Winter 2022-23 early thoughts - general chat

[Premiere Neige]

On 23/09/2022 at 22:39, Mike Poole said:

Yes, quite similar, but those 3 month average plots can hide a lot of detail, can’t they?  Nonetheless, I will be making the same early prediction this year as last year.  That of potential for a front loaded winter with cold for the UK in December, before the polar vortex can belatedly ramp up, and without prejudice of a SSW delivering something later into winter.  It proved to be a bust last year, I’ll level with you, but I felt we were in with a good chance and the dice didn’t fall for us, while there was a chance before New Year.  I think pretty much the same cards are on the table this year, surely we can draw a better hand?  (Mixed metaphor overload, there).  

Well, in a way, the same cards would be on the table, it is a repeat La Niña year, like last year, so a double repeat, although I think the fact that it is a repeat Nina means more than the fact that it is the third in a row (although these are rare, data is short!).  What has been clear throughout the other seasons for the last two years - both bookended by La Niña winters - is the total lack of significant weather from the Atlantic.

And the current model output, and the seasonal models, seem keen on an Atlantic ridge going into autumn and so I am suggesting we go into winter this year with potential for blocking, and a subdued Atlantic.  There is then a window for a cold pattern to take hold in December, before the polar vortex gets too wound up…it just needs luck this year that eluded us last year.  

ECM seasonal model, split into Dec, Jan and Feb:

You can see what I mean about the 3 month average plots hiding useful stuff, because the pattern in December is very different to February, and I think the Atlantic ridge scenario in December gives a chance.  Difficult to read too much into February (obviously it is different) because the runs will no doubt have ensemble members in which there has been a SSW and ones where there hasn’t and you have to factor that in.  

But that’s for later, I think the first chase will be a front loaded December evolution of the current blocked pattern, then maybe a SSW and all the drama that brings to follow…

I'd definitely take those charts just now and you never know when an SSW might turn up? If I remember correctly we didn't have one last year so hopefully we're due one this winter and the dice land in our favour. When I say "our" I'm speaking from a coldie perspective...

[Mike Poole]

On 24/09/2022 at 11:21, Met4Cast said:

The SST analogues provided by the World Climate Service paint a rather grim picture for Oct > Dec.

Very warm, wet & possibly windy. Based on SST's alone of course, but given the almost uniformly warm Atlantic, it makes sense. Complete opposite of the La-Nina "front loaded" winter idea, but as we've seen for the past two winters now that can't really be relied upon as a factor, with other drivers more often than not overriding the signal. 

For me, going into this winter isn't looking promising for cold lovers, everything seems to be stacked against us. SST's are a big factor in my opinion, more important than ENSO in most cases.

wQBO limits the potential for Sudden Stratospheric Warmings, so we might not be able to rely on that for a significant change to colder weather patterns.

I can’t see this as likely, to be honest, it goes against the predictions of all the main seasonal models for a dryer than average winter, and lots of blocking.  From the modelling, while I do think there is a decent prospect of an early cold spell, I think the main hostage to fortune for coldies this winter would be a preponderance of mid-latitude blocking, not an Atlantic driven rain and wind fest.  Which is why I will be looking for some better indication of the blocking setting up in favourable locations in the October and November updates of the seasonal models.  

6 hours ago, Premier Neige said:

I'd definitely take those charts just now and you never know when an SSW might turn up? If I remember correctly we didn't have one last year so hopefully we're due one this winter and the dice land in our favour. When I say "our" I'm speaking from a coldie perspective...

Correct, there wasn’t one last year.  Or ever looked likely to be, to be honest.  I’m not sure we’re ‘due’ one, I don’t think it works like that!  But they are slightly more common than average in Nina winters, I believe.  On the other hand, the similarities in the models to last year may give the same result.  We would probably need a SSW to avoid a milder second half of winter this year, I think.  We will see…long way to go yet.

