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Gandalf The White
24 December 2023 13:26:34
 Very quiet in here; wonder why? 🙂

GFS ensemble suite still trending noticeably colder towards the latter stages of the run. Several easterlies in the mix, with Pert 23 producing an old-fashioned Scandi High at 1,050 mb.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


Brian Gaze
24 December 2023 14:04:10
ECM ENS stamps at days 15/16 have some very promising solutions for cold weather fans. With that said, there is a big range of outcomes and the signal remains very uncertain.

https://www.theweatheroutlook.com/twodata/ecmhrens.aspx 
 
Brian Gaze
Berkhamsted
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Gandalf The White
24 December 2023 14:15:49

ECM ENS stamps at days 15/16 have some very promising solutions for cold weather fans. With that said, there is a big range of outcomes and the signal remains very uncertain.

https://www.theweatheroutlook.com/twodata/ecmhrens.aspx 
 

Originally Posted by: Brian Gaze 



That’s a much less clear trend than the GFS 06z run shows.  As you say, very uncertain.

Meanwhile it’s close to 14c here and without the strong wind it would feel almost springlike.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


Saint Snow
24 December 2023 16:07:43

Significant number of GEFS raising heights to our N again later on, with a few decent SH options.
The chase, albeit subdued, is still on. Now someone will chip in with the fact Lance Delacroix in the Halifax, Nova Scotia lighthouse has gone home for Christmas and data return is compromised.

Originally Posted by: nsrobins 



Did Lance have a few sick days off a fortnight(ish) ago, too?

Every one of the models, at various times across several days, showed a mid-North Atlantic ridge and big low over the North Sea/Scandinavia for the 24th/25th/26th timeframe, bringing widespread snow NW of a line roughly from Cardiff to Lincoln.

Then it all went to sh*t.

Forgive me for being super-sceptical about the whole model output palava for a while. The weather gods are in a mean mood this winter.

​​​​​​

Martin
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CField
24 December 2023 16:25:19

Did Lance have a few sick days off a fortnight(ish) ago, too?

Every one of the models, at various times across several days, showed a mid-North Atlantic ridge and big low over the North Sea/Scandinavia for the 24th/25th/26th timeframe, bringing widespread snow NW of a line roughly from Cardiff to Lincoln.

Then it all went to sh*t.

Forgive me for being super-sceptical about the whole model output palava for a while. The weather gods are in a mean mood this winter.

​​​​​​

Originally Posted by: Saint Snow 

yes frustrating as this winter doesn't seem to want to play ball at present Developments last week of January look critical for the UKs chances of a significant cold spell.I know it will be February but as in Brian's winter forcast the best chance for this winter, I just can't see this early Jan wobble developing into anything for the South at least.But if February is to deliver there should be promising signals in late Feb.2018 started to show end of January. 
Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
Retron
24 December 2023 16:45:53

Significant number of GEFS raising heights to our N again later on, with a few decent SH options.
The chase, albeit subdued, is still on. Now someone will chip in with the fact Lance Delacroix in the Halifax, Nova Scotia lighthouse has gone home for Christmas and data return is compromised.

Originally Posted by: nsrobins 


Meh, frankly.

I proved several years ago - several years in a row - that the data loss over Christmas was both real and had an effect on the accuracy of the forecasts.

The ECMWF themselves put an article together about it during early Covid, as that also saw a loss of aeroplane data. (I posted the link at the time, but here it is again - have a read.)

https://www.ecmwf.int/en/about/media-centre/news/2020/drop-aircraft-observations-could-have-impact-weather-forecasts 

In short - aircraft data as late as 2020 had a noticeable impact on accuracy, particularly affecting forecasts in the 200mb region - i.e. the jet stream. That explains why we used to see amazing charts every Christmas, as with a lack of data the jetstream wasn't modelled properly and for whatever reason, it made the models much more "blocky" in our region. As data then returned to normal, the mirage faded and we went back to our normal much less exciting output.

