Brian Gaze
16 December 2022 08:08:19
I've locked the last MO thread because it had gone completely off track again. 

Just to recap, it is looking relatively mild for much of the coming week in southern Britain at least. Further north there is a higher chance of cold incursions. The Christmas period itself remains uncertain.

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Brian Gaze
Berkhamsted
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DEW
  • DEW
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16 December 2022 08:12:32
WX temps show 0C isotherm retreating to E Europe and Scandinavia from week 1 into week 2 but not as much as yesterday's pm charts; by week 2 Germany and Britain are back to cool (2C isotherm, 0C patches in the mountains), while France and Spain hang onto something a bit milder. Rain/snow on Atlantic coasts, Britain getting the worst of this in week 1.

GFS Op - starts with LP running from mid-Atlantic now  to Norway Fri 23rd, SW-lies at first but bringing cooler N-lies behind for Xmas Day (esp for the N); the next LP heads for Spain with quiet weather and rise of pressure for Britain 1035mb Wed 28th before very deep LP 940mb S Iceland Sat 30th dictates Sw-lies then W-lies.

ECM runs the 'next LP' closer to SW Ireland for Xmas Day so weak E-lies rather than N-lies.

GEFS temps up (Mon 19th, Fri 23rd) and down (Wed 21st and after 24th, esp later on for Scotland) but little agreement between ens members after 24th, op and control cool at first, mean near norm. Rain /snow in most places at some time, for Scotland heaviest now and later on, for England heaviest around Mon 19th.

 
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Chichester 12m asl
Ally Pally Snowman
16 December 2022 08:20:13
I actually think there is a better chance than normal that the  ensembles for the southern half of the UK could flip colder soon. As the cold air is often very close to our north. Ops playing around with Greenland blocking as well.
 
Bishop's Stortford 85m ASL.
MRayner
16 December 2022 08:25:50
Way to go GEM 👏, well until the next run 🙄
Location Whisky 🥃 country, Cragganmore ,Moray, 440 AMSL
Joe Bloggs
16 December 2022 08:45:31
Morning everyone.

We’ve firmed up now on a much milder spell from Sunday through to approx middle of next week at least. The problem is the European High - how many times have we seen low pressure systems wind up in an Arctic flow to our west, with the UK ending up on the mild side? Many times in my experience. It has scuppered many a cold spell in the past.

There are signs of a cold vs mild battle towards Christmas with lows straddling the UK. No point labouring this too much yet. More runs needed. 

Manchester City Centre, 31m ASL

moomin75
16 December 2022 08:57:40
Originally Posted by: Joe Bloggs 

Morning everyone. We’ve firmed up now on a much milder spell from Sunday through to approx middle of next week at least. The problem is the European High - how many times have we seen low pressure systems wind up in an Arctic flow to our west, with the UK ending up on the mild side? Many times in my experience. It has scuppered many a cold spell in the past. There are signs of a cold vs mild battle towards Christmas with lows straddling the UK. No point labouring this too much yet. More runs needed.

A very fair assessment of where we are at.

From my perspective, the sooner this milder weather gets in the better to wipe away the most miserable, abysmal cold spell I have ever experienced.

​​​​​​​It has been an unmitigated disaster here, serving only to put me out of work for two weeks as my local radio football commentaries have gone for a Burton, without even a flake of snow to compensate. 
Witney, Oxfordshire
100m ASL
nsrobins
16 December 2022 09:29:48
Originally Posted by: Ally Pally Snowman 

I actually think there is a better chance than normal that the  ensembles for the southern half of the UK could flip colder soon. As the cold air is often very close to our north. Ops playing around with Greenland blocking as well.
 


I concur. There is a huge amount yet to be resolved for the period from the 23rd Dec, and most hinging on whether the troughs phase or not. I give GEM a decent amount of respect these days.
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
Brian Gaze
16 December 2022 09:32:32
Originally Posted by: nsrobins 

I concur. There is a huge amount yet to be resolved for the period from the 23rd Dec, and most hinging on whether the troughs phase or not. I give GEM a decent amount of respect these days.




It's ahead of GFS at the moment.

