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Rob K
16 November 2024 15:56:34
12z GFS nudges the snow risk ever so slightly southwards
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
Retron
16 November 2024 16:55:49
Tuesday's shaping up to be very interesting in terms of the rapid switch in airmass - unusual for our neck of the woods, but quite common in continental climates.

The MetO raw for here has temperatures falling from 9C at 3AM to 4C at 9AM, or 6C to 3C for Reading.

The GFS though is far more abrupt, falling from 8C to 3C in just 3 hours here, or from 11C to 2C in 3 hours at Reading!

It's no wonder high winds keep cropping up across various models, as that's going to be one heck of an active front...
Leysdown, north Kent
Rob K
16 November 2024 17:07:21
Looking at the 12Z GFS output we have potential for both minimum and maximum date records over the next 10 days or so!
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
doctormog
16 November 2024 17:14:31
It looks like the medium/longer range 12z charts may have been right at the warmest end of the options for a time at least (around the 25th).
Retron
16 November 2024 17:38:48
Quite a shift south in the GEFS for Tuesday's low, with several members now showing snow (or perhaps sleet!) all the way down to the south coast as the low pulls away. GEM/MetO op runs keep the low further north, deeper with stronger winds as a result as it pulls away.

Here's the *mean* position of the low at just T+60:

https://images.meteociel.fr/im/87/9719/gens_31_1_60bgo8.png 

UserPostedImage
Leysdown, north Kent
ballamar
16 November 2024 18:12:48
Circa 26 degree spread around 26th on GEFS, really does highlight uncertainty!
Joe Bloggs
16 November 2024 19:32:34
Doc - can’t believe you leaked the 12z ECM early on NW! Shame on you 😉! lol! 
Anyway certainly an interesting outlook. M62 corridor v much in play at the moment. 12z GFS my favourite I think (snow shadow permitting) . 

Manchester City Centre, 31m ASL

Summer1995
16 November 2024 19:54:51

Doc - can’t believe you leaked the 12z ECM early on NW! Shame on you 😉! lol! 

Originally Posted by: Joe Bloggs 


Nick Sussex is based in Cyprus, why every winter he gets all hung up about winter prospects in this country beats me. 
Chunky Pea
16 November 2024 20:06:02
The ecmwf 'control run' shows broadly cooler conditions than the main run. Can someone very briefly explain what a control run is and even if it is worth considering? Thanks. 
Current Conditions
https://t.ly/MEYqg 


"You don't have to know anything to have an opinion"
--Roger P, 12/Oct/2022
doctormog
16 November 2024 20:14:56

The ecmwf 'control run' shows broadly cooler conditions than the main run. Can someone very briefly explain what a control run is and even if it is worth considering? Thanks. 

Originally Posted by: Chunky Pea 


As far as I’m aware it is has the same input data as the operational run but with a lower resolution (and no perturbations).
Gandalf The White
16 November 2024 22:32:41
The GFS 18z takes the LP on Monday-Tuesday a few miles further south again. More notable is a significant southward shift in the incoming mild push at the end of next week, with the cold air showing as still in place north of a line from South Wales to the Essex/Suffolk border; that’s about 400-500 miles south of where it was shown on the 12z.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


ballamar
16 November 2024 22:49:37

The GFS 18z takes the LP on Monday-Tuesday a few miles further south again. More notable is a significant southward shift in the incoming mild push at the end of next week, with the cold air showing as still in place north of a line from South Wales to the Essex/Suffolk border; that’s about 400-500 miles south of where it was shown on the 12z.

Originally Posted by: Gandalf The White 


Hopefully a trend!! Next week is certainly up in the air - bit more interesting than usual but think that happens most Novembers. As usual the Euro high will dictate everything!
DEW
  • DEW
  • Advanced Member
17 November 2024 08:13:06
WX charts in week 1 show a cold Europe with freezing conditions in mountainous areas including Scotland, though the bulk of the freezing weather has withdrawn to Scandinavia and N Russia, In week 2 these areas get colder and expand SE-wards again, coming up against milder air from the south which reaches England (not Scotland), France and Germany. PPtn for much of Europe (exc Spain) in both weeks, week 1 heaviest along the Channel and the Low Countries, week 2 further south for S France and the Alps.

