Model Output Discussion - Into Winter

[Premiere Neige]

21 minutes ago, MATTWOLVES 3 said:

Firstly folks I would like to say a massive thanks for all the well wishes I've received from many of you over the loss of my best mate and dad. I showed them to my mom and she was genuinely moved. Its given me a lift that so many show so much care and sympathy during difficult times. Your an amazing bunch and I really hope you get all the rewards you crave for.

For the weather I said a while back that backend of December next month could change. And I'm seeing from a few ens that the pv could be about to be displaced maybe even a split....I feel your pain regarding the way things have gone wrong for this latter part of this month....but do remember we are not alone...The USA has been very mild and largely snowless also!

No downgrade from Exeter regarding colder conditions perhaps becoming more likely next month. We have plenty of time and I feel the pattern will be completely shook up post Xmas.

Once again...much love guys and gals...you've cheered up this rather sad individual right now. And I will continue to try and inject a positive vibe into this gr8 thread.

Sorry to hear your sad news @MATTWOLVES 3

[Cold Winter Night]

6 hours ago, Cold Winter Night said:

After Christmas, the extended ensemble output is now more convincingly pointing at the combination of a Pacific Coast Ridge-Labrador Trough-East Atlantic Ridge pattern I mentioned in earlier posts.

This pattern is now well reflected in the extended clusters:

After I wrote this in the afternoon, it's nice to see variations of the same theme from the ensemble reflected in the later frames of the GFS and ECM Operationals.

GFS is slower, with the "East Atlantic" ridge over Scandinavia:

ECM sets it up sooner, with the ridge much further West over Iceland:

But the direction of a Ridge-Trough pattern over Canada, with the next ridge in the East Atlantic sector is the same.

[Sweatyman]

6 minutes ago, Purga said:

A very marked D10 difference between ECM 0z & 12z just highlighting how much uncertainty there is.

0z                                                                   12z

crazy! massive difference

[Mucka]

On 10/12/2023 at 17:40, Mucka said:

Big Picture and why cold spell/snap is probable in the  run up to Christmas.

Don't worry about FI charts or how flat the longwave is at 168, it is about the forcing of the Euro trough and upstream amplification post 168 as we know we will have a UK high with the jet forced over the top out to then,

The Euro trough will be  a big player and comes prior to any retrogression and Atlantic blocking.

GFS has been modelling it to push W and then NW phasing with the Atlantic trough or weakening heights to our W and causing toppler flatter scenarios until this afternoon.

Here is GFS 00z handling of the trough, the purple arrows and lines show movement and forcing pattern through the important period 15th to 18th Dec.

 

And below is the 12z over the same period for comparison.

And here is UKMO for Dec 17th, note the Euro trough.

 

So long as the Euro trough does not move NW and phase with the upper trough and prevent retrogression of the high we have a good chance because the other alternatives should all lead to at least a cold snap.

The rest is down to getting a nice clean transition of the Arctic trough W to E and hoping we don't get any spoilers preventing ridging into Greenland,

Even if it phases early as with previous runs and GEM we still have a shot, albeit a delayed one with more potential hurdles and I would say this mornings ECM run was dubious at best.

So personally I would favour cold with the caveat that FI longwave patterns even when favourable aren't always a perfect guide to what weather our small Island will receive.

 

 

 

And so it came to pass

that Christmas was alas

not white as I'd forecast.

 

[DOdo]

Today is December 18th not 22nd or 23rd but 18th. We have a full week to go.  Things can change

[Gregulator]

Sometimes if feels like we are fishing in a pond with no fish

[The PIT]

4 minutes ago, Sweatyman said:

crazy! massive difference

Not really models tend to struggle that far out unless the conditions are really benign i.e weak jet stream.

[MP-R]

2 hours ago, Day_9 said:

Tbf we get more white easters than xmas’

Not this myth again… comes out every year

[cyclonic happiness]

11 minutes ago, Mucka said:

 

And so it came to pass

that Christmas was alas

not white as I'd forecast.

 

there's still a chance......do you have a lamb to slaughter to the gods??

[WYorksWeather]

7 minutes ago, MP-R said:

Not this myth again… comes out every year

I wonder whether the stat would work e.g. for Valentines Day vs. Christmas Day? Or the start of meteorological Spring i.e. 1st March vs. Christmas Day? Anyway, taking things a bit off topic.

To get back to the models, the GFS 12z OP appears to have been a mild outlier, so all is not yet lost. Possibly enough in the ensembles to not rule out a White Christmas further south, odds against but a better chance in Northern England, and good chances for Scotland. I would say it all depends on where you are in the country as to whether there's any cause for optimism.

[WYorksWeather]

In the short-term, today's UKV still looks quite nasty for Thursday.

I think a good proactive decision from Exeter to issue the yellow warning early.

[Harsh Climate]

1 minute ago, WYorksWeather said:

In the short-term, today's UKV still looks quite nasty for Thursday.

