Model Output Discussion - moving into Winter

[MattStoke]

4 minutes ago, IDO said:

ECM ops have been shocking over the last few days with consistent outliers. No exception on the 0Z:

Ignore post D7 on this run as statistically it is useless.

Now that’s the definition of an outlier. Wow

[Penrith Snow]

Wow, stunning ECM, I love the Northern England Blizzard at +240, haven't seen a chart like that since 1979.

In Cumbria for example 850 temperatures stays below -7c from next Wednesday morning to the end of the run, ain't nothing marginal about those uppers.

GFS is better for the south but really at this range it's just variation on a theme, it's going to get damn cold if those runs verify.

And that's my only concern, that the cold is still 5 days away and with shortwave now in the mix this could still go wrong.

I have been in Southern Spain since early September and like the uk it's been exceptionally warm, landing at Manchester airport next Wednesday afternoon is going to be a shock! Andy

[nick sussex]

13 minutes ago, Jayces said:

Can't help thinking I read a variation of this every year from you Nick when something promising on the wintery front shows up. There's always a shortwave here or shift in a different direction there!

I'm looking forward to a surprise post along the lines of oh that all went really smoothly, enjoy the snow all

Still early days, winter has just started and no need for folks to throw on the towel just yet, the building blocks seem to be falling in place for an early taste of wintery weather for some.

Very funny ! In an ever changing world isn’t it nice to know some things stay the same ! 

I tend to look at the models and UK cold from what can go wrong and margin for error .

Once those factors are fed into my supercomputer and the all systems go threshold is met I’ll be happy to report that ! 

At the moment there’s still some changes likely within the overall set up and how far west the cold plunge occurs .

[NewEra21]

Thankfully ECM is a huge outlier with that low later in the run. And as we all know anyway, these lows more often than not trend further and further south in a cold set up as time draws nearer. Barely scraping the south coast usually!

[Anthony Burden]

Morning all.GFS/ECM along with other models showing a very cold blast from the north snow in many places,once again Atlantic lows trying to push in from the south southwest lot’s of uncertainty on how much inroads it can make against the cold heavey block.Could be winter wonder land.

[Skullzrulerz]

Good runs from GFS and ECM (bar that low at the end) this morning, the latter high risk but high reward.

Shame to be living the far south west as we are bound to miss out on the fun.

[Nick F]

2 minutes ago, IDO said:

ECM ops have been shocking over the last few days with consistent outliers. No exception on the 0Z:

Ignore post D7 on this run as statistically it is useless.

Think the differences between the models with handling the development of low pressure near the UK later next week is down to how they handle deep cold pool / upper vortex dropping south from Svalbard earlier in the week. EC moves a deeper vortex south towards the UK, which results in larger pressure falls further north over UK  than GFS which takes the upper vortex more into Scandinavia. can also see, below, the different shape of the Greenland high.

Don't think the models will resolve this upper feature dropping down from data sparse arctic well at this range, particularly when they differ as early as day 5 with the shape of the block over Greenland and the deep cold vortices being dislodged from the north pole as a result.

So perhaps not worth analysing too much detail and thus marginality later next week ...

[Light Without Heat]

10 minutes ago, Weathizard said:

Blimey, if Carlsberg did outliers….

They’d probably taste like dishwater.

Isn't Carlsberg dishwater run off anyway

[carinthian]

11 minutes ago, Lukesluckybunch said:

ECM mean is nice 850's between -4 and -8 throughout the run..the op was something of a outlier towards the end of run

Yep thats the feeling from the team over here. The milder air into mainland Europe and Southern Britain far too advanced ( ECM  latest op at 240t ) Their own latest figurations at 240 t show UK entrenched in a resilient cold air mass. Hope that helps . Our fine mesh model will start to produce snow predictions ( out parameter results for UK ) from Sunday for 72t in advance. I will keep you updated. 

C

[Geordiesnow]

10 minutes ago, IDO said:

ECM ops have been shocking over the last few days with consistent outliers. No exception on the 0Z:

Ignore post D7 on this run as statistically it is useless.

Just because something is an outlier, it does not mean it's wrong so no... It should not be binned. 

