Model Output Discussion - Into Winter

[Catacol]

Just now, blizzard81 said:

You touched on the fact that solar activity hasn't been mentioned much this season. I 'used' to bring the subject up quite often as I believe it has a significant effect on winter weather synoptics. I gave up mentioning it on here though as I got sick to the back teeth of the nay sayers and the snidy remarks. My philosophy now is that people will hopefully research this phenomenon in their own time if they are willing and open to the scientific reasonings behind it. 

It's definitely a factor and the one factor that I think was pointing in clearly the wrong direction going into the winter. As I have come to see it, high solar activity whips up the jet. Low solar leads to a less active jet. There are papers on it now, and I remember way back in the early days when it was rubbished by many including (from memory) the MetO and then, lo and behold, some proper research conducted and the above conclusion very broadly reached. We are not at solar minimum, but the hope is that one signal on its own will not drown out all the others. 

When we get to the end of the season I wonder where we will be on our ENSO analysis. Strong at the start of the season, predicted to wane to moderate by season's end. Part of the back loaded call was linked to ENSO. If Nino stays strong under a similarly strong solar umbrella than the outcome could be grim!

[blizzard81]

2 minutes ago, Catacol said:

It's definitely a factor and the one factor that I think was pointing in clearly the wrong direction going into the winter. As I have come to see it, high solar activity whips up the jet. Low solar leads to a less active jet. There are papers on it now, and I remember way back in the early days when it was rubbished by many including (from memory) the MetO and then, lo and behold, some proper research conducted and the above conclusion very broadly reached. We are not at solar minimum, but the hope is that one signal on its own will not drown out all the others. 

When we get to the end of the season I wonder where we will be on our ENSO analysis. Strong at the start of the season, predicted to wane to moderate by season's end. Part of the back loaded call was linked to ENSO. If Nino stays strong under a similarly strong solar umbrella than the outcome could be grim!

I agree with everything you say there

[Penguin16]

1 hour ago, Continental Climate said:

There are many people on here who put a great deal of time and effort into researching and explaining the background signals in the hope of better learning about the weather. I know I look forward to their posts as I find them so interesting. 

Then there are people who seem to want to undermine all that hard work and effort with silly one line posts, as seen above. 

I’m not undermining anyone and I enjoy reading about them and the work they put in to it. Over the years more often that not I’ve seen nothing come of these positive background signals regarding cold in winter. Even subsequent post mentions were such a tiny island it can easily go wrong even if the background signals align perfectly hence my point. IMO too much weight is given to them for us for that very reason and something unexpected can suddenly  happen that scuppers any outlook based on background signals.

Anyway I didn’t realise criticising the accuracy of background signals was blasphemy on here and gets twisted in to me attacking people who put a lot of effort in to explaining them. Mental how imaginative and sensitive some people are.

[MATTWOLVES 3]

I sense a touch of towel throwing on the 19th of December...2 days before Winter starts for some astronomically! Guys never give in hope,without it we would merely only exist...but not be living.

There's much going on with our Atmosphere over the weeks ahead and the possibility of some wintry goods is far better than last year..thats my honest opinion.

Mogreps 6z look a tad colder and some further North could see snow falling around the festive period..others further South less likely but the chance remains.

And for me the chances will increase into the New Year...

If your gonna give in then take a break...otherwise hold fire til the backend of March.

Come on you lot...chins up head held high and stay positive.

[cheeky_monkey]

22 minutes ago, Catacol said:

If Nino stays strong under a similarly strong solar umbrella than the outcome could be grim!

100% agree Nino shows no sign of weakening much as we head towards the new year ..hence the reason we have such a massive positive anomaly across the whole of the NA continent..i was expecting a milder than average winter in my location but the run of above temperatures has surpassed anything i would imagine..the next 10 days looks even more ridiculous for warmth ..no snow for xmas and the new year with temps close to double digits when it should be -25c 

[TillyS]

3 hours ago, blizzard81 said:

I did post the chart. Have a look at my post again. 

I've found the one at T240 which I also posted: yours being the whole NH version.

