Stratosphere and Polar Vortex Watch 2020

[Mike Poole]

21 hours ago, damianslaw said:

Jetstream pattern default position all year, very weak - resulting in lengthy dry periods, and shorter unsettled more trough/cyclonic conditions with propensity for low pressure to anchor itself to the south of the UK. Quite an unusual set up.. and notable for its persistance.. indeed in a couple of months time, it would be offering significant wintry potential.. alas its September.

Jet stream very weak, yes, here GFS T6 and T384:

And split as well.  I have a view that the NH has not recovered from last winter…yet…the last thing it needs to do now is suddenly return to form with the Atlantic barrelling through.  Hope it holds the line, until we see what the more important signals through October and November show…

Anyone care to resurrect the OPI this year?  Thought not.  

[damianslaw]

12 minutes ago, Mike Poole said:

Jet stream very weak, yes, here GFS T6 and T384:

And split as well.  I have a view that the NH has not recovered from last winter…yet…the last thing it needs to do now is suddenly return to form with the Atlantic barrelling through.  Hope it holds the line, until we see what the more important signals through October and November show…

Anyone care to resurrect the OPI this year?  Thought not.  

Certainly seems the case. We've barely had a zonal atlantic flow since December, just the odd spell or two, and shortlived. Reasons why it has stayed so sluggish I don't know. 

We have quite an intense low pressure development to our NW and marked temp gradient which is going to inject some energy into it and low and behold high pressure to the east is disrupting the trough. If this was Sprng or early summer I wouldn't be surprised. However we are approaching autumn equinox and wouldn't normally expect to see such development. 

Last time we had such a quiet Atlantic was 2010...

[Mike Poole]

1 minute ago, damianslaw said:

Last time we had such a quiet Atlantic was 2010...

Yes, I know.  And I’m very aware that I have called 3 out of the last zero ‘front loaded winters’, since being here on Netweather…but none the less I’m calling this one…after all 4/0 is still a meaningless quantity called infinity.  Who knows…yet, but it is interesting re winter on so many perspectives, apart from the one that will scupper the whole thing (NE pacific SSTs is one already lined up to to take the fall!!).

[SqueakheartLW]

A initial promising sign for a weaker vortex to develop as we head further into autumn when looking at the ECM forecast

After our early strong start the process of strengthening slows down enough that the blue mean line ends up dipping below average as we head into mid October time.

Also another interesting feature of the latest 42 day ECM charts is the dominant Atlantic regime charts

That is one hell of a lot of the block regime featured there. A sure sign that raging Atlantic zonality is basically dead.

[damianslaw]

11 minutes ago, SqueakheartLW said:

A initial promising sign for a weaker vortex to develop as we head further into autumn when looking at the ECM forecast

After our early strong start the process of strengthening slows down enough that the blue mean line ends up dipping below average as we head into mid October time.

Also another interesting feature of the latest 42 day ECM charts is the dominant Atlantic regime charts

That is one hell of a lot of the block regime featured there. A sure sign that raging Atlantic zonality is basically dead.

An early strong PV is having no effect it seems then.

 Otherwise high pressure would be losing out to Atlantic lows.. other factors must be countering it.

Would be good to know what the SSTs were in NE Pacific back in autumn 2010.

One similarity is the solar cycle, in 2010 we slowly came out of the low point . We are in the same place now, and I strongly feel this is the overriding factor at present.. 

Autumn 2010 was fairly quiet with alot of anticyclonic influence.. 

[jules216]

18 minutes ago, SqueakheartLW said:

A initial promising sign for a weaker vortex to develop as we head further into autumn when looking at the ECM forecast

After our early strong start the process of strengthening slows down enough that the blue mean line ends up dipping below average as we head into mid October time.

Also another interesting feature of the latest 42 day ECM charts is the dominant Atlantic regime charts

That is one hell of a lot of the block regime featured there. A sure sign that raging Atlantic zonality is basically dead.

I dont necesary agree blocked weather regime is all that good sign or indicator of good pattern going forward, block can easily mean Euro High pressure and endless mind weather 

 

 

[summer blizzard]

1 hour ago, damianslaw said:

Certainly seems the case. We've barely had a zonal atlantic flow since December, just the odd spell or two, and shortlived. Reasons why it has stayed so sluggish I don't know. 

We have quite an intense low pressure development to our NW and marked temp gradient which is going to inject some energy into it and low and behold high pressure to the east is disrupting the trough. If this was Sprng or early summer I wouldn't be surprised. However we are approaching autumn equinox and wouldn't normally expect to see such development. 

Last time we had such a quiet Atlantic was 2010...

As optimistic as your being it’s arguable that 2016 was much more blocked than 2010, it led to naught.

 

 

[Premiere Neige]

2 hours ago, damianslaw said:

An early strong PV is having no effect it seems then.

 Otherwise high pressure would be losing out to Atlantic lows.. other factors must be countering it.

Would be good to know what the SSTs were in NE Pacific back in autumn 2010.

One similarity is the solar cycle, in 2010 we slowly came out of the low point . We are in the same place now, and I strongly feel this is the overriding factor at present.. 

Autumn 2010 was fairly quiet with alot of anticyclonic influence.. 

Chart for 14th October 2010. Looks like SST's were colder than average in the NE Pacific . Perhaps if La Nina strengthens over the coming weeks the SAT'S off Pacific Canada and Alaska will come down...

 

[damianslaw]

3 minutes ago, Premier Neige said:

Chart for 14th October 2010. Looks like SST's were colder than average in the NE Pacific . Perhaps if La Nina strengthens over the coming weeks the SAT'S off Pacific Canada and Alaska will come down...