There is an element of risk of getting the northerly in quicker however it could be high reward but only if the cold air gets far enough south and has enough depth to it! The ECM 00Z op seems fairly simple, it pulls the set up too far north and west, still a very good run mind but because of that it does open the door to milder air in the south, high reward potentially if your in the right spot but dissapointment for others. 

Pleasing UKMO after yesterday's run but today's GFS is a dissapointment and I still have that feeling there's a chance the northey could end up being too weak to bring significant cold. GFS run has a feel your rewards will come if your patient enough but it never will. 

Getting not too far off the stage where even the details to an extent will be nailed on, I think the northerly is nailed but how cold will it be and what happens after if the trough does end up over the UK. 

[BLAST FROM THE PAST]

It’s. ‘One of those’ days guys.  From when I started at 0500 it’s now colder….a getting colder day.  Love it

 

BFTP

[Eastern Scotland WX]

4 minutes ago, Geordiesnow said:

Just because something is an outlier, it does not mean it's wrong so no... It should not be binned. 

There is an element of risk of getting the northerly in quicker however it could be high reward but only if the cold air gets far enough south and has enough depth to it! The ECM 00Z op seems fairly simple, it pulls the set up too far north and west, still a very good run mind but because of that it does open the door to milder air in the south, high reward potentially if your in the right spot but dissapointment for others. 

Pleasing UKMO after yesterday's run but today's GFS is a dissapointment and I still have that feeling there's a chance the northey could end up being too weak to bring significant cold. GFS run has a feel your rewards will come if your patient enough but it never will. 

Getting not too far off the stage where even the details to an extent will be nailed on, I think the northerly is nailed but how cold will it be and what happens after if the trough does end up over the UK. 

GFS is fantastic lol, nice slack easterly across the UK and it only strengthens later on. Lots of snow showers for the E. Northerly is good but snow risk reduced.

[Chesil View]

3 minutes ago, BLAST FROM THE PAST said:

It’s. ‘One of those’ days guys.  From when I started at 0500 it’s now colder….a getting colder day.  Love it

 

BFTP

Love those days too. Blast.

[TSNWK]

The way ECM blows up the low to our south west tmhas two precedence.

1 We are seeing in effect what hsppens all the time in Western Atlantic in that cold air spilling off a land mass into the ocean creates a low pressure, just this time its off euro continent instead of American 

2nd similar thing happened to end 2018 beast.

So I'm putting more confidence in day 9 and 10 than want too 

[nick sussex]

You çan see what causes the blowing up of the low if you look at that blue blob heading sw just to the northeast of the ECM low . This parcel of lower heights as it phases with the low adds to the deepening .

The depth of the low for newbies effects its track so in effect the deeper the low the more ne momentum you get .

You really want to see a shallower feature moving ene and then the block adding enough forcing to disrupt that energy more east .

With snow there is of course a lot of IMBYISM which is understandable.

As a rule the how far north the polar front goes with these lows moving in shows the strength of the blocking .

Although of course everyone wants the fun of that frontal snow it’s not possible to please everyone and longer term cold spells rarely take that too far north as that signifies the Atlantic gaining the upper hand and the block giving up the fight .

The bellwether for that cold extension is energy disrupting east through the Channel and the block forcing beating back the low which of course means the frontal snow staying further south .

Given the unstable flow earlier there should be plenty of snow opportunities so let’s hope there’s enough to go around and everyone can join in the fun .

 

 

[Mike Poole]

ECM clusters T120-T168:

Clusters 1 to 3 nicely illustrate the easterly or westerly extent of the initial cold plunge, with cluster 2 the most westerly (including the op), cluster 3 the most easterly and cluster 1 in the middle, the orientation of the block being important.  Cluster 4 rather different with heights already gaining in Scandi.

T192-T240:

Need to know where the cold is already to properly comment on these, but cluster 3 has the developing story this morning of the dual Greenland Scandi highs - one to watch re prolonging longevity of the spell.

There is only one cluster for T264+ so that won’t tell us anything, besides, there’s enough going on before that!

Edited December 2, 2022 by Mike Poole

[Snowyowl9]

GEM to to the longer GFS outlook..keeps the easterlies going..

