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some faraway beach
03 December 2020 14:17:35


 


Only a guess, but this could be part of the reason for the ongoing uncertainty and flip-flopping in the later stages of many model runs at the moment. I think I saw someone else mention this a few days ago.


The way I am looking at it, I think that pretty much anything could happen as we go further into December. While there is no sign of any "winter wonderland" type scenarios from the models, what I am not seeing either is anything resembling the set-up we had this time last year which was a total nightmare for cold fans.


Originally Posted by: David M Porter 


Yes. It was me, referencing the descent of the easterly phase of the QBO. Models famously can't model turbulence, and we're currently seeing the ultimate example of turbulence - like suddenly reversing the direction in which you're stirring your tea. It always results in a mess.


2 miles west of Taunton, 32 m asl, where "milder air moving in from the west" becomes SNOWMAGEDDON.
Well, two or three times a decade it does, anyway.
Heavy Weather 2013
03 December 2020 14:33:24


 


If you want to believe everything the models show you crack on pal. 


Originally Posted by: DPower 


Whats your problem. This is model discussion. Leave it out with the attitude. The debate and discussion on here have been great this weekend. Reasoned and informed.


Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Saint Snow
03 December 2020 14:34:26


 


If you want to believe everything the models show you crack on pal. 


Originally Posted by: DPower 


 



This thread discusses what the models show. People were clear that the more extreme scenarios were unlikely to come off. 


What do you want to see discussed in the model output thread?


 



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
Rob K
03 December 2020 14:55:09


 


If you want to believe everything the models show you crack on pal. 


Originally Posted by: DPower 


Believing it doesn't come into it. It's about discussing what they show. Several models show the chance of wintry precipitation in southern England over the next day or two, so it's worthy of discussion. I don't think anyone expects any accumulations, except perhaps over the highest ground for a time.


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
Gooner
03 December 2020 14:56:52


 


If you want to believe everything the models show you crack on pal. 


Originally Posted by: DPower 


I haven't seen any post that say's  " this is going to happen " this thread is to discuss every possibility / scenario that the models are showing , I am sure most if not all know that reliable timeframe with the models is 96 -120 hours , and sometimes that's pushing it.


This time last year there was very little to discuss apart from wind and rain , at least this year there is room for optimism 


 



 


 


 


 


Remember anything after T120 is really Just For Fun



Marcus
Banbury
North Oxfordshire
378 feet A S L


Bolty
03 December 2020 15:10:09

Looks like a right conveyor belt of lows heading into Iberia next week, with a low moving through more or less ever day, on the 06Z GFS run. If it comes to fruition, I can see Portugal, Spain and parts of Southern France having a very wet week next week. We might even see some flooding problems for those areas...


It would be a taste for them of some of our recent winters.


Scott
Blackrod, Lancashire (4 miles south of Chorley) at 156m asl.
My weather station 
AJ*
  • AJ*
  • Advanced Member
03 December 2020 15:26:28


 


The comedy I referred to was from the other forum, although I was surprised to see silly talk of snow fall over east anglia, southeast or central southern England appearing in the discussion for tomorrow. 


Weather enthusiasts yes experts NO.


Originally Posted by: DPower 


The MetO Thursday afternoon forecast 03/12/20 on their website shows snow over some higher parts of central southern England at 8.00am Friday, and the presenter discusses a slight possibility of snow over northern Norfolk at around the same time.


See https://www.metoffice.gov.uk/public/weather/forecast/map#  especially from 2:00 - 2:30 on the video.


So the discussion on this thread, far from being 'silly talk', could perhaps have been entirely rational and prescient.


Angus; one of the Kent crew on TWO.
Tonbridge, 40m (131ft) asl
llamedos
03 December 2020 15:36:26


 


If you want to believe everything the models show you crack on pal. 


Originally Posted by: DPower 

Please read the pm I've sent you regarding your recent posts, meanwhile.....


