The Weather Outlook

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Rob K
10 July 2025 11:58:34
The 06Z GFS op run is notable "chilly" compared to the 00Z: it has TWO days that fail to reach 30C rather than just one!
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

Devonian
10 July 2025 12:03:22

Remarkably the GFS 6z is pretty much as hot throughout like the 0z. GFS can be excellent at being the first at picking up changes in the pattern so maybe it's onto something.  It can also be completely rubbish sometimes. 

Originally Posted by: Ally Pally Snowman 

Have a look at the synoptics for July 1972. Not dissimilar to this year: a blob of the Azores High moves NE over us to Scandinavia mid month, then N blocking or high over the country for the rest of the month.

That the CET for July 1972 was 15.6C should sober up anyone with some meteorological knowledge.

Gandalf The White
10 July 2025 12:42:48

I suppose my neighbour with his Range Rover will be complaining again about the leaves from my Silver Birch tree spoiling his outdoor meals on his paved over back garden. 😖

Originally Posted by: fairweather 

We’ve had leaves dropping from our two weeping willows for a couple of months now.  The effect of the heavy rain of just a few days ago has already gone.  

Hopefully ECM will be nearer the mark regarding the temperatures over the next few days: warm rather than baking.

I see the overnight ECM Op run delivers almost 100mm of rain in 36 hours with a bullseye on Essex on 23rd, with 50-75 quite widely across much of East Anglia and northern Home Counties.  Hopefully that won’t verify.


Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E



Gandalf The White
10 July 2025 12:45:42

Have a look at the synoptics for July 1972. Not dissimilar to this year: a blob of the Azores High moves NE over us to Scandinavia mid month, then N blocking or high over the country for the rest of the month.

That the CET for July 1972 was 15.6C should sober up anyone with some meteorological knowledge.

Originally Posted by: Devonian 

That’s 50+ years of a steady uptick in global air and sea temperatures - and a 30% increase in CO2 (327 to 428)


Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E



Ally Pally Snowman
10 July 2025 13:03:14

That’s 50+ years of a steady uptick in global air and sea temperatures - and a 30% increase in CO2 (327 to 428)

Originally Posted by: Gandalf The White 

The equivalent month now would probably be 17.6c . The final third of July could be anything from unsettled to record heat atm.


Bishop's Stortford 85m ASL.
Brian Gaze
10 July 2025 13:20:13

Surely the control run is another "OMG" moment in the history of numerical weather prediction. 😂😂

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Brian Gaze

Berkhamsted

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scillydave
10 July 2025 13:32:54

Surely the control run is another "OMG" moment in the history of numerical weather prediction. 😂😂

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Originally Posted by: Brian Gaze 

Crazy stuff.

More worrying is that it represents a 'possibility' based on the current synoptics.


Currently living at roughly 65m asl North of Cowbridge in the Vale of Glamorgan.

Formerly of, Birdlip, highest village in the Cotswolds and snow heaven in winter; Hawkinge in Kent - roof of the South downs and Isles of Scilly, paradise in the UK.

TimS
  • TimS
  • Advanced Member
10 July 2025 13:38:13

Surely the control run is another "OMG" moment in the history of numerical weather prediction. 😂😂

UserPostedImage

Originally Posted by: Brian Gaze 

Looks like a chilly pattern change to me. Temperatures struggling to get much past 42C, low pressure on the 24th with likely flooding and maxes in the teens. 

The cool washout summer continues. 


Brockley, South East London 30m asl
cultman1
10 July 2025 13:40:33

????

Taylor1740
10 July 2025 13:56:52

Surely by now people must realise that the GFS is way overcooking the heat in the extended range. I lose count of the amount of 40c+ days the GFS has modelled this Summer in the extended range, and in reality the highest we've had is 35c and this heatwave doesn't look like exceeding that either.


NW Leeds - 150m amsl
Brian Gaze
10 July 2025 14:07:50

Surely by now people must realise that the GFS is way overcooking the heat in the extended range. I lose count of the amount of 40c+ days the GFS has modelled this Summer in the extended range, and in reality the highest we've had is 35c and this heatwave doesn't look like exceeding that either.

Originally Posted by: Taylor1740 

An individual run is showing a theoretical possibility. I don’t think anyone has ever suggested that 40°C is the favoured outcome, and that’s not what the GFS has shown. The i paper spoke to me about it last month and you can see what I said here:

https://inews.co.uk/news/no-uk-wont-hit-40c-june-despite-warm-spell-3747167 


Brian Gaze

Berkhamsted

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The Beast from the East
10 July 2025 14:10:43

Remarkably the GFS 6z is pretty much as hot throughout like the 0z. GFS can be excellent at being the first at picking up changes in the pattern so maybe it's onto something.  It can also be completely rubbish sometimes. 

Originally Posted by: Ally Pally Snowman 

Its great when it shows what you want! 

