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Global Warming
30 August 2021 19:49:18

This thread is for all comments, discussion, and analysis of temperatures in the UK during September, with particular emphasis on the Central England Temperature (CET), for the simple reason that it is the longest-running temperature series in the world with over 360 years of data. But you can comment on any interesting temperature statistics or data from across the UK, including your own backyard.  


For those taking part in the competition, all CET predictions for September should be sent directly to me via the forum private message system. Please do not post them directly into the thread.    


Historic CET summary for September


1981-2010 (30 years) 14.03C


1991-2020 (30 years) 14.17C 


2001-2020 (last 20 years) 14.27C 


Last year September was average at 14.0C. Actually the Setember CET  has been very similar and very close to average for the past 4 years varying between 13.5C and 14.3C. 2016 was very warm with 16.0C and 2015 was cold with 12.7C.


Here is a chart of the September CET for all years since 1961   


UserPostedImage 


Direct link to a larger version of the chart


Current model output     


The first week shows 850s above average but that is deceptive due to lots of cloud. So unlikely to see surface temperatures much above average - mean of 21C for a few days in London. After that the 850s are close to average with a lot of scatter. 


GEFS 


https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=2&run=99&lid=ENS&bw=


https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=5&run=99&lid=ENS&bw=


ECM (de Bilt) looks similar with temperatures struggling to push above 20C at any point.


http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png


Met Office contingency planners outlook  


https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/business/public-sector/civil-contingency/3moutlook-son-v1-secure.pdf


A 50/50 split between an average and a warm September based on the probabilities. The Met Office had almost the same split for August and we ended up with the average figure. I rather suspect the same will happen in September.


Precipitation also looks close to average. Another rather nondescript month in the offering I fancy.


A quick look at an interesting statistic. The CET figures for the last four months are remarkably similar to 2010. 


Year            May      June     July      August


2010           10.7C   15.2C   17.1C   15.3C


2021           10.1C   15.5C   17.7C   15.8C


The only other year with a similar pattern is 1994 (although June was 1C colder than 2021). Nov 1994 was of course a record CET and it was followed by a very mild winter. My gut feeling is that this year will more closely follow 2010 than 1994, although I do not expect a negative CET in December.


September 2010 saw a CET of 13.8C. I expect 2021 to come in somewhere close to 14C.

Hungry Tiger
01 September 2021 09:32:48


I am just temporally adding this comment here to prevent this thread from being relegated to page two of the list of threads on this forum once I have added my usual threads for the beginning of each month and season and updated various other threads as part of that process.

This is a thread which is always stickied by a mod and this is something which would normally have happened by now, but I will then delete this comment once that has happened.


Originally Posted by: johncs2016 


Just seen it - stickied it.


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


Hippydave
01 September 2021 20:33:28

Be interesting to see the spread of guesses/methodically arrived at predictions this month. Things are looking a touch warmer for the first 7 days this evening than when I made my guess, makes me wonder if I shouldn't have gone a bit more ballsy and seen if I could fluke another unlikely result


Home: Tunbridge Wells
Work: Tonbridge
ARTzeman
02 September 2021 13:11:49

Met Office Hadley     14.4c      Anomaly    -0.5 