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moomin75
20 December 2022 10:10:11
No surprise here that GFS's backtrack is now pretty much complete. 

No doubt someone will come on to say it still looks incredible, but it really doesn't.
Wet and mild for the majority sums it up.
Witney, Oxfordshire
100m ASL
Rob K
20 December 2022 10:14:16

No surprise here that GFS's backtrack is now pretty much complete. 

No doubt someone will come on to say it still looks incredible, but it really doesn't.
Wet and mild for the majority sums it up.

Originally Posted by: moomin75 



The majority being Kent and Sussex, presumably? 😉

UserPostedImage
Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome
+1
Jacee
20 December 2022 10:14:20
A matter of a couple of hundred miles will make a huge difference, just look at the cold vs mild battleground on the 06z GFS!

UserPostedImage

Given the differences at just three days ahead with how the low in the Atlantic is modelled, I would expect to see further changes for the festive period and beyond.

 
Jacee, Hucknall (Notts) 😽 x
+1
Matty H
20 December 2022 10:17:09
For what it’s worth (nothing really) the iPhone weather app was showing snow after Xmas yesterday for here. Now shows the mild weather continuing through the Xmas period

I don’t know what model it gets it’s data from, but it’s more of a novelty app as it’s utterly useless beyond a couple of days, as they all are generally. 
Yate, Nr Bristol
Say NO to misogyny 
https://human-rights-channel.coe.int/stop-sexism-en.html 
Rob K
20 December 2022 10:17:22
Anyone calling definitively mild for the Xmas period (or definitively cold) is just guessing at this stage. Global models are not going to have nailed down the boundary at this stage.

But JFF:

UserPostedImage


@Matty H I was curious about the iPhone app and I looked into it a while back. It uses data from the Weather Channel which comes from IBM's own weather model. Whether it uses an operational run or an ensemble mean I don't know. I generally find the app much improved recently, in terms of giving alerts for incoming showers etc, it is pretty good. But as it goes out 10 days it will always fluctuate a lot at times like this!
Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome
fairweather
20 December 2022 10:17:53

The GEFS comprises a control run and 30 perturbations, none of which are excluded.

The Op run is referred to, correctly, as an outlier when it falls is outside the spread of the ensemble suite.

As for the meaning of ‘very mild’, ‘mild’, ‘cold’ or ‘very cold’, it should be relative to the normal for that location and time of the year. Right now, for London, the normal maximum is around 9c and the minimum around 5c. If the forecast was for a high of 5-6c I’d call that ‘cold’; if it was down around 2-3c I’d call that ‘very cold’.  For above normal, I’d call 11-12c ‘mild’ and 14c+ ‘very mild’.

As for the Xmas weather, I agree with you. Things are finely poised still but current output would favour mild for the far south and cold for much of Scotland, with something of a guessing game across the 400 odd miles between the two.

Originally Posted by: Gandalf The White 


Yes that is how a layman would perceive it and whoever did, it was one in that case on December 31st by that definition. But for the reasons explained a statistician or modeller wouldn't call it an outlier just because it was the furthest from the mean.
S.Essex, 42m ASL
David M Porter
20 December 2022 10:20:27

No surprise here that GFS's backtrack is now pretty much complete. 

No doubt someone will come on to say it still looks incredible, but it really doesn't.
Wet and mild for the majority sums it up.

Originally Posted by: moomin75 



Not sure I see any backtrack taking place in this chart, Kieren:

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=gfs&var=1&run=6&time=168&lid=OP&h=0&mv=0&tr=6#mapref 

 
Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
Downpour
20 December 2022 10:29:29
I think it's all to play for beyond Christmas Day Kieron. 

Regarding Christmas Eve / Day I think mild and largely forgettable weatherwise for the majority is right.

However, we might yet squeeze a dry day out on the 25th which would be a vast improvement on recent years!
Chingford
London E4
147ft
moomin75
20 December 2022 10:32:01

I think it's all to play for beyond Christmas Day Kieron.  Regarding Christmas Eve / Day I think mild and largely forgettable weatherwise for the majority is right. However, we might het squeeze a dry day out on the 25th which would be a vast improvement on recent years!

