Stratosphere and Polar Vortex Watch

[Redbull165]

3 hours ago, Catacol said:

To be fair - this is hardly a disaster. Next to no one looking at the winter in advance saw much chance of an icy December, and the vast majority of interpretations have suggested that we will need to wait for the second half of winter to produce the right combination of vortex disruption and pacific forcing to put the default westerly circulation under pressure. Look out for the impacts of MJO progression towards the end of the month in terms of blocking and possibly also vortex distress via renewed wave 2 forcing. The longer it remains pushed off its central axis through the middle part of this month the better. QBO interaction come end of January should also be favourable.

Good point.

[mountain shadow]

39 minutes ago, Summer Sun said:

 

Yeh. Looks like any early promise has now gone without delivering. 

I suspect come month end we'll see the Euro High start to make an appearance as the jet returns North. 

[feb1991blizzard]

5 minutes ago, mountain shadow said:

Yeh. Looks like any early promise has now gone without delivering. 

I suspect come month end we'll see the Euro High start to make an appearance as the jet returns North. 

I have said this a lot recently, i think it is because of climate change that we are now viewing charts in November and thinking the polar vortex is weak but really we should be judging the strength of a mid Nov vortex against a mid Oct Vortex in the 80's, i never got completely suckered in by this, indeed i actually think a very strong vortex would have been better, the theory being that it surely cannot sustain right the way through winter without any disruption, however, i am glad it its about to intensify now rather than Jan, still think we will have enough mechanism to break it down in time for February. - Mid to late Jan SSW for me.

[Mike Poole]

Gone are any signs of a SSW now, here the zonal winds from the 0z suite:

Notable, given recent discussion the massive outlier that is the GFS op - if this new FV3 is totally unreliable re the strat, it is going to make it difficult for all of us amateurs because as it is free access it is the output we see the most of.  just saying.

[Catacol]

4 hours ago, swfc said:

hi.bit of a novice here.i understand the mechanics of a ssw etc but just had a query ?Are they a seasonal thing ie "every year" or are they a symptom of certain atmospheric or synoptic circumstances? Tia

Certainly not every year and yes: a product of tropospheric patterns. In this respect troposphere and stratosphere are closely linked, though there is often a debate as to which leads the "dance" between the two. Ozone levels and distribution is important too, and the QBO has an impact on the extend to which any stratospheric disruption ends up imprinting onto the troposphere.

And the majority of proper SSWs happen in Jan/Feb and not December because the vortex tends to be spinning up to max strength in December and is more resilient at that point. By the end of January, as it is starting to fade in any case, it is more vulnerable. The fact that no SSW is showing up in the next two weeks is "normal" - and December looks like being predominantly westerly as the vortex builds in strength. Again - normal. We really out to ignore 2010 as a rather massive outlier!

Edited December 8, 2019 by Catacol

[Paul_1978]

2 hours ago, Mike Poole said:

Gone are any signs of a SSW now, here the zonal winds from the 0z suite:

Notable, given recent discussion the massive outlier that is the GFS op - if this new FV3 is totally unreliable re the strat, it is going to make it difficult for all of us amateurs because as it is free access it is the output we see the most of.  just saying.

Just shows that all those “toasty” strat chart postings at T+384 that we’ve been seeing are completely futile. 

[Kirkcaldy Weather]

 

[Kirkcaldy Weather]

From Judah Cohen's latest blog "I have a hard time predicting a significant PV disruption in the foreseeable future.  And I strongly believe that without a disrupted PV or if the PV strengthens and becomes circular in shape, then it is nearly impossible for cold air to gain a foothold across the NH with some regionalized exceptions.  This scenario is becoming a greater risk in my opinion.

  I strongly believe in the Arctic influence on our winter weather borne out in my own observational analysis and the vast majority observational analysis performed by my colleagues.  And I think during these emotional rollercoasters, you need to stick with the more rational analysis performed under less stressful moments.  As they say “the captain always goes down with the ship” and at least for this winter, if the Arctic ship goes down I am going down with it.

Also, the PV center is predicted to remain displaced towards northwest Eurasia over the next two weeks.  The displacement of the PV center towards Scandinavia is likely contributing to a tropospheric reflection helping to deepen the troughing across Siberia next week (e.g., Figure 5).  Despite the displacement of the stratospheric PV towards Eurasia and more WAFz there are no real signs of a more significant PV disruption."

 

[mb018538]

Looks like we can kiss goodbye to anything strat related for quite a while now:



Zonal winds look to be heading well north of 40m/s as we head towards the last third of the month. After being pulled around a bit the GFS settles it back slap bang over the pole as head towards Christmas:

 

[Duane S.]

Wave 2 arrives in the nick of time to save the sinking ship...?

 

[Don]

22 minutes ago, mb018538 said:

Looks like we can kiss goodbye to anything strat related for quite a while now:



Zonal winds look to be heading well north of 40m/s as we head towards the last third of the month. After being pulled around a bit the GFS settles it back slap bang over the pole as head towards Christmas:

 

Are getting to the stage where the only way is up?!

[ArHu3]

1 hour ago, Don said:

Are getting to the stage where the only way is up?!

EC had the vortex peaking around the 16-17th 1hPa dropping of, usually the lower levels follow a bit later

[BelgiumKiwi]

Maybe ECMWF will give us some smile, with incoming Geopotential Wave-1/2 activity!

[Summer Sun]

 

[bluearmy]

5 hours ago, s4lancia said:

Wave 2 arrives in the nick of time to save the sinking ship...?

 

was wondering about this as the middle/upper vortex looks quite stretched later on in yesterdays run and again this morning ……...

[Catacol]

9 hours ago, s4lancia said:

Wave 2 arrives in the nick of time to save the sinking ship...?

