Stratosphere and Polar Vortex Watch 2020

[northwestsnow]

2 hours 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. 

 

I was very underwhelmed too.

September will hopefully be much better.

 

[Uncertainty]

As @CreweCold has alluded to, the CFS going all out for winter blocking. Meteofrance also goes for an all Winter affair.

Looks a lot like last year. 

If only we could get those low heights over SE Europe...

[SqueakheartLW]

Is something weird going on with the QBO again?

Take a look at the latest QBO chart

Now the delay to the EQBO descent is not unusual as I have seen this in many of the past EQBO phases where the WQBO takes some time to disappear from below 40hpa in particular

1 - What appears to be unusual here is how the EQBO got down to 40hpa almost and just recently the WQBO appears to be pushing back upwards towards 30hpa again and a clear slowing down of the EQBO at 30hpa can be seen with the blues getting replaced by the light greens again. Hope this isn't the first signs of yet another failure of the EQBO

2 - The last time the WQBO pushed back upwards in the 2019/2020 season we all know what happened next. The main bit of hope however is that this is happening lower down and so could have less bad of an effect on the EQBO prospects for winter 2021/2022

Look at this QBO chart too and see the weird happening here too

Now the progression of the QBO on these charts should be anticlockwise lines drawn around the central point at varying speeds depending on the descent speed of the QBO

1 - Notice how the line on this occasion first enters a weaker than average EQBO and initially almost follows the same weakness at the failed EQBO line before diverging on a better path. The strange part here is how we come to a stop then make an almost reverse path in recent times. This does look strange on this chart to see a backwards progression of the QBO.

2 - It would seem this backwards progression isn't a unique event as it would seem it also happened early in 2018 as well.

The big difference here is how much weaker the current EQBO is compared with the 2018 one. Our current EQBO appears to be amongst the weakest on record with only 2020 and a couple of other EQBO years as weak or weaker than this year compared with 2018 which was amongst the strongest EQBO's on the record.

[philglossop]

On 20/08/2021 at 11:26, SqueakheartLW said:

Is something weird going on with the QBO again?

Take a look at the latest QBO chart

Now the delay to the EQBO descent is not unusual as I have seen this in many of the past EQBO phases where the WQBO takes some time to disappear from below 40hpa in particular

1 - What appears to be unusual here is how the EQBO got down to 40hpa almost and just recently the WQBO appears to be pushing back upwards towards 30hpa again and a clear slowing down of the EQBO at 30hpa can be seen with the blues getting replaced by the light greens again. Hope this isn't the first signs of yet another failure of the EQBO

2 - The last time the WQBO pushed back upwards in the 2019/2020 season we all know what happened next. The main bit of hope however is that this is happening lower down and so could have less bad of an effect on the EQBO prospects for winter 2021/2022

Look at this QBO chart too and see the weird happening here too

Now the progression of the QBO on these charts should be anticlockwise lines drawn around the central point at varying speeds depending on the descent speed of the QBO

1 - Notice how the line on this occasion first enters a weaker than average EQBO and initially almost follows the same weakness at the failed EQBO line before diverging on a better path. The strange part here is how we come to a stop then make an almost reverse path in recent times. This does look strange on this chart to see a backwards progression of the QBO.

2 - It would seem this backwards progression isn't a unique event as it would seem it also happened early in 2018 as well.

The big difference here is how much weaker the current EQBO is compared with the 2018 one. Our current EQBO appears to be amongst the weakest on record with only 2020 and a couple of other EQBO years as weak or weaker than this year compared with 2018 which was amongst the strongest EQBO's on the record.

Agree- something is happening again. It's a very weak EQBO as you highlighted. The only similar year I could see like this is from summer 1988- and the WQBO came back very quickly following a weak rapid descent. Those brown colours in the very top of the stat around a month ago set me off wondering (even if some didn't think my concern was needed).

If you do the animation on the QBO SIngapore- you'll see what I mean with 1988. and to a point 1991. Could this be the shorted EQBO as it was stuck in the stat from 2019 onwards I wonder?

 

Edited August 22, 2021 by philglossop

[sebastiaan1973]

Prelim 2021-22 Winter Outlook (weatherbell.com)

https://www.weatherbell.com/prelim-2021-22-winter-outlook

The Verdict

Overall it's a very bullish signal for early winter. I have left out of the analog some heavy pre-21st-century big-hitting winters. If those would get into the package, it would seal the deal. There is enough variance and swing, so prepare for bursts of higher than normal wintery weather, followed by a backing off. The wintery period will outduel the milder periods for the end result being a bit snowier than normal (population-weighted) with near-normal temperatures overall.