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Brian Gaze
Berkhamsted
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fairweather
16 December 2022 09:38:18
It would be nice if Boxing Day became the day when there were signs of itturning cold again. I have fond memories of that from 1963. Of course it is pretty much the ideal time with still low solar input and SSTs and Europe colder than they were at the start of this recent cold spell.
S.Essex, 42m ASL
AJ*
  • AJ*
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16 December 2022 09:58:40
From the previous MO thread:

Originally Posted by: fairweather 

I'm pretty confident the GFS ensembles at least showed good agrrement from about two weeks ago that this cold spell would finish around the 17th. It may be a day or to later now. I remember because I have a specific journey to make on the 17th and I would prefer it if it wasn't affected by severe cold. 



I would entirely back this up, as from my memory the majority of GEFS ensemble members have been showing the cold spell ending about now for at least the past ten days.

As for the 00z GEFS it looks as though the scatter of unpredictability starts around the 22nd, though I note with interest that the OP shows a cold snap from the 25th - 28th.  (I tend to give the OP slightly higher credibility because I understand it to be run at a higher resolution than the other ensemble members, so will pick up on smaller features that affect the progression of the forecast.)
Angus; one of the Kent crew on TWO.
Tonbridge, 40m (131ft) asl
ballamar
16 December 2022 10:14:17
Think the key is the blob over the Arctic and if it can join to Greenland the n I think it could mean business Christmas and beyond
warrenb
16 December 2022 10:17:31
I think something a lot of people are missing is how stormy it could be next week, looking at possible named storm territory.
Heavy Weather 2013
16 December 2022 10:22:12
The heights over europe really are a pain on the latest GFS.
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Heavy Weather 2013
16 December 2022 10:23:27
But, this looks like another good run from the 23rd. Potentially.
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
doctormog
16 December 2022 10:25:14
Originally Posted by: Heavy Weather 2013 

The heights over europe really are a pain on the latest GFS.



Yes the 06z GFS op run highlights that well so far with a string cold airmass to the north battling with a large mild one to the south. Fascinating but potentially very frustrating. Still a lot to be determined for the run up to Christmas and the festive period itself.
moomin75
16 December 2022 10:26:18
Originally Posted by: Heavy Weather 2013 

But, this looks like another good run from the 23rd. Potentially.


Yes, for once, I would agree with you. The height rise towards Greenland on this run looks, shall we say, interesting. 
A good few milder and unsettled days to get through first, but yes, I agree with you that T+192 looks primed for something. 
Another new trend maybe, or just a pebble in the stream?
Witney, Oxfordshire
100m ASL
Charmhills
16 December 2022 10:28:18
Gandalf The White
16 December 2022 10:29:30
Originally Posted by: AJ* 

From the previous MO thread:



I would entirely back this up, as from my memory the majority of GEFS ensemble members have been showing the cold spell ending about now for at least the past ten days.

As for the 00z GEFS it looks as though the scatter of unpredictability starts around the 22nd, though I note with interest that the OP shows a cold snap from the 25th - 28th.  (I tend to give the OP slightly higher credibility because I understand it to be run at a higher resolution than the other ensemble members, so will pick up on smaller features that affect the progression of the forecast.)



Yes, the Op Runs at a higher resolution, but you're still left with the inevitable errors creeping in. Plus, those short wave features often come and go and get modeled differently as we approach T+0.  Another factor is that short waves can affect the long wave pattern, particularly at the margins, ie they can change the weather we get. For example, in a cold Polar flow a short wave development that runs across the south can turn an innocuous north-westerly into something more potent for the south of it gets beyond the Prime Meridian.

Back to the models and the GFS 06z run has another variation on a buckling jet stream again. A deep LP develops and moves NE along the Eastern Seaboard around T+168 but then stalls over eastern Canada, promoting quite a strong surge of WAA on its eastern flank.  Not sure it's going to withstand the next push from the jet stream but interesting nonetheless.
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Ally Pally Snowman
16 December 2022 10:33:54
GFS 6z has some seriously cold air into Scotland Christmas day.  -12c 850s.
 
Bishop's Stortford 85m ASL.
Rob K
16 December 2022 10:34:04
Just reaching Xmas day and Boxing day on the GFS and it looks tantalisingly close to something fun. Heavy rain turning to snow across the Midlands?
Yateley, NE Hampshire, 73m asl
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