The Weather Outlook

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fairweather
16 January 2026 16:15:12

I've been analysing today's 0Z GFS and ECM ensembles to see what they show for the 850mb temperature for SE England for 31st January. The GFS ensemble has 32 members if you include the Op and Control. The ECM ensemble has 51 including the Op (discounting Control, as it seems to be broken, the 850mb temp. being shown as identical to the Op throughout the run).

GFS: Op -9.1   Avg. -5.2   >0  2   -5 to 0  16   -10 to -5  10  -15 to -10  4

ECM: Op -6.0  Avg. -3.6   >0  8   -5 to 0  27   -10 to -5  13  -15 to -10  3 

So the ECM ensemble for 31st Jan is a good deal warmer than the GFS. But for both ensembles, around 50% of the members are in the -5 to 0 range: 16 out of 32 for the GFS and 27 out of 51 for the ECM. The GFS has 14 members (almost 50%) being colder than -5, but the ECM has only 16, so only about one-third.

Originally Posted by: jhall 

Is that different to the mean shown on the ensemble graphs? 


S.Essex, 42m ASL
fairweather
16 January 2026 16:16:55

An interesting BBC article on AI weather models, focusing on AIFS, ECM's version:

https://www.bbc.co.uk/weather/articles/cwy6ykp7049o 

An excerpt on reliability:

Just like traditional models, AI models are less accurate the further ahead in the future they're trying to predict - a consequence of the chaotic nature of the atmosphere. Looking 10 days ahead, none of the AI models (or traditional models) were able to offer forecasts considered to be of much use in terms of accuracy.

Originally Posted by: Arbroath 1320 

So my natural intelligence has known that fact for years!


S.Essex, 42m ASL
squish
16 January 2026 16:17:52
12z gfs looks more tantalising than the 06z did at the point I commented on earlier (+132/144)

Energy splitting off from the NW and running SE seems to be the key ( or part of it ) . More energy diving SE in conjunction with a better  build to our NE seems to promote a better outcome down the line .

Very finely balanced still 


D.E.W on Dartmoor. 300m asl
squish
16 January 2026 16:19:08
Now looking like one of the AI runs ! 
D.E.W on Dartmoor. 300m asl
Quantum
16 January 2026 16:20:56
The ARPEGE12Z is closer to the ICON12Z solution.

The track isn't that different between ICON and GFS but it makes a big difference. The deep warm bubble in the ICON case gets swept to the south of Scandanavia, while in the GFS case it gets absorbed over Scandi and plumps the high up.

Ironically this is the exact reverse of what we saw with the 0Zs with the ICON favouring the warm bubble ending up over scandi, and the GFS flushing it to southern Europe. 

Also the warm bubble now has a little friend:

(https://modeles12.meteociel.fr/modeles/icon/archives/2026011612/iconnh-6-69.png?12)

See Shetland. Not sure how the baby bubble affects things, if it gets a bit stronger on the next few runs I can only see it being a positive, but it definitely makes things a bit more complicated.


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
16 January 2026 16:30:15
Lovely vertical profile of that frigid continental air at 132h. This is west to east with the mountains visible being the pennines going all the way to the north sea.

https://www.meteociel.fr/modeles/coupegfs/coupegfs_137_13_551_11_132_0_1000_250.png 

Notice the warm tongue of air in the far east; this is before the cold uppers have arrived, note how the cold arrives at the surface first. 


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

Brian Gaze
16 January 2026 16:31:58
GFS 12Z is a crowd pleaser this afternoon.

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
16 January 2026 16:34:44

GFS 12Z is a crowd pleaser this afternoon.

Originally Posted by: Brian Gaze 

I feel sorry for the people at the Metoffice, they probably wished they'd waited a few more hours before publishing their week ahead forecast having de facto ruled out anything very cold next week.


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

aceandy79
16 January 2026 16:37:49

GFS 12Z is a crowd pleaser this afternoon.

There ought to be a Carry On style whistle noise to go with that chart 

Originally Posted by: Brian Gaze 


Andy

Hedge End, Hampshire, 26m asl

doctormog
16 January 2026 16:38:30

I feel sorry for the people at the Metoffice, they probably wished they'd waited a few more hours before publishing their week ahead forecast having de facto ruled out anything very cold next week.

Originally Posted by: Quantum 

I’d be surprised if this wasn’t one of those “earlier cold” options in the ensembles. If the 12z ECM and GEFS show the same timescale perhaps then it’s something to pay attention to.


Hippydave
16 January 2026 16:43:22

I’d be surprised if this wasn’t one of those “earlier cold” options in the ensembles. If the 12z ECM and GEFS show the same timescale perhaps then it’s something to pay attention to.

Originally Posted by: doctormog 

I suspect it's got things wrong, just because it shows snow for your part of the world from an easterly 🤡

Bit daft looking too much at specifics but unless it's cold and dry weather you want, the 12z isn't a great run so far. It also looks more likely to slowly wander south from T240, with milder air pushing down from the NW. Entirely possible I'm wrong of course and it may hold on and/or move to somewhere more interesting later on.

