will likely mean a stronger vortex in the heart of winter ……. That’s pretty much understood and why some are expecting a front loaded winter.  My query was that we aren’t looking at an early reversal but just a weakened vortex. Surely rossby waves can propagate effectively into a weakened spv ……

the 6 runs of the monthly cfs bias corrected have two with a strong recovery post this weakening, two which stay pretty weak before recovery in  December and two which which go onto a technical reversal end nov before recovery by the new year 

Correction - was not monthly cfs run.  

[sheikhy]

Is the warming over canada still on for the end of this month?!!

[Catacol]

4 hours ago, sheikhy said:

Is the warming over canada still on for the end of this month?!!

18-25 Oct on ECM

25 Oct - 1 Nov

Edited October 11, 2021 by Catacol

[Don]

6 hours ago, sheikhy said:

Is the warming over canada still on for the end of this month?!!

Latest GLOSEA5 update for November, December and January looking pretty grim for those wanting a cold early winter at least.  Perhaps not making much of the Canadian warming having an impact, or other factors at play?

Edited October 11, 2021 by Don

[sheikhy]

32 minutes ago, Don said:

Latest GLOSEA5 update for November, December and January looking pretty grim for those wanting a cold early winter at least.  Perhaps not making much of the Canadian warming having an impact, or other factors at play?

Any charts mate?!!cant remember the last time glosea predicited a cold winter!!maybe 2009/2010?!!im sure when it forecasts mild it normally ends up true

[Don]

14 minutes ago, sheikhy said:

Any charts mate?!!cant remember the last time glosea predicited a cold winter!!maybe 2009/2010?!!im sure when it forecasts mild it normally ends up true

Here we go

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean

I think it predicted a cold winter for 2018/19 which didn't happen.  Not the be all and end all but I would rather it showed a cold outlook than mild!

[Frigid]

On 11/10/2021 at 17:23, Don said:

Here we go

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean

I think it predicted a cold winter for 2018/19 which didn't happen.  Not the be all and end all but I would rather it showed a cold outlook than mild!

And 2009 predicted a mild winter and we got the coldest winter since 78/79. Not the end..yet

   

 

Edited October 11, 2021 by Frigid