The Weather Outlook

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overland
12 June 2025 13:51:18

The issue is that the increasing frequency of extreme heat is the canary in the coal mine.

Just a few decades back a very warm day in England was notable at 25c and 30c was exceptional.  Now we seem to hit the high 20s quite routinely and 35c+ is occurring with worrying regularity.

Originally Posted by: Gandalf The White 

That's so true as I remember the red symbols the BBC used to use (end of 80s, early 90s?) for a temperature of 25c or above seemed to only make rare appearances - nowadays it's almost every week!


Mumbles, Swansea. 80m asl
Brian Gaze
12 June 2025 15:34:35

Latest GFS 6z P17 has 42c on the 27th

Originally Posted by: Ally Pally Snowman 

Here's a static snapshot so it won't be lost when the GEFS updates. 

UserPostedImage


Brian Gaze

Berkhamsted

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Retron
12 June 2025 15:38:35

Here's a static snapshot so it won't be lost when the GEFS updates. 

UserPostedImage

Originally Posted by: Brian Gaze 

Hmm, something's going on there - here's the MC equivalent:

https://images.meteociel.fr/im/52/21419/gensfr_17_4_372lcx8.png 

Hot or very hot, yes, but not "off the scale" heat as the TWO version shows. Any idea what's going on there?

UserPostedImage

EDIT: And the Wetterzentrale rendering has some 39s for "London" and Watford, but not into the 40s. It's closer than the MC version though!


Leysdown, north Kent
Brian Gaze
12 June 2025 15:49:11

Hmm, something's going on there - here's the MC equivalent:

https://images.meteociel.fr/im/52/21419/gensfr_17_4_372lcx8.png 

Hot or very hot, yes, but not "off the scale" heat as the TWO version shows. Any idea what's going on there?

UserPostedImage

EDIT: And the Wetterzentrale rendering has some 39s for "London" and Watford, but not into the 40s. It's closer than the MC version though!

Originally Posted by: Retron 

I'm not sure, although the MC one is labelled "Temperature 2m" which suggests they may not be plotting the 2m max temperature variable. I'll try and replicate the download and plot on my development server.


Brian Gaze

Berkhamsted

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Retron
12 June 2025 15:54:20

I'm not sure, although the MC one is labelled "Temperature 2m" which suggests they may not be plotting the 2m max temperature variable. I'll try and replicate the download and plot on my development server.

Originally Posted by: Brian Gaze 

Mmm, that's a good point - MC doesn't provide max and min temperatures on its detailed charts, so I've looked at the "tableaux" version instead. And that comes up with a 39.5 for London, which makes more sense. Looks like it's just a dodgy bit of plotting on the detailed charts, then, and hopefully you read this before spending time on your dev server! 

https://images.meteociel.fr/im/57/22593/tablemlu4.php.png 

UserPostedImage


Leysdown, north Kent
Brian Gaze
12 June 2025 15:57:14

Mmm, that's a good point - MC doesn't provide max and min temperatures on its detailed charts, so I've looked at the "tableaux" version instead. And that comes up with a 39.5 for London, which makes more sense. Looks like it's just a dodgy bit of plotting on the detailed charts, then, and hopefully you read this before spending time on your dev server! 

https://images.meteociel.fr/im/57/22593/tablemlu4.php.png 

UserPostedImage

Originally Posted by: Retron 

I've set up an automated job on my development server for validation. However, as you mentioned, it appears more consistent with the table data.


Brian Gaze

Berkhamsted

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Retron
12 June 2025 15:59:46

I've set up an automated job on my development server for validation. However, as you mentioned, it appears more consistent with the table data.

Originally Posted by: Brian Gaze 

There's something gained from this, anyway: turns out that TWO is the only one of the "big three" that provides the TMax data for the ensemble members, which is worth shouting about! TBH I'm surprised the others don't bother with it... it comes into its own at times like this, when we're playing "spot the massive outlier". (And as I loathe heat, I'm trying *not* to remember that the 2022 record started off in much the same vein!)


Leysdown, north Kent
Matty H
12 June 2025 16:24:31

Yes, I like warm sunny weather in the upper twenties but why the craving for unbearable heat waves that are just plain uncomfortable and tiring.?