You also posted this chart which is T216 but without any explanation.Can you expand please, patiently and gently as to why this chart was interesting for cold aspirants?

As a general point I do find it a little confusing when people post charts, sometimes with emojis, but no commentary on why the rest of us are supposed to sit up. For newbies it’s especially confusing sometimes. Some sort of explanation is really helpful, especially when it’s the whole northern hemisphere chart. It’s bad enough trying to pick out the UK on that, let alone the apparent signals for cold

 

[ANYWEATHER]

53 minutes ago, blizzard81 said:

You touched on the fact that solar activity hasn't been mentioned much this season. I 'used' to bring the subject up quite often as I believe it has a significant effect on winter weather synoptics. I gave up mentioning it on here though as I got sick to the back teeth of the nay sayers and the snidy remarks. My philosophy now is that people will hopefully research this phenomenon in their own time if they are willing and open to the scientific reasonings behind it. 

Quite agree with you! A lot of people ridicule others with regard to this line of thought. A lot more work/ research has to be done on solar output, but I’m in agreement that these solar cycles have a lot more to how the weather behaves around the planet than what is given credit for……

[Dignity]

8 minutes ago, TillyS said:

I've found the one at T240 which I also posted: yours being the whole NH version.

You also posted this chart which is T216 but without any explanation.Can you expand please, patiently and gently as to why this chart was interesting for cold aspirants?

As a general point I do find it a little confusing when people post charts, sometimes with emojis, but no commentary on why the rest of us are supposed to sit up. For newbies it’s especially confusing sometimes. Some sort of explanation is really helpful, especially when it’s the whole northern hemisphere chart. It’s bad enough trying to pick out the UK on that, let alone the apparent signals for cold

 

Heights building towards Iceland introducing a northerly flow alongside the trough digging in to the north east.

Bit of a shaky and weak east Atlantic area of high pressure which would easily get moved by other connections.

 

I think

[Alexis]

21 minutes ago, TillyS said:

I've found the one at T240 which I also posted: yours being the whole NH version.

You also posted this chart which is T216 but without any explanation.Can you expand please, patiently and gently as to why this chart was interesting for cold aspirants?

As a general point I do find it a little confusing when people post charts, sometimes with emojis, but no commentary on why the rest of us are supposed to sit up. For newbies it’s especially confusing sometimes. Some sort of explanation is really helpful, especially when it’s the whole northern hemisphere chart. It’s bad enough trying to pick out the UK on that, let alone the apparent signals for cold

 

One way to begin to get cold is for pressure to rise over Greenland. So that chart looks promising because we're up to 1025mb up there (you also want to see the pressure extending outside Greenland itself).

Down the line it can lead to northerly, north westerly or north easterly winds (there's a slack northerly over the UK already on there)

 

Edited December 19, 2023 by Alexis

[Troubleatmill]

4 minutes ago, Alexis said:

One way to begin to get cold is for pressure to rise over Greenland. So that chart looks promising because we're up to 1025mb up there (you also want to see the pressure extending outside Greenland itself).

Down the line it can lead to northerly, north westerly or north easterly winds.

I thought it was because if you turned it upside down the PV looks a bit like Dumbo sat down? Dam,blast...i'll get there

Edited December 19, 2023 by Troubleatmill
Idjut sorry edit

[MJB]

It certainly looks like we need luck or every single bit of the 1,000 piece jigsaw for the UK to get a decent Winter.

A lot of chat about the Zonal winds dropping light, a favourable MJO , EQBO as background signals to aid our hunt for snow and cold.

Currently the charts aren't even dangling much of a carrot ,though as Matt has said December 21st is the start of winter ( for me its December 1st ) nonetheless it hasn't started or only just, depending on your POV.

Plenty of time to go yet, I have read a post writing off the Winter before it started, come off it.

We all know what Jan / Feb and March can bring . 

Don't give up the ghost.....................just yet.

[Pembroke Dangler]

1 minute ago, MJB said:

It certainly looks like we need luck or every single bit of the 1,000 piece jigsaw for the UK to get a decent Winter.

