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Offline Rob K  
#21 Posted : 05 July 2022 15:58:24(UTC)
Rob K

Rank: Advanced Member

Joined: 02/05/2006(UTC)
Posts: 25,061
Location: Northeast Hampshire

Originally Posted by: Quantum Go to Quoted Post

OK so to help out and explain what I've been doing with ensembles I introduce to you the Adiabaitc lapse equation!

Its quite simple.

Take your temperature at 850hpa and multiply by 1.053 and you will get what the surface temp should be in ideal conditions! Again for these extreme hot plumes this is going to be a good approximation. Again you will need a low humidity and cloudless skies for this to be reached.

 

The equation is in kelvins so for 25C at 850 you have to do (25+273.15)*1.053  - 273.15 which gets you 40C

 

Applying this equation for a few T850s we get:

T850 22C -> 37.6C

T850 23C -> 38.7C

T850 24C -> 39.7C

T850 25C -> 40.8C

T850 26C -> 41.9C

T850 27C -> 42.9C

T850 28C -> 43.9C

T850 29C -> 45.0C

T850 30C -> 46.0C

T850 31C -> 47.1C

T850 32C -> 48.1C

T850 33C -> 49.2C

T850 34C -> 50.3C

 

You can perhaps see why I got so excited about that 18Z run last night showing 28C on the south coast. So for the magic 40 we do really need T850s above 25C (allowing for a bit of lee way with clouds and moisture) .

 

 

Nice. So that record sounding back in 2019 would have given just over 40C had conditions been optimal. I'm not sure what the 850mb temperature actually was when the 38.7C record was set - by 00Z the following day the 20C isotherm was pretty well hugging the east coast.

 

This is a good site for discussion of the 2019 heatwaves - the graphic comparison of the soundings really shows up the differences. https://www.stratusdeck.co.uk/blog/the-anatomy-of-a-mega-heatwave

 

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

Offline Quantum  
#22 Posted : 05 July 2022 16:11:56(UTC)
Quantum

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Joined: 27/11/2009(UTC)
Posts: 26,662

Originally Posted by: Rob K Go to Quoted Post

 

 

Nice. So that record sounding back in 2019 would have given just over 40C had conditions been optimal. I'm not sure what the 850mb temperature actually was when the 38.7C record was set - by 00Z the following day the 20C isotherm was pretty well hugging the east coast.

 

This is a good site for discussion of the 2019 heatwaves - the graphic comparison of the soundings really shows up the differences. https://www.stratusdeck.co.uk/blog/the-anatomy-of-a-mega-heatwave

 

Great link, thanks!

Will add that for that plume, even if the conditions had been optimal I don't think it would have happened because I'm not convinced there is anywhere inland enough in the SW for the sea breeze to not have a major effect. So that plume in 2019 was much too far west aswell as moisture being brought in.

 

One other factor I didn't mention is that I've simplified the equation by making the assumption the pressure is 1020mb, in higher pressure you don't need quite as high T850s and in lower pressure you need higher ones.

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.

Offline Ally Pally Snowman  
#23 Posted : 05 July 2022 16:50:45(UTC)
Ally Pally Snowman

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Location: Bishop's Stortford, Hertfordshire

GFS 12z drops the furnace heat.

GEM looks a very hot run though.

 

 

Bishop's Stortford 85m ASL.
Offline DEW  
#24 Posted : 05 July 2022 17:38:00(UTC)
DEW

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Location: Chichester 12m. asl

Originally Posted by: Quantum Go to Quoted Post

The equation is in kelvins so for 25C at 850 you have to do (25+273.15)*1.053  - 273.15 which gets you 40C

Applying this equation for a few T850s we get:

T850 22C -> 37.6C

T850 23C -> 38.7C

T850 24C -> 39.7C

T850 25C -> 40.8C

T850 26C -> 41.9C

T850 27C -> 42.9C

T850 28C -> 43.9C

T850 29C -> 45.0C

T850 30C -> 46.0C

T850 31C -> 47.1C

T850 32C -> 48.1C

T850 33C -> 49.2C

T850 34C -> 50.3C

Useful, thanks

"The sky was an exquisitely deep blue just then, with filmy white clouds drawn up over it like gauze"
Offline TimS  
#25 Posted : 05 July 2022 21:17:36(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

So when do we officially consider this hot spell to begin?