Edited September 25, 2022 by Mike Poole

[RJBingham]

27 minutes ago, Mike Poole said:

I can’t see this as likely, to be honest, it goes against the predictions of all the main seasonal models for a dryer than average winter, and lots of blocking.  From the modelling, while I do think there is a decent prospect of an early cold spell, I think the main hostage to fortune for coldies this winter would be a preponderance of mid-latitude blocking, not an Atlantic driven rain and wind fest.  Which is why I will be looking for some better indication of the blocking setting up in favourable locations in the October and November updates of the seasonal models.  

Correct, there wasn’t one last year.  Or ever looked likely to be, to be honest.  I’m not sure we’re ‘due’ one, I don’t think it works like that!  But they are slightly more common than average in Nina winters, I believe.  On the other hand, the similarities in the models to last year may give the same result.  We would probably need a SSW to avoid a milder second half of winter this year, I think.  We will see…long way to go yet.

Westerly QBO this year as well.

[Don]

6 minutes ago, RJBingham said:

Westerly QBO this year as well.

Whilst an Easterly QBO is more favourable for a colder winter, a westerly QBO by no means spells curtains for a cold winter.  If you look at Gavs Weather Vids fourth winter update today, there are a fair few cold westerly QBO winters within the analogues.  2020/21 had a Westerly QBO but was close to being a nationwide cold winter.  Last winter was an Easterly QBO but was very mild.

[sebastiaan1973]

https://easternmassweather.blogspot.com/2022/09/enso-continues-to-stagnate-as-winter.html

[Premiere Neige]

1 hour ago, Mike Poole said:

I can’t see this as likely, to be honest, it goes against the predictions of all the main seasonal models for a dryer than average winter, and lots of blocking.  From the modelling, while I do think there is a decent prospect of an early cold spell, I think the main hostage to fortune for coldies this winter would be a preponderance of mid-latitude blocking, not an Atlantic driven rain and wind fest.  Which is why I will be looking for some better indication of the blocking setting up in favourable locations in the October and November updates of the seasonal models.  

Correct, there wasn’t one last year.  Or ever looked likely to be, to be honest.  I’m not sure we’re ‘due’ one, I don’t think it works like that!  But they are slightly more common than average in Nina winters, I believe.  On the other hand, the similarities in the models to last year may give the same result.  We would probably need a SSW to avoid a milder second half of winter this year, I think.  We will see…long way to go yet.

When I said "due one" I read somewhere that the average was once every 2 years. Not sure how accurate that is though. But as you say, one is probably required to avoid a mild second half of winter. 

Edited September 25, 2022 by Premier Neige

[RJBingham]

1 hour ago, Don said:

Whilst an Easterly QBO is more favourable for a colder winter, a westerly QBO by no means spells curtains for a cold winter.  If you look at Gavs Weather Vids fourth winter update today, there are a fair few cold westerly QBO winters within the analogues.  2020/21 had a Westerly QBO but was close to being a nationwide cold winter.  Last winter was an Easterly QBO but was very mild.

Sorry, should have been clearer, I was referring to the chances of a SSW. 

[Don]

5 minutes ago, RJBingham said:

Sorry, should have been clearer, I was referring to the chances of a SSW. 

No problem.  However, they do occur during Westerly QBO winters for example early January 2021 and late January 2009.  Less of a chance but again, far from out of the question.

Edited September 25, 2022 by Don

[Georgina]

11 hours ago, Premier Neige said:

Where did you learn to speak emoji?

It’s a gift

[P-M]

Not sure if this has already been posted somewhere,  but really interesting read about the polar vortex and how it's already being disrupted.  The article suggests some bigger implications for the NH as winter progresses. 

Weather: An early disruption event is starting for the Polar Vortex, with pressure anomalies setting the stage for something bigger later in Winter » Severe Weather Europe

WWW.SEVERE-WEATHER.EU

---

A stratospheric disruption event is starting over the North Pole, affecting the Polar Vortex and potentially having an impact on the...

 

[Don]

1 hour ago, P-M said:

Not sure if this has already been posted somewhere,  but really interesting read about the polar vortex and how it's already being disrupted.  The article suggests some bigger implications for the NH as winter progresses. 