Originally Posted by: fairweather 

That’s how I feel about cold and snow. Why on earth would anyone want that?

personally, the hotter and more humid the better. Bring it on! It’s looking promising. Just waiting to view the afternoon runs 


Yate, Nr Bristol

TBFTEIARBSC

Brian Gaze
12 June 2025 17:09:50
I've regenerated the historic GEFS 2m Maximum Temperature chart to:

1. Validate it using a newly downloaded dataset.

2. Increase the resolution.

The resulting PNG image is 2200×2200 pixels. 

I kindly request:

1. If you use this chart, please credit "The Weather Outlook" with a link to

https://www.theweatheroutlook.com/ .

2. If you'd like access to the uncompressed original version for media use or other purposes, please contact me via the site feedback form.

https://www.theweatheroutlook.com/twoother/twofeedback.aspx 

UserPostedImage


Brian Gaze

Berkhamsted

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Hungry Tiger
12 June 2025 19:14:41

Personal preference: I'm happy doing manual work in my garden in temperatures up to 35°C and really enjoy the heat. That said, once it pushes up to 40°C it falls into the 'experience' rather than 'enjoyable' category. For what it's worth, I think the chance of reaching 35°C to 40°C this year is higher than normal.

Originally Posted by: Brian Gaze 

I've just seen another forecast models showing 38C and over for East Anglia and the SE. 🙁🙁🙁


Gavin S. FRmetS.

TWO Moderator.

Contact the TWO team - [email protected]

South Cambridgeshire. 93 metres or 302.25 feet ASL.



Brian Gaze
12 June 2025 20:15:46

I've just seen another forecast models showing 38C and over for East Anglia and the SE. 🙁🙁🙁

Originally Posted by: Hungry Tiger 

Yes. This evening's GFS 12Z.

UserPostedImage


Brian Gaze

Berkhamsted

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Hungry Tiger
12 June 2025 20:52:51

Yes. This evening's GFS 12Z.

UserPostedImage

Originally Posted by: Brian Gaze 

We're in for a roasting like 3 years ago unless things change suddenly- which can happen.  😞 


Gavin S. FRmetS.

TWO Moderator.

Contact the TWO team - [email protected]

South Cambridgeshire. 93 metres or 302.25 feet ASL.



Devonian
12 June 2025 21:35:04

We're in for a roasting like 3 years ago unless things change suddenly- which can happen.  😞 

Originally Posted by: Hungry Tiger 

Two weeks out?

Is a deep, 985mb, cold low likely on June 27th? No. Is warm, settled weather more likely? More likely, especially in this '1.5C' world. Record breaking heat? I'll ask that question next week.

Rob K
12 June 2025 21:51:47

I don’t think remember ever seeing a 40C modelled for the UK before 2022, but now they seem to crop up quite frequently on the models. 

And a 100F on the GFS op run this evening. 


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

Hungry Tiger
12 June 2025 22:10:35

I don’t think remember ever seeing a 40C modelled for the UK before 2022, but now they seem to crop up quite frequently on the models. 

And a 100F on the GFS op run this evening. 

Originally Posted by: Rob K 

When I first saw that in 2022 I thought someone was in the wakky baccy. But as we all know it verified. Much to our shock and horror. And I won't forget the fact that it showed 2 weeks in advance. Just like now.  😮 


Gavin S. FRmetS.

TWO Moderator.

Contact the TWO team - [email protected]

South Cambridgeshire. 93 metres or 302.25 feet ASL.



Matty H
12 June 2025 22:43:35

We're in for a roasting like 3 years ago unless things change suddenly- which can happen.  😞 

Originally Posted by: Hungry Tiger 

Hopefully it doesn’t change. Interesting and exciting times 


Yate, Nr Bristol

TBFTEIARBSC

The Beast from the East
13 June 2025 00:29:32

Hopefully it doesn’t change. Interesting and exciting times 

Originally Posted by: Matty H 

Its gonna be hot even if we dont reach 40, but the middle east going up in flames is perhaps more concerning for us all in terms of the economy


Purley, Surrey, 70m ASL

"We have some alternative facts for you"

Kelly-Ann Conway - former special adviser to the President

Brian Gaze
13 June 2025 05:46:44

Another 40C chart. This time from last night's GFS 18Z.

