The Weather Outlook

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Matty H
27 December 2024 00:05:11
Anyone seen the NY day snow event lately?
Yate, Nr Bristol

TBFTEIARBSC

CField
27 December 2024 00:15:13
Think AIFS have forgotten it's mid winter not spring on those cracking charts....
Favourite snowstorm

Famous channel low

Dec 31st 1978

Hastings East Sussex

Foot of level snow severe drifting

Next day max temp -4 degrees Celsius

Gandalf The White
27 December 2024 00:55:21

Anyone seen the NY day snow event lately?

Originally Posted by: Matty H 

Do you mean the ‘Just for fun’ snow event that was far into the future and not supported? 😉


Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E



The Beast from the East
27 December 2024 01:08:31
So GFS wants to collapse heights over greenland but ECM doesnt.  Better that way round I suppose! Lets see what the morning brings


Purley, Surrey, 70m ASL

"We have some alternative facts for you"

Kelly-Ann Conway - former special adviser to the President

Retron
27 December 2024 05:02:14
Based on this morning's output, I would wager the main story will be the New Year's Day storm, and wouldn't be at all surprised if it ended up being named due to the strength of the wind. (GFS has 62 gusts here, even the conservative MetO raw has 45, and further north it's stronger).

It's still a way off, and I hope it weakens, but unlike snowy nirvana when the models pick up on a storm over the UK they often stick with it!


Leysdown, north Kent
doctormog
27 December 2024 06:18:01
The whole period looks unsettled and very messy. On this morning’s GEFS ensemble set there is a 19°C range in t850hPa values here on the 1st of January with anything from mild and wet to blizzard and everything in between.

The 500hPa spread chart shows the uncertainty nicely: 

https://www.wetterzentrale.de/maps/GFSSPREU00_138_1.png 


Retron
27 December 2024 06:24:28

The whole period looks unsettled and very messy. On this morning’s GEFS ensemble set there is a 19°C range in t850hPa values here on the 1st of January with anything from mild and wet to blizzard and everything in between.

The 500hPa spread chart shows the uncertainty nicely: 

https://www.wetterzentrale.de/maps/GFSSPREU00_138_1.png 

Originally Posted by: doctormog 

There's around a 15C spread at 850 down here, too, but that hides the marked switch. Yesterday's ensemble output for the 1st had a majority cluster around -7, this morning it's a majority cluster around +2... just a 9C rise overnight! It's not unexpected (given the usual Christmas data issues), but it's still not great to see as a cold fan.

The further north you are the more likely the colder cluster is, but even Aberdeen has gone from clustering around -8 to a proper mess this morning - quite a switch.

At least confidence should improve markedly now, as we're that much closer.


Leysdown, north Kent
Ally Pally Snowman
27 December 2024 07:01:51
Back to a snoozefest again this morning,  maybe a couple of colder days in the new year but even that's not certain. It's hard to be a weather enthusiast in this country as it's just so boring most of the time. Looks like a major fail from the ECM AI as well. GFS leading the way again .
Bishop's Stortford 85m ASL.
Quantum
27 December 2024 07:30:05

Back to a snoozefest again this morning,  maybe a couple of colder days in the new year but even that's not certain. It's hard to be a weather enthusiast in this country as it's just so boring most of the time. Looks like a major fail from the ECM AI as well. GFS leading the way again .

Originally Posted by: Ally Pally Snowman 

Not over yet. Most of the ensembles don't agree with the OP. ICON, GEM, JMA, UKMO are all fairly good too.


25/26 (850hpa temp) 11 days snow/sleet falling

18/11 (-4) 19/11 (-6) 20/11 (-6) 01/01 (-7) 04/01 (-10) 10/01 (-7) 11/01 (-3) 30/01 (-1) 13/02 (-6) 15/02 (-4) 18/02 (-6)

24/25 10d

18/11 (-6) 19/11 (-6) 23/11 (-2) 22/12 (-5) 04/01 (-5) 05/01 (0)14/02 (0) 15/02 (0)12/03 (-6) 13/03 (-6)

23/24 8d

29/11 (-6) 30/11 (-6) 02/12 (-5) 03/12 (-5) 04/12 (-3) 16/01 (-3) 18/01 (-8)08/02 (-5)

22/23 7d

18/12 (-1)06/03 (-6) 08/03 (-8) 09/03 (-6) 10/03 (-8) 11/03 (-5) 14/03 (-6)

21/22 12d

doctormog
27 December 2024 07:43:13

Not over yet. Most of the ensembles don't agree with the OP. ICON, GEM, JMA, UKMO are all fairly good too.