My benchmark has generally been somewhere breaching 28C. We’re nowhere near so far this week - nothing above 24C. Could happen on Friday, or at a push and with a following wind (and less cloud than forecast) Thursday.

Quite an unusual heatwave where we don’t know if in only 4 or 5 days it will be 30C or mid 20s, but we kind of know it’s likely to be in the 30s in over a week’s time.

Brockley, South East London 30m asl
Offline White Meadows  
#26 Posted : 05 July 2022 21:51:28(UTC)
White Meadows

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Joined: 14/11/2011(UTC)
Posts: 3,019
Location: West Sussex

Originally Posted by: TimS Go to Quoted Post
So when do we officially consider this hot spell to begin?

My benchmark has generally been somewhere breaching 28C. We’re nowhere near so far this week - nothing above 24C. Could happen on Friday, or at a push and with a following wind (and less cloud than forecast) Thursday.

Quite an unusual heatwave where we don’t know if in only 4 or 5 days it will be 30C or mid 20s, but we kind of know it’s likely to be in the 30s in over a week’s time.

Probably as early as Saturday TBF

30c knocking on the door for many places by then. 

 

Offline TimS  
#27 Posted : 06 July 2022 07:29:13(UTC)
TimS

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Posts: 11,006
Location: Brockley

It remains on, despite this morning’s GFS op.

And this morning’s GFS op doesn’t stint on the European heat either, it just displaces it. Southern Iberia gets to 45+ this weekend and then sticks with it every day until 384 hours, peaking at 50C. Unprecedented.

All other op runs showing heatwave conditions for the UK. Only question is whether we threaten records.

Brockley, South East London 30m asl
Offline springsunshine  
#28 Posted : 06 July 2022 10:34:03(UTC)
springsunshine

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Posts: 1,854
Location: Bournemouth

At the moment it is looking likley the uk will get 2 or 3 days at most of extreme heat,very similar to what happened mid June. It certainly does not look as if it is going to last,thank god! As with the models in winter overcooking the cold iam awaiting the inevitable downgrades wef this weekend. My bet is somewhere will hit 35c-36c on one day but to get 40c in this country we need a prolonged spell of heat beforehand.It might happen but very unlikley imo.

Offline TimS  
#29 Posted : 06 July 2022 11:05:21(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

Originally Posted by: springsunshine Go to Quoted Post

At the moment it is looking likley the uk will get 2 or 3 days at most of extreme heat,very similar to what happened mid June. It certainly does not look as if it is going to last,thank god! As with the models in winter overcooking the cold iam awaiting the inevitable downgrades wef this weekend. My bet is somewhere will hit 35c-36c on one day but to get 40c in this country we need a prolonged spell of heat beforehand.It might happen but very unlikley imo.

Well this morning's 06z GFS gives us one day of 41C. And I would say the op was a disappointment/downgrade. A downgrade that gives the UK 41C is quite something.

Ideal for me would be at least a week of 28-32C and then one extremely hot day, or 2 at a push.

Brockley, South East London 30m asl
Online Chunky Pea  
#30 Posted : 06 July 2022 16:03:30(UTC)
Chunky Pea

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Man
Ireland
Location: East Galway, Ireland 35 m asl

Some interesting facts about the highest recorded temps in each of the European states:

Highest temperatures in Europe: A map and list of records • viborc.com

A good chunk of them have recorded 40c or more in the past, even in the 'near continent' regions, but Greece contunes to hold onto the the top spot with its 48c that was recorded in Athens 

Ireland 2022 Monthly Average/D.F. 81-10.

May: 12.3c / +1.4c

June: 13.7c / +0.4c

Year (up to July 2nd) 9.3c / +0.9c

Offline TimS  
#31 Posted : 06 July 2022 16:30:17(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

While we wait, worth monitoring where’s hot in Europe right now.

Current continental hotspot, with a mere 40C, is Kryvyi Ri airport in Ukraine, near Dnipro.

