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Brian Gaze
01 December 2023 07:08:52



Longer term it was at the top of the pack, but looking at the pressure patterns there is a lot to play for, as the ensembles equally show anything could happen. 

Originally Posted by: Heavy Weather 2013 



I'd not describe it top of the pack in the longer term on the TWO Plots. Were you looking at 00Z updates?

UserPostedImage
Brian Gaze
Berkhamsted
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Brian Gaze
01 December 2023 07:12:15
At a glance, it looks like about 20% of the GEFS runs are going for colder solutions in the south in the longer term. 
Brian Gaze
Berkhamsted
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Heavy Weather 2013
01 December 2023 07:30:04

I'd not describe it top of the pack in the longer term on the TWO Plots. Were you looking at 00Z updates?

UserPostedImage

Originally Posted by: Brian Gaze 



I won’t lie, I think I was still half asleep lol
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Heavy Weather 2013
01 December 2023 07:31:11
On another note, starting to see some potential opportunities on Tuesday for some snow as well.
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
DEW
  • DEW
  • Advanced Member
01 December 2023 07:37:29
Given the wild swings in GFS and other outputs yesterday, the charts described here are 'as is' - or as Groucho Marx nearly said "If you don't like my forecasts, I have others" . Just come back later ...

WX temp charts - in week 1 France, Spain and Britain are near norm, around the Aegean is above norm, while the rest of Europe is  definitely cold. In week 2 the milder air spreads further E-wards, to Poland, while the tongue of ultra-cold air from the NE recedes, forming a larger but broader mass covering all of Russia from Moscow E-wards. Pptn much as yesterday, i.e. for both weeks affecting Atlantic coastal countries with an extension through the Alps to the Aegean, the extension becoming more prominent in week 2.

GFS Op - Light N-ly drift to start with before HP over S Russia 1050mb preventing Atlantic LPs making inland progress, the first of these Tue 5th reaches Kent 995mb before filling in situ. The next two LPs 970mb Fri 8th N England, 985mb Tue 12th Ireland, tend to drift up the coast of Norway, then an LP 985 mb Thu 14th Cornwall heading SE-wards, yet another 990 mb Orkney Sun 17th heading NE-wards. Wind directions most often from the S but plenty of interludes with variations from all points of the compass.

ECM - similar to GFS though LPs tending to be deeper with stronger winds/gales from the SW.

GEM has little to add to the above

GEFS - briefly wet and almost mild in the S Wed 4th otherwise dry but everywhere recovering from cold to norm by Thu 7th with good ens agreement. Then the mean and most runs stay close to or a little below norm but a significant number (jncl control) dip deeply on the cold side. Rain everywhere from the 7th, very heavy in SW, small chances of snow in the far N.
War does not determine who is right, only who is left - Bertrand Russell

Chichester 12m asl
White Meadows
01 December 2023 07:40:04
Arctic sea ice now falling to an all time low in the records:

https://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png 

is there some correlation or link with a disrupted PV i wonder?… 
Brian Gaze
01 December 2023 07:43:01
I noticed the discussion about whether the 00Z updates have a tendency to show more mobility than the 12Z ones. I have no idea if that is the case and can't think why it would be. However, I wonder if there is an element of confirmation bias involved? Most people look at the 00Z runs before reading the commentary, so they are forced to draw their own conclusions. However, as the day progresses it is the cold charts which are disproportionately posted across social media and forums. Therefore, a cold "narrative" starts to take hold and some people agree with it despite not even looking at the charts. The next day the cycle repeats. Complete speculation on my part. 😀
Brian Gaze
Berkhamsted
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"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
Tim A
01 December 2023 08:01:32

I noticed the discussion about whether the 00Z updates have a tendency to show more mobility than the 12Z ones. I have no idea if that is the case and can't think why it would be. However, I wonder if there is an element of confirmation bias involved? Most people look at the 00Z runs before reading the commentary, so they are forced to draw their own conclusions. However, as the day progresses it is the cold charts which are disproportionately posted across social media and forums. Therefore, a cold "narrative" starts to take hold and some people agree with it despite not even looking at the charts. The next day the cycle repeats. Complete speculation on my part. 😀

