Model Output Discussion - Into Winter

[Ladyofthestorm]

It is telling that many of the models are pointing to an atypical el Nino winter for NW Europe. , blocking high pressure to our North and East . 

 

Where we expect above average temps and the prospects of  an Atlantic driven winter. 

We have none. 

 

Interesting that the all model ensemble run, global ... Looks cold for Europe. 

Take heed. 

[Uncertainty]

As @MATTWOLVES 3 says the zonal winds are getting into the actual - there’s an ssw on the way category 

As long as the monster Ural ridge verifies we’re going to be right in the game once the pacific starts to fire…

[Harsh Climate]

21 minutes ago, Tim Bland said:

Worth noting that the majority of the population haven’t seen any snow this past week or so...Note “population” not land mass… So something more than recent Synoptics are required for most areas 

Fair point. For me this is 3rd day running we've got atleast a dusting of snow with a light covering this morning.. Very memorable for this time of year. So maybe a bit IMBYism.. 

But look at the event parts of Cumbria had yesterday, the North East, parts of Scotland and a small part of Midlands have seen some snowfall.. So not exclusively in my kneck of the woods. 

Point is doesn't take much for unexpected events for good snowfall when ya get locked into -5 uppers for few days.. Unfortunately for the South it just wasn't your turn.

 

 

[Catacol]

Surprised there isn't more commentary on the outer edges of the ECM Op tonight. 

240h

Same general them as the GFS op and ensemble suites earlier today. I still dont think we will see the pattern click cold until later in the month, but from mid month we have undercutting and high tendencies backing west. Wouldn't rule out some wintry scenarios in the middle third despite the sense it will be a generally mobile pattern.

 

Edited December 3, 2023 by Catacol

[Dennis]

its back on track friends 

 

[WYorksWeather]

ECMWF ensemble. Flat as a pancake from a temperature point of view for London.

Colder for longer in Aberdeen.

And this time, the cold is hanging on better into Scandinavia.

Slightly more optimistic than the 06z GFS was looking earlier - let's see how this goes over the next few runs.

[Mizzle]

3 hours ago, Catacol said:

Yes - strong phase 7/8 progged by EPS also.

GWO now starting to climb back into Nino phases, 

supported by a solid rise in relative AAM

+EAMT starting to engage as a driver in this

courtesy of high pressure sweeping SE over the Tibetan Plateau. 

 

Teleconnective end result looks about as nailed on as it can be and given the speed of the MJO through the IO changes may occur at the early end of the “final third” envelope.

A SSW at the turn of the year on top?

 

I can't remember who mentioned it much earlier in the thread, but it was highlighted that an SSW could potentially scupper the prospects of cold if the teleconnections are aligned favourably. Is that the case or did I misunderstand?

[Empire Of Snow]

38 minutes ago, Harsh Climate said:

Fair point. For me this is 3rd day running we've got atleast a dusting of snow with a light covering this morning.. Very memorable for this time of year. So maybe a bit IMBYism.. 

But look at the event parts of Cumbria had yesterday, the North East, parts of Scotland and a small part of Midlands have seen some snowfall.. So not exclusively in my kneck of the woods. 

Point is doesn't take much for unexpected events for good snowfall when ya get locked into -5 uppers for few days.. Unfortunately for the South it just wasn't your turn.

 

 

Our snow "event" occurred again from WSW via more organised systems. Otherwise we would still be waiting for a shower to reach us from the NE and last around 15min. Ofc this setup doesn't benefit the south of the country. 

[bluearmy]

Day 6 on ecm was getting close to interesting and funnily enough the control had varied from the op a little by this time with a slightly more notable easterly across the northern half of the U.K. 

if the Atlantic trough is mis modelled at this point with some delay/less depth/ non appearance of the runner then that ridge could take hold to our north 

[Jason M]

25 minutes ago, Catacol said:

Surprised there isn't more commentary on the outer edges of the ECM Op tonight. 

240h

Same general them as the GFS op and ensemble suites earlier today. I still dont think we will see the pattern click cold until later in the month, but from mid month we have undercutting and high tendencies backing west. Wouldn't rule out some wintry scenarios in the middle third despite the sense it will be a generally mobile pattern.

 

Ooh, Spanish plume!!!! Does that mean i can turn my meeting off 

Looking through the GEFS earlier there was a an increasing number of runs building pressure over Iberia, so something like this isn't completely out of the question IMHO.

[LRD]

6 minutes ago, Jason M said:

Ooh, Spanish plume!!!! Does that mean i can turn my meeting off 

Looking through the GEFS earlier there was a an increasing number of runs building pressure over Iberia, so something like this isn't completely out of the question IMHO.

Every time I'm on a tedious work call on Teams I ask myself this very question

[Allseasons-Si]

Hi everyone,...just crept out of the regionals for a sec as it still is snowing here

this from CPC/NOAA looks nice towards day 14...

[pinball wizard]

41 minutes ago, Dennis said:

its back on track friends 

 

No offence but anyone could post a chart from the JMA and make case for cold!!

[WYorksWeather]

Been a few days since I did the ECM SST forecasts, so let's break them out again. Remember that a week ago we were showing major reductions in the SST anomalies by day 15, but in another update a couple of days later, this signal had weakened a lot. Let's see how it looks this time.

Currently, we have near-normal SSTs to our immediate SW and NE, milder than average near Greenland and Iceland, and much milder than average around the Azores. 

