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Steam Fog
04 July 2013 09:56:44


What actually constitutes a Heatwave? Does the temp have to exceed a certain figure over a number of days for it to be called a heatwave?
Some of our experts will surely know this??

Originally Posted by: Downpour 


Heatwave thresholds by region/nation (Scotland and NI dont have official thresholds, presumably because they so rarely have heatwaves!UserPostedImage)

Threshold temperatures

RegionDay max (°C)Night min (°C)

North East England
28
15


North West England
30
15


Yorkshire & Humber
29
15


East Midlands
30
15


West Midlands
30
15


East of England
30
15


South East England
31
16


London
32
18


South West England
30
15


Wales
30
15




Originally Posted by: Kev71 



I believe those are actually the values for when a Health Heatwave is triggered which will lead to certain steps being taken by emergency services. A Heatwave has a looser definition, but depending on the definition would not need temperatures as high as those.
Col
  • Col
  • Advanced Member
04 July 2013 10:01:01



What actually constitutes a Heatwave? Does the temp have to exceed a certain figure over a number of days for it to be called a heatwave?


Some of our experts will surely know this??


Originally Posted by: Downpour 


Heatwave thresholds by region/nation (Scotland and NI dont have official thresholds, presumably because they so rarely have heatwaves! )


 


Threshold temperatures





















































RegionDay max (°C)Night min (°C)
North East England2815
North West England3015
Yorkshire & Humber2915
East Midlands3015
West Midlands3015
East of England3015
South East England3116
London3218
South West England3015
Wales3015


Originally Posted by: Kev71 


I wonder why NW England has a higher threshold than Yorks & Humberside? If it's based on average max temps (as it would appear to be for everywhere else) I would expect Leeds for example to be a little warmer than Manchester. I'd understand the threasholds being the same but NW England being higher seems a little odd. Perhaps in the very hottest conditions that can ocurr with an easterly or even a south easterly, wiinds from the north sea mean that Yorks & Humberside are a little cooler than NW England.


Col
Bolton, Lancashire
160m asl
Snow videos:
http://www.youtube.com/channel/UC3QvmL4UWBmHFMKWiwYm_gg
Ally Pally Snowman
04 July 2013 10:15:06

Already 22c in Doncaster. Many 21s and 20s. Should easily get 25/26 today. Hottest sustained spell for 7 years has begun.


Bishop's Stortford 85m ASL.
Essan
04 July 2013 10:48:46


I can not wait this will be the first time since returning from Thailand I will have considered sitting outside, although I really do not expect it to get that hot here, but the sunshine alone will be nice.


_______________________________________________________________________________________________________________________


Gary


Originally Posted by: domma 



Whereas I'll be sat indoors the whole time as it becomes too hot to go out ......   Weather has been great for outdoor activities so far this summer (dry, often breezy) but that's all about to end.   Oh well, can't have it all!


Andy
Evesham, Worcs, Albion - 35m asl
Weather & Earth Science News 

Anyone who is capable of getting themselves made President should on no account be allowed to do the job - DNA
Essan
04 July 2013 11:01:14


Heatwave thresholds by region/nation (Scotland and NI dont have official thresholds, presumably because they so rarely have heatwaves! 

Originally Posted by: Downpour 



They don't have cold weather health warnings either  - the heat health advisories (issued by the Met Office to Dept of Health criteria) only cover England and Wales.

Of course, the threshold for an heat health advisory has no more bearing in whether it's a heatwave than the thresholds for a cold advisory do on whether it's a deep freeze



Andy
Evesham, Worcs, Albion - 35m asl
Weather & Earth Science News 

Anyone who is capable of getting themselves made President should on no account be allowed to do the job - DNA
Sevendust
04 July 2013 11:08:22

Methinks there is a danger of this thread being overrun with a few overexcited heat rampers and a few more doom mongers about how its not going to be that warm or those who are going to die in the heat. Reminds me winter in an opposite sort of way!


Seriously though, the heat will bring a mix of issues, both good and bad. If we see a static HP cell parked over the UK for days then air quality will fall quite quickly, especially in London and that poses risks for asthmatics and others with breathing issues. I recall being in London in August 1990 on a "sunny" day at 34'C. Days of heatbuild had led to a notable petrochemical smog that made the sun very hazy. My half mile walk to the train station amongst the big buildings in the square mile was a sauna!