Weather: An early disruption event is starting for the Polar Vortex, with pressure anomalies setting the stage for something bigger later in Winter » Severe Weather Europe

WWW.SEVERE-WEATHER.EU

---

A stratospheric disruption event is starting over the North Pole, affecting the Polar Vortex and potentially having an impact on the...

 

I understand this has happened a lot in recent years but the PV has then ramped up to very strong levels come early winter?

[P-M]

1 hour ago, Don said:

I understand this has happened a lot in recent years but the PV has then ramped up to very strong levels come early winter?

Hopefully the dice will land in our favor this time!  

[Sunny76]

On 24/09/2022 at 00:13, Allseasons-si said:

Yes i remember Oct 2008 with wintry showers from the north,was there settling snow down the eastern side of the country,...i cannot remember now,i am sure i had a dusting here

It snow in London in late October 2008. I remember it feeling very cold and unusual. Light flurries was all that fell, but this was the precursor to the next 4-5 years of mainly colder winters in the U.K.

[Catacol]

On 24/09/2022 at 11:21, Met4Cast said:

The SST analogues provided by the World Climate Service paint a rather grim picture for Oct > Dec.

Very warm, wet & possibly windy. Based on SST's alone of course, but given the almost uniformly warm Atlantic, it makes sense. Complete opposite of the La-Nina "front loaded" winter idea, but as we've seen for the past two winters now that can't really be relied upon as a factor, with other drivers more often than not overriding the signal. 

For me, going into this winter isn't looking promising for cold lovers, everything seems to be stacked against us. SST's are a big factor in my opinion, more important than ENSO in most cases.

wQBO limits the potential for Sudden Stratospheric Warmings, so we might not be able to rely on that for a significant change to colder weather patterns.

I find myself pondering SSTs quite a lot, not least because of the constant bombardment of anomaly graphs we see over an ever moving baseline. Very difficult to interpret I'd say.

This image is interesting:

It is from the US Environment agency and shows the trend over 120 years for SSTs. Note that area to the SE of Greenland which has actually cooled on average - due to ice melt presumably. The question in my head - what does this do for us in the UK given it is so close to home? Enhanced temperature gradient through the atlantic for sure, so deeper depressions perhaps over time. Enhanced +NAO potential too with lower pressure encouraged over Greenland perhaps. But is it also reflective of a slowing AMOC - of an ocean tipping point that might be reached in my grandchildren's lifetime? However the ice cap is continuing to melt so any decline in the conveyor would not appear to be saving the ice cap.

Never easy to interpret these things. However for the coming winter I'll say again - the warming continent (and the seasonals once again have pressure high over Eastern Europe that will enhance this warmth) means that dense and frigid air masses needed to give us the battleground conditions for snowfall are rare. Add to that the loss of frigid air to our north and we need a special setup to give us an 80s style winter again. If it isnt through an SSW then I don't quite know where it comes from, though the vortex shard that dropped over us in Dec 10 always gives hope.

Edited September 26, 2022 by Catacol

[Don]

1 hour ago, P-M said:

Hopefully the dice will land in our favor this time!  

It all depends on whether the PV powers up to very strong levels by early winter, but yes, hopefully the stratosphere will be more favorable for us this time!

[Don]

8 minutes ago, Catacol said:

Never easy to interpret these things. However for the coming winter I'll say again - the warming continent (and the seasonals once again have pressure high over Eastern Europe that will enhance this warmth) means that dense and frigid air masses needed to give us the battleground conditions for snowfall are rare. Add to that the loss of frigid air to our north and we need a special setup to give us an 80s style winter again. If it isnt through an SSW then I don't quite know where it comes from, though the vortex shard that dropped over us in Dec 10 always gives hope.

This is the ever increasing issue for our islands these days!  Remember though, snowfall can still occur from a non exceptional setup - think late January/early February 2019 for example.