"Life with the Lions"

TWO Moderator
Chichesterweatherfan2
03 December 2020 15:53:53


Please read the pm I've sent you regarding your recent posts, meanwhile.....


Originally Posted by: llamedos 


 


 thank you Moderators...Doing a great job along with Brian deleting the last thread that had been spoilt at the end... personally I am finding the discussion on here very interesting, realistic but at the same time, as there is colder weather (sure no where near as cold as some of us would like) a very good chat  and possibilities....

nsrobins
03 December 2020 15:57:05
Meanwhile - the next 48hrs are a decent chance to examine the idiosyncrasies of the precipitation type and distribution algorithms in some of the high-res output. As it stands it looks like some of the more ‘extravagant’ solutions with respect snowfall may be wide of the mark but time will tell.
In my experience I can’t see anything to get too excited about and it’s certainly a long way off even considering a mention on my local forecast group.
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
warrenb
03 December 2020 16:28:30
Little more resistance on this run, probably won't come to anything, but even what is happening today makes me feel positive for the rest of winter that the atmosphere is not in its usual mood.
ballamar
03 December 2020 16:43:00

Little more resistance on this run, probably won't come to anything, but even what is happening today makes me feel positive for the rest of winter that the atmosphere is not in its usual mood.

Originally Posted by: warrenb 


need the cold to flow round the NE of the Russian high to break the link to the milder air. Signs of it on this run

Steve Murr
03 December 2020 16:56:54

Afternoon All-

I have been reviewing the GFS closely over the past 24 hours run by run.

When the crazy ECM charts came out for snow the GFS & ICON & Aperge all had zilch for the SE > not even any rain.

Over the past 4 runs the GFS has steadily increased the moisture content of the system over the channel, so now most ENS have about 15-20mm of rain in Kent / London suffolk etc & with each run the system nudges west.

Whats also interesting is the fact that the initialisation of the GFS & the above models was woeful V the actual radar. The area of vorticity depicted in the models is on the radar quite a way NW ( say 50-75 Miles ) & also better developed.

The closest High resolution model for 12z was the HIRLAM ( now Harmonie )

Whats still missing though from the GFS ( apart from 1 amazing one ) is the wintryness element, however they are changing as the panels for GFS now bring some snow into Suffolk & Kent.

So in my mind the ECM & its forecasts have been much better >>> Barring that hurdle ...
Can we make that leap - I still think as highlighting from the start +150M could see a covering & if some of the echoes do appear that are now appearing on the GEFS panels there could be a fast 5-10cm.

Brian if you have the snowdepth chart for GEFS PTB 25 for T21 or 24 I would be interested to see it...

Thanks
S

warrenb
03 December 2020 17:14:06

I think GFS has gone into "I haven't got a clue" mode. The trough over us now, is just over us or slightly to the west in 384 hrs time, nothing moves.


Rob K
03 December 2020 18:06:16
12Z GFS a bit keener on the northern blocking but not too convincing. Variations beyond the next week are so great that it's impossible to make a call.
Interesting signs of undercutting around the T168 mark (next Thursday) so I will be keeping an eye on that and seeing if the block can assert itself.

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
ballamar
03 December 2020 18:49:00
Those straight lines on ECM at 192 - if only it would pump up warm air and flood the cold out!
Laths
03 December 2020 19:05:22
The jank at the end of the 12z ECM is not what we was hoping for after promising signs earlier in the week .
John
Wallington
Surrey
(London Borough of Sutton)
Rob K
03 December 2020 19:09:36

The jank at the end of the 12z ECM is not what we was hoping for after promising signs earlier in the week .

Originally Posted by: Laths 


It's not great but it doesn't have the look of a long-lived return to zonality to me - it's still quite an amplified pattern.


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
xioni2
03 December 2020 19:10:26

The setup for tonight and tomorrow morning in the SE is still rather finely balanced: most models have converged towards less precip (mainly to the SE and then NE of London and less engagement of the cold air with very little snow as a result, but they could still underestimate the intensity and westward extent of the precip.  There still is a reasonable chance of 5-15cm over the North Downs above 150m or so, but it's an uncertain forecast.