As for maxes, the orientation of windflow will favour certain places more than others.In 1990 it was Barbourne(Worcestershire) that recorded the hottest.


Places near me to the west or SW of London can do very well in a easterly drift.


I shall be off work next week so expect to be heading for the coast! 

Downpour
04 July 2013 12:09:55



Heatwave thresholds by region/nation (Scotland and NI dont have official thresholds, presumably because they so rarely have heatwaves! 

Originally Posted by: Essan 



They don't have cold weather health warnings either  - the heat health advisories (issued by the Met Office to Dept of Health criteria) only cover England and Wales.

Of course, the threshold for an heat health advisory has no more bearing in whether it's a heatwave than the thresholds for a cold advisory do on whether it's a deep freeze



Originally Posted by: Downpour 


 


That's true - the Office themselves have no god given right to define it I guess.


Also I wonder why London's is higher? You'd think a heat advisory threshold in London would be lower, due to the oppressive effect of concrete, tubes etc, and fewer opportunities/spaces to cool off. 


Chingford
London E4
147ft
Gavin P
04 July 2013 12:28:25

What is it about years ending in "3" having good summers? 1983. 2003. 2013?


On heatwave definitions, I always thought the WMO defined a heatwave as five consecutive days with temperatures of 5c or more above average - On that definition the coming week does indeed look like a "heatwave" to me.


Rural West Northants 120m asl
Short, medium and long range weather forecast videos @ https://www.youtube.com/user/GavsWeatherVids
Jiries
04 July 2013 12:30:25


What is it about years ending in "3" having good summers? 1983. 2003. 2013?


Originally Posted by: Gavin P 


Yes let hope this summer do the same.  1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.

Sevendust
04 July 2013 12:31:52


What is it about years ending in "3" having good summers? 1983. 2003. 2013?


On heatwave definitions, I always thought the WMO defined a heatwave as five censecutive days with temperatures of 5c or more above average - On that definition the coming week does indeed look like a "heatwave" to me.


Originally Posted by: Gavin P 


1993 crap though!

Gavin P
04 July 2013 12:35:36



What is it about years ending in "3" having good summers? 1983. 2003. 2013?


On heatwave definitions, I always thought the WMO defined a heatwave as five censecutive days with temperatures of 5c or more above average - On that definition the coming week does indeed look like a "heatwave" to me.


Originally Posted by: Sevendust 


1993 crap though!


Originally Posted by: Gavin P 


Yeah that was funny. All the hot summers in the 90's, yet the one you would think odds on to be hot, 1993, was the worst, with 1998, of the decade.


 


Rural West Northants 120m asl
Short, medium and long range weather forecast videos @ https://www.youtube.com/user/GavsWeatherVids
Edicius81
04 July 2013 12:37:56



What is it about years ending in "3" having good summers? 1983. 2003. 2013?


Originally Posted by: Jiries 


Yes let hope this summer do the same.  1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.


Originally Posted by: Gavin P 


That said, The record temeratures in 2003 were in August. There's definitely still time for all that

Downpour
04 July 2013 13:48:12



What is it about years ending in "3" having good summers? 1983. 2003. 2013?UserPostedImage

Originally Posted by: Edicius81 


Yes let hope this summer do the same. 1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.UserPostedImage

Originally Posted by: Jiries 


That said, The record temeratures in 2003 were in August. There's definitely still time for all that UserPostedImageUserPostedImage

Originally Posted by: Gavin P 




That's right - August is still the top dog summer month. The top four hottest days ever were all in August I believe.
Chingford
London E4
147ft
Steam Fog
04 July 2013 13:57:02
Met Office blog.

What is a Heatwave? (short answer is there is no official UK definition)

http://metofficenews.wordpress.com/2013/07/04/what-is-a-heat-wave/ 
LeedsLad123
04 July 2013 14:04:06


I wonder why NW England has a higher threshold than Yorks & Humberside? If it's based on average max temps (as it would appear to be for everywhere else) I would expect Leeds for example to be a little warmer than Manchester. I'd understand the threasholds being the same but NW England being higher seems a little odd. Perhaps in the very hottest conditions that can ocurr with an easterly or even a south easterly, wiinds from the north sea mean that Yorks & Humberside are a little cooler than NW England.