Next few days it’s going to be Spain.

Brockley, South East London 30m asl
Offline TimS  
#32 Posted : 06 July 2022 17:24:10(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

Another 39C in this evening's GFS, though GEM looks like it would peak lower. Meanwhile the 40s start in Southern Iberia. 41C tomorrow, then it's up from there: 44, 46, 45, 45, 45, 48, 48, 45, 42 

Brockley, South East London 30m asl
Offline TimS  
#33 Posted : 06 July 2022 19:05:08(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

The Beeb are finally getting off the fence. Schafernaker just said it’ll probably be above 30 in the South all next week.
Brockley, South East London 30m asl
Offline scillydave  
#34 Posted : 06 July 2022 19:05:48(UTC)
scillydave

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Location: Quantocks, West Somerset, 90masl

A good chance of the all time Spanish record going I'd think. For reference it's 47.4c recorded just last August.

Currently living at about 80m asl just off the Quantocks in Somerset.

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.

Offline TimS  
#35 Posted : 06 July 2022 19:09:00(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

Originally Posted by: scillydave Go to Quoted Post
A good chance of the all time Spanish record going I'd think. For reference it's 47.4c recorded just last August.

And the Portuguese record also of 47.4C set way back in 2003.

Brockley, South East London 30m asl
Online SJV  
#36 Posted : 06 July 2022 19:09:36(UTC)
SJV

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Joined: 22/11/2015(UTC)
Posts: 19,698
Man
Location: Sheffield, 133m ASL

Originally Posted by: TimS Go to Quoted Post

Another 39C in this evening's GFS, though GEM looks like it would peak lower. Meanwhile the 40s start in Southern Iberia. 41C tomorrow, then it's up from there: 44, 46, 45, 45, 45, 48, 48, 45, 42 

Haven't had chance to check but over on the other side there was mention of a 40C in N Kent on the GFS.

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Offline nsrobins  
#37 Posted : 06 July 2022 21:51:16(UTC)
nsrobins

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Posts: 18,855
Location: South Hampshire

Some consolidation now for a few days of extreme heat later next week as we tap into the heat dome across Spain and France.

Not certain of course, but the all-time could be under threat.

Neil

Fareham, Hampshire 28m ASL (near estuary)

Stormchaser, Member TORRO

Offline Crepuscular Ray  
#38 Posted : 07 July 2022 05:55:57(UTC)
Crepuscular Ray

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United Kingdom
Location: Blackford in south Edinburgh

A bit of hysteria from the model generators I feel! Looks to me like at least a week of fine warm or hot weather for the south and east of Scotland & England, 25 - 32 C.

For the Pennine areas, Cumbria and Western Scotland more cloud at times with drizzly rain 15 - 20 C

Jerry

Clappersgate, Ambleside, Lake District.

Offline TimS  
#39 Posted : 07 July 2022 08:27:25(UTC)
TimS

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Joined: 13/04/2010(UTC)
Posts: 11,006
Location: Brockley

The timing and peaks of this look like being uncannily like August 2003, but 2 days in advance, so it's worth running a day by day comparison. Yesterday was Friday 1 August - cloudy, with a high of 25C in the far SE (Manston that year if I recall). Today is Saturday 2nd August when in 2003 it reached 27C. We hit 30C on the Sunday.  

Arome is now in view and gives maxima of 26 or possibly 27C today, and 29-30C tomorrow.

Brockley, South East London 30m asl
Offline Rob K  
#40 Posted : 07 July 2022 09:12:58(UTC)
Rob K

Rank: Advanced Member

Joined: 02/05/2006(UTC)
Posts: 25,061
Location: Northeast Hampshire

Originally Posted by: Chunky Pea Go to Quoted Post

Some interesting facts about the highest recorded temps in each of the European states:

Highest temperatures in Europe: A map and list of records • viborc.com

A good chunk of them have recorded 40c or more in the past, even in the 'near continent' regions, but Greece contunes to hold onto the the top spot with its 48c that was recorded in Athens 

Since that article was written, Italy took over the top spot - see the updates near the top.

The European record is now 48.8C in Syracuse, Sicily, on August 11 2021.

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

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