Originally Posted by: Downpour 

 Beyond Christmas, yes, I agree.But the chance of a cold Christmas Day is now just for the far north.​​​​​​​As I said yesterday though, I'd happily give up a chance of a White Christmas for a more sustained wintry spell after it.  
Witney, Oxfordshire
100m ASL
ballamar
20 December 2022 10:34:28
Record high pressure on meteociel at 222h - that will be difficult to budge 10300 hpa
Jacee
20 December 2022 10:39:28

Beyond Christmas, yes, I agree.But the chance of a cold Christmas Day is now just for the far north.​​​​​​​As I said yesterday though, I'd happily give up a chance of a White Christmas for a more sustained wintry spell after it.  

Originally Posted by: moomin75 



I agree with you when taking the GFS 06z in isolation, but when comparing that operational to the ECM 00z mean and the most recent MOGREPS suite you'd have to say more places than just the far north (I assume you mean the Scottish borders northwards?) are in play for a cold Christmas. To a lesser extent, GEM and ICON can also be added to the latter group (GEM for instance does bring the -5C line into the southern half of northern England) ☺

 
Jacee, Hucknall (Notts) 😽 x
idj20
20 December 2022 10:42:35
It is all feeling like a cartoon drawing coming out wrong. That's when I scrunch it up into a ball ready for chucking into the bin and will try again with fresh eyes in a few days time.  
Folkestone Harbour. 
Heavy Weather 2013
20 December 2022 10:53:09
I took a few days away after the cold spell hoping for clarity when I returned. 

It seems there is none, and as ever this means there is always hope. Seeing the winter wonderland dissapear was proper sad.
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Phil24
20 December 2022 11:14:24

This guy is excellent

https://twitter.com/judah47/status/1604850030812499968?s=46&t=8_8jnqMd8jyBD142FSOPaQ 

Originally Posted by: Matty H 



Been following him for some time. His weekly updates are well worth a read, released on Wednesdays late afternoon. 

he’ll even reply to comments in a constructive way and has a great sense of humour.  
ballamar
20 December 2022 11:28:05
From Greenland to Turkey on that GFS op run the high migrates. Would be pants if that was the case but I would think many changes from that outcome
Taylor1740
20 December 2022 11:35:34
Looks like the usual problem of high pressure to the South will spoil any chance of a widespread cold spell unfortunately.
NW Leeds - 150m amsl
Joe Bloggs
20 December 2022 11:39:41
I’ve missed the past few updates but for Christmas Day itself the cold air is a fair bit further north on the 06z GEFS compared to earlier runs. 

https://www.wetterzentrale.de/maps/GFSAVGEU06_126_2.png 
































 

Manchester City Centre, 31m ASL
Phil24
20 December 2022 11:39:47
For those concerned about it all falling apart in the run up to Christmas and the new year, this might not make good reading.

[/twitter]https://twitter.com/judah47/status/1604989227099426816?s=46&t=x8H4cxwJRxS8V8t2x7nG7g 

Blog is free late tomorrow. 
Quantum
20 December 2022 11:42:30
I mean there is obviously potential for an all time classic snow event here. The big ones tend to be marginal situations with 'stuff coming into cold air'

Details are yet to be worked out, however remember the two rules:

i) The milder solution wins
ii) Sliders trend south

i usually takes precedence over ii but if the cold is established over the northern part of the UK then expect the frontal zone to be a couple of hundred miles further south than projected.
 
2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)

Total: 8 days with snow/sleet falling.

2022/2023 Snow days (approx 850hpa temp):

18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)

Total: 7 days with snow/sleet falling.

2021/2022 Snow days (approx 850hpa temp):

26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.
Gary L
20 December 2022 11:44:13

For those concerned about it all falling apart in the run up to Christmas and the new year, this might not make good reading.

