Model Output Discussion - Into Winter

[Cheshire Freeze]

GEM looks like the 18z GFS…so clear as mud again this morning!

[Cheshire Freeze]

With the amount of amplification upstream the 0z GFS could well go on to be a banger

 

[Daniel*]

People often rave about UKMO but that’s a substantial difference between 12z now more in line with others, Azores being a pain clearly we are not going to see major high lat blocking… whether we can get a wedge which forces the pattern south remains to be seen. Struggling to remember such a woeful period of modelling clearly a lot of complexity involved. There does seem to be growing confidence Scotland is going to be in that colder boundary leading into Xmas so a white Christmas does look to be on for some.

[Kentspur]

Anyone able to interpret this better? My understanding is that it's showing a clear trend to +NAO Jan to March periods and might explain why there were so many epic 1960s winters. And why so many more recent winters such as 1989-90 and 90s winters and recent ones have been so mild and poor. Is it the Hadley Cell expansion causing more +NAO winters/March's also?

Edited December 18, 2023 by Kentspur

[Mucka]

10 minutes ago, Kentspur said:

Anyone able to interpret this better? My understanding is that it's showing a clear trend to +NAO Jan to March periods and might explain why there were so many epic 1960s winters. And why siwinters such as 1989-90 and 90s winters and recent ones have been so poor. Is it the Hadley Cell expansion causing more +NAO winters/March's also?

The NAO is a measure of the atmospheric state not a driver of it, so the question would rather be are there more positive NAO Winters now and then, if so, why.

It is an interesting graph but there isn't nearly enough data to make any conclusions IMO.

[KTtom]

6 hours ago, danm said:

After countless times being burned over many, many years, I’ve learned that whilst I still pay attention to what’s being shown beyond 4 or 5 days ahead, I do not get in the slightest bit excited by cold and/or snowy charts at that range any longer. For all the advances in NWP, it is still the case that nothing is remotely guaranteed until we get to within about 96 hours. Too many small variables affect our chances here in the UK, any one of those can change at any point until 4 or so days away that makes the whole set up crash down like a pack of cards. 

It’s the price we pay for our geographical location! 

The other thing ive learned is to stick to the same 3 models and look for consistancy, the obvious 3 for me being GFS, UKMO and ECM. When you get ICON and JMA being rolled out you know its desperation time. There are so many models, ens out there look hard enough and you will find what you want to see. 

[TillyS]

Stormy run from the 0z GFS. I know it has it a habit of overdoing Atlantic storms, but sometimes it gets these right. This is just a selection of panels from a sequence of pretty wild days ahead, mostly in the north of the UK:

[TillyS]

1 hour ago, Daniel* said:

People often rave about UKMO but that’s a substantial difference between 12z now more in line with others,

Yes indeed. The UKMO was giving the coldest setups until now when it has backed away and as you say, more in line with others.

Interestingly, the MeteoGroup / BBC forecasters didn’t go along with the UKMO model. Would I be right in thinking they use the ECM foremost?

[nick sussex]

After yet more deliberations the jury is still unable to reach a verdict !

Sums up the Christmas week forecast !

The models do seem to be making a drama of the upstream pattern highlighted by the big changes in the UKMO.

At the moment the day itself looks to be on the cold side but snow wise too early to say although Scotland and northern areas look to have the best chance .

What happens into Boxing Day , varied options on the menu . 

The UKMO day 7 for example is trying to disrupt some energy se wards . You can see that circled red . A complication is the shortwave circled black near Iceland .

The ECM coming out now . We await its verdict !

Day 6 certainly looks better than the GFS .

Edited December 18, 2023 by nick sussex

[Vikos]

Meeehhhh… white Xmas at nearly 0%

[nick sussex]

6 minutes ago, Vikos said:

Meeehhhh… white Xmas at nearly 0%

Hold your fire for the day 7 . You might be surprised !

So we were not surprised ! Don’t really but its evolution from day 6 into 7 . 

Edited December 18, 2023 by nick sussex

[feb1991blizzard]

25 minutes ago, nick sussex said:

After yet more deliberations the jury is still unable to reach a verdict !

Sums up the Christmas week forecast !

The models do seem to be making a drama of the upstream pattern highlighted by the big changes in the UKMO.

At the moment the day itself looks to be on the cold side but snow wise too early to say although Scotland and northern areas look to have the best chance .

What happens into Boxing Day , varied options on the menu . 

The UKMO day 7 for example is trying to disrupt some energy se wards . You can see that circled red . A complication is the shortwave circled black near Iceland .

The ECM coming out now . We await its verdict !

Day 6 certainly looks better than the GFS .

That attempt to disrupt that low enough looks ropey as it is as it looks very round, even without the added complication of the shortwave near Iceland.

[feb1991blizzard]

It doesn't make it on ECM either.

[carinthian]

29 minutes ago, nick sussex said:

After yet more deliberations the jury is still unable to reach a verdict !

Sums up the Christmas week forecast !

The models do seem to be making a drama of the upstream pattern highlighted by the big changes in the UKMO.

At the moment the day itself looks to be on the cold side but snow wise too early to say although Scotland and northern areas look to have the best chance .

What happens into Boxing Day , varied options on the menu . 

The UKMO day 7 for example is trying to disrupt some energy se wards . You can see that circled red . A complication is the shortwave circled black near Iceland .

The ECM coming out now . We await its verdict !

Day 6 certainly looks better than the GFS .