The EC has gone from ~30cm to almost zero now. 

tallyho_83
03 December 2020 19:25:22


 


Only a guess, but this could be part of the reason for the ongoing uncertainty and flip-flopping in the later stages of many model runs at the moment. I think I saw someone else mention this a few days ago.


The way I am looking at it, I think that pretty much anything could happen as we go further into December. While there is no sign of any "winter wonderland" type scenarios from the models, what I am not seeing either is anything resembling the set-up we had this time last year which was a total nightmare for cold fans.


Originally Posted by: David M Porter 


Yes could also be the fact that we have some warming of the Stratosphere at 10hpa around the ARCTIC regions.


Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
---------------------------------------
Sean Moon
Magical Moon
www.magical-moon.com


fairweather
03 December 2020 19:29:10


Afternoon All-

I have been reviewing the GFS closely over the past 24 hours run by run.

When the crazy ECM charts came out for snow the GFS & ICON & Aperge all had zilch for the SE > not even any rain.

Over the past 4 runs the GFS has steadily increased the moisture content of the system over the channel, so now most ENS have about 15-20mm of rain in Kent / London suffolk etc & with each run the system nudges west.

Whats also interesting is the fact that the initialisation of the GFS & the above models was woeful V the actual radar. The area of vorticity depicted in the models is on the radar quite a way NW ( say 50-75 Miles ) & also better developed.

The closest High resolution model for 12z was the HIRLAM ( now Harmonie )

Whats still missing though from the GFS ( apart from 1 amazing one ) is the wintryness element, however they are changing as the panels for GFS now bring some snow into Suffolk & Kent.

So in my mind the ECM & its forecasts have been much better >>> Barring that hurdle ...
Can we make that leap - I still think as highlighting from the start +150M could see a covering & if some of the echoes do appear that are now appearing on the GEFS panels there could be a fast 5-10cm.

Brian if you have the snowdepth chart for GEFS PTB 25 for T21 or 24 I would be interested to see it...

Thanks
S


Originally Posted by: Steve Murr 


In S.Essex I had not expected 15mm of heavy rain from the forecasts and there is still more to come. Of course there was no wintriness as expected, with temperatures of 7C but the amount of rain we will get by the morning comes as a surprise. I would like to see the same pattern later in the winter with a colder Continent and N.Sea to lower surface temperatures.


S.Essex, 42m ASL
fairweather
03 December 2020 19:33:03


ECM 12z Brings 10 inches of snowfall for Surrey & Shires !!
( obviously at elevation ) EURO 4 is 6 inches SE of London...


Originally Posted by: Steve Murr 


...... I think the charts must have meant to say rain 


S.Essex, 42m ASL
doctormog
03 December 2020 19:33:31


The setup for tonight and tomorrow morning in the SE is still rather finely balanced: most models have converged towards less precip (mainly to the SE and then NE of London and less engagement of the cold air with very little snow as a result, but they could still underestimate the intensity and westward extent of the precip.  There still is a reasonable chance of 5-15cm over the North Downs above 150m or so, but it's an uncertain forecast.


The EC has gone from ~30cm to almost zero now. 


Originally Posted by: xioni2 


It has about an inch of snow for here by tomorrow morning. I think that is about right, allowing for the inch of snow overestimation.


llamedos
03 December 2020 19:56:47


 


It has about an inch of snow for here by tomorrow morning. I think that is about right, allowing for the inch of snow overestimation.


Originally Posted by: doctormog 

very droll 


"Life with the Lions"

TWO Moderator
Ally Pally Snowman
03 December 2020 20:19:04

In Harmonie we trust. 


 


http://www.meteociel.fr/modeles/harmonie.php?ech=19&mode=1&map=523


 


Bishop's Stortford 85m ASL.

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