[Catacol]

5 hours ago, P-M said:

Not sure if this has already been posted somewhere,  but really interesting read about the polar vortex and how it's already being disrupted.  The article suggests some bigger implications for the NH as winter progresses. 

Weather: An early disruption event is starting for the Polar Vortex, with pressure anomalies setting the stage for something bigger later in Winter » Severe Weather Europe

WWW.SEVERE-WEATHER.EU

---

A stratospheric disruption event is starting over the North Pole, affecting the Polar Vortex and potentially having an impact on the...

 

Regardless of any early season vortex weakening (we have seen this before and it seems to have little impact on winter as a whole - indeed the bounce back can perhaps intensify it even further) it would be good to have a season of very high siberian snow cover extending south as well as west just to give this Cohen theory a proper good go. The jury is very much out on the whole idea I'd say. Interesting that Andrej is suggesting a high snow index may be on its way.

 

 

[Don]

23 minutes ago, Catacol said:

Regardless of any early season vortex weakening (we have seen this before and it seems to have little impact on winter as a whole - indeed the bounce back can perhaps intensify it even further) it would be good to have a season of very high siberian snow cover extending south as well as west just to give this Cohen theory a proper good go. The jury is very much out on the whole idea I'd say. Interesting that Andrej is suggesting a high snow index may be on its way.

 

 

This was what I was alluding to in my earlier post.

As far as Siberian snow cover goes, it has got off to a good start!

[Don]

Met Office Contingency Forecast has updated for October, November and December.  Temperatures and precipitation expected to be close to average overall.

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/business/public-sector/civil-contingency/3moutlook-ond-v1.pdf

[January Snowstorm]

The upper temperatures look very medoliocre for this time of year. Little in the way of proper cold! Early days I know but you can't help thinking that a front loaded winter(if it were to happen) may deliver synoptically but would not have a proper pool of cold to feed from. Autumn's are definitely becoming more benign as the cold is just not there to power up the jet

[Don]

8 minutes ago, January Snowstorm said:

The upper temperatures look very medoliocre for this time of year. Little in the way of proper cold! Early days I know but you can't help thinking that a front loaded winter(if it were to happen) may deliver synoptically but would not have a proper pool of cold to feed from. 

A very good example of this was February 2005!!

[damianslaw]

13 hours ago, Don said:

I understand this has happened a lot in recent years but the PV has then ramped up to very strong levels come early winter?

Yes recently we've seen a very slow PV formation in November and start of Dec, only for a switch to be turned on and in no time its on turbo charge it seems. 

[damianslaw]

3 hours ago, Don said:

Met Office Contingency Forecast has updated for October, November and December.  Temperatures and precipitation expected to be close to average overall.

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/business/public-sector/civil-contingency/3moutlook-ond-v1.pdf

Very average then, in a rather non-average year so far, warmth and dry have ruled.. so it suggests the jetstream will finally dominate things..

[damianslaw]

9 hours ago, Don said:

This was what I was alluding to in my earlier post.

As far as Siberian snow cover goes, it has got off to a good start!

2012 was the last year when a sudden late Oct snow expansion west backed up the theory such events correlate with colder conditions in Europe, alas winter 12-13 was never very severe and very episodic, the real cold came late in March.

I think its the rate of expansion second half of Oct the key factor, not growth in September.

[Don]

4 minutes ago, damianslaw said:

2012 was the last year when a sudden late Oct snow expansion west backed up the theory such events correlate with colder conditions in Europe, alas winter 12-13 was never very severe and very episodic, the real cold came late in March.

I think its the rate of expansion second half of Oct the key factor, not growth in September.

Yes, it has crossed my mind that snow may be developing a little too early this year?!  The more snow earlier, the less of a rapid expansion later in October!

 

8 minutes ago, damianslaw said:

Very average then, in a rather non-average year so far, warmth and dry have ruled.. so it suggests the jetstream will finally dominate things..

Possibly, but it does state that although near average rainfall is most likely, there is a slight increase in the likelihood of dry.  Also it says there is a probable decrease in storminess compared to normal for late autumn and early winter, so it does not look overly zonal?