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Gandalf The White
07 December 2023 16:33:43

GFS 12z. We may have something to focus on again.

Cold air to the east. A good place for it to be at this stage if this is to develop into a MLB, provided of course it doesn't topple south !

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=gfs&var=2&time=186&run=12&lid=OP&h=0&mv=0&tr=6 

Originally Posted by: Gusty 



Not sure the weather is going to come from the east?  Nice if it did, but only one or two perturbations from the 06z showed that.

Similar evolution so far on the 12z. Just looking at that surge of Arctic air coming down through eastern Canada and the HP over the US, following on. That helped the block form on the 06z and the cut-off low to the south.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


Gandalf The White
07 December 2023 16:43:12
Nicely buckling jet at Day 11 and significant HP cell over Scotland >1050mb

https://www.meteociel.fr/modeles/gfse_cartes.php?&ech=252&mode=5&carte=1 
 
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


doctormog
07 December 2023 16:46:53
Retron
07 December 2023 16:49:02

Yes, did someone say high pressure?

https://www.wetterzentrale.de/maps/GFSOPUK12_276_1.png  

Originally Posted by: doctormog 


That'd be a new UK pressure record if that were to happen...

https://www.torro.org.uk/extremes/summary 
 
Leysdown, north Kent
doctormog
07 December 2023 16:59:10

That'd be a new UK pressure record if that were to happen...

https://www.torro.org.uk/extremes/summary 
 

Originally Posted by: Retron 



I remember that one well. Stupid anticyclonic muck. 🤡

https://www.wetterzentrale.de/maps/archive/1902/noaa/NOAA_1_1902020100_1.png 
UserPostedImage
Gandalf The White
07 December 2023 17:11:18

I remember that one well. Stupid anticyclonic muck. 🤡

https://www.wetterzentrale.de/maps/archive/1902/noaa/NOAA_1_1902020100_1.png 
UserPostedImage

Originally Posted by: doctormog 



Richard?  😉
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


nsrobins
07 December 2023 17:24:58
I’m actually quite liking the direction the GFS suite is going at the moment. 
If it’s a solid foundation for a potential robust cold spell you’re after then I’d take a persistent MLB over the UK. 
What happens next could be very interesting.
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
ballamar
07 December 2023 17:35:45

I’m actually quite liking the direction the GFS suite is going at the moment. 
If it’s a solid foundation for a potential robust cold spell you’re after then I’d take a persistent MLB over the UK. 
What happens next could be very interesting.

Originally Posted by: nsrobins 



settled foggy weather was often a precursor to a cold spell when I was growing up
squish
07 December 2023 17:38:57
 I like the 12z control run 
 
D.E.W on Dartmoor. 300m asl
Jiries
07 December 2023 18:34:52

settled foggy weather was often a precursor to a cold spell when I was growing up

Originally Posted by: ballamar 



That true as I remember 1985 severe frost and fog with temperatures well below -10C follow by big freeze and deep snow cover.  Nowadays the fog are mild one that prevent very cold temps and stopping any snowfall occurring. 
Brian Gaze
07 December 2023 18:43:52



The postage stamp ECM ensembles only go out to 168, nothing much of interest on them for the time being:

https://charts.ecmwf.int/products/enplot?base_time=202312070000&valid_time=202312140000 

As ever, it's going to be a slog to get through to more interesting charts.

 

Originally Posted by: Retron 



I've got ECM ENS mslp stamps out to t+364. Open in a new tab and then zoom for the best view.



UserPostedImage
 
Brian Gaze
Berkhamsted
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Saint Snow
07 December 2023 19:19:15

I've got ECM ENS mslp stamps out to t+364. Open in a new tab and then zoom for the best view.



UserPostedImage
 

Originally Posted by: Brian Gaze 




Not exactly stellar, but not without interest.

Top row, right hand side would do for me, and there's a few perts that have a similar set-up.

Greenland high ridging south into the mid-Atlantic, low to the N/NE, combining to create a cold flow from the Arctic and a likely unstable NW'ly. I know wouldn't raise much of an eye in the SE, but for the bulk of the UK, that's always a promising type of chart.

Martin
Home: St Helens (26m asl) Work: Manchester (75m asl)
A TWO addict since 14/12/01
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Aneurin Bevan
CField
08 December 2023 06:05:45
Great start on the 00z gfs run....looking good for Xmas snow for many down the east....going to change but keep the trend.....
Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
Heavy Weather 2013
08 December 2023 06:50:09
0z again isn’t without interest. It’s going to be fun the next few days watching how the MLB moves around. 
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Ally Pally Snowman
08 December 2023 07:19:53
Yep remarkable consistency from the GFS Op for HLB to return to Greenland about 22nd ish . These things rarely if ever countdown to the zero hour smoothly.  But atm best chance for a proper white Christmas in a very long time.🥶🥶🥶🤞🤞🤞
Bishop's Stortford 85m ASL.
Ally Pally Snowman
08 December 2023 07:45:46
A decent cold cluster showing up now about 22nd. Long way to go though.