Morning all, I would go with that Nick. Yes," another manic Monday " in the words of the old Bangles song (oh oh ). Pressure on the forecasting agencies to come up with the goods and predict Christmas pickings. Would not like that , thinking egg on their faces ! So from the safety of my arm chair and morning comfort of a strong cup of Yorkshire tea, what do the models show this morning, I would say still a lot of uncertainties but as a safe bet, go for a rather cold Christmas Day for many with possibly a bit of snow up north and be always a bit vague !  The rest of the holiday ? Think we could have problems out west as developments along the Polar front heading into Blighty. Even end of this week not nailed.

C

[Gizzy]

54 minutes ago, TillyS said:

Yes indeed. The UKMO was giving the coldest setups until now when it has backed away and as you say, more in line with others.

Interestingly, the MeteoGroup / BBC forecasters didn’t go along with the UKMO model. Would I be right in thinking they use the ECM foremost?

Yes I would be interested to know what model the met/bbc use as, though they do sometimes get it wrong, more often than not they get it right and that is both short and longer term.

Long time lurker in here and although this is a good place for the hints at longer term signals, bizarrely, it seems the closer it gets the more it goes wrong in here.

I do tend to pick up bits in here but always revert to the met longer term for confirmation.

[IDO]

After all, the models made a meal out of it; the initial thoughts that the end of December would move to a cold zonal pattern seem to be where the models now indicate. Looking at the London pressure mean (red line), that is classic zonality:

1.  2.  3. 

1. GEFS mean pressure - 2. GEM mean for comparison 3. Temp-wise, average fare. GEFS London

Looking at the D8-16 mean NH, nothing is showing for any amplification apart from the Canadian high. The above-average Euro heights dissipate after D12, which may help for a better UK trough into Jan (e.g. the OP retrogresses to the Azores).

 

[TillyS]

From the ECM’s own website, some wintry precipitation for Scotland on the 23rd and again the evening of the 25th. Nothing south of the border (Edit: maybe the Cheviots and Pennines).

 

The models are settling into consistency now. Colder for two or three days around 23rd to 26th but any wintriness mainly confined to high ground in the north.

Pretty windy at times over the next 7-10 days. There’s a lot of North Atlantic jetstream energy at the moment, so patterns are mobile. That introduces some finer detail uncertainty, especially wrt northerlies, but the models are more aligned on the pattern.

Edited December 18, 2023 by TillyS

[mountain shadow]

For the Christmas period, the ECM has moved towards the UKMO solution and is a little more applied.

Aside from that, any prolonged cold spell ( 5 days +) remains weeks away.

[Blessed Weather]

15 minutes ago, Gizzy said:

Yes I would be interested to know what model the met/bbc use as, though they do sometimes get it wrong, more often than not they get it right and that is both short and longer term.

Long time lurker in here and although this is a good place for the hints at longer term signals, bizarrely, it seems the closer it gets the more it goes wrong in here.

I do tend to pick up bits in here but always revert to the met longer term for confirmation.

MeteoGroup buy in data from the big 3 models ECM, GFS and UKMO and then use their own internal computer modelling plus human tweeking by their own meteorologists to arrive at the final forecast provided to customers such as the BBC. Full details in their own document:

https://medium.com/@meteogroup/the-making-of-a-weather-forecast-4ee5bfcc942e

[CoventryWeather]

Regardless of the next few days/weeks, the forecast today was poorly modelled. Currently raining quite heavily here, and showed absolutely nothing last night or this morning on met office forecasts. Shows a complete dry day. 

[Gizzy]

27 minutes ago, Blessed Weather said:

MeteoGroup buy in data from the big 3 models ECM, GFS and UKMO and then use their own internal computer modelling plus human tweeking by their own meteorologists to arrive at the final forecast provided to customers such as the BBC. Full details in their own document:

https://medium.com/@meteogroup/the-making-of-a-weather-forecast-4ee5bfcc942e

Thanks Blessed.

[Beanz]

8 hours ago, danm said:

After countless times being burned over many, many years, I’ve learned that whilst I still pay attention to what’s being shown beyond 4 or 5 days ahead, I do not get in the slightest bit excited by cold and/or snowy charts at that range any longer. For all the advances in NWP, it is still the case that nothing is remotely guaranteed until we get to within about 96 hours. Too many small variables affect our chances here in the UK, any one of those can change at any point until 4 or so days away that makes the whole set up crash down like a pack of cards. 

It’s the price we pay for our geographical location! 

Absolutely! Nothing more ridiculous than people posting 300hr precip and snow accum charts - and the same people still do it every year. 

[Gizzy]

Just now, Beanz said:

Absolutely! Nothing more ridiculous than people posting 300hr precip and snow accum charts - and the same people still do it every year. 

I agree, it is exciting to read but the reality is often way off. Its even worse if your like me, when you get excited with it all and tell the family there is a mighty freezing spell on its way with copious amounts of snow and we end up with a thirteen degree westerly haha.

[BartyHater]

Really struggling to work out where we are this morning. On the one hand it’s very disappointing to see the UKMO’s lurch away from colder, but at least the GFS has also lurched away from its super mild 18 horror show.

When in doubt, cliché it out…..more runs needed!

 

[Rob 79812010]

16 minutes ago, Gizzy said:

I agree, it is exciting to read but the reality is often way off. Its even worse if your like me, when you get excited with it all and tell the family there is a mighty freezing spell on its way with copious amounts of snow and we end up with a thirteen degree westerly haha.

I always hope they've forgotten when I tell them its gonna freeze. To be honest, I don't think they listen anyway!!