In the past couple of years the accuracy over Christmas has been higher than it used to be and that'll be because there are more satellite observations entered. You will still have the data loss (which will kick in from the 0z runs tonight, FWIW; there's always a late burst of flights on Christmas Eve so that there's actually more data than usual for the 12z and 18z runs on Christmas Eve), but the effects hopefully won't be as severe as they used to be.

Still, with that in mind, don't be at all surprised if one of the GFS ops is amazing tomorrow! 😉
Leysdown, north Kent
doctormog
24 December 2023 17:20:53
Another op run from the GFS (the 12z) which suggests a White Christmas here tomorrow. https://www.wetterzentrale.de/maps/GFSOPUK12_30_53.png 

Personally I am not totally convinced but it will be a close thing. 
Downpour
24 December 2023 18:39:59

Another op run from the GFS (the 12z) which suggests a White Christmas here tomorrow. https://www.wetterzentrale.de/maps/GFSOPUK12_30_53.png 

Personally I am not totally convinced but it will be a close thing. 

Originally Posted by: doctormog 



It’s a shame that we are unlikely to break the date records this Christmas in the populous parts of the UK. If it’s going to be mild or very mild (as I forecast!) then it might as well be a record breaker. But looks like we will come up short. No problem, on to the next chase - whether it be cold or mild… merry Christmas to all TWOers. 
Chingford
London E4
147ft
Nick Gilly
24 December 2023 18:56:09
It looks like we have broken a date record for the 24th (although it happened at around 4 am so presumably will be counted as the 23rd), with the temperature at Rhyl peaking at 16.13C:

UserPostedImage
picturesareme
24 December 2023 22:26:16

It looks like we have broken a date record for the 24th (although it happened at around 4 am so presumably will be counted as the 23rd), with the temperature at Rhyl peaking at 16.13C:

UserPostedImage

Originally Posted by: Nick Gilly 



Probably a dodgy reading as zero mention from the met office about it. They have said Heathrow hit 15.3C making it the warmest since 1997.
Quantum
24 December 2023 22:57:59
Shetland looks like it could get battered by actual blizzards on the 27th/28th. Suprised no warning has been issued.
 
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.
Ally Pally Snowman
25 December 2023 04:49:42
MERRY CHRISTMAS fellow Twoers. 

Another interesting end to the GFS a growing theme recently.  High pressure over Greenland, can we count it down to zero though?

The 0z ends with a very impressive snow storm and lots of HLB over Greenland still. If only!
 
Bishop's Stortford 85m ASL.
CField
25 December 2023 05:15:11
Be interesting if we are living in a time where a Strong Greenland high still will not deliver to the South because of strong heights to the South.?
Favourite snowstorm
Famous channel low
Dec 31st 1978
Hastings East Sussex
Foot of level snow severe drifting
Next day max temp -4 degrees Celsius
Retron
25 December 2023 05:15:40
Merry Christmas one and all!

And following on from my post yesterday, no surprise to see a winter wonderland with snow across the UK from the GFS. Will this be the year that the usual Christmas mirage finally turns into reality?

https://images.meteociel.fr/im/36/11753/gfs_16_384uwy7.png 
UserPostedImage
Leysdown, north Kent
Caz
  • Caz
  • Advanced Member
25 December 2023 06:36:58
Merry Christmas everyone!  
Market Warsop, North Nottinghamshire.
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Ally Pally Snowman
25 December 2023 07:16:58
Shows what can happen with the right set up even in this warming world. Could January be our turn?

https://www.bbc.co.uk/news/world-asia-china-67818872 
 
Bishop's Stortford 85m ASL.
Ally Pally Snowman
25 December 2023 07:21:45
ECM still playing Grinch though. Flat as a pancake. 🥞🥞🥞
Bishop's Stortford 85m ASL.
Bertwhistle
25 December 2023 08:14:46
Happy Christmas model watchers. Thanks for the regular synopses Dew!
Bertie, Itchen Valley.
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DEW
  • DEW
  • Advanced Member
25 December 2023 08:40:47
WX temps - this week as ever cold towards the north incl Scotland  but cold over W Europe generally. Week 2 does not follow up on yesterday's major advance of cold weather from the NE, instead something much more modest with freezing weather only getting to Poland, plus patches in mountainous areas. Cooler generally though and some very cold weather developing in the far N of Scandinavia and Iceland. Rain/snow for Britain and the N Sea area in week 1, and staying there (extending across France) in week 2, instead of heading off south as shown yesterday. Very wet for Turkey in week 2.

