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DEW
  • DEW
  • Advanced Member
21 December 2023 17:14:44

If the ECM 00z has it right, flooding could be a real issue next week!!


Originally Posted by: Charmhills 



GFS on board with this, too
https://www.wetterzentrale.de/topkarten.php?map=1&model=gfs&var=18&run=12&time=192&lid=OP&h=0&mv=0&tr=6#mapref 

I have difficulties with colour vision but it looks to me like 2" - 4" for the whole of Britain 25th - 29th Dec, with Scotland getting extra as it starts earlier there.
War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Saint Snow
21 December 2023 17:35:21
The theme of this winter seems to be high pressure ridging north over Spain and France, buggering up chances of amplification favourable to the UK.

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
CField
21 December 2023 18:10:18
CFS putting the UK in a Jan 87 freezer....
Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
Downpour
22 December 2023 00:45:57

The theme of this winter seems to be high pressure ridging north over Spain and France, buggering up chances of amplification favourable to the UK.

Originally Posted by: Saint Snow 



Agreed. The raw output for Nice makes nice (aka grim) reading. 15-17c daily under mostly sunny skies with a stubborn high pressure seemingly in charge for the foreseeable. Essentially the French have banked spring in winter and we are the victims. 
Chingford
London E4
147ft
White Meadows
22 December 2023 03:13:44

Agreed. The raw output for Nice makes nice (aka grim) reading. 15-17c daily under mostly sunny skies with a stubborn high pressure seemingly in charge for the foreseeable. Essentially the French have banked spring in winter and we are the victims. 

Originally Posted by: Downpour 

 

Yep, imagine having mentioned this a couple of weeks ago. Oh heavens. 
15c looking a distinct possibility for 24-25th: https://www.wetterzentrale.de/en/show_diagrams.php?geoid=49069&model=gfs&var=202&run=18&lid=ENS&bw=1 

 



 
Jiries
22 December 2023 05:37:57

Agreed. The raw output for Nice makes nice (aka grim) reading. 15-17c daily under mostly sunny skies with a stubborn high pressure seemingly in charge for the foreseeable. Essentially the French have banked spring in winter and we are the victims. 

Originally Posted by: Downpour 



That the severe issue preventing our winter and summer seasons lately which dislodged spring and autumn time with winter and summer supposed set up attacked those 2 seasons. 
Lionel Hutz
22 December 2023 05:53:16
https://www.theweatheroutlook.com/twodata/gefs.aspx?run=na&lg=850&lglocation=dublin&charthour=006&chartname=ps_500hpa&chartregion=na-region&p=1&charttag=PS%20500hPa%20(GPDM) 

A mild Christmas Day and probably wet for many too. But a decent prospect of something more seasonal between Christmas and New Year looking likely, even if nothing terribly cold either, if the GFS ensembles are to be believed. 
Lionel Hutz
Nr.Waterford , S E Ireland
68m ASL



doctormog
22 December 2023 06:59:24
What’s quite funny is that none of the models except the extended ECM ensembles and C.FS actually covered the 24/25th of December period a couple of weeks ago. 

Anyway looking forward, what is interesting is that with the exception of the colder then milder blips over the next few days the ensemble mean here is bang on average for the entirety of the remainder of the. GEFS output here: 

UserPostedImage

“Seasonal” seems about right!
DEW
  • DEW
  • Advanced Member
22 December 2023 07:40:09
WX temp charts after showing a modest advance of cold weather yesterday has gone back to mild. In week 1 all of Europe except Norway and - just about - Portugal is above normal and even the freezing weather in Russia is not extreme. In week 2 the cold weather arranges itself to cover the north, from Scotland (just) to the northern Baltic and on to Russia with a touch of deep cold in the far NE. Mild weather from S England to the Caspian Sea, just a few slightly cooler patches in mountainous areas. Looking wet for Britain in both weeks, linked to the Baltic in week 1 and to France in week 2.

GFS Op - Atlantic HP moving SE to S France and Scandinavian LP filling puts an end to NW-ly gales and ushers in a spell of mild W-lies over Christmas. On Wed 27th the Atlantic revives and projects a series of LPs across or close to Britain, looking very wet and often cool as the said LPs drag in air from the NW. (980mb Hebrides Thu 28th, 970mb S Scotland Sun 31st becoming a broad trough from the N Tue 2nd, 980mb N Ireland Thu 4th, possibly relenting Sun 7th with LP sticking mid-Atlantic and winds going round to SW)

ECM - like GFS to Thu 28th but the LP on that date runs across England 985mb and stops in the N Sea but with a weak ridge of HP appearing from the S Mon 1st, thus the opposite of GFS.