I think a good proactive decision from Exeter to issue the yellow warning early.

Just be a typical windy day in Yorkshire.. 

 

 

[nick sussex]

Oh dear another wild goose chase ! 

Having stolen the Xmas pressies and trashed the tree the ECM wants to make up .

Thanks but no thanks ! 

Oh okay then one last heave of hope ! 

 

[WYorksWeather]

Just now, Harsh Climate said:

Just be a typical windy day in Yorkshire.. 

 

 

Yeah it's not that unusual, hence the yellow. Probably need a bit more certainty about where, if anywhere, will see 80mph+ for it to be amber-worthy.

[snefnug]

24 minutes ago, Mucka said:

 

And so it came to pass

that Christmas was alas

not white as I'd forecast.

 

Personally I blame the Greg Lake Effect.

[Harsh Climate]

Just now, WYorksWeather said:

Yeah it's not that unusual, hence the yellow. Probably need a bit more certainty about where, if anywhere, will see 80mph+ for it to be amber-worthy.

I think for the western isles of Scotland and any high-sided vehicles headed north maybe over the Pennines, they want to stay tuned.. Anywhere else any damage should be quite sporadic, Blanket yellow warning certainly warranted like ya say.

[cheeky_monkey]

49 minutes ago, blizzard81 said:

 

 

that really is an incredibly chart for NA ..above freezing right across the continent almost touching the arctic ocean in places 

[BartyHater]

 

9 minutes ago, nick sussex said:

Oh dear another wild goose chase ! 

Having stolen the Xmas pressies and trashed the tree the ECM wants to make up .

Thanks but no thanks ! 

Oh okay then one last heave of hope ! 

. 

Edited December 18, 2023 by BartyHater

[carinthian]

Evening , going by that fax chart ,looks like Met Office will be ramping up a powerful wind potential during Thursday. 82mb difference between Southern Scandinavia and the high to the SW of British Isles centred over the Atlantic.  Models all out of sync at the moment. Not only Christmas period forecast  unpredictable at the moment but the Winter Solstice  forecast even in jeopardy. Think some rapid changes over the next few days.

Edited December 18, 2023 by carinthian

[stodge]

Evening all

ECM at T+240 does throw the live grenade into the sack of presents but as others have opined it's hard to take seriously until and unless we see some support.

It's always looked like a milder interlude through Christmas and New Year especially for the south but perhaps wetter than I had first thought with a succession of shallow LP moving through the British Isles. As to the start of 2024, no real clues - glancing at the 10HPA on GFS still piques the interest for a strong warming but I doubt we'll see any benefit as all it will do initially is knock the PV back over to our side of the northern hemisphere so if I had to hazard a forecast for the first part of January, I'd go with unsettled, possibly stormy at times and mild.

 

 

[northwestsnow]

EC I'm being trolled by a computer model 

If day 10 comes in I'll plat fog.

 

[BartyHater]

13 minutes ago, nick sussex said:

Oh dear another wild goose chase ! 

Having stolen the Xmas pressies and trashed the tree the ECM wants to make up .

Thanks but no thanks ! 

Oh okay then one last heave of hope ! 

the cheek. 

Edited December 18, 2023 by BartyHater
Wrong person answer

[Laurence Hill]

3 minutes ago, carinthian said:

Evening , going by that fax chart ,looks like Met Office will be ramping up a powerful wind potential during Thursday. 82mb difference between Southern Scandinavia and the high to the SW of British Isles centred over the Atlantic.  Model all out of sync at the moment. Not only Christmas period forecast  unpredictable at the moment but the 

You didn’t finish Carinthian, especially as you are one of the few sane posters at the moment

[AO-]

5 minutes ago, stodge said:

Evening all

ECM at T+240 does throw the live grenade into the sack of presents but as others have opined it's hard to take seriously until and unless we see some support.

It's always looked like a milder interlude through Christmas and New Year especially for the south but perhaps wetter than I had first thought with a succession of shallow LP moving through the British Isles. As to the start of 2024, no real clues - glancing at the 10HPA on GFS still piques the interest for a strong warming but I doubt we'll see any benefit as all it will do initially is knock the PV back over to our side of the northern hemisphere so if I had to hazard a forecast for the first part of January, I'd go with unsettled, possibly stormy at times and mild.

 

 

At least EC is consistent in shaking up the pattern albeit in the FI. It has taken several runs where the vortex gets punches, let alone the EC00. This run is a nice example of how something wintry might pop up in a few days. The past, november 2010 as the most recent example, has shown nice similarities to this run. Not to get too exited, but I really like this operarional.

Edited December 18, 2023 by AO-

[carinthian]

3 minutes ago, Laurence Hill said:

You didn’t finish Carinthian, especially as you are one of the few sane posters at the moment

Sorry Laurence, pressed submit button to soon ? Have edited.

 Must be getting excited about my Christmas visit back to blighty !