UserPostedImage


Brian Gaze

Berkhamsted

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Caz
  • Caz
  • Advanced Member
13 June 2025 05:55:40

Yes, I like warm sunny weather in the upper twenties but why the craving for unbearable heat waves that are just plain uncomfortable and tiring.?

Originally Posted by: fairweather 

I completely agree, although I appreciate some wouldn’t.  These days mid 20’s are about the limit for me, especially if it comes with humidity but I think it’s an age thing because I used to think the hotter the better.   Hopefully Brian’s suggesting an extended spell of dry, warm weather.  


Market Warsop, North Nottinghamshire.

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Retron
13 June 2025 05:55:43

Another 40C chart. This time from last night's GFS 18Z.

Originally Posted by: Brian Gaze 

Thankfully (from my POV) the 0z op is the polar opposite at that time! As an aside it's interesting how many runs we see each summer that bring the 20C 850 isotherm over the UK in one way or another - yesterday's 18z op had 24C 850s, a gnat's whisker away from the record 25C plume in 2022. It wasn't that long ago that the 20C isotherm was a mythical beast in our land...


Leysdown, north Kent
Ally Pally Snowman
13 June 2025 06:12:44

That 18z run is the hottest I can remember for an Op run in June.

The 0z is less extreme but still hot at times. 

GEM also hot this morning 


Bishop's Stortford 85m ASL.
DEW
  • DEW
  • Advanced Member
13 June 2025 08:03:24

GFS Op 00z; current trough steadily moving NE and clear of Scotland by late Sunday. Warm air and HP arrive from SW and dominate Britain until Fri 20th when a move of HP to the east plus LP on the Atlantic create a re-load of the present situation, i.e. a trough from the south with warm/hot and potentially thundery SE-lies for the following weekend. The coming week's weather is then almost identically repeated in the second week with the thundery breakdown scheduled for the 28th

ECM; As GFS to Sat 21st, but the trough is less marked and the following week starts quite differently with trough from Iceland running into Scotland Mon 23rd and cool NW-lies for the rest of Britain

GEM; also  has something of a thundery breakdown on Fri 20th but confined to the south; a toppling ridge of HP crosses Scotland and by Mon 23rd is over the N Sea with LPs approaching from both  Greenland and Biscay

 

GEFS; In the S warm and wet now, then temps near norm and dry to Thu 19th with good ens agreement. A variety of outcomes from then onwards, most ens members rather warm and dry to Sun 22nd, then mean temps back to norm (control rather cold) and increasing chance of rain (in more runs than yesterday). In the N, rainfall profile similar, but temps never far from norm  and better supported in this with better ens agreement (though op warms towards end of period but control goes cooler),. 

Current rainfall prediction from metO; rain now in W Scotland fading out. New (quite localised) storms arrive into SW England this afternoon and run north through Wales, and a separate batch into SE England this evening, running up the east coast. In both cases some bits and pieces left over as the main two areas unite over mainly C & E Scotland tomorrow, clearing from the NE late in the day


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

Chichester 12m asl

The Beast from the East
13 June 2025 09:42:16

That 18z run is the hottest I can remember for an Op run in June.

The 0z is less extreme but still hot at times. 

GEM also hot this morning 

Originally Posted by: Ally Pally Snowman 

ECM good news for Darren and me! 


Purley, Surrey, 70m ASL

"We have some alternative facts for you"

Kelly-Ann Conway - former special adviser to the President

Rob K
13 June 2025 11:10:10
6Z GFS keeps the heat going after a slightly cooler interlude next week. 20C upper air hitting on June 27th again. 35C modelled for the 28th.
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

GezM
  • GezM
  • Advanced Member
13 June 2025 11:15:59

Both GFS and ECM are keen to build the heat next week according to the 0Z ensembles. Whether or not things cool off after that point (for a while) is less clear. The GFS Op 0z and 6z keep it hot for a long time after and if anything make it even hotter. 


Living in St Albans, Herts (116m asl)

Working at Luton Airport, Beds (160m asl)

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