GEFS  - very mild up to Christmas itself, then back to norm on Boxing Day and fair agreement between ens members for that to be the continuing outcome to Mon 1st after which many possibilities. Rain frequent and heavy from Wed 27th in S, a day or two earlier in the N, (N Scotland gets an extra burst on the 23rd) lasting to about Wed 3rd after which some signs of becoming drier. Snow row figures about 50% for Inverness, up to 25% elsewhere in Scotland and nothing for the S.
War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
Axlbert
22 December 2023 08:00:05
Further out from the New Year the GFS has been showing warming in the strat at 10hpa for the last few days ..ECM suggests a drop in the wind too... 
it's something to watch in the search for a change in the pattern of this winter so far,  I guess...

 
NMA
  • NMA
  • Advanced Member
22 December 2023 08:13:00

That the severe issue preventing our winter and summer seasons lately which dislodged spring and autumn time with winter and summer supposed set up attacked those 2 seasons. 

Originally Posted by: Jiries 


Je ne comprends pas Jiries.
Vale of the Great Dairies
South Dorset
Elevation 60m 197ft
nsrobins
22 December 2023 08:37:27

Further out from the New Year the GFS has been showing warming in the strat at 10hpa for the last few days ..ECM suggests a drop in the wind too... 
it's something to watch in the search for a change in the pattern of this winter so far,  I guess...

 

Originally Posted by: Axlbert 



In the annual winter model-watching poker tournament, the SSW card often gets dropped as the river the guy holding a low pair needs to stay in the game. 
The science is well-described, as is the fact that any consequential displacement or even split of the PV does not necessarily mean a cold spell will result, or more especially where it will occur, but is just (based in reanalysis) more likely.
Another contentious issue is how ‘well’ the NWP suites handle a reduction of the mean zonal flow, or even an SSW (reversal). The answer is the models handle it as well as any other parameter (in theory) so the idea of ‘chaos’ and ‘it’s not very good at handling it’ is probably complete nonsense. 
If the trend in zonal flow leads to a technical SSW in January, I’m looking forward to seeing where the pieces of the puzzle fall. A few classic UK cold spells followed an SSW, but some didn’t and many cold spells occur without one. 
In the annual cold spell poker match, there's still plenty of time before calling it let alone folding.
 
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
UncleAlbert
22 December 2023 08:54:46

In the annual winter model-watching poker tournament, the SSW card often gets dropped as the river the guy holding a low pair needs to stay in the game. 
The science is well-described, as is the fact that any consequential displacement or even split of the PV does not necessarily mean a cold spell will result, or more especially where it will occur, but is just (based in reanalysis) more likely.
Another contentious issue is how ‘well’ the NWP suites handle a reduction of the mean zonal flow, or even an SSW (reversal). The answer is the models handle it as well as any other parameter (in theory) so the idea of ‘chaos’ and ‘it’s not very good at handling it’ is probably complete nonsense. 
If the trend in zonal flow leads to a technical SSW in January, I’m looking forward to seeing where the pieces of the puzzle fall. A few classic UK cold spells followed an SSW, but some didn’t and many cold spells occur without one. 
In the annual cold spell poker match, there's still plenty of time before calling it let alone folding.
 

Originally Posted by: nsrobins 



Sounds like the perfect warning label to be read before commencing SSW pursuit.  I suppose it's fair to say as well that it would be quite possible for a cold period that otherwise would have happened to be scuppered by a reversal.
Arbroath 1320
22 December 2023 09:00:49
A very interesting ECM op run this morning for the period between Christmas and New Year. It looks like there could be a fair amount of snow, particularly North of the LP systems tracking across the UK.

The model has been pointing towards such a set up for a few runs now. 
GGTTH
David M Porter
22 December 2023 10:18:30

In the annual winter model-watching poker tournament, the SSW card often gets dropped as the river the guy holding a low pair needs to stay in the game. 
The science is well-described, as is the fact that any consequential displacement or even split of the PV does not necessarily mean a cold spell will result, or more especially where it will occur, but is just (based in reanalysis) more likely.
Another contentious issue is how ‘well’ the NWP suites handle a reduction of the mean zonal flow, or even an SSW (reversal). The answer is the models handle it as well as any other parameter (in theory) so the idea of ‘chaos’ and ‘it’s not very good at handling it’ is probably complete nonsense. 
If the trend in zonal flow leads to a technical SSW in January, I’m looking forward to seeing where the pieces of the puzzle fall. A few classic UK cold spells followed an SSW, but some didn’t and many cold spells occur without one. 
In the annual cold spell poker match, there's still plenty of time before calling it let alone folding.
 