Originally Posted by: Brian Gaze 



I agree it has to be mostly down to human factors. People also just seem more optimistic in the evenings and are almost looking for things that are not quite  there 'Its not far from something great" etc. Note I don't really see it on this forum but elsewhere. Perhaps watching each frame of each run coming out also makes you more optimistic whereas in the morning you tend to see all the runs and ensembles collectively which points to a more sensible picture. 
Tim
NW Leeds
187m asl

 My PWS 
Brian Gaze
01 December 2023 08:03:09

I agree it has to be mostly down to human factors. People also just seem more optimistic in the evenings and are almost looking for things that are not quite  there 'Its not far from something great" etc. Note I don't really see it on this forum but elsewhere. Perhaps watching each frame of each run coming out also makes you more optimistic whereas in the morning you tend to see all the runs and ensembles collectively which points to a more sensible picture. 

Originally Posted by: Tim A 



That is a very good point.
Brian Gaze
Berkhamsted
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Col
  • Col
  • Advanced Member
01 December 2023 08:03:11

I noticed the discussion about whether the 00Z updates have a tendency to show more mobility than the 12Z ones. I have no idea if that is the case and can't think why it would be. However, I wonder if there is an element of confirmation bias involved? Most people look at the 00Z runs before reading the commentary, so they are forced to draw their own conclusions. However, as the day progresses it is the cold charts which are disproportionately posted across social media and forums. Therefore, a cold "narrative" starts to take hold and some people agree with it despite not even looking at the charts. The next day the cycle repeats. Complete speculation on my part. 😀

Originally Posted by: Brian Gaze 



The psychology of model watching 🙂
Col
Bolton, Lancashire
160m asl
Snow videos:
http://www.youtube.com/channel/UC3QvmL4UWBmHFMKWiwYm_gg
Gusty
01 December 2023 08:13:29
Attempt no.1 to reinstate the Atlantic for Monday 4th December appears to have failed, the low slides south prolonging the cold spell to Wednesday 6th December when another more definitive and successful push appears likely (for now).

An interesting start to winter 2023/24.

 
Steve - Folkestone, Kent
Current conditions from my Davis Vantage Vue
https://www.wunderground.com/dashboard/pws/IFOLKE11 
Join Kent Weather on Facebook.
https://www.facebook.com/stevewall69/ 



Heavy Weather 2013
01 December 2023 08:21:01

Attempt no.1 to reinstate the Atlantic for Monday 4th December appears to have failed, the low slides south prolonging the cold spell to Wednesday 6th December when another more definitive and successful push appears likely (for now).

An interesting start to winter 2023/24.

 

Originally Posted by: Gusty 



I was thinking about you the other day Steve. Good to see you here. Cheers to a wonderful winter of model watching. 
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Brian Gaze
01 December 2023 08:23:15
ICON-D2 and UKV both suggest snow in the Chilterns / Midlands on Saturday night.

UserPostedImage
Brian Gaze
Berkhamsted
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Heavy Weather 2013
01 December 2023 08:29:59

ICON-D2 and UKV both suggest snow in the Chilterns / Midlands on Saturday night.

UserPostedImage

Originally Posted by: Brian Gaze 



ECM also has snow on Monday in the south. Meanwhile METOffice app has a snow symbol for me later on this morning. 
Mark
Beckton, E London
Less than 500m from the end of London City Airport runway.
Tim A
01 December 2023 09:25:41
Also, at first glance today's chart looks stunning on Meteociel 
https://modeles16.meteociel.fr/modeles/gfs/run/gfs-0-6.png?0 

Would send people into a frenzy at T+144 but in reality it's dry and cold for most.   Meteociel doesn't help because it makes things look a lot more dramatic than the more beneign looking Wetterzentrale version.  On Wetterzentrale it is more apparent that the setup is too slack and not overly cold for massive convection. 
Tim
NW Leeds
187m asl

 My PWS 
Rob K
01 December 2023 09:39:06

Also, at first glance today's chart looks stunning on Meteociel 
https://modeles16.meteociel.fr/modeles/gfs/run/gfs-0-6.png?0 

Would send people into a frenzy at T+144 but in reality it's dry and cold for most.   Meteociel doesn't help because it makes things look a lot more dramatic than the more beneign looking Wetterzentrale version.  On Wetterzentrale it is more apparent that the setup is too slack and not overly cold for massive convection. 

