Model Output Discussion - Into Winter

[johncam]

12 minutes ago, TSNWK said:

So the ec controls end like this….

Yep terrible , but a lot of water under the bridge before then 

[ItNeverSnowsInWindsor]

43 minutes ago, bluearmy said:

What ? Cumbria ?

the cold over Scandinavia is deep and will indeed be tough to shift 

the cold over us without a cold dense block across nw Europe will not hold back the less cold uppers in our longtitude 

Encouraging ens as week 2 progresses with plenty of amplification on show 

The cold air (including snow cover) needs to be over the whole of us not just the North to cause problems with its displacement!

Close but no cigar down South as per usual!

Edited December 2, 2023 by prolongedSnowLover

[WYorksWeather]

Not seeing anything overly mild on the ECM charts tonight. I think some people forgetting what normal is for the time of year - temperatures by day in the high single figures and by night in the low single figures are just average. It's only if we start seeing daily means approaching double figures that I'd call it mild weather for the time of year. This looks to me like a reversion to the mean, nothing more.

 

GFS relatively similar, though overall the ensemble is somewhat less keen on hanging onto the colder air further north.

 

There also remains a cross-model consensus to retain the cold into western Scandinavia (using the Oslo chart) at least up to day 7,  after which the signal diminishes, but nothing much to be worried about. 

Here's GFS, GEM, ICON and ECM:

   

[Cambrian]

The 12z ECM ensemble mean at day 6 is eye-catching, with a two-pronged amplification attack (hey, great name for a band that - Amplification Attack!) on the Arctic. 

One up through Novaya Zemlya and the other up through the Norwegian Sea to Iceland. Leaves a lovely cleft for lower heights to sink through Scandinavia and settle into Europe. 

 

These help keep the overtly disrupted, extension of the Atlantic trough aligned southeast into Europe through the UK and Ireland, which in turn is serving to drive more heights northwest toward Iceland, further hindering the eastward progress of the trough.

It’s a particularly interesting setup for how precarious it is - and despite the supportive teleconnections, for how surprisingly reticent the Atlantic is to march on through. 

[johncam]

26 minutes ago, WYorksWeather said:

Not seeing anything overly mild on the ECM charts tonight. I think some people forgetting what normal is for the time of year - temperatures by day in the high single figures and by night in the low single figures are just average. It's only if we start seeing daily means approaching double figures that I'd call it mild weather for the time of year. This looks to me like a reversion to the mean, nothing more.

 

GFS relatively similar, though overall the ensemble is somewhat less keen on hanging onto the colder air further north.

 

There also remains a cross-model consensus to retain the cold into western Scandinavia (using the Oslo chart) at least up to day 7,  after which the signal diminishes, but nothing much to be worried about. 

Here's GFS, GEM, ICON and ECM:

   

High single temps are only now the norm for December, used to be a lot lower , sign of the times.

[WYorksWeather]

11 minutes ago, johncam said:

High single temps are only now the norm for December, used to be a lot lower , sign of the times.

You're right that more recent averages have risen a bit, but even 'back in the day' if we look at things like the Met Office CET averages for 1961-1990, the average max was still 7.2C in December. And that's for December as a whole, so at this time of year specifically, probably round it up to about 8C.

[LRD]

No comments on the 18z GFS sums it up. Ensembles are looking less and less cold (850s-wise) with each run too. Iberian heights too prevalent for my liking

But the Met Office longer term updates continue to hold out some hope

Edited December 2, 2023 by LRD

[Don]

1 hour ago, TSNWK said:

So the ec controls end like this….

T-shirt and shorts at the ready!! 

[mountain shadow]

11 minutes ago, LRD said:

No comments on the 18z GFS sums it up. Ensembles are looking less and less cold (850s-wise) with each run too. Iberian heights too prevalent for my liking

But the Met Office longer term updates continue to hold out some hope

Looks fantastic to me, with a proper ridge into Greenland.

It's quiet because loads are getting snow in Wales, England and Scotland. 

[Met4Cast]

Short term crap. 

Long term good. 

 MJO progression continues on track with recent modelling updates amplifying the next WWB event in the Pacific even further, possibly the strongest and most sustained WWB so far this El Nino. This should drive GLAAM sharply upwards. A period of less cold (probably not excessively mild) is likely, lots of rain into the south too for example. Don't be surprised to see very blocked patterns appearing at the end of GFS runs in around 10 days time. 

Tick..tock.. 

[LRD]

3 minutes ago, mountain shadow said:

Looks fantastic to me, with a proper ridge into Greenland.

It's quiet because loads are getting snow in Wales, England and Scotland. 

At Day 10. If that comes into view 96 hours out then fair enough

[WYorksWeather]

Going to take my GFS chart from the 12z for London, and see what happens vs. the 18z as the ensemble rolls out.

So far, out to the 8th, it looks fairly similar. Squinting at it, it's ever so slightly later with the arrival of mild (breaking through the mean early on the 8th rather than late on the 7th), but has a slightly higher peak.

