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glenogle
13 December 2023 17:50:49
"Remember if the heights are as low as being suggested - expected parameters for snowfall could be more in our favour. "
pinning my hopes on this aspect as I feel the 850s are creeping higher each day closer it gets.
UserPostedImage LLTNP 105m asl 
doctormog
13 December 2023 18:05:26

"Remember if the heights are as low as being suggested - expected parameters for snowfall could be more in our favour. "
pinning my hopes on this aspect as I feel the 850s are creeping higher each day closer it gets.

Originally Posted by: glenogle 



Not really in terms of the period where the cold incursion has initially been shown: https://www.wetterzentrale.de/maps/GFSOPUK12_246_2.png 

This is of course subject to significant change, nevermind the period beyond that over Christmas itself.
Aberdeen
Current conditions (personal WS) 
+2
Ally Pally Snowman
13 December 2023 19:10:36
Ecm joins the party. Snowy for the NW. 
Bishop's Stortford 85m ASL.
+1
glenogle
13 December 2023 19:24:49
Hmm, was sure I replied doc but it's gone.
I use -7 as my general guide and the 06z ensembles were floating around -5, where previously i felt they looked lower.
UserPostedImage LLTNP 105m asl 
glenogle
13 December 2023 19:26:54
50cm on the snow graph for Glasgow on 12z ensembles by 29th 🤣🤣🤣
UserPostedImage LLTNP 105m asl 
Ally Pally Snowman
13 December 2023 19:29:11
If I was living in Scotland or the North England I'd be getting a bit excited snow chances seem to be increasing and just before Christmas, doesn't get much better than that.
 
Bishop's Stortford 85m ASL.
doctormog
13 December 2023 19:34:21
I think there are a few gremlins in the TWO forum server today. The White Christmas possibility is still very much there but more so for prone NWern areas with elevation. A few more op runs like the 12z GFS May indocta e higher chance more generally but as things stand it looks potentially very unsettled around Christmas with a cool W or NWly flow.
Aberdeen
Current conditions (personal WS) 
White Meadows
13 December 2023 19:38:53
In the midst of some balmy nights to come, Met office update this arvo not without interest for the period after Christmas, into new year and towards middle part of Jam,…sorry I mean Jan:

“Short-lived colder spells remain possible, with hazards such as snow and ice, particularly in the north. The chance of these colder spells increases moving into January, with a low likelihood of a more prolonged spell of cold weather developing around mid-month”.

For the given range, I’d say that is a distinct and pronounced indicator on the table. I wonder what the signal is coming from. Strat warming? Shut down if the NAD? An asteroid impact winter??
+1
Quantum
13 December 2023 20:14:56

I think there are a few gremlins in the TWO forum server today. The White Christmas possibility is still very much there but more so for prone NWern areas with elevation. A few more op runs like the 12z GFS May indocta e higher chance more generally but as things stand it looks potentially very unsettled around Christmas with a cool W or NWly flow.

Originally Posted by: doctormog 



I think you'll do okay, especially around 22nd or 23rd, the winds are strong and the cold is deep, much deeper (i.e at the 500hpa level) than from any easterly; the showers will make it all the way to you.

I'm less sure for me East of the pennines. It is quite unusual for me to do well out of a northwesterly but not impossible.
 
Twitter: @QuantumOverlord (general), @MedicaneWatch (medicane/TC stuff)
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.
Quantum
13 December 2023 20:19:07

Hmm, was sure I replied doc but it's gone.
I use -7 as my general guide and the 06z ensembles were floating around -5, where previously i felt they looked lower.

Originally Posted by: glenogle 



Remember though the pressure is alot lower than normal. If the pressure is 20-30mb lower than normal then the height of the 850mb layer is at least 200m lower. -5C in normal circumstances is easily enough for snow at 200m ASL.

Also there is another effect, the cold air is more heavily modified at the surface than it would be in an easterly, but the corrolory of that is the air is also colder higher up so there is more heat needed to raise the temperature than usual.
 
Twitter: @QuantumOverlord (general), @MedicaneWatch (medicane/TC stuff)
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.
Crepuscular Ray
13 December 2023 22:36:26
Even mild ramper Darren Bett mentions the 'S' word tonight. In the form of showers from the NW, especially over Scotland. He was showing that on the Friday (22nd) synoptic 🤔
Jerry
Edinburgh, in the frost hollow below Blackford Hill
David M Porter
13 December 2023 22:46:05

Even mild ramper Darren Bett mentions the 'S' word tonight. In the form of showers from the NW, especially over Scotland. He was showing that on the Friday (22nd) synoptic 🤔

Originally Posted by: Crepuscular Ray 



Interesting that they mentioned that given that the 22nd is still over a week away. There was once a time when the BBC forecasts were very reticent about looking more than a week ahead.

There does seem to be something of a trend in the models now for a cold blast of sorts from the N/NW as we head towards Christmas, although it is still to far out to be sure of what exactly is likely to transpire. Nevertheless, the output at the moment does look a little more interesting than was the case a few days ago.
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
johncs2016
13 December 2023 22:56:25

Interesting that they mentioned that given that the 22nd is still over a week away. There was once a time when the BBC forecasts were very reticent about looking more than a week ahead.

There does seem to be something of a trend in the models now for a cold blast of sorts from the N/NW as we head towards Christmas, although it is still to far out to be sure of what exactly is likely to transpire. Nevertheless, the output at the moment does look a little more interesting than was the case a few days ago.

Originally Posted by: David M Porter 



Let's hope that this comes off then, and doesn't end up being cancelled at the very last minute as what happened back in 2021.
 