Here are the charts for day 5, day 10 and day 15. Throughout the period. we see a general trend towards decreased moderation of NE and direct W spells. The Azores continues to show very high SST anomalies, and the NW is still somewhat milder than average.

Hence, we really want easterly setups for notable cold, which may be more impressive than of late. A NW / SE jet stream alignment probably has a lower chance of delivering cold than usual, and there's a greater than normal chance of unusually mild conditions if we get any south-westerlies originating from the Azores.

  

[Ali1977]

This would be a good place to be by day 8 I think!! 

[blizzard81]

I actually still think the cold block to our north east is giving the models some headaches. The ecm op tonight is quite an eye opener and I can't believe it hasn't received much coverage on here this evening. 

[Met4Cast]

It’s not even worth speculating on the Det runs when the ensembles look like this. An absolute mess with no signal on a route forward.

[blizzard81]

3 minutes ago, Met4Cast said:

It’s not even worth speculating on the Det runs when the ensembles look like this. An absolute mess with no signal on a route forward.

Indeed. I've felt for the last couple of days that the models are in a state of flux. 

[WYorksWeather]

5 minutes ago, Met4Cast said:

It’s not even worth speculating on the Det runs when the ensembles look like this. An absolute mess with no signal on a route forward.

By the 17th December it is just laughable! Range from -12C to +14C on the 850s. By the way, I'm almost certain that +14C would be a record breaker for mid-December? What would that be under the right conditions - 20C at the surface maybe?

And of course -12C would be an interesting run up to Christmas...

I always find these ensemble charts interesting for precisely this reason - if you think as I do that the ensembles are kind of like possible worlds, it's interesting to think that there's a potential world where we're out in shorts and T-shirts in mid-December, and also one where we're prepping for an absolute snow-fest.

All interesting but nonetheless unlikely to verify. Then again, we all though that when 40C was first picked up by a rogue GFS run in early July last year...

[Howie]

9 minutes ago, Met4Cast said:

It’s not even worth speculating on the Det runs when the ensembles look like this. An absolute mess with no signal on a route forward.

Got no clue do they?

[Vikos]

Pub run, ordered on Wish

[LetItSnow!]

Just now, WYorksWeather said:

By the 17th December it is just laughable! Range from -12C to +14C on the 850s. By the way, I'm almost certain that +14C would be a record breaker for mid-December? What would that be under the right conditions - 20C at the surface maybe?

And of course -12C would be an interesting run up to Christmas...

I always find these ensemble charts interesting for precisely this reason - if you think as I do that the ensembles are kind of like possible worlds, it's interesting to think that there's a potential world where we're out in shorts and T-shirts in mid-December, and also one where we're prepping for an absolute snow-fest.

All interesting but nonetheless unlikely to verify. Then again, we all though that when 40C was first picked up by a rogue GFS run in early July last year...

Warmest I've ever seen was uppers of about 10-12C in December back on the 27th of December, 1983 but there may be instances of it being higher. That spell brought temperatures of 15-17C so you could imagine at least 17-19C being possible. I don't think it has anything more than approximately 1% chance of verifying!

[icykev]

25 minutes ago, Met4Cast said:

It’s not even worth speculating on the Det runs when the ensembles look like this. An absolute mess with no signal on a route forward.

Imo these two distinct clusters show the direction of travel around mid month. Teleconnections coming into play as yourself and a few others have suggested. One to watch 

Edited December 3, 2023 by icykev

[Eagle Eye]

There's some definite baroclinic tilt on the forecasted Stratospheric development as we get further into the future with the potential of some development into a warming episode. With this being the time of large Stratospheric zonal development, the shifting southwestwards of the upper Stratospheric vortex is important for initial weakening and that allows for quicker downwelling of wavebreaking with a non-stable vortex structure evolving. Quite a lot of SSW's are known to begin in the upper parts of the Stratosphere which are much more unstable than the mid Stratosphere with larger EHF's (Eddy Heat Flux) than the mid-stratosphere.

We have the initial large EHF's in the upper part downwelling, creating that tilt and then there's a quick upwelling connecting with the mid-stratosphere and that drives up into the upper stratosphere and I suspect beyond the current forecasting period will properly begin the wave breaking. This appears to be a very good setup at first sight, very interesting to see how close the initial weakening is, often that appears to be hardest to get recently.

The actual flux vectors setup is typical of pre-wavebreaking as well. What we need this to do is the eddy driver jet in the mid troposphere driving up with the tropical wave extension forcing baroclonic wave tilting between the troposphere and the stratosphere into the stratosphere as it does, to displace the vortex equator ward an most of the force appears to be looking towards doing that and suppressing vortex development. There's not enough poleward eddies on the surface with most of the EHF vectors pointing equatorwards or up in the atmosphere. However, that could and should change with the main event which is probably at the end of forecasting range where it's unreliable or out of forecasting range for now. If that equator ward displacement in the upper Stratosphere were to happen, it'd reverse the pole zonal winds. If you look right up to 1hPa, you can see that it's slowing down quite significantly already at this forecasted point.

Looking down towards the Tropopause at 192 hours, there's a very good setup if it were to happen as a 2-Wave pincer in the Stratosphere which it could do eventually. A Siberian wave development and Canadian wave development is a fairly good setup for the craved split that displaces the whole vortex.

So, all in all, Stratosphere looking good. The troposphere, who even knows.

 

Edited December 3, 2023 by Eagle Eye

[feb1991blizzard]

@Cheshire Freeze This run's right up your street - as you would say, dddddd strat-busters!