Originally Posted by: Col 


I've asked myself this question before - one just needs to look at the historical data for both Leeds and Manchester to see that Leeds is usually warmer, both on average and during heatwaves, and the same applies for the rest of Yorkshire vs NW England - Yorks is almost always warmer. 


Whitkirk, Leeds - 85m ASL.
idj20
04 July 2013 14:07:42

What is it about years ending in "3" having good summers? 1983. 2003. 2013?UserPostedImage

Originally Posted by: Downpour 

Yes let hope this summer do the same. 1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.UserPostedImage

Originally Posted by: Edicius81 

That said, The record temeratures in 2003 were in August. There's definitely still time for all that UserPostedImageUserPostedImage

Originally Posted by: Jiries 

That's right - August is still the top dog summer month. The top four hottest days ever were all in August I believe.

Originally Posted by: Gavin P 



I remember August 1990 when there was a week of 30 C-plus temperatures over the South and South East where apparently it peaked on the 3rd with 37.7 C (a whisker short of the 100 F mark) at Cheltingham.
   I was very fortunate in being off work on holiday leave on that week (it was booked a month in advance) - that was also when I was fresh into my first ever proper relationship, I was 23 at the time and I wasn't really of much use on that week due to how stifling hot it was. I rode my motorbike from my girlfriend's house to my house in just my shorts (as well as a helmet of course!) and it felt like being blasted at by a hairdryer as I rode along.
 
Anyway, in addition to my last post in this thread, I do have mixed feelings about it all. On the one hand I'd like it to be hot and sunny so that I could sit in the garden and get a bit of a tan on as I'm looking quite pale and close to getting rickets, but then the Addams Family next door will want to do the same thing and I get to hear all of them SHOUTING at the top of their voices as well as the smell of cigarette smoke and dope wafting my way.
  Like I said before, it looks like bike rides out into the countryside or beach - with camera on tow of course - will be a regular thing for me. But if it does tend to get cool and misty then those bike rides would become less appealing, but on the other hand it'll make it quiter and peaceful around here as no one would want to hang around outside for too long.

The proof will be in the pudding over the next few days regarding the weather for this location.


Folkestone Harbour. 
04 July 2013 14:12:13

Heatwaves are ok, as long as there is a real good thunder breakdown at the end of it


Let's get some cracking storms going, for pete's sake


Must say, my confidence is low on that, at the moment


Being a hayfever sufferer, i'm not looking forward to the very high pollen counts


Desktop fan will be purchased tomorrow... stay cool


Bring on the heat

Rob K
04 July 2013 14:23:34


What is it about years ending in "3" having good summers? 1983. 2003. 2013?UserPostedImage

Originally Posted by: idj20 

Yes let hope this summer do the same. 1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.UserPostedImage

Originally Posted by: Downpour 

That said, The record temeratures in 2003 were in August. There's definitely still time for all that UserPostedImageUserPostedImage

Originally Posted by: Edicius81 

That's right - August is still the top dog summer month. The top four hottest days ever were all in August I believe.

Originally Posted by: Jiries 



I remember August 1990 when there was a week of 30 C-plus temperatures over the South and South East where apparently it peaked on the 3rd with 37.7 C (a whisker short of the 100 F mark) at Cheltingham.


Originally Posted by: Gavin P 


Nitpick - 37.1C. The hottest 5 days on record are


10 Aug 2003: 38.5C (38.1C at Kew if you discount the Brogdale reading)


3 Aug 1990: 37.1C


9 Aug 1911: 36.7C


2 Aug 1990: 36.6C (potentially a dodgy reading)


19 July 2006: 36.5C


 


Just illustrates how much hotter 2003 was. None of these measly few tenths, but a full degree (or more) hotter.