Sadly ECM and GEM are awful and Moomin could well have the last laugh


Purley, Surrey, 70m ASL

"We have some alternative facts for you"

Kelly-Ann Conway - former special adviser to the President

The Beast from the East
10 July 2025 14:15:02

Surely the control run is another "OMG" moment in the history of numerical weather prediction. 😂😂

Originally Posted by: Brian Gaze 

one to save for the archives before it disappears soon.  the hot version of the Steve Murr Feb 2007 cold spell.  The -20isotherm phantom appearance before pete tong gatecrashed the party


Purley, Surrey, 70m ASL

"We have some alternative facts for you"

Kelly-Ann Conway - former special adviser to the President

Brian Gaze
10 July 2025 14:16:19

Its great when it shows what you want! 

Sadly ECM and GEM are awful and Moomin could well have the last laugh

Originally Posted by: The Beast from the East 

I'm not sure I would call the ECM deterministic awful and it was at the lower end of the ensemble too.

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Brian Gaze

Berkhamsted

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Rob K
10 July 2025 14:35:32

Looking through the 6Z GEFS tables for my location there is not a single day in the next 16 that doesn't have at least one run hitting 30C.

https://www.meteociel.fr/modeles/gefs_table.php?x=283&y=152&run=6&ext=1&mode=7&sort=1 

And those are 6 hourly snapshots, not even maxima.


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

scillydave
10 July 2025 14:56:59

I'm not sure I would call the ECM deterministic awful and it was at the lower end of the ensemble too.

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Originally Posted by: Brian Gaze 

I would in terms of lack of rainfall!  Drought is going to increasingly cause problems if this continues. 


Currently living at roughly 65m asl North of Cowbridge in the Vale of Glamorgan.

Formerly of, Birdlip, highest village in the Cotswolds and snow heaven in winter; Hawkinge in Kent - roof of the South downs and Isles of Scilly, paradise in the UK.

Rob K
10 July 2025 15:14:40

Speaking of the ECm the 240hr chart is quite odd to look out: from the isobars it looks quite unsettled and yet the heights are very high with yellows even in the low pressure. Usually summer charts have a lot more green on them when the Atlantic nudges in!

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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

Brian Gaze
10 July 2025 15:34:28
ICON-G looks quite toasty today.

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Brian Gaze

Berkhamsted

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Retron
10 July 2025 15:40:40

Never mind all this ***** hot weather. Here's someone who believes that next winter will be snowier and colder than recent winters, and calls in at least some meteorological principles to support his thesis.

https://www.severe-weather.eu/long-range-2/early-forecast-data-weak-polar-vortex-united-states-canada-winter-2025-2026-fa/ 

Originally Posted by: DEW 

Hmm - while I'd jump at the chance of an SSW, as they do increase the odds of a cold outbreak here in winter, I can't help but note the conclusion:

"With strong signs emerging for a weak Polar Vortex in 2025/2026, the likelihood increases for more colder winter days and snowfall over the United States, Canada, and parts of Europe."

We've seen the way things have changed in the past 20 years or so, and every winter the media seems to whip up hype in the States about a record-breaking cold spell, snow storms, "polar vortex" and so forth. (We see similar hype here, of course, with those clickbaity "the EXACT DAY a 400 MILE WALL OF SNOW will hit the UK" articles based on a single model run, but unlike the US/Canada a cold outbreak is by no means guaranteed every winter). 

And odds are that the "parts of Europe" will be a) Greece and b) parts that people don't think of as getting snow, e.g Spain... it's so woolly in fact that any snow anywhere in Europe would allow them to claim a successful forecast.

Predict that at some point in the afternoon it'll be 3PM and you won't be wrong. It's the same principle.

WRT one of the other things being discussed, the low dewpoints modelled on some of the output, I was thinking earlier - it reminds me of the stories about desertification of the Iberian peninsula, and indeed if you look at the likes of the Sahara and the Mojave Desert - where Las Vegas lies - you'll often see days in the 30s and dewpoints around freezing, or even a fair bit below. You can see the theory in action: such dry air desiccates vegetation, and if it starts happening more often than not the vegetation just dies. That then removes moisture from the system (as trees of course draw up water and it evaporates from their leaves), and it becomes a self-reinforcing cycle.

At least where we are, surrounded by sea and ocean, we have a source of moisture most of the time, but I do wonder about France and areas further south: we saw the "canicule" back in 2003, but temperatures were broadly higher in 2022 and, as we've seen this year, there are plenty of runs which show 40s again there (and occasionally here). 2022 was remarkable as what started as an outrageous outlier gradually gained support - the memory of that lingers, and like most I'm wary of seeing 40s modelled again. 