Originally Posted by: Tim A 


Well, it's certainly very wintry - no snow here but everything is almost as white as if there had been. A nice set up for the start of advent.

Longer term, yesterday's hints of heights to the north seem to have almost vanished, but not completely.
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
Quantum
01 December 2023 10:52:34
Flicking through the 6Z ensembles, this has not been resolved yet. Not all the members push that low through, hope is not lost yet. In fact the OP seems to be a progressive outlier. Alot of the ensembles offer major resistance against the mild air.
 
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.
Brian Gaze
01 December 2023 10:54:16
ECM ENS pointing to a milder midterm, but there are still some colder runs in the mix. 

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
Quantum
01 December 2023 11:04:32
There are essentially 3 scenarios:
Neither is particularly dominant at the moment though in the last day or so progressive has become a bit more favoured.


The progressive:
UserPostedImage
The easterly reload:
UserPostedImage
The battleground:
UserPostedImage
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.
Quantum
01 December 2023 11:05:57

ECM ENS pointing to a milder midterm, but there are still some colder runs in the mix. 

UserPostedImage

Originally Posted by: Brian Gaze 


And with some of those scenarios being cold undercuts from the SE; even more of those ensembles keep the cold going at the surface for longer. We are still in play.
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.
overland
01 December 2023 11:10:25

I noticed the discussion about whether the 00Z updates have a tendency to show more mobility than the 12Z ones. I have no idea if that is the case and can't think why it would be. However, I wonder if there is an element of confirmation bias involved? Most people look at the 00Z runs before reading the commentary, so they are forced to draw their own conclusions. However, as the day progresses it is the cold charts which are disproportionately posted across social media and forums. Therefore, a cold "narrative" starts to take hold and some people agree with it despite not even looking at the charts. The next day the cycle repeats. Complete speculation on my part. 😀

Originally Posted by: Brian Gaze 



Interesting point and as I rarely look at the charts I can't comment on whether they do actually show less mobility on the later runs. Personally, I've dismissed it but I'd suggest there might be something in it, as the posters noting it include ones whose views I respect. If true, it is odd as it's hard to understand why this would be. Having said that l had thought the often trotted out phrase towards the end of a cold spell, that a cold air mass is harder to shift, was straw clutching by coldies. However John Holmes on Netweather has confirmed it's right and it isn't very well modelled.



 
Mumbles, Swansea. 80m asl
Arbroath 1320
01 December 2023 11:10:47
The models are clearly struggling with the orientation and trajectory of the Atlantic low next mid-week, signified by the flip flopping of output over the last few days.

Today's runs so far, suggest a much more progressive, mobile flow but as others have pointed out, the ENS still have enough split in them to suggest next week's pattern is not nailed on yet. 
GGTTH
nsrobins
01 December 2023 11:13:30

. . . but as others have pointed out, the ENS still have enough split in them to suggest next week's pattern is not nailed on yet. 

Originally Posted by: Arbroath 1320 


Indeed. I recommend a skeg through the GEFS 06Z set. Some significant disruption on many of them.
Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
Ally Pally Snowman
01 December 2023 11:22:02
Still a decent amount of the GFS 6z ensembles go cold again by the 10th. Probably about 30% so still lots of uncertainty about what December will hold.
 
Bishop's Stortford 85m ASL.
doctormog
01 December 2023 11:23:23
Re. The progressive runs on the 00z output, recently at least, it has absolutely nothing to do with perception. The 12z op runs have been more blocked/less progressive than the 00z equivalent for the ECM and GFS without a doubt. It's not an interpretation skewed by any factor, just an observation of the charts. The difference between the 12z output yesterday and the 00z runs today is clear. As was the difference between the 12z and 00z runs yesterday.

For example yesterday's 12z GFS op run had an easterly with t850s at -7⁰C here for next Friday, this morning the t850s were +3 at the same point on the 00z op run. The difference in the ECM was less extreme but a similar pattern.

The ensemble data as you would expect are less susceptible to such swings.

In short it is not perception, it is evidence-based observation. 

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