GFS Op - W-ly or NW-ly until Wed 27th when deep LP approaches N Scotland 970mb with SW gales further S. Most of this moves to Scandinavia by Sun 31st but breaks up with some bits hanging back in a mostly N-ly flow. A brief respite Mon 1st before another LP does the same Tue 2nd - Fri 5th after which a N-S ridge of HP leaves Britain on an unstable edge between Atlantic LP and S-lies and Scandinavian LP with N-lies.

ECM - rather different from Sun 31st with less hang-back as HP builds from the SW, at  1030mb over Spain Mon 1st and enough extension NE-wards for mild weather from the S at first, the ridge toppling so that by Thu 4th Britain is sandwiched between the Spanish HP and LP 975mb Faeroes, with strong W-lies, cold in Scotland.

GEFS - present mild temps in the S dropping to cool Mon 1st (the N less mild at this time anyway) with good ens agreement, and after that mean is near or a little below norm but agreement poor, op tending to be mild and control cold at first then reversing. Rain most likely always in the W and heaviest week beginning Fri 29th in the S, 27th in the N, but never completely dry. Snow row figures quite high for Inverness, but not exciting elsewhere.
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Chichester 12m asl
Gandalf The White
25 December 2023 08:50:06

Be interesting if we are living in a time where a Strong Greenland high still will not deliver to the South because of strong heights to the South.?

Originally Posted by: CField 



Merry, mild Christmas everyone. Cloudy but mercifully fairly calm.

I think it depends on whether the northern arm of the jet stream dominates and goes over the Pole or whether it goes into the southern arm and drives across the top of the Azores High.

Interesting that last nights GFS 18z also blew up a huge Greenland high at the end of the run, when data volumes shouldn’t have been compromised.  For the last stages of the run we’re back in the battleground again this morning, but either way there’s a lot of unwanted precipitation on the cards.
Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


DPower
25 December 2023 10:54:35
Merry Christmas to all on two.
After the failed amplification  and cold spell running up to and over Christmas that was touted by myself and others of which I personally think was and is more to do with strat warming and downward propagation of zonal winds rather than teleconnections etc. The outlook as we move into the second week of January and beyond is looking as good as we could possibly hope for from a cold and wintry perspective. 
The holy grail of winter synoptics that I spoke of a couple of weeks back could very well become a reality with a split vortex sending one portion over to Canada and another over to norther Europe and high pressure rising up through Greenland and into northern Russia. The model output do to holiday period MAY  be suspect today and tomorrow but I think it will not be long before we start seeing some mouth watering synoptics. 
Have a great day everyone.
UncleAlbert
25 December 2023 11:02:00

ECM still playing Grinch though. Flat as a pancake. 🥞🥞🥞

Originally Posted by: Ally Pally Snowman 


Even the ECM ens 850s are taking a dive by days 15 to 16, so in general, may be a glimmer for cold weather fans for week 2 of January.  

Most importantly though, a very happy and peaceful Christmas to all!
The Beast from the East
25 December 2023 11:21:08
Some exceptional warmth possible to start the year

https://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=0&mode=1&carte=0&ext=0 
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The Beast from the East
25 December 2023 11:22:10

Even the ECM ens 850s are taking a dive by days 15 to 16, so in general, may be a glimmer for cold weather fans for week 2 of January.  

Most importantly though, a very happy and peaceful Christmas to all!

Originally Posted by: UncleAlbert 



Its always 2 weeks away though! Like a mirage never gets closer. Bah Humbug!

 
"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President
Bolty
25 December 2023 11:23:42
Crikey, I wouldn't rule out the possibility of a record or two in the usual Foehn spots. Get some sunshine with that, and it would feel like April for many:

UserPostedImage
Scott
Blackrod, Lancashire (4 miles south of Chorley) at 156m asl.
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