Oh, and FWIW - here's the 6z GFS run on the day of that heat in 2022. Note the pool of subzero dewpoints, something I pointed out at the time as being dangerous:

https://images.meteociel.fr/im/64/14014/9_101UKiiv3.GIF 

UserPostedImage 

EDIT: And one model at least does in fact show a nice snowy flow over the UK just after Christmas. It's the CFS, of course... wouldn't it be nice if just once it got it right!

https://images.meteociel.fr/im/5/17304/cfs_0_4092hsm1.png 

UserPostedImage


Leysdown, north Kent
Heavy Weather 2013
10 July 2025 15:54:01

Hmm - while I'd jump at the chance of an SSW, as they do increase the odds of a cold outbreak here in winter, I can't help but note the conclusion:

"With strong signs emerging for a weak Polar Vortex in 2025/2026, the likelihood increases for more colder winter days and snowfall over the United States, Canada, and parts of Europe."

We've seen the way things have changed in the past 20 years or so, and every winter the media seems to whip up hype in the States about a record-breaking cold spell, snow storms, "polar vortex" and so forth. (We see similar hype here, of course, with those clickbaity "the EXACT DAY a 400 MILE WALL OF SNOW will hit the UK" articles based on a single model run, but unlike the US/Canada a cold outbreak is by no means guaranteed every winter). 

And odds are that the "parts of Europe" will be a) Greece and b) parts that people don't think of as getting snow, e.g Spain... it's so woolly in fact that any snow anywhere in Europe would allow them to claim a successful forecast.

Predict that at some point in the afternoon it'll be 3PM and you won't be wrong. It's the same principle.

WRT one of the other things being discussed, the low dewpoints modelled on some of the output, I was thinking earlier - it reminds me of the stories about desertification of the Iberian peninsula, and indeed if you look at the likes of the Sahara and the Mojave Desert - where Las Vegas lies - you'll often see days in the 30s and dewpoints around freezing, or even a fair bit below. You can see the theory in action: such dry air desiccates vegetation, and if it starts happening more often than not the vegetation just dies. That then removes moisture from the system (as trees of course draw up water and it evaporates from their leaves), and it becomes a self-reinforcing cycle.

At least where we are, surrounded by sea and ocean, we have a source of moisture most of the time, but I do wonder about France and areas further south: we saw the "canicule" back in 2003, but temperatures were broadly higher in 2022 and, as we've seen this year, there are plenty of runs which show 40s again there (and occasionally here). 2022 was remarkable as what started as an outrageous outlier gradually gained support - the memory of that lingers, and like most I'm wary of seeing 40s modelled again. 

Oh, and FWIW - here's the 6z GFS run on the day of that heat in 2022. Note the pool of subzero dewpoints, something I pointed out at the time as being dangerous:

https://images.meteociel.fr/im/64/14014/9_101UKiiv3.GIF 

UserPostedImage 

EDIT: And one model at least does in fact show a nice snowy flow over the UK just after Christmas. It's the CFS, of course... wouldn't it be nice if just once it got it right!

https://images.meteociel.fr/im/5/17304/cfs_0_4092hsm1.png 

UserPostedImage

Originally Posted by: Retron 

Excellent post as ever Darren. Interestingly, 2022 delivered snow in London which settled  and perhaps it’s just an interesting quirk, but some of my most memorable summers have then delivered in winter or winters has delivered and then a good summer.


Mark

Beckton, E London

Less than 500m from the end of London City Airport runway.

Chichesterweatherfan2
10 July 2025 15:54:35

I suppose my neighbour with his Range Rover will be complaining again about the leaves from my Silver Birch tree spoiling his outdoor meals on his paved over back garden. 😖

Originally Posted by: fairweather 

I can 100% picture your neighbour, FW….we have a few like that around us who drive huge range rovers around Chichester…gardens are 100% paved over…anything that looks like a weed is doused with lethal chemical, cars washed every Sunday morning with gallons going down the drain…the only thing that cheers me up are the Woodpigeons around here which are plentiful, sometimes crap on their drives and vehicles…

The Beast from the East
10 July 2025 15:57:47

UKMO looking very unsettled and cool,


Purley, Surrey, 70m ASL

"We have some alternative facts for you"

Kelly-Ann Conway - former special adviser to the President

warrenb
10 July 2025 16:10:07

ICON 12z for SE, one cooler day (24c) then hot again


Chunky Pea
10 July 2025 16:12:37

Low dewpoints are never to be complained about! 

Increasing chance of some thunderstorms into early next week. Hopefully they will help take some of the heat out of the atmosphere. 


Patrick,

East Galway, Ireland.

doctormog
10 July 2025 16:12:38

ICON 12z for SE, one cooler day (24c) then hot again

Originally Posted by: warrenb 

Yes, the 12z UKMO looks like that too at first glance. I suspect It will end up as a couple of more unsettled days with temperatures closer to average before it warms up again. We’ll see what the other runs show shortly.


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