Edit - and yup, my sinking pattern/comment was indeed incorrect! Holds on and rebuilds albeit with milder but still chilly uppers injected in to the mix along with more moisture and some more widespread precip/snow.


Home: Tunbridge Wells

Work: Tonbridge

Quantum
16 January 2026 16:43:44

I’d be surprised if this wasn’t one of those “earlier cold” options in the ensembles. If the 12z ECM and GEFS show the same timescale perhaps then it’s something to pay attention to.

Originally Posted by: doctormog 

UKMO12z is closer than recent runs, much more similar to the GFS than the ICON. GEM is on team ICON.


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

Brian Gaze
16 January 2026 16:46:07

I feel sorry for the people at the Metoffice, they probably wished they'd waited a few more hours before publishing their week ahead forecast having de facto ruled out anything very cold next week.

Originally Posted by: Quantum 

I've not seen that forecast but they will almost certainly have sifted through the ensemble data, including MOGREPS-G which can be a steadier hand at the range we're looking at.


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
16 January 2026 16:50:46
12Z GEFS seem to be an upgrade on the 6Z set. High positioned further north, and cold airmass further west, more undercutting from the atlantic.


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

Ally Pally Snowman
16 January 2026 16:51:04
GFS 12z takes a big step towards the AI crew.
Bishop's Stortford 85m ASL.
jhall
16 January 2026 17:03:27

Is that different to the mean shown on the ensemble graphs? 

Originally Posted by: fairweather 

The ensemble graphs are what I used for my analysis. If you hover your mouse pointer over a particular X co-ordinate then it lists all the values for that date and time. (At least that's what happens on the Wetterzentrale version.)

I'll try to repeat the analysis later today using the 12Z runs to see whether prospects have got better or worse compared to the 0Z.


Cranleigh, Surrey
Matty H
16 January 2026 17:17:44

I feel sorry for the people at the Metoffice, they probably wished they'd waited a few more hours before publishing their week ahead forecast having de facto ruled out anything very cold next week.

Originally Posted by: Quantum 

They’ll be looking at all model ens rather than a solitary operational output. I’d imagine they’ll be ok with their forecast unless the entire set has flipped and the other major models follow suit 

Edit: this forum is horrible to post on using mobile these days 


Yate, Nr Bristol

TBFTEIARBSC

Hippydave
16 January 2026 17:33:36
It'll be interesting to see the next MOGREPS when they come out. The UKMO T168 could go mild/er with too much energy in the atlantic, slowly fill as the block holds firm or drop energy south and help pull the HP over us. The 6z ens set would I think suggest it'll slowly sink that low south or south east and bring a fairly strong airflow in from the east as a result. 

UserPostedImage

UserPostedImage


Home: Tunbridge Wells

Work: Tonbridge

jhall
16 January 2026 18:17:58
At first sight, the 12Z GFS ensemble doesn't look quite as good as the 0Z. Against that, it could be good news that the Op run brings in the proper cold earlier than T+240, since that means its within its timeframe with higher resolution and at least in theory ought to mean it's more likely to come off.
Cranleigh, Surrey
Hippydave
16 January 2026 18:46:02
Well the ECM run is interesting I guess, ending with a deep LP and rain turning increasingly to snow north of the M4 (of course it is, sigh). 

It never really brings any decently cold uppers in but for all that looks generally between average and chilly in the mid to long term. I suspect it'll be bouncing around the middle of the pack in the ens suites as seems fairly representative of the majority cluster in the longer term - i.e chilly and somewhat unsettled.  


Home: Tunbridge Wells

Work: Tonbridge

Quantum
16 January 2026 19:23:03
JMA asks the question, what happens if we make the Svalbard bubble really strong. Very tasty outcome!


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
16 January 2026 19:31:42
ECM AI ensemble mean is better on the 12z compared to 6Z.

Mostly upgrades all round this evening.


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

Rob K
16 January 2026 19:50:37

ECM AI ensemble mean is better on the 12z compared to 6Z.

Mostly upgrades all round this evening.

Originally Posted by: Quantum 

Whereas the GEFS ensemble mean is a degree or so less cold on the whole - just when the op run goes cold!


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

western100
16 January 2026 20:11:41
It looks to me like cold prospects are decent this evening

Very cold and severe cold look unlikely at the moment

However. There's a chance of an average CET month for January, possible slightly below which is basically the holy grail in the world as it is now. 

Brian said at the start of the winter, about the backgrounds as to why so many mid winter easterlies have disappeared,  so that virtually nailed on the chances we would end up with the beast making its first appearance since 2018 and that was a Spring easterly 


Worcestershire / Warwickshire Border

100m ASL

X…..@Weather4u2

Polar Low
16 January 2026 20:45:29

JMA asks the question, what happens if we make the Svalbard bubble really strong. Very tasty outcome!

Originally Posted by: Quantum 

Ridiculous500  profile around  Greenland 1070mb it’s had problems for sometime with regard to that area unfortunately one for the bin

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