The north of Edinburgh, usually always missing out on snow events which occur not just within the rest of Scotland or the UK, but also within the rest of Edinburgh.
scarborough whiteout
13 December 2023 22:59:43
Interesting 18z. Long way to go though.
Saint Snow
13 December 2023 23:25:51

Interesting 18z. Long way to go though.

Originally Posted by: scarborough whiteout 



Indeed (on both counts!)

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
Retron
14 December 2023 05:40:55
Number 11, please. The first run I've seen which brings snow (and a fair bit of it too) across the whole of the UK in the run up to Christmas! Some spots even see snow on Christmas Day...

https://www.meteociel.fr/modeles/gefs_cartes.php?code=11&ech=192&mode=0&carte=0&ext=0 

 
Leysdown, north Kent
CField
14 December 2023 05:57:59
Very 92/93ish as we head into the New Year...had 3 months of strong predominantly dry South Westerlies that made the ground rock hard by early March at the 93 Cheltenham Festival.That followed a Boxing Day bog at Kempton.
 
Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
doctormog
14 December 2023 06:24:20
The GFS op run shows a technical White Christmas for much of Scotland i.e. falling snow, but also snow cover for much of Scotland too by the 25th: https://www.wetterzentrale.de/maps/GFSOPUK00_276_25.png 

Still a long way out though and still a high chance of very unsettled conditions before and over the festive period.
Aberdeen
Current conditions (personal WS) 
Retron
14 December 2023 06:27:42


W

The GFS op run shows a technical White Christmas for much of Scotland i.e. falling snow, but also snow cover for much of Scotland too by the 25th: https://www.wetterzentrale.de/maps/GFSOPUK00_276_25.png 

Originally Posted by: doctormog 


It also shows widespread damaging winds before then - it's unusual to see an op run going for low 80s inland.

This is something which has popped up in the ensembles, but as before - it's a trend I'd like to see discontinued!

That said, we're in for a bit of a blow the way it stands, as the jet will probably be moving south over the UK as the cold air sinks south. Given the strength of it we'll do well to avoid gales.

UserPostedImage
Leysdown, north Kent
nsrobins
14 December 2023 07:25:37
I too believe wind rather than wintry will be the primary feature going into next weekend.
It isn’t however a given - just 7 days ago we were looking at this weekend being calm and cold with fog and frost. 
 
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
doctormog
14 December 2023 07:35:02
The rest of the output suggests a winter storm of some sort: strong winds, deep low pressure, rain, snow. Dynamic to say the least!

The ECM op run also shows snow across much of the north on the approach to Christmas.
Aberdeen
Current conditions (personal WS) 
DEW
  • DEW
  • Advanced Member
14 December 2023 07:53:16
WX temps back to a cooling trend - from week 1 where most of NW/C Europe is mild and freezing weather is tucked away in N Scandinavia and Russia to week 2 where Europe returns to norm and Scandinavia and Iceland drop back into the freezer - even a touch of the freeze in the Highlands. Pptn in week 1 on the N Atlantic, affecting Scotland, and also a small amount in Russia; in week 2 widespread across Europe with the axis of the heaviest from Scotland to Germany. Only Spain stays dry throughout.

GFS Op - HP steadily developing from the SW reaching 1040mb France for the weekend with mild SW-lies for Britain. This HP is absorbed by a new centre 1050mb mid-Atlantic with the wind moving to NW by Wed 20th. A piece of the LP near Iceland breaks off and arrives in the N Sea 955mb Fri 22nd with violent N-gales for Britain, the N-lies persisting up to Sun 24th though less strong as the LP moves to Scandinavia. The winds then go back to W on Christmas Day, eventually SW and milder under the influence of HP Spain 1030mb Sat 30th.

ECM similar though the LP Fri 22nd is less deep with only 'normal' gales and moves away more quickly with N-lies soon relaced by W-lies.

GEM places the LP Fri 22nd in S Sweden with NW-ly gales for Britain but as in ECM a quick return to W-lies.

GEFS - temps reaching peak mildness Mon 18th (10C above norm for the S) with very abrupt decline to below norm Wed 20th. Small rebound then a period of temps below norm through to Mon 25th; poor agreement on this cold period but very much underwritten by both op & control. Then very wide variation in ens members but probably a little milder. Rain starting around Wed 20th and becoming heavier and more persistent over the next 10 days esp in W. Chances of snow in the days after the 20th, 30-40% on low ground in N England/Scotland, almost guaranteed in the Highlands.
War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
+3
Ally Pally Snowman
14 December 2023 08:11:34

W
It also shows widespread damaging winds before then - it's unusual to see an op run going for low 80s inland.

This is something which has popped up in the ensembles, but as before - it's a trend I'd like to see discontinued!

That said, we're in for a bit of a blow the way it stands, as the jet will probably be moving south over the UK as the cold air sinks south. Given the strength of it we'll do well to avoid gales.

UserPostedImage

Originally Posted by: Retron 



The Nightmare before Christmas!!!!!!
Bishop's Stortford 85m ASL.
Ally Pally Snowman
14 December 2023 08:21:28
Thankfully ECM is much calmer. But it does blow the cold through very quickly. 
 
Bishop's Stortford 85m ASL.
Gandalf The White
14 December 2023 08:54:02

I too believe wind rather than wintry will be the primary feature going into next weekend.
It isn’t however a given - just 7 days ago we were looking at this weekend being calm and cold with fog and frost. 
 

Originally Posted by: nsrobins 



A very good point. The output has been changing so much that no detail for the run up and over the Christmas period is going to be resolved for some time. Probably another week at least.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


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