A lot of chat about the Zonal winds dropping light, a favourable MJO , EQBO as background signals to aid our hunt for snow and cold.

Currently the charts aren't even dangling much of a carrot ,though as Matt has said December 21st is the start of winter ( for me its December 1st ) nonetheless it hasn't started or only just, depending on your POV.

Plenty of time to go yet, I have read a post writing off the Winter before it started, come off it.

We all know what Jan / Feb and March can bring . 

Don't give up the ghost.....................just yet.

The Met office outlook still points towards a colder start to next month and a small chance of being prolonged so totally agree with you there shouldn’t be so much despondency the outlook is still looking decent. Patients needed  

[MattH]

Just further to my earlier post, been keeping a close eye on the observed GSDM data, given the current Central Pacific activity and one of the key features (there are others) that stands out here is the anomalies that have developed, in terms of frictional torque, over the last 5 days or so and that continues in the latest (17th) update, as below...

The key feature here is the -ve FT tendencies at circa 50-60N, this is what you want to see if you wish to see a more amplified jet stream pattern. This is all linked to the Rossby wave packets and how they propagate northwards and eastwards from the tropics. The significant region of +ve Frictional Torque at 30-40N is linked to the MJO event and the associated -VP200 anomalies and associated Westerly Wind Burst near the Central Pacific that remains ongoing. If this were the opposite where frictional torque tendency is negative towards 30N it creates a negative inflexion point in the Equatorial Pacific and adds momentum to the jet stream downstream in the extratropics. A -ve FT regime at circa 30N, from my understanding, is what can 'prop up' sub-tropical anticyclones and it is the compensating momentum that increases the polar jet through the mid-lats.

This is just one piece of the puzzle, but what we are seeing now is what the likes of myself, Tamara, Catacol etc, touted as would arrive through Dec, but it has been delayed given the MJO evolution.

It just links back into those few slides earlier and how I used the word 'unusual' looking ahead, especially when you add to the mix the ongoing winter eQBO, weakening sPV (which is also displaced) and a disorganised trop vortex too.

Regards, Matt.

 

[MJB]

1 minute ago, MattH said:

Just further to my earlier post, been keeping a close eye on the observed GSDM data, given the current Central Pacific activity and one of the key features (there are others) that stands out here is the anomalies that have developed, in terms of frictional torque, over the last 5 days or so and that continues in the latest (17th) update, as below...

The key feature here is the -ve FT tendencies at circa 50-60N, this is what you want to see if you wish to see a more amplified jet stream pattern. This is all linked to the Rossby wave packets and how they propagate northwards and eastwards from the tropics. The significant region of +ve Frictional Torque at 30-40N is linked to the MJO event and the associated -VP200 anomalies and associated Westerly Wind Burst near the Central Pacific that remains ongoing. If this were the opposite where frictional torque tendency is negative towards 30N it creates a negative inflexion point in the Equatorial Pacific and adds momentum to the jet stream downstream in the extratropics. A -ve FT regime at circa 30N, from my understanding, is what can 'prop up' sub-tropical anticyclones and it is the compensating momentum that increases the polar jet through the mid-lats.

This is just one piece of the puzzle, but what we are seeing now is what the likes of myself, Tamara, Catacol etc, touted as would arrive through Dec, but it has been delayed given the MJO evolution.

It just links back into those few slides earlier and how I used the word 'unusual' looking ahead, especially when you add to the mix the ongoing winter eQBO, weakening sPV (which is also displaced) and a disorganised trop vortex too.

Regards, Matt.

 

That went right over my head.................................I am guessing you are saying we are still in with a shout lol ?? 

[Downburst]

58 minutes ago, ANYWEATHER said:

Quite agree with you! A lot of people ridicule others with regard to this line of thought. A lot more work/ research has to be done on solar output, but I’m in agreement that these solar cycles have a lot more to how the weather behaves around the planet than what is given credit for……

Well accurate solar spot info goes back to 1650 or so doesn't it? Very easy to do reanalysis I would expect. I'll keep an open mind of course, but hope any thoughts on this are based on scientific principles and not simply because of the immense magnitude of the sun, which can lead people into correlations that don't necessarily exist. 