The antics of the MJO will be huge. Each winter weekly update will be dealing closely with that, as it's a huge driver. Models unfortunately are horrible at forecasting it, but I hope you have noticed that since the spring of 2020 we have had skill in hitting what it's up to. The MJO has also been a big help in 1-2 month forecasting for everything from summer cooldowns to hotter periods and hurricanes. After seeing last winter and the forcing we saw, a valuable lesson was taught and what I decided to do is start constructing this winter's ideas this past spring. I am showing you some of the links here and so the lesson of last year may have given us some knowledge as to how to deal with this year. Obviously, any future event is not etched in stone. Given how bad modeling is I should probably not be happy it agrees with the flow chart analogs we are using. For now, that is a good sign, though.

Edited August 22, 2021 by sebastiaan1973

[Cheshire Freeze]

From that, it looks to be suggesting similar to my thoughts…blocked early winter period.

[Ols500]

Does the MJO always move through its phases 1-8 ,numerically, in order, or could it go into phase 1, then into 8, back to 7, 6, 5, then switch again back to 6,7 etc? If you know what i mean 

[Kirkcaldy Weather]

23 minutes ago, Ols500 said:

Does the MJO always move through its phases 1-8 ,numerically, in order, or could it go into phase 1, then into 8, back to 7, 6, 5, then switch again back to 6,7 etc? If you know what i mean 

No it doesn't always go through the phases in numerical order, looking through the data for an example, back in June it went 7,2,1,2

[summer blizzard]

53 minutes ago, Ols500 said:

Does the MJO always move through its phases 1-8 ,numerically, in order, or could it go into phase 1, then into 8, back to 7, 6, 5, then switch again back to 6,7 etc? If you know what i mean 

It usually moves sequentially but not through all the numbers so it may start in 3 and go to 8 ect.. You have to think of it as a clock.

[damianslaw]

5 hours ago, CreweCold said:

From that, it looks to be suggesting similar to my thoughts…blocked early winter period.

This is not a prediction, and feet are firmly on the ground.. but I've said there have been some similiarities with 2010 this year. In 2010 we had locked in lengthy blocked atlantic periods, ditto this year... 

[knocker]

A Warming event is now starting in the Stratosphere above the South Pole, with temperatures over 30 degrees above normal, marking the end of South Winter

https://www.severe-weather.eu/global-weather/winter-south-pole-stratosphere-warming-forecast-fa/?fbclid=IwAR0r2qg7WNg296_he93rOWmcPNf4ARtSJMvzXi2UCdh5Xmw1dZCcU_5s28M

[SqueakheartLW]

4 hours ago, knocker said:

A Warming event is now starting in the Stratosphere above the South Pole, with temperatures over 30 degrees above normal, marking the end of South Winter

https://www.severe-weather.eu/global-weather/winter-south-pole-stratosphere-warming-forecast-fa/?fbclid=IwAR0r2qg7WNg296_he93rOWmcPNf4ARtSJMvzXi2UCdh5Xmw1dZCcU_5s28M

Hope that doesn't lead to a feedback like in 2019 that ends up giving us a polar vortex of doom again. Don't want another one of those to happen and ruin winter for us do we?

[knocker]

1 hour ago, SqueakheartLW said:

Hope that doesn't lead to a feedback like in 2019 that ends up giving us a polar vortex of doom again. Don't want another one of those to happen and ruin winter for us do we?

Rather depends on what one considers 'the ruination of winter'

[philglossop]

17 hours ago, SqueakheartLW said:

Hope that doesn't lead to a feedback like in 2019 that ends up giving us a polar vortex of doom again. Don't want another one of those to happen and ruin winter for us do we?

I’ve just read that article and it’s click bate. The southern polar vortex is still firmly in place and will come under some pressure towards the end of the latest model run (which is a bit like our polar vortex having a warming in March). As you read it, you’d think a suddenly strat warming was the like the world ending! 
 

Yes it may effect Australia weather for early Spring - ie Wetter than normal but I’m not concerned for us at this stage.

[jules216]

22 hours ago, SqueakheartLW said:

Hope that doesn't lead to a feedback like in 2019 that ends up giving us a polar vortex of doom again. Don't want another one of those to happen and ruin winter for us do we?