GFS Op 0z - the initial N-lies generated by the LP over Scandinavia stay over the N Sea until Tue 19th when a secondary LP runs up the Channel to 990mb Holland and drags them more directly over Britain, affecting especially eastern regions. There is then a repeat on Thu 21st with an LP crossing N France 985mb. Another brief Channel runner on Sat 23rd precedes an Atlantic depression as the Scandinavian LP withdraws. The Atlantic LP crosses to Scandinavia with another burst of N-lies (one day only) Tue 26th. After a brief ridge of HP yet another Atlantic LP moves in 995mb S Ireland Sat 30th, interacting with the semi-permanent LP in Scandinavia for a NE-ly flow with gales for SE England Sun 1st. The final chart Tue 3rd has HP 1045mb Brittany calming the weather down for Europe generally.

A stormy and cold couple of weeks looking likely to produce snowfalls for northern hills and for lower ground in the NE.

ECM - rather different from Thu 21st as the original Channel runner form Tue 19th settles 965mb Baltic keeping N'lies down the N Sea coast, milder in the far W, and no secondary crossing N France. Then instead of a new LP from the SW, it arrives from the NW and is predicted 965mb Scottish borders Sun 24th with cold and stormy conditions for all except the far south. As this moves away, it is followed by HP over Scotland 1025mb Wed 27th with some weak NE-lies left over SE England,

GEM - closer to ECM with stormy conditions for Scotland on the 24th (950mb Clyde). The HP following is slower to arrive, delayed by a secondary LP 985mb running up the Channel to join the main LP as it moves NE-ward

GEFS - cold or very cold soon setting in, occasional pulses of rain or snow, and lasting until Sat 23rd when abruptly milder with much heavy rain, Some wide variation in ens members from this point but the tendency is for temps back to norm and rain slowly diminishing through to Tue 3rd. (But the op run stays much colder in the N). Snow row figures intermittently high almost anywhere until 23rd, but then much lower; however not a great deal of pptn to go with that except in NE England. 
War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Brian Gaze
17 November 2024 08:26:59
GEFS shows a very impressive climb in temperatures ~23/11 with only a few runs (850s have a similar profile) keeping the south under colder air. 
UserPostedImage

On the other hand, MOGREPS-G still favours colder conditions at that time.

UserPostedImage


Brian Gaze
Berkhamsted
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"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
Ally Pally Snowman
17 November 2024 08:30:23
North Midlands looking the sweet spot for Tuesdays snow atm. 
Interesting end to the ECM goes very cold in FI. With just enough of a block hanging on in Iceland allowing cold air from the NE. Goes full GH by the end. Hopefully a trend.

Bishop's Stortford 85m ASL.
CField
17 November 2024 08:44:51
Frustration for snow starved southerners continues by end of Gfs 0z run ....mainly dry benign same old same as December arrives...ECM shows more hope though
Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
Polar Low
17 November 2024 09:23:02

The ecmwf 'control run' shows broadly cooler conditions than the main run. Can someone very briefly explain what a control run is and even if it is worth considering? Thanks. 

Originally Posted by: Chunky Pea 



Yes it is worth looking as you would know the lower resolution is having a affect ie (less horizontal and vertical grid points)
Because it’s running with the same data as the opp you can see if the resolution is having an affect also on the ens spread rather than the initial  changes across the spread especially suspicious at a sudden change at a date

Caz
  • Caz
  • Advanced Member
17 November 2024 09:38:20
We now have a Met Office yellow warning of snow and ice on Monday and Tuesday.  
Market Warsop, North Nottinghamshire.
Join the fun and banter of the monthly CET competition.
The Beast from the East
17 November 2024 10:10:32

North Midlands looking the sweet spot for Tuesdays snow atm. 
Interesting end to the ECM goes very cold in FI. With just enough of a block hanging on in Iceland allowing cold air from the NE. Goes full GH by the end. Hopefully a trend.

Originally Posted by: Ally Pally Snowman 


Believe it when I see it! For those of us below the M4 corridor it all looks the worst of all worlds.  Cold rain followed by wind and milder rain.  After such a benign and dry period its going to be a massive shock
"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President
Ally Pally Snowman
17 November 2024 10:32:55

Believe it when I see it! For those of us below the M4 corridor it all looks the worst of all worlds.  Cold rain followed by wind and milder rain.  After such a benign and dry period its going to be a massive shock

Originally Posted by: The Beast from the East 


Yes , although it's been a boring mainly cloudy spell it's so nice to have such a long dry period. Hardly any rain here in 3 weeks just some drizzle from time to time. Its not even muddy here unheard of in November. 

Bishop's Stortford 85m ASL.
17 November 2024 10:43:17
Still standard fare on all models. You'll be lucky to see a flake south of Midlands. Good for Scotland.
Just a northerly. It's odd we see this spell as something special as it was just standard fare 20 years ago.
Berkshire

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