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
idj20
04 July 2013 14:31:33



What is it about years ending in "3" having good summers? 1983. 2003. 2013?UserPostedImage

Originally Posted by: Rob K 

Yes let hope this summer do the same. 1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.UserPostedImage

Originally Posted by: idj20 

That said, The record temeratures in 2003 were in August. There's definitely still time for all that UserPostedImageUserPostedImage

Originally Posted by: Downpour 

That's right - August is still the top dog summer month. The top four hottest days ever were all in August I believe.

Originally Posted by: Edicius81 



I remember August 1990 when there was a week of 30 C-plus temperatures over the South and South East where apparently it peaked on the 3rd with 37.7 C (a whisker short of the 100 F mark) at Cheltingham.


Originally Posted by: Jiries 


Nitpick - 37.1C. The hottest 5 days on record are


10 Aug 2003: 38.5C (38.1C at Kew if you discount the Brogdale reading)


3 Aug 1990: 37.1C


9 Aug 1911: 36.7C


2 Aug 1990: 36.6C (potentially a dodgy reading)


19 July 2006: 36.5C


 


Just illustrates how much hotter 2003 was. None of these measly few tenths, but a full degree (or more) hotter.


Originally Posted by: Gavin P 



Indeed, had a feeling 37.7 C wasn't the correct figure as I noticed it down on my personal records (was too lazy to google it up), still, the 37.1 C achieved was memorable as that was the first time I've "seen with my own eyes" that kind of heat as I was into meteorology for about ten years at the time (I was 8 in 1976 and I remember the 33 C in July '83 as that was my last year at school).

But getting back to the here-and-now. I'm glad I'm no longer in the tomato greenhouse trade, I would be greeting this upcoming warm spell in utter contempt!


Folkestone Harbour. 
Hungry Tiger
04 July 2013 15:38:02




What is it about years ending in "3" having good summers? 1983. 2003. 2013?UserPostedImage

Originally Posted by: idj20 

Yes let hope this summer do the same. 1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.UserPostedImage

Originally Posted by: Rob K 

That said, The record temeratures in 2003 were in August. There's definitely still time for all that UserPostedImageUserPostedImage

Originally Posted by: idj20 

That's right - August is still the top dog summer month. The top four hottest days ever were all in August I believe.

Originally Posted by: Downpour 



I remember August 1990 when there was a week of 30 C-plus temperatures over the South and South East where apparently it peaked on the 3rd with 37.7 C (a whisker short of the 100 F mark) at Cheltingham.


Originally Posted by: Edicius81 


Nitpick - 37.1C. The hottest 5 days on record are


10 Aug 2003: 38.5C (38.1C at Kew if you discount the Brogdale reading)


3 Aug 1990: 37.1C


9 Aug 1911: 36.7C


2 Aug 1990: 36.6C (potentially a dodgy reading)


19 July 2006: 36.5C


 


Just illustrates how much hotter 2003 was. None of these measly few tenths, but a full degree (or more) hotter.


Originally Posted by: Jiries 



Indeed, had a feeling 37.7 C wasn't the correct figure as I noticed it down on my personal records (was too lazy to google it up), still, the 37.1 C achieved was memorable as that was the first time I've "seen with my own eyes" that kind of heat as I was into meteorology for about ten years at the time (I was 8 in 1976 and I remember the 33 C in July '83 as that was my last year at school).

But getting back to the here-and-now. I'm glad I'm no longer in the tomato greenhouse trade, I would be greeting this upcoming warm spell in utter contempt!


Originally Posted by: Gavin P 


You can enjoy this warm/hot spell this time Ian. I remember the pics you put on here of your tomatoes after the hot July of 2006.


Amazing that is now 7 years ago.


 


Gavin S. FRmetS.
TWO Moderator.
Contact the TWO team - [email protected]
South Cambridgeshire. 93 metres or 302.25 feet ASL.


TimS
  • TimS
  • Advanced Member
04 July 2013 16:01:38

So, do people think this weather we're about to get marks one of those "pattern changes" that occasionally happen, like May 2007, Nov/Dec 1988 etc. Or is it just a spell of nice weather before the topsy turvy jet re-establishes for the next 5 years?


It strikes me that the North Atlantic pattern we are seeing, with depressions spilling continuously over the Southern end of Greenland, is something that has happened rarely if at all for many years.