Originally Posted by: Quantum 

I guess it could be a resolution issue as the ECM op run is very much at the top end of the data set too (more notably up here ). Perhaps the higher resolution op runs are picking up the extra level of detail missed in the ensemble suites?


Quantum
27 December 2024 07:50:27

I guess it could be a resolution issue as the ECM op run is very much at the top end of the data set too (more notably up here ). Perhaps the higher resolution op runs are picking up the extra level of detail missed in the ensemble suites?

Originally Posted by: doctormog 

I'm not convinced tbh, the uncertainty is pretty high wrg to the movements of these sliders and I'm not sure the extra resolution dominates over the natural uncertainty of the tracks.

Also we should keep in mind that people only think the GFS is bad because of stuff that is happening at 168h. I don't think as much has changed as people think in the last 24h


25/26 (850hpa temp) 11 days snow/sleet falling

18/11 (-4) 19/11 (-6) 20/11 (-6) 01/01 (-7) 04/01 (-10) 10/01 (-7) 11/01 (-3) 30/01 (-1) 13/02 (-6) 15/02 (-4) 18/02 (-6)

24/25 10d

18/11 (-6) 19/11 (-6) 23/11 (-2) 22/12 (-5) 04/01 (-5) 05/01 (0)14/02 (0) 15/02 (0)12/03 (-6) 13/03 (-6)

23/24 8d

29/11 (-6) 30/11 (-6) 02/12 (-5) 03/12 (-5) 04/12 (-3) 16/01 (-3) 18/01 (-8)08/02 (-5)

22/23 7d

18/12 (-1)06/03 (-6) 08/03 (-8) 09/03 (-6) 10/03 (-8) 11/03 (-5) 14/03 (-6)

21/22 12d

DEW
  • DEW
  • Advanced Member
27 December 2024 08:30:57
WX temp charts - after a couple of days of raising hope for a cold first week i January, with freezing conditions advancing across Europe, WX this morning has dashed the hopes of the coldies. From a situation in week 1 where W Europe is close to norm and E Europe above, in week 2 the cold air has pulled back to Russia and N Scandinavia, and milder weather has taken over NW Europe up to the Baltic, this including Britain. Rain mostly for NW Scotland and coastal Norway in both weeks, most of continental Europe dry and in week2 very dry Spain - France - England.

GFS Op 00z - The first cold plunge up to Tue 31st now staying well to the east with current HP still dominating Britain. Then a two-day wonder moving rapidly E-wards, Wed 1st 970mb E Scotland with N/NE-ly gales and arctic air. Presumably this isn't long enough to affect the WX weekly average, as by Fri 3rd HP from the SW is back again. That HP controls British weather through to Sun 12th, tending to be to the south with SW-lies to start, later to the SW with cooler W-lies. For most of the next two weeks there are semi-permanent LPs over Greenland and N Russia, the latter importing Polar Maritime air into Siberia which is not really cold for that area at that time.

ECM - similar though the 'wonder' is a day later and at its deepest 960mb Western Isles. The ECMWF extended forecast for 2m temps shows below average temps (1-3C) around Britain w/b Mon 29th, resolving into a cold pool moving south over France in the following week. After that through to 10th Feb, W Europe is near norm, E Europe well above and the cold stuff is stuck fast over Greenland.

GEFS - temps bumping down to a cold spell Wed 1st - Sun 5th; in the S pptn is heaviest as this spell starts and finishes, in Scotland heaviest Mon 29th - Fri 3rd. Thereafter dry and mild for most runs, op & control notably above norm. 