[/twitter]https://twitter.com/judah47/status/1604989227099426816?s=46&t=x8H4cxwJRxS8V8t2x7nG7g 

Originally Posted by: Phil24 



It's a bit unclear until the blog comes out what the implications are for our part of the world. Met office still persisting with the higher chance of cold spells narrative through mid January. 
Saint Snow
20 December 2022 11:50:15

I’ve missed the past few updates but for Christmas Day itself the cold air is a fair bit further north on the 06z GEFS compared to earlier runs. 

https://www.wetterzentrale.de/maps/GFSAVGEU06_126_2.png 

 

Originally Posted by: Joe Bloggs 




At 12pm, the layer isn't that different to previous runs. The dig difference is that it doesn't continue sinking southwards (eg, yesterday's 6z had the -5c 850 line only about 50 miles south of that at midday, but at the Bristol Channel by 6pm. This run, the line doesn't really move.

Martin
Home: St Helens (26m asl) Work: Manchester (75m asl)
A TWO addict since 14/12/01
"How can wealth persuade poverty to use its political freedom to keep wealth in power? Here lies the whole art of Conservative politics."
Aneurin Bevan
+1
Phil24
20 December 2022 11:52:14

It's a bit unclear until the blog comes out what the implications are for our part of the world. Met office still persisting with the higher chance of cold spells narrative through mid January. 

Originally Posted by: Gary L 



it’s worth taking a look at last weeks blog from him. He was alluding to this happening and this seems to be the case, though, from past experience, I wouldn’t be surprised if it isn’t short lived as I think he’s warming to the idea of the intense low now forming in NE states to influence the building of a potent high over Greenland. 
Saint Snow
20 December 2022 11:54:13

It's a bit unclear until the blog comes out what the implications are for our part of the world. Met office still persisting with the higher chance of cold spells narrative through mid January. 

Originally Posted by: Gary L 




Correct me if I'm wrong, but isn't Cohen more focusing on the US? 

If he's predicting a mild winter for the Eastern Seaboard, that may benefit us in the UK due to reduced cyclogenesis (but all depends on teleconnecting positioning of systems, I guess)

Martin
Home: St Helens (26m asl) Work: Manchester (75m asl)
A TWO addict since 14/12/01
"How can wealth persuade poverty to use its political freedom to keep wealth in power? Here lies the whole art of Conservative politics."
Aneurin Bevan
Phil24
20 December 2022 11:59:23

Correct me if I'm wrong, but isn't Cohen more focusing on the US? 

If he's predicting a mild winter for the Eastern Seaboard, that may benefit us in the UK due to reduced cyclogenesis (but all depends on teleconnecting positioning of systems, I guess)

Originally Posted by: Saint Snow 



you are slightly correct in his bias, but his blogs do cover Europe and beyond as his forecast tend to have a broader meaning in the interconnectivity of systems around the world in general.  I find his analysis very useful in looking at the way our little part of the planet is influenced globally.  
Joe Bloggs
20 December 2022 12:05:37

At 12pm, the layer isn't that different to previous runs. The dig difference is that it doesn't continue sinking southwards (eg, yesterday's 6z had the -5c 850 line only about 50 miles south of that at midday, but at the Bristol Channel by 6pm. This run, the line doesn't really move.

Originally Posted by: Saint Snow 



A few days ago the -5C isotherm (GEFS mean chart) was south of the M62 at 12z Christmas Day. It’s much further north (north of the Scottish border) now so the likelihood is we are now too far south for cold Christmas Day (according to the GEFS). 

However just to emphasise the uncertainty - the ECM det run has it cold enough for wintry showers by the evening time on Christmas Day, in complete contrast to the MetO global model which has us under mild southerlies! 

https://www.wetterzentrale.de/maps/ECMOPEU00_138_1.png 


https://www.wetterzentrale.de/maps/UKMHDOPEU00_138_1.png 
 

Manchester City Centre, 31m ASL

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