 

Pretty much on cue - and the 10 days following this will be fairly critical I think. Seeing the vortex fire up now is not a concern to me really as it was always likely to do this during this quiet pacific phase at this time of December - BUT if the winter forecast I put out is to head down the colder of the two routes the disruption at the end of this month needs to be sufficient to leave it open to a knock out blow later in January. If the end of December does not produce the goods in terms of a slow down and at the very least an elongation then the prospects of anything other than a very bog standard westerly dominated winter recede. 

900 is a decent start on that upper strat reading above, but ideally I'd like to see it at least 50% higher over the days that follow. All eyes on the pacific, and the extent to which the MJO can break out of the Indian Ocean and enhance wave activity downstream. Various plots disagree about the extent and magnitude of that breakout so take all FI runs with a serious pinch of salt at the moment. I'm not convinced modelling of the MJO and pacific convection in general is ever particularly accurate, and the standing wave scenario in phase 2 at the moment probably magnifies the volatility of output even more than usual. In these scenarios - go with the gut....and my gut feeling is that we will get enough of a push through to phase 6/7/8 to encourage the kind of wave breaking and blocking signals to get that wave 2 reading pumped up to more exciting levels.

Who needs Peaky Blinders when the global weather patterns can keep you on the edge of your seat like this? The only negative is the driving wind and rain outside at the moment. Grrr. We in the UK deserve some winter and summer luck given the sort of atlantic driven nonsense we have to put up with 85% of the time....

[jules216]

2 minutes ago, Catacol said:

Pretty much on cue - and the 10 days following this will be fairly critical I think. Seeing the vortex fire up now is not a concern to me really as it was always likely to do this during this quiet pacific phase at this time of December - BUT if the winter forecast I put out is to head down the colder of the two routes the disruption at the end of this month needs to be sufficient to leave it open to a knock out blow later in January. If the end of December does not produce the goods in terms of a slow down and at the very least an elongation then the prospects of anything other than a very bog standard westerly dominated winter recede. 

900 is a decent start on that upper strat reading above, but ideally I'd like to see it at least 50% higher over the days that follow. All eyes on the pacific, and the extent to which the MJO can break out of the Indian Ocean and enhance wave activity downstream. Various plots disagree about the extent and magnitude of that breakout so take all FI runs with a serious pinch of salt at the moment. I'm not convinced modelling of the MJO and pacific convection in general is ever particularly accurate, and the standing wave scenario in phase 2 at the moment probably magnifies the volatility of output even more than usual. In these scenarios - go with the gut....and my gut feeling is that we will get enough of a push through to phase 6/7/8 to encourage the kind of wave breaking and blocking signals to get that wave 2 reading pumped up to more exciting levels.

Who needs Peaky Blinders when the global weather patterns can keep you on the edge of your seat like this? The only negative is the driving wind and rain outside at the moment. Grrr. We in the UK deserve some winter and summer luck given the sort of atlantic driven nonsense we have to put up with 85% of the time....

@Catacol Iam on the edge with prospects ahead,that cyclonic wave break in Atlantic is my wild card to save festive cold

[Blessed Weather]

Some interesting discussions going on in here, but I'm afraid they were not on-topic so I have moved them to the Winter Chat thread here.

Please stick to Strat and PV discussions in this thread. Many thanks.

[Duane S.]

Pressure being applied at the top...

Edited December 11, 2019 by s4lancia

[RJBingham]

Quote

*Monthly outlook* The stratospheric polar vortex will survive all attacks and is coming at us with a vengeance! Late December and January are expected to be milder, with only brief cold episodes!

https://www.severe-weather.eu/global-weather/motnhly-outlook-vortex-vengeance-forecast-january-mild-fa/

[Dennis]

heat flux growing - good progress to weakening polarvortex 

[Redbull165]

1 hour ago, Dennis said:

heat flux growing - good progress to weakening polarvortex 

The dynamics in the next few week will be quite favourable for wave (warming) driven activity. As the Azores high will dominate the circulation over the Europe, and will push a lot of warm air towards the north, into Russia, Scandinavia. And it might start to penatrate the vortex again slowly, but surely starting from the top parts of the stratosfere at around 1 hPa. Soon we might see also the QBO (east) effect, which propagation might help with slowing the zonal-winds down. As it is usually the case. Interesting time we have ahead of us.

 

Edited December 12, 2019 by Redbull165

[Dennis]

1 minute ago, Redbull165 said:

The dynamics in the next few week will be quite favourable for wave (warming) driven activity. As the Azores high will dominate the circulation over the Europe, and will push a lot of warm air towards the north, into Russia, Scandinavia. And it might start to penatrate the vortex, slowly, but surely starting from the top parts of the stratosfere at around 1 hPa. Soon we might see also the QBO (east) effect, which propagation might help with slowing the zonal-winds down. As it is usually the case. Interesting time we have ahead of us.

yes indeed the QBO is moving 

[Duane S.]

OK, this is going to get interesting. General concensus on a rapidly growing SPV. Wave and flux activity looking very promising.

Intrigued how this is going to play out.

A huge Wave 1, sprawling wave 2, coinciding with the vortex winding up...

Edited December 12, 2019 by s4lancia

[Interitus]

2 hours ago, Dennis said:

heat flux growing - good progress to weakening polarvortex 

5 days later on this run, the 10mb 60N wind has recovered to a healthy 53.7 ms.

Wave forcing initially reduces zonal wind by changing the vortex shape, but also enhances the wind locally. Interestingly, at T357 (26/12 21:00) the 1mb wind reaches 177.9 ms just off the Scottish coast, or in units most might be more familiar with, a incredible 398 mph (640 kmh) -