[joggs]

9 minutes ago, MattH said:

Just further to my earlier post, been keeping a close eye on the observed GSDM data, given the current Central Pacific activity and one of the key features (there are others) that stands out here is the anomalies that have developed, in terms of frictional torque, over the last 5 days or so and that continues in the latest (17th) update, as below...

The key feature here is the -ve FT tendencies at circa 50-60N, this is what you want to see if you wish to see a more amplified jet stream pattern. This is all linked to the Rossby wave packets and how they propagate northwards and eastwards from the tropics. The significant region of +ve Frictional Torque at 30-40N is linked to the MJO event and the associated -VP200 anomalies and associated Westerly Wind Burst near the Central Pacific that remains ongoing. If this were the opposite where frictional torque tendency is negative towards 30N it creates a negative inflexion point in the Equatorial Pacific and adds momentum to the jet stream downstream in the extratropics. A -ve FT regime at circa 30N, from my understanding, is what can 'prop up' sub-tropical anticyclones and it is the compensating momentum that increases the polar jet through the mid-lats.

This is just one piece of the puzzle, but what we are seeing now is what the likes of myself, Tamara, Catacol etc, touted as would arrive through Dec, but it has been delayed given the MJO evolution.

It just links back into those few slides earlier and how I used the word 'unusual' looking ahead, especially when you add to the mix the ongoing winter eQBO, weakening sPV (which is also displaced) and a disorganised trop vortex too.

Regards, Matt.

 

Thanks for the update. What lag time would you be talking about to start affecting the models?.

Tia 

[Catacol]

1 hour ago, Penguin16 said:

IMO too much weight is given to them for us for that very reason and something unexpected can suddenly  happen that scuppers any outlook based on background signals.

 

One gentle addition to this phrase - I would be interested to see if anyone can find a cold spell from the modern archives we have access to that was not aligned with background forcings. I would agree that such forcings do not always come up trumps. But I am not aware of a spell we have had, when we have data we can look at, where that spell came out of nowhere and in contradiction to what the drivers were indicating.

In other words...snow doesn't always lead to the building of a snowman. But without snow there can be no snowman.....

Edited December 19, 2023 by Catacol

[MJB]

Just now, Catacol said:

One gentle push back on this phrase - I would be interested to see if anyone can find a cold spell from the modern archives we have access to that was not aligned with background forcings. I would agree that such forcings do not always come up trumps. But I am not aware of a spell we have had, when we have data we can look at, where that spell came out of nowhere and in contradiction to what the drivers were indicating.

In other words...snow doesn't always lead to the building of a snowman. But without snow there can be no snowman.....

I'm sure there is a combination that is stronger than others that can give the cold and snow, but which combination of factors and in what sequence? 

Or doesn't it work like that ?

[Catacol]

21 minutes ago, MJB said:

I'm sure there is a combination that is stronger than others that can give the cold and snow, but which combination of factors and in what sequence? 

Or doesn't it work like that ?

The more drivers that align the better. Quantity is good.

Your question is an interesting Pub Quiz style approach though. I quite like the idea of coming up with the theoretical "best mix" combo for an upcoming cold spell. 

For me I'd go:

1. Weak to moderate El Nino. Allows a positive momentum context without too much to scupper things...

2. eQBO for sure. This is key for enhancing blocking scenarios.

3. Low solar. Evidence suggests this weakens the jet.

4. QBO orbiting phases 5-8. Nino phases, so atmosphere in harmony with the ENSO backdrop.

5.  Then - once this is all in place, I'd look for a high amplitude MJO progression through 7/8/1 combined with the right pressure differential over China to extend the pacific jet. This creates the right kind of Rossby wave setup along with a momentum burst for wave eddy opportunity. Get this at a time of points 1-4 and you have a pretty damned good chance of a cold shot.