Will have to wait a little longer to see where the ensemble goes later in the run.

[Cheshire Freeze]

D10 EC and 18z GFS look very similar to my eyes. 

[Tim Bland]

That’ll Do

[LRD]

Just now, Tim Bland said:

That’ll Do

Mild for the UK and the heights in Greenland about to collapse. Met4cast's excellent MJO commentary the one (significant?) straw

[Tim Bland]

6 minutes ago, LRD said:

Mild for the UK and the heights in Greenland about to collapse. Met4cast's excellent MJO commentary the one (significant?) straw

Wouldn’t say Greenland  high will definitely collapse … if the low sinks into Europe and props it up

Edited December 2, 2023 by Tim Bland

[LRD]

1 minute ago, Tim Bland said:

Wouldn’t say green high will definitely collapse … if the low sinks into Europe and props it up

Heights randomly hold on just south of Greenland but it all looks flimsy. I realise it's all moot at that range and it is encouraging to see high pressure wanting to build to our NW at all but I ain't convinced

[LRD]

In FI the building pressure over south Europe predictably drags the north Atlantic High down to it. It'll be nice and frosty but a few days later it'll all collapse to a Euro High. Miles out so nothing to worry about but that's the latest GFS run

[LRD]

But the EC46 (which I don't necessarily rate) seems to have flipped to potential cold from the 18 Dec

Pressure is too high over Iberia but it's something to work with

Could be worse

 

Interesting

[WYorksWeather]

4 minutes ago, SollyOlly said:

Yep, I see your point. But having some historical frame of reference is surely helpful...if we use rolling averages, then the creeping warming seems 'normal' rather than being able to see its true impact. Just my view, I accept that other see it differently.

There is also a weather regime effect. Don't want to derail this thread too much, but hope this is still considered relevant, as it does have implications for e.g. model output showing cold and/or blocked patterns.

Just a moment...

RMETS.ONLINELIBRARY.WILEY.COM

Quote

In Europe, the increase in temperatures caused by climate change has been particularly fast in the cold season. Although the magnitude of this change is relatively well known, less research has been done on how the increase of temperatures is manifested in different large-scale weather types, called weather regimes. For example, one could expect that the weather patterns in which air is flowing from the rapidly-warming Arctic would have warmed faster than other weather patterns in recent decades. Here we show that such an asymmetric warming actually occurs in the four Euro-Atlantic weather regimes. In northern Europe, the weather regime which is typically associated with cold airmasses from the Arctic (NAO–) has warmed about 25% faster than the cold-season days on average, and about 60% faster than the regime where the air flows from the North Atlantic (NAO+). Consequently, the weather regime that on average brings the coldest weather is warming the fastest in a large part of northern Europe. In contrast, the weather regime that typically brings the warmest weather has warmed the slowest, especially in the continental Europe. Our results provide a new perspective on the reported decrease of sub-seasonal temperature variability.

Useful chart:

In short, there is a higher bar to clear, even within the -NAO regime which is best for cold in our part of the world, to have it be cold enough to deliver anything wintry.

Here's another chart from the same paper which illustrates this effect very well:

[The Enforcer]

5 hours ago, Ali1977 said:

ECM is crazy for wales, things shifted south a little!! 

 

rain turning back to snow as it clears Monday night!! 

 

5 hours ago, Metwatch said:

Parts of the north and north west could really get a dumping by next Weds - Thurs, follwing today's event in parts of the Lake District.

Waiting for some snow tonight down here, fingers crossed! I'll be in the Midlands thread mostly tonight if anyone from there is in here, join that one!

Ice day here, still -1C DP 0C, precipitation heavy (yellow echoes on the radar) and it's still rain. Don't hold your breath.

Edited December 3, 2023 by The Enforcer

[Norrance]

Please stick to comments on the models in this thread. Thanks.

[WYorksWeather]

10 minutes ago, johncam said:

Sorry they weren't that high up here 5.6 C was ave high ,not everyone stays in the south 

Sorry yes was replying quickly - forgot to take account of your location. Based on Coatbridge, your nearest station would be Salsburgh. Average high is 5.4C in Dec (so somewhere 6C ish given we're in early Dec). On 1961-1990 your average high is 5.0C, so there is a small increase.

Here's your GEFS plot from the 18z. Mostly in line to a little below the relevant averages beyond the current cold spell, and/or no signal.

[WYorksWeather]

In any case, continuing to look at model output, and comparing the 18z to the 12z, we don't see much of a difference on the ensembles, except a little less spread later on. The lesson I think is to not get too hung up on the individual OP runs - there's really nothing much to see here from an ensemble perspective. Probably all you can say is an increased chance of near-normal temperatures, with a reduced chance of anything overly cold or mild compared to the 12z. Net result being that the mean is almost unchanged.

 

More runs needed...

[alexisj9]

2 hours ago, Don said:

T-shirt and shorts at the ready!! 

Nah definitely not warm enough for that.