War is God's way of teaching Americans geography - Ambrose Bierce

Chichester 12m asl

nsrobins
27 December 2024 08:35:24
JMA looking good this morning. Do I need to say more? 😂⚠️


Neil

Fareham, Hampshire 28m ASL (near estuary)

Stormchaser, Member TORRO

Ally Pally Snowman
27 December 2024 09:00:23
The robots still believe! 🤖❄️❄️❄️

Another very cold run buy AIFS.

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=aifs&var=1&run=0&time=144&lid=OP&h=0&mv=0&tr=6#mapref 


Bishop's Stortford 85m ASL.
nsrobins
27 December 2024 09:09:19

The robots still believe! 🤖❄️❄️❄️

Another very cold run buy AIFS.

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=aifs&var=1&run=0&time=144&lid=OP&h=0&mv=0&tr=6#mapref 

Originally Posted by: Ally Pally Snowman 

The engine driving AIFS (in its current form) is largely based on data from 1979–2018 reanalysis. Perhaps there’s already an inherent bias here as things were quite a bit different then, especially the 80s, with regard winter patterns. Just a thought. 


Neil

Fareham, Hampshire 28m ASL (near estuary)

Stormchaser, Member TORRO

Gandalf The White
27 December 2024 09:18:30

The engine driving AIFS (in its current form) is largely based on data from 1979–2018 reanalysis. Perhaps there’s already an inherent bias here as things were quite a bit different then, especially the 80s, with regard winter patterns. Just a thought. 

Originally Posted by: nsrobins 

I have been pondering that same point.  But is the AIFS model is starting with the evolution to T+0 or is it starting with a static position?  If the former then wouldn’t that bias be minimised?


Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E



doctormog
27 December 2024 09:23:50

I have been pondering that same point.  But is the AIFS model is starting with the evolution to T+0 or is it starting with a static position?  If the former then wouldn’t that bias be minimised?

Originally Posted by: Gandalf The White 

At a glance the T+0 hr chart is identical to the ECM op chart for the same time point.  For what it’s worth, here is the end of the 120 hr chart from the 06z ICON (which is as far out as it goes):

https://www.wetterzentrale.de/maps/ICOOPEU06_120_1.png 


Ally Pally Snowman
27 December 2024 09:24:45

The engine driving AIFS (in its current form) is largely based on data from 1979–2018 reanalysis. Perhaps there’s already an inherent bias here as things were quite a bit different then, especially the 80s, with regard winter patterns. Just a thought. 

Originally Posted by: nsrobins 

I didn't know that, this would be a significant victory for it if we do get a cold spell. 


Bishop's Stortford 85m ASL.
Ally Pally Snowman
27 December 2024 09:26:30

At a glance the T+0 hr chart is identical to the ECM op chart for the same time point.  For what it’s worth, here is the end of the 120 hr chart from the 06z ICON (which is as far out as it goes):

https://www.wetterzentrale.de/maps/ICOOPEU06_120_1.png 

Originally Posted by: doctormog 

Decent,  would be nice to get a swing back to cold today. 


Bishop's Stortford 85m ASL.
Brian Gaze
27 December 2024 09:38:04
For those interested, there is more about AIFS here:

Overview

https://www.ecmwf.int/en/newsletter/178/news/aifs-new-ecmwf-forecasting-system 

Technical paper

https://arxiv.org/pdf/2406.01465 


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

doctormog
27 December 2024 10:08:51

For those interested, there is more about AIFS here:

Overview

https://www.ecmwf.int/en/newsletter/178/news/aifs-new-ecmwf-forecasting-system 

Technical paper

https://arxiv.org/pdf/2406.01465 

Originally Posted by: Brian Gaze 

Very interesting thanks Brian, and at a glance it suggests the AI model would typically perform better than the ECM beyond day 4 or 5.

Another point to note is that the AI model has also been “fine-tuned” using data from 2019-20.

 hadn’t looked into the model much until recently but I am surprised about how well it seems to perform (not necessarily in the upcoming period, just more generally).


Quantum
27 December 2024 10:09:55
Regardless the N coast of Scotland and the northern isles are going to get hammered with snow from the 29th onwards.