 

The other method would be the potent Ural/Aleutian Combo. There is the perfect blueprint for this. Go and look at hemispheric charts for 14 Jan 2018. That synoptic pattern set the vortex up for a shattering and a top down frictional setup that made all tropospheric drivers irrelevant such was the force of this occurrence. The vortex split, the negative winds dropped down through the layers and we had that vortex shard work from E to W across Siberia and towards Eastern Europe that led to the unbelievable chart showing winds blowing from Siberia to Canada the wrong way. I'm not sure if such a stratospheric event will ever happen like this again in my lifetime - I live in hope, and in hope that it can happen a few weeks earlier/faster - but it showed an alternative route to cold that may end up being, in the fullness of time, the best hope for sustained UK cold. The problem with points 1-5 at the top of this post is that CC is messing around with the ENSO context, the Hadley Cell has shifted north and overall the reliability of these factors to provide a sustained NE flow in winter when the vortex is present is reducing. Remember too that CC is creating a warming troposphere but a cooling stratosphere. We see this most years now with temps in the stratosphere noticeably below climatological average most of the time. This whips up the stratospheric vortex, and that alone makes winter high lat blocks harder to achieve.

This year we have a ropey 1 (Nino is a bit strong), 2 and chances at 4 + 5. We don't have 3. It isn't a perfect setup....but its better than many other years we have had recently.

Edited December 19, 2023 by Catacol

[northwestsnow]

Looks like the background drivers are still positive from a coldies POV.

Let's see where we are in 7 days regards to NWP,obviously we'd want to see some momentum away from Euro heights as a first staging post..

[Tamara]

3 hours ago, Penguin16 said:

Are background signals on a par with fortune telling by this stage? 

The term" background signals" rather grates with its overuse, dumbing down of its actual diagnostic purpose, & its incorrect use in adherence to bias synoptic outcomes - which is largely why so many are left scratching their heads when too often they don't appear "to work".

This is the aggregate global wind-flow fluxing budget plot - in simple terms, a cross section of direction & strength of wind-flow eddy anomalies across the  Equator, Tropics & Extra Tropics (emphasis on the NH section)

This reveals the off Equator fluxing (shaded red close to the Equator) that is a good part of total directional flux and why inflated sub tropical ridging is so evident across Iberia. When looking at angular momentum budgets themselves, this equatorial portion of +ve momentum indicates that it has been offsetting the rest of the +ve torque processes attempting to propagate from the tropics, c/o MJO related activity, into the extra tropics.

If one thinks of an inflection point where either -ve forcing exceeds +ve forcing (-ve frictional torque) or vice versa  (+ve frictional torque) then this is simply the turning force (a torque) exhibited on the jet stream - to deflect & alter its strength & direction whether it is decelerating or accelerating. Expressed as a change, downwards or upwards, in angular momentum tendency.

The recent state of equatorial fluxing has to be taken into account when looking at the MJO component of the wind-flow budget and the fact that it continues (for the time being & read below) not to be optimally conducive to poleward propagation of +AAM anomalies. It is just not always as simple as MJO phase x = outcome y as gets posted so many times, each day, at this time of the year - in search of a desired outcome. Tropical forcing is just part of global wind flow forcing. I think I could maybe put this disclaimer in my profile/signature

The same principle applies at any time of year in respect of weather pattern diagnosis. 

However, also on that GSDM plot, there is now evidence of +ve momentum (red shading at 30N) now propagating from the tropics & heading towards the extra tropics (above 30N) as a starting pistol towards poleward momentum setting off. The wavelength for frictional torque fluxes is lagged some 14 to 20 days to impact from source of origin to final destination (according to direction of fluxing).

Analysis of Azores ridging finds that this ridge is strongest under subdued frictional torque wavelengths across the tropics (stronger easterly trade wind inertia) and weakest when a switch to a +ve frictional torque has propagated +AAM anomalies into the extra tropics and in association therefore suppress the NAO (North Atlantic Oscillation). The ongoing -ve torque wavelength began (very strongly) in last third of November,  and has now reversed. Hence why in recent and ongoing modelling the Azores High has/is being dominant, reflecting the strength of that original signal, based on the lag times.