Originally Posted by: nsrobins 



From what I recall reading in the past I think neither the mid-December 2009 to mid-January 2010 and December 2010 freezes, to name two instances, came about as a result of SSW.
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
Ally Pally Snowman
22 December 2023 11:14:05
A half decent GFS 6z.  A small wedge of heights to our north is all we need to stay in the cold. 
Bishop's Stortford 85m ASL.
Brian Gaze
22 December 2023 12:03:26

What’s quite funny is that none of the models except the extended ECM ensembles and C.FS actually covered the 24/25th of December period a couple of weeks ago.


“Seasonal” seems about right!

Originally Posted by: doctormog 



Don't forget the GEFS 00Z also goes out to 35 days ahead.

https://www.theweatheroutlook.com/twoforecasts/gefs-35-day.aspx 

 
Brian Gaze
Berkhamsted
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"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
Brian Gaze
22 December 2023 12:06:44
On balance, it still looks like the snow risk between now and the start of January will mostly be over high ground in the northern half of Britain. ECM ENS looks distinctly underwhelming. However, I wouldn't discount a more widespread snow event in the north, even if only a transient one. In the southern half of the UK snow isn't completely out of the question, albeit unlikely.

UserPostedImage
Brian Gaze
Berkhamsted
TWO Buzz - get the latest news and views 
"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
Ally Pally Snowman
22 December 2023 12:13:17
Agree the ECM ensembles are underwhelming but the latest GEFS from the 6z look like they have taken a significant shift colder from about the 30th.

https://www.wetterzentrale.de/en/show_diagrams.php?geoid=50893&model=gfs&var=2&run=6&lid=ENS&bw=1 

 
Bishop's Stortford 85m ASL.
Retron
22 December 2023 12:36:53


I have difficulties with colour vision but it looks to me like 2" - 4" for the whole of Britain 25th - 29th Dec, with Scotland getting extra as it starts earlier there.

Originally Posted by: DEW 


I prefer this chart - showing how much of it has fallen as snow, and is now on the ground!

https://images.meteociel.fr/im/91/6053/198_780UKepd2.GIF 
UserPostedImage

That said, if you're after totals - Meteociel provide much easier to read charts. Here's their version of the total rain to 192 chart:

https://images.meteociel.fr/im/48/3956/192_777UKyak0.GIF 
UserPostedImage
Leysdown, north Kent
Ally Pally Snowman
22 December 2023 12:51:57
Nothing spectacular yet but that is a big shift colder from the GEFS. 


UserPostedImage

 
Bishop's Stortford 85m ASL.
CField
22 December 2023 15:40:10
Especially for hillier northern districts

Nothing spectacular yet but that is a big shift colder from the GEFS. 


UserPostedImage

 

Originally Posted by: Ally Pally Snowman 


Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
Surrey John
22 December 2023 17:21:39
Suggestions of a SSW sudden stratospheric warming and a much colder January over Scandinavia due to changes in polar vortex

The whole process is explained very clearly longhand in this article

https://www.severe-weather.eu/global-weather/early-stratospheric-warming-forecast-polar-vortex-event-cold-united-states-january-2024-fa/ 

Wouldn't be beyond bounds of possibility for cold to move a few hundred miles towards UK

 
Bradford on Avon, Wiltshire
35m ASL
Matty H
22 December 2023 17:49:28

From what I recall reading in the past I think neither the mid-December 2009 to mid-January 2010 and December 2010 freezes, to name two instances, came about as a result of SSW.

Originally Posted by: David M Porter 



Barely anyone in here had ever heard of a SSW prior to this. Now it’s all anyone talks about in winter, lol
David M Porter
22 December 2023 17:54:12

Barely anyone in here had ever heard of a SSW prior to this. Now it’s all anyone talks about in winter, lol

Originally Posted by: Matty H 



Yeah, I think it was early 2010 (late Jan or early Feb I think) when I first remember it being discussed here Matty. The big freeze that began just before Xmas '09 had ended by that point but the rest of the winter was mostly on the cold side, at least in my area.
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

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