25/26 (850hpa temp) 11 days snow/sleet falling

18/11 (-4) 19/11 (-6) 20/11 (-6) 01/01 (-7) 04/01 (-10) 10/01 (-7) 11/01 (-3) 30/01 (-1) 13/02 (-6) 15/02 (-4) 18/02 (-6)

24/25 10d

18/11 (-6) 19/11 (-6) 23/11 (-2) 22/12 (-5) 04/01 (-5) 05/01 (0)14/02 (0) 15/02 (0)12/03 (-6) 13/03 (-6)

23/24 8d

29/11 (-6) 30/11 (-6) 02/12 (-5) 03/12 (-5) 04/12 (-3) 16/01 (-3) 18/01 (-8)08/02 (-5)

22/23 7d

18/12 (-1)06/03 (-6) 08/03 (-8) 09/03 (-6) 10/03 (-8) 11/03 (-5) 14/03 (-6)

21/22 12d

Quantum
27 December 2024 10:15:02
Clear large scale upgrade on the 6Z. Main difference is the trop polar vortex is further east and ridging is stronger over Canada and the arctic.


25/26 (850hpa temp) 11 days snow/sleet falling

18/11 (-4) 19/11 (-6) 20/11 (-6) 01/01 (-7) 04/01 (-10) 10/01 (-7) 11/01 (-3) 30/01 (-1) 13/02 (-6) 15/02 (-4) 18/02 (-6)

24/25 10d

18/11 (-6) 19/11 (-6) 23/11 (-2) 22/12 (-5) 04/01 (-5) 05/01 (0)14/02 (0) 15/02 (0)12/03 (-6) 13/03 (-6)

23/24 8d

29/11 (-6) 30/11 (-6) 02/12 (-5) 03/12 (-5) 04/12 (-3) 16/01 (-3) 18/01 (-8)08/02 (-5)

22/23 7d

18/12 (-1)06/03 (-6) 08/03 (-8) 09/03 (-6) 10/03 (-8) 11/03 (-5) 14/03 (-6)

21/22 12d

Quantum
27 December 2024 10:18:18
ARPEGE6Z looks alot better than the GFS or ICON at T+72h.

Don't lose the faith. We have a long way to go yet.


25/26 (850hpa temp) 11 days snow/sleet falling

18/11 (-4) 19/11 (-6) 20/11 (-6) 01/01 (-7) 04/01 (-10) 10/01 (-7) 11/01 (-3) 30/01 (-1) 13/02 (-6) 15/02 (-4) 18/02 (-6)

24/25 10d

18/11 (-6) 19/11 (-6) 23/11 (-2) 22/12 (-5) 04/01 (-5) 05/01 (0)14/02 (0) 15/02 (0)12/03 (-6) 13/03 (-6)

23/24 8d

29/11 (-6) 30/11 (-6) 02/12 (-5) 03/12 (-5) 04/12 (-3) 16/01 (-3) 18/01 (-8)08/02 (-5)

22/23 7d

18/12 (-1)06/03 (-6) 08/03 (-8) 09/03 (-6) 10/03 (-8) 11/03 (-5) 14/03 (-6)

21/22 12d

Quantum
27 December 2024 10:24:07
ICON going for 50cm of snow near parts of the northern Scottish mainland by NYD.

https://modeles12.meteociel.fr/modeles/icon/runs/2024122706/iconeu_uk1-46-120-0.png?27-10 


25/26 (850hpa temp) 11 days snow/sleet falling

18/11 (-4) 19/11 (-6) 20/11 (-6) 01/01 (-7) 04/01 (-10) 10/01 (-7) 11/01 (-3) 30/01 (-1) 13/02 (-6) 15/02 (-4) 18/02 (-6)

24/25 10d

18/11 (-6) 19/11 (-6) 23/11 (-2) 22/12 (-5) 04/01 (-5) 05/01 (0)14/02 (0) 15/02 (0)12/03 (-6) 13/03 (-6)

23/24 8d

29/11 (-6) 30/11 (-6) 02/12 (-5) 03/12 (-5) 04/12 (-3) 16/01 (-3) 18/01 (-8)08/02 (-5)

22/23 7d

18/12 (-1)06/03 (-6) 08/03 (-8) 09/03 (-6) 10/03 (-8) 11/03 (-5) 14/03 (-6)

21/22 12d

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