With directional flux now shifting, though not so apparent yet currently in 10 day modelling, over the festive period itself it is quite likely that there will be gradual signs modelled of the Azores High losing some of its grip & a look out for some sub tropical flow returning. Much then depends on how the polar cell responds and in respect of the movements of the polar vortex which continue to show disorganisation heading into the New Year - and when, perhaps, some more significant disruption occurs during January.

So it could be that the static pattern with chilly nights & sunny days down here in SW Europe starts to eventually become more warmer Atlantic influenced and at the same time, signs that associated Atlantic low pressure systems also start to undercut blocking structures across mid to higher latitudes. A trend to build ridging through Europe towards Iceland & Scandinavia - which retrogresses -ve inertia towards Greenland heading through January as the NAO turns more negative and there is a shift in the polar front southwards

In this sense, the extended January monthly modelling does have some credence. Time as always will tell.

41 minutes ago, MattH said:

The key feature here is the -ve FT tendencies at circa 50-60N, this is what you want to see if you wish to see a more amplified jet stream pattern. This is all linked to the Rossby wave packets and how they propagate northwards and eastwards from the tropics. The significant region of +ve Frictional Torque at 30-40N is linked to the MJO event and the associated -VP200 anomalies and associated Westerly Wind Burst near the Central Pacific that remains ongoing. If this were the opposite where frictional torque tendency is negative towards 30N it creates a negative inflexion point in the Equatorial Pacific and adds momentum to the jet stream downstream in the extratropics. A -ve FT regime at circa 30N, from my understanding, is what can 'prop up' sub-tropical anticyclones and it is the compensating momentum that increases the polar jet through the mid-lats.

This is just one piece of the puzzle, but what we are seeing now is what the likes of myself, Tamara, Catacol etc, touted as would arrive through Dec, but it has been delayed given the MJO evolution.

How about that?  Completed my post and poised to send, and then saw this. Which uncannily discusses the very same elements and to to look out for the same things...and even talks of "inflection points". Spooky. But no genuine collaboration between the two posts.

[Gowon]

2 hours ago, Catacol said:

It's definitely a factor and the one factor that I think was pointing in clearly the wrong direction going into the winter. As I have come to see it, high solar activity whips up the jet. Low solar leads to a less active jet. There are papers on it now, and I remember way back in the early days when it was rubbished by many including (from memory) the MetO and then, lo and behold, some proper research conducted and the above conclusion very broadly reached. We are not at solar minimum, but the hope is that one signal on its own will not drown out all the others. 

When we get to the end of the season I wonder where we will be on our ENSO analysis. Strong at the start of the season, predicted to wane to moderate by season's end. Part of the back loaded call was linked to ENSO. If Nino stays strong under a similarly strong solar umbrella than the outcome could be grim!

 

2 hours ago, blizzard81 said:

I agree with everything you say there

Hi both,

The last solar minimum didn't produce cold winters for us, so I doubt there is a connection?

[northwestsnow]

GFS = chilly Xmas

Edited December 19, 2023 by northwestsnow

[damianslaw]

I sense the dispondency in here today regarding the immediate outlook, would not be quite to the same degree, if christmas wasn't looming and if certain thoughts about cold prospects for the end of the month had not been touted, a double whammy knock down.

A more heightened blow affect has pervaded..

The old adage stick to the reliable, usually 5 days tops springs to mind, something I bring out time and time again when we see changes in the nearer short term scuppering medium term previous outlooks. I sometimes wish the models only went out to 5 days in this respect!

In the meantime its just a case of watching how far the polar troughs digs in time for christmas day, still alot of uncertainty how far south over the UK the colder air filters, Scotland at least still in with a good shout of a seasonal cold feel, this might extend further south.. but time will tell. 

[nick sussex]

2 minutes ago, northwestsnow said:

GFS = chilly Xmas

It’s a bit messy but shows a pretty weak jet and it could develop more interest.

The UKMO at day 6 is unfortunately very poor .