It was the anomalous +IOD that killed the winter 2019/20 not SSW in southern hemisferic winter. +IOD send the tropical forcing to the wrong place and it did feedback to a strong Euro high, the reverse is true of -IOD that sets up tropical forcing in phases 4-7(Indonesia/Pacific) that teleconnects with more blocking in the North Atlantic

[Tom Quintavalle]

1 hour ago, jules216 said:

It was the anomalous +IOD that killed the winter 2019/20 not SSW in southern hemisferic winter. +IOD send the tropical forcing to the wrong place and it did feedback to a strong Euro high, the reverse is true of -IOD that sets up tropical forcing in phases 4-7(Indonesia/Pacific) that teleconnects with more blocking in the North Atlantic

Further to the post of jules216 above, below is a link to an article regarding the anomalously high +IOD, and its impacts on the NAO of the Winter, of 2019/20.

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO - Hardiman - 2020 - Atmospheric Science Letters - Wiley Online Library

Regards,

Tom. 

 

[damianslaw]

4 minutes ago, TomSE12 said:

Further to the post of jules216 above, below is a link to an article regarding the anomalously high +IOD, and its impacts on the NAO of the Winter, of 2019/20.

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO - Hardiman - 2020 - Atmospheric Science Letters - Wiley Online Library

Regards,

Tom. 

 

What is the IOD expected to do this autumn. Or cannot it not be forecast well..

[Tom Quintavalle]

4 minutes ago, damianslaw said:

What is the IOD expected to do this autumn. Or cannot it not be forecast well..

Hi dl,

Below is a link to where the IOD is at the moment and where current thoughts suggest it's likely to be, in the Northern Hemispheric Winter:

Climate Driver Update (bom.gov.au)

Regards,

Tom. 

[jules216]

1 hour ago, damianslaw said:

What is the IOD expected to do this autumn. Or cannot it not be forecast well..

It should be negative, i hope most negative since 2016, more negative the more convection in MJO phases 4-7 that bring that La Nina like mid Atlantic ridge late autumn/early winter with a bit of a chance of -NAO if corelate with low solar flux<90.

[damianslaw]

37 minutes ago, jules216 said:

It should be negative, i hope most negative since 2016, more negative the more convection in MJO phases 4-7 that bring that La Nina like mid Atlantic ridge late autumn/early winter with a bit of a chance of -NAO if corelate with low solar flux<90.

2016 brought a mild westerly flow late on, but I guess ENSO was different.

Last December brought anamoulous mid Atlantic heights that built north at times.. with weak trough to our SE indeed we've been locked in this state ever since. On occasion heights have transferred NE as now and in early Feb but in the main have been centred to the NW. 

 

 

[philglossop]

So the QBO keeps us guessing. The last week has seen a definite weakening of the Westerlies in the Strat and a move of the Easterly finally down to 40 HPA.  Looks much more promising than a fortnight ago. 

[Mike Poole]

Just catching up on this thread over the last couple of pages.  Good news on the EQBO potentially giving us something, I think.  We’re also on the rise out of the solar minimum which has been a good signal in the past too (53 days with no sunspots so far, well short of last year).  

I like the idea that a front loaded winter may be possible.  However, in recent years, I have found that patterns that might have led to that, have rather been thwarted, certainly for us down south, by excessive warmth hanging over from summer.  There is a chance that this year that might not be the case, as summer has been largely cool in comparison to recent years, in the UK especially so, apart from early July.  

Then there is the Atlantic SST angle, which could well go in our favour this year, most signals suggest a tripole is likely as we go into winter.  Early days, early hopes…

[sebastiaan1973]

-13.17 augustus QBO

[jules216]

The Holton–Tan effect varies over longitude. The QBO induces stronger planetary wave forcing to the mean flow in the extratropical lower stratosphere between Indonesia and Alaska. The North Pacific polar stratosphere responds to this before other longitudes. What follows is a shift in the position of the polar vortex toward Eurasia (North America) during easterly (westerly) QBO. This initiates downstream planetary wave responses over North America, the North Atlantic, and Siberia.

[sebastiaan1973]

ACPD - Long Range Prediction and the Stratosphere (copernicus.org)

 

Abstract. Over recent years there have been parallel advances in the development of stratosphere 37 resolving numerical models, our understanding of stratosphere-troposphere interaction and the 38 extension of long-range forecasts to explicitly include the stratosphere. These advances are now 39 allowing new and improved capability in long range prediction. We present an overview of this 40 development and show how the inclusion of the stratosphere in forecast systems aids monthly, seasonal 41 and decadal climate predictions. We end with an outlook towards the future of climate forecasts and 42 identify areas for improvement that could further benefit these rapidly evolving predictions.

Edited September 3, 2021 by sebastiaan1973