Brockley, South East London 30m asl
idj20
04 July 2013 16:06:36





What is it about years ending in "3" having good summers? 1983. 2003. 2013?UserPostedImage

Originally Posted by: Hungry Tiger 

Yes let hope this summer do the same. 1983 was constant warm to hot so we are possible looking at 1983 type here instead of 2003 as no models showing high 30's temps here and low 40's over France.UserPostedImage

Originally Posted by: idj20 

That said, The record temeratures in 2003 were in August. There's definitely still time for all that UserPostedImageUserPostedImage

Originally Posted by: Rob K 

That's right - August is still the top dog summer month. The top four hottest days ever were all in August I believe.

Originally Posted by: idj20 



I remember August 1990 when there was a week of 30 C-plus temperatures over the South and South East where apparently it peaked on the 3rd with 37.7 C (a whisker short of the 100 F mark) at Cheltingham.


Originally Posted by: Downpour 


Nitpick - 37.1C. The hottest 5 days on record are


10 Aug 2003: 38.5C (38.1C at Kew if you discount the Brogdale reading)


3 Aug 1990: 37.1C


9 Aug 1911: 36.7C


2 Aug 1990: 36.6C (potentially a dodgy reading)


19 July 2006: 36.5C


 


Just illustrates how much hotter 2003 was. None of these measly few tenths, but a full degree (or more) hotter.


Originally Posted by: Edicius81 



Indeed, had a feeling 37.7 C wasn't the correct figure as I noticed it down on my personal records (was too lazy to google it up), still, the 37.1 C achieved was memorable as that was the first time I've "seen with my own eyes" that kind of heat as I was into meteorology for about ten years at the time (I was 8 in 1976 and I remember the 33 C in July '83 as that was my last year at school).

But getting back to the here-and-now. I'm glad I'm no longer in the tomato greenhouse trade, I would be greeting this upcoming warm spell in utter contempt!


Originally Posted by: Jiries 


You can enjoy this warm/hot spell this time Ian. I remember the pics you put on here of your tomatoes after the hot July of 2006.


Amazing that is now 7 years ago.


 


Originally Posted by: Gavin P 



The heat on that fateful day was so intense, it destroyed half the crop under glass (there was a bad outbreak of red spider mites as well so it was a double whammy effect). However, because every tomato greenhouses around the county suffered the same fate, it caused fruit prices to go shooting right up as it became a valuable commodity. As a result we actually made a profit on that year!


Folkestone Harbour. 
Essan
04 July 2013 16:52:57


So, do people think this weather we're about to get marks one of those "pattern changes" that occasionally happen, like May 2007, Nov/Dec 1988 etc. Or is it just a spell of nice weather before the topsy turvy jet re-establishes for the next 5 years?


It strikes me that the North Atlantic pattern we are seeing, with depressions spilling continuously over the Southern end of Greenland, is something that has happened rarely if at all for many years.


Originally Posted by: TimS 



I think it's a continuation of the pattern we've been seeing for the past few years due to a weak, meandering jet stream.  Only this time we're in the right position to tap into some heat rather than cold and wet!  


Andy
Evesham, Worcs, Albion - 35m asl
Weather & Earth Science News 

Anyone who is capable of getting themselves made President should on no account be allowed to do the job - DNA
Rob K
04 July 2013 17:09:37



I think it's a continuation of the pattern we've been seeing for the past few years due to a weak, meandering jet stream.  Only this time we're in the right position to tap into some heat rather than cold and wet!  


Originally Posted by: Essan 


You could be right - after all the pattern of the last six years has resulted in several heatwaves in Europe, just too far east to affect us.


 


BTW re August 1990 I do remember that heatwave - probably the first one I can place. I was on a Scout camp in Devon. I remember on the hottest day we all went swimming in the local river for most of the day to cool off. 


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
LeedsLad123
04 July 2013 17:13:08

30C for Yorkshire and north Midlands at the end of the 'high-res' GFS run.


http://cdn.nwstatic.co.uk/gfsimages/gfs.20130704/12/192/ukmaxtemp.png


Whitkirk, Leeds - 85m ASL.

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