Stratosphere and Polar Vortex Watch

[Don]

38 minutes ago, Kirkcaldy Weather said:

 

Come at the wrong time of the year for them!

[Dorsetbred]

27 minutes ago, Don said:

Come at the wrong time of the year for them!

Sounds familiar...

[Kirkcaldy Weather]

 

[Frozen Britain]

Quote

https://twitter.com/MJVentrice/status/1180279305902927872

Will this verify? 

Something to watch in the coming days and weeks to see if the trend continues....................

 

Edited October 5, 2019 by Frozen Britain

[Frozen Britain]

[Don]

3 hours ago, Frozen Britain said:

Will this verify? 

Something to watch in the coming days and weeks to see if the trend continues....................

 

A sluggish refreeze with that!

[Kirkcaldy Weather]

 

[Mike Poole]

Now into October and the stratospheric polar vortex has been going through the gears, now average per time of year and GFS forecast to increase strength further :

We look to be approaching winter, as last year, with a big disconnect between the strat and trop vortices, compare the serene white contours for the strat, and the angrier black ones for the trop.  The feature in blue is a unicorn, apparently.

Edited October 6, 2019 by Mike Poole

[Kirkcaldy Weather]

 

[frederiksen90]

A strengthened PV with + AO is well up to winter, as it is understood that the air around the Arctic will be colder than normal. At a weak PV there is higher pressure and the air mass will be warmer over the Arctic. Then it will be difficult to get cold. So that's why it's good that PV is amplified to begin with. The most important thing is that NAO does not follow. The worst thing is, if it changes phase, then it becomes difficult. But keeping it neutral to negative while AO goes in + can a subsequent weakening of PV give us even colder air in Europe than if PV had not been strengthened? And where one can hope that the forecasts go wrong, could just be the link between strato and tropo, which signals a strong jet across the Atlantic. If SST anomalies maintain an attenuated gradient and -NAO continues after PV is strengthened, then you must probably see it as good signs It will be exciting to follow.

[booferking]

1 minute ago, frederiksen90 said:

A strengthened PV with + AO is well up to winter, as it is understood that the air around the Arctic will be colder than normal. At a weak PV there is higher pressure and the air mass will be warmer over the Arctic. Then it will be difficult to get cold. So that's why it's good that PV is amplified to begin with. The most important thing is that NAO does not follow. The worst thing is, if it changes phase, then it becomes difficult. But keeping it neutral to negative while AO goes in + can a subsequent weakening of PV give us even colder air in Europe than if PV had not been strengthened? And where one can hope that the forecasts go wrong, could just be the link between strato and tropo, which signals a strong jet across the Atlantic. If SST anomalies maintain an attenuated gradient and -NAO continues after PV is strengthened, then you must probably see it as good signs It will be exciting to follow.

Agree

[Interitus]

On 06/10/2019 at 16:51, Mike Poole said:

We look to be approaching winter, as last year, with a big disconnect between the strat and trop vortices, compare the serene white contours for the strat, and the angrier black ones for the trop.  The feature in blue is a unicorn, apparently.

Not really, what is the contour interval?

Can see a 700 metre depression in geopotential height at the 500mb level in the image above, whilst it is up to 800 metres at the 10mb level with a suitable contour resolution -

 

[Kirkcaldy Weather]

 

[chionomaniac]

Early indications suggest a strong autumnal Strat vortex in the coming weeks. I’d rather see it now than the start of winter. We may have to suffer a wild late autumn but I am cautiously optimistic for mid winter. I suspect that teleconnective conditions, from low solar to neutral to weakly positive ENSO will reflect this though with unprecedented arctic melt long term forecasts will be more unpredictable than ever. 

[knocker]

Rare warming over Antarctica reveals power of stratospheric models

Improved understanding of conditions in the stratosphere are helping to produce more-accurate short-term climate forecasts.

https://www.nature.com/articles/d41586-019-02985-8?utm_source=twt_nnc&utm_medium=social&utm_campaign=naturenews&sf221306965=1

[blizzard81]

Three of the most severe winter spells of the last century. Moral of the story? The PV doesn't have to be obliterated to kingdom come. 

[booferking]

1 hour ago, blizzard81 said:

Three of the most severe winter spells of the last century. Moral of the story? The PV doesn't have to be obliterated to kingdom come. 

Yes as per top 2 charts a displaced raging PV towards Siberia can led to some of the most potent cold this side of the pond.

[JeffC]

6 minutes ago, booferking said:

Yes as per top 2 charts a displaced raging PV towards Siberia can led to some of the most potent cold this side of the pond.

Where do I sign?!

[booferking]

3 minutes ago, JeffC said:

Where do I sign?!

On the dotted line ....................

[MattStoke]

On ‎13‎/‎10‎/‎2019 at 22:51, chionomaniac said:

Early indications suggest a strong autumnal Strat vortex in the coming weeks. I’d rather see it now than the start of winter. We may have to suffer a wild late autumn but I am cautiously optimistic for mid winter. I suspect that teleconnective conditions, from low solar to neutral to weakly positive ENSO will reflect this though with unprecedented arctic melt long term forecasts will be more unpredictable than ever. 

Something I don't really understand is that SST's apparently point to a negative NAO but all season models are predicting the opposite.

As one of the most knowledgeable posters on here, I was wondering if you had any thoughts on this.

Edited October 15, 2019 by MattStoke

[mb018538]

11 hours ago, blizzard81 said:

Three of the most severe winter spells of the last century. Moral of the story? The PV doesn't have to be obliterated to kingdom come. 

It doesn't - but all of those have a heavily displaced PV, which still requires a hell of a lot to achieve! We all know it'll probably set up it's semi-permanent home to the N/NW of the UK, like this:

[coldwinter]

10 minutes ago, MattStoke said:

Something I don't really understand is that SST's apparently point to a negative NAO but all season models are predicting the opposite.

As one of the most knowledgeable posters on here, I was wondering if you had any thoughts on this.

Well i would say SST's are pointing to a weak -VE NAO but you have to remember that SST's are one piece of one very big and complex puzzle, it's never as simple as A=B, and the seasonals may well of been reacting to what is a very cold strat at the moment i believe. We are still a long way off  

[Seasonality]

54 minutes ago, mb018538 said:

It doesn't - but all of those have a heavily displaced PV, which still requires a hell of a lot to achieve! We all know it'll probably set up it's semi-permanent home to the N/NW of the UK, like this:

That chart needs a trigger warning.

[Kirkcaldy Weather]

 

[Yarmy]

2 minutes ago, Kirkcaldy Weather said:

 

It will be interesting to see whether the "blocky" tropospheric pattern showing for T168 onwards in the model output has any effect in terms of upward wave propagation on the stratosphere. There's little or no evidence of that in the latter stages of the GEFS as far as I can tell. One for the strat gurus.