UserPostedImage
Bishop's Stortford 85m ASL.
DEW
  • DEW
  • Advanced Member
08 December 2023 07:58:39
WX temp summaries show little change from yesterday; for two weeks they show freezing weather more or less static east of Poland (and including Scandinavia) and N of the Black Sea. W Europe mild and above norm in week 1, cooler and close to norm week 2. Of note, however, is that ultra-cold weather over Russia declines to norm for that area. Pptn also similar; for Atlantic coastal countries and down through France to the Alps, all clearing away in favour of a large dry area (new; Spain, France, Britain, even Denmark) in week 2 but today dry area also including much of C Europe. Rain on S coasts of Mediterranean.

GFS Op - deep LP currently S of Greenland (945mb) projecting a trough across Britain, to 985mb Hebrides tomorrow, the whole system filling and moving E-wards to 1000mb S Scotland Tue 12th (and link to 1005mb Baltic). The section over Scotland moves off to S Europe, pressure rises and by by Fri 15th HP 1040mb is centred over Cornwall. This pressure is maintained somewhere over Britain until Wed 20th when it first retrogresses and then moves N to Greenland 1045mb Sun 24th, at which time Britain is under N-lies controlled by LP 1000mb S Baltic.

ECM - similar to GFS but HP slower to move in, 1040mb not attained until Mon 18th, and then situated further S with SW-lies for Scotland.

GEM - somewhere between GFS and ECM

GEFS - mild (in S) or near norm (in N) to Wed 13th with pulses of rain, cooler around Fri 15th, good ens agreement to this point, then with increasing uncertainty milder again near Mon 18th (many ens members very mild) and a distinct cooling to below norm approaching Christmas Eve. Mainly dry after Wed 13th. 

 
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Chichester 12m asl
Brian Gaze
Ally Pally Snowman
08 December 2023 08:48:35
Both GEM and ECM ensembles have the same cold cluster starting about the 22nd. That's fairly unusual for something so far out.
 
Bishop's Stortford 85m ASL.
nsrobins
08 December 2023 09:56:04

Both GEM and ECM ensembles have the same cold cluster starting about the 22nd. That's fairly unusual for something so far out.
 

Originally Posted by: Ally Pally Snowman 


They do and given previous experience it's just half an eye slightly open on this one at this stage.
The EC clusters do leave the door open for decent retrogression from the 20th but as always if the atmosphere can find a way of preventing a deep arctic push coming our way it will.
The first step will be to get pressure building close to or over the UK and that is well-modeled now. Then we wait to see if the signal (a weak one just now) for MLB to HLB via retrogression via a NW route, or better still for the Holy Grail via a NE route, is still there or strengthens.

As others have said, the pieces of the jigsaw are certainly there this year. We just need to avoid losing the crucial ones under the sofa.
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
The Beast from the East
08 December 2023 09:58:12

They do and given previous experience it's just half an eye slightly open on this one at this stage.
The EC clusters do leave the door open for decent retrogression from the 20th but as always if the atmosphere can find a way of preventing a deep arctic push coming our way it will.
The first step will be to get pressure building close to or over the UK and that is well-modeled now. Then we wait to see if the signal (a weak one just now) for MLB to HLB via retrogression via a NW route, or better still for the Holy Grail via a NE route, is still there or strengthens.

As others have said, the pieces of the jigsaw are certainly there this year. We just need to avoid losing the crucial ones under the sofa.

Originally Posted by: nsrobins 



Channel 5 is showing "White Christmas of 1981" on Saturday evening.  At least we cannot rule it out at this stage, normally its a done deal by now for a green xmas
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Gandalf The White
08 December 2023 10:48:47
Out to Day 11-12 and the jet stream pattern looks very similar to a few runs ago, with a strong jet streak heading SE from southern Greenland straight down over the country, whilst the southern arm of the jet is gaining strength over central and southern US.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


Heavy Weather 2013
08 December 2023 10:56:34
Gosh the 06z continues the theme. It really is thing of beauty.
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Russwirral
08 December 2023 10:57:34
Some nice FI consistency here for Xmas
 
Retron
08 December 2023 11:05:28

Some nice FI consistency here for Xmas
 

Originally Posted by: Russwirral 


Two different routes to get there, but the end result is the same - a chunk of the PV stuck over Scandinavia and us on the cold side of it.

I remember decades ago reading on usw that getting a winter high over the UK, something like 1040hPa or more, is often the precursor to a cold spell. While doubtless some would go on about wave-breaking and other overly technical stuff, it's more like a rock in a stream: it messes up the flow. We're seeing that with the GFS 0z and 6z runs, whether or not the ECM and GEM runs would get there if they went out far enough remains to be seen...

 
Leysdown, north Kent
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