GFS has a gold star award though..

 

[I remember Atlantic 252]

4 minutes ago, Eastern Scotland WX said:

GFS is fantastic lol, nice slack easterly across the UK and it only strengthens later on. Lots of snow showers for the E. Northerly is good but snow risk reduced.

I'd rather northerly! E'lys are not always cold, like next few days still fairly mild before northerly arrives on Wed, FI low on EC, looks very snowy for a time, but too far north for the south to avoid a thaw

[BarometerCat]

  Slight noob(ish) question but looking at that 528 dam line/thickness, does this strongly suggest higher probability of wintery stuff from about next Thursday?

 And this looking like cold uppers  (for Mids in this case) across the near period into mid December?

Looking good, yes? 

Edited December 2, 2022 by B-C

[mhielte]

5 minutes ago, TSNWK said:

The way ECM blows up the low to our south west tmhas two precedence.

1 We are seeing in effect what hsppens all the time in Western Atlantic in that cold air spilling off a land mass into the ocean creates a low pressure, just this time its off euro continent instead of American 

2nd similar thing happened to end 2018 beast.

So I'm putting more confidence in day 9 and 10 than want too 

It should definitely not be discounted, but the intensity and suddenness of the low as well as the lack of support for it (currently) means it remains a very unlikely verification, IMO.

[Geordiesnow]

10 minutes ago, Eastern Scotland WX said:

GFS is fantastic lol, nice slack easterly across the UK and it only strengthens later on. Lots of snow showers for the E. Northerly is good but snow risk reduced.

It takes a while to get the significant cold in(uppers of  -8) and if its too ENE'ly early on then the warm north sea will come into play. Feels likes it's "jam tomorrow" type of stuff on this GFS run. 

[Anthony Burden]

12 minutes ago, Nick F said:

Think the differences between the models with handling the development of low pressure near the UK later next week is down to how they handle deep cold pool / upper vortex dropping south from Svalbard earlier in the week. EC moves a deeper vortex south towards the UK, which results in larger pressure falls further north over UK  than GFS which takes the upper vortex more into Scandinavia. can also see, below, the different shape of the Greenland high.

Don't think the models will resolve this upper feature dropping down from data sparse arctic well at this range, particularly when they differ as early as day 5 with the shape of the block over Greenland and the deep cold vortices being dislodged from the north pole as a result.

So perhaps not worth analysing too much detail and thus marginality later next week ...

High Nick,totally agree could go down to 48 hrs /72hrs before a more positive picture is shown,but the north looks likely to get a lot of the white stuff.The south is 50/50 at present but as you say positioning of the high plus the heavey cold column of Arctic air.

[Singularity]

What makes the ECM 00z suspect later on isn’t that it develops a deep low, that’s reasonable if such low heights make it so far southwest. It’s that the low becomes extremely intense, putting it right in the uppermost reaches of what’s physically feasible… that makes it an inherently unlikely outcome.

There are plenty of ensemble runs with deep lows heading east into mainland Europe with a flat northern flank. As usual it’s a game of chance for the south while in the north it’s more a question of how much will fall from the sky to begin with.

Still, I do wonder just how much more the blocking pattern might continue to be adjusted, altering how close high pressure is to our north.

[Met4Cast]

Longer term.. A huge -EAMT event is currently on-going highlighting our retrogression signal & we're seeing a sharp decline in the AAM as a result. The MJO is forecast to re-emerge and run through phases 5/6/7 mid December perhaps supporting a renewed block later in Dec.

Stratospheric zonal winds are forecast to be below average - I'd expect to see blocking beginning to wane 20th-25th but perhaps re-developing again towards the new year. May need a more amplified MJO signal for the above though given a likely -ve AAM at that juncture.

With that in mind - Potential for a below average December overall, perhaps significantly so (-1/-1.5c) with a further potential for renewed blocking into early January, presuming the timing of the new MJO signal can be trusted to play out as currently forecasted.

[jules216]

It appears now that us in Slovakia will end up on the wrong side of the low with plenty of rain. To me its a 2020 rather then 2010 scenario. For now I am at least enjoying some frost with now regular minimas of below -6°C.