 

SSTs NE Pacific were just as warm last autumn as now, and we ended up with at least some cold weather at times in the winter, and before the SSW, Late Dec/early Jan was quite cold.. and early December.

[Premiere Neige]

4 minutes ago, damianslaw said:

SSTs NE Pacific were just as warm last autumn as now, and we ended up with at least some cold weather at times in the winter, and before the SSW, Late Dec/early Jan was quite cold.. and early December.

Just had a quick look at latest SST anomaly and it does look as though something of a cooling is taking place in the area of interest (he said hopefully!)....

 

[sebastiaan1973]

Winter 2021-22: the chance for a weaker than normal stratospheric polar vortex has been well-chronicled by climate models Rode cirkel

As the season gets closer & the signal persists, it's looking more likely.

Early winter high-latitude blocking could dislodge Arctic air southward... https://twitter.com/bennollweather

& december UKMO

[SqueakheartLW]

On 17/09/2021 at 10:58, sebastiaan1973 said:

Winter 2021-22: the chance for a weaker than normal stratospheric polar vortex has been well-chronicled by climate models Rode cirkel

As the season gets closer & the signal persists, it's looking more likely.

Early winter high-latitude blocking could dislodge Arctic air southward... https://twitter.com/bennollweather

& december UKMO

Not a very good chart. We need to be getting rid of that red area to our SE over Europe. That chart maybe shows a weaker Atlantic than normal but also shows a Sceuro high which would keep us stuck in a mild S or SW flow up from Africa.

[mb018538]

On 15/09/2021 at 20:01, SqueakheartLW said:

A initial promising sign for a weaker vortex to develop as we head further into autumn when looking at the ECM forecast

After our early strong start the process of strengthening slows down enough that the blue mean line ends up dipping below average as we head into mid October time.

Also another interesting feature of the latest 42 day ECM charts is the dominant Atlantic regime charts

That is one hell of a lot of the block regime featured there. A sure sign that raging Atlantic zonality is basically dead.

How quickly this has changed from Monday...on the time longitude diagram, just look at how that red block running right through October in our vicinity is now a blue block out to the 7th October. The ridge/trough pattern has been pushed much further east, hence the trough now in our locale from next week.

Edited September 17, 2021 by mb018538

[Kirkcaldy Weather]

 

[sebastiaan1973]

It's all about this part of the tweets

  https://t.co/w1QWChSou5" / Twitter

In 28 years of seasonal ECMWF guidance issued in September, there was a signal (≥1σ) for an SSW in 4 Decembers before this year. An SSW happened in 3 out of 4 of those winters, but there were misses in the early 2000s. The signal in 2021-22 is the 2nd strongest of all cases.

 

Edited September 18, 2021 by sebastiaan1973

[bluearmy]

Interesting……….

ec seasonal does have some high lat blocking and euro troughing  in jan ……you’d expect it to react to those ssw dec signals to some degree ……

[northwestsnow]

13 minutes ago, bluearmy said:

Interesting……….

ec seasonal does have some high lat blocking and euro troughing  in jan ……you’d expect it to react to those ssw dec signals to some degree ……

I'm getting a little excited about the upcoming Winter.

A cold seasonal Nov and Dec would be great.

Nina hopefully not too strong.

QBO stays easterly

Looking forward to Oct update.

[Mike Poole]

On 15/09/2021 at 20:16, damianslaw said:

An early strong PV is having no effect it seems then.

 Otherwise high pressure would be losing out to Atlantic lows.. other factors must be countering it.

Would be good to know what the SSTs were in NE Pacific back in autumn 2010.

One similarity is the solar cycle, in 2010 we slowly came out of the low point . We are in the same place now, and I strongly feel this is the overriding factor at present.. 

Autumn 2010 was fairly quiet with alot of anticyclonic influence.. 

SST anomaly this time in 2010:

And now:

Some similarities there.

Edited September 18, 2021 by Mike Poole

[Mike Poole]

ECM 12z T240 and showing signs of a pattern that would really restrict the development of the polar vortex, Siberian high, Aleutian low.  If this persists, I’m doubling down on the front loaded winter!

[Don]

1 hour ago, Mike Poole said:

SST anomaly this time in 2010:

And now:

Some similarities there.

So the NE Pacific was also warm at this time in 2010!  I'm surprised by that, but feel a little better about this year now!  Do you have any concerns about this warm September being a poor sign for the upcoming winter?

Edited September 18, 2021 by Don

[Mike Poole]

8 minutes ago, Don said:

So the NE Pacific was also warm at this time in 2010!  I'm surprised by that, but feel a little better about this year now!  Do you have any concerns about this warm September being a poor sign for the upcoming winter?

Not really Don, I think the summer was sufficiently average, and September isn’t going to do much to change that, that if, I repeat, if, things continue the way they are at the moment, that signs for early winter for the UK are good, there will be time for things to cool down.  Whether that delivers for us down here in the south is another matter entirely, we actually tend to do much better from back loaded winters.

[Spah1]

[sebastiaan1973]

22 hours ago, Kirkcaldy Weather said:

 

i guess the background signal is good for SSWs. Literature wise, this is true (eQBO, Low solar acitivty). So  i would like to give some credit to the EC output. 

[jules216]

36 minutes ago, sebastiaan1973 said:

i guess the background signal is good for SSWs. Literature wise, this is true (eQBO, Low solar acitivty). So  i would like to give some credit to the EC output. 

Yes, background signals are in line with observed publications from Grey et al. and others.

[northwestsnow]

A SSW in Dec would be really interesting.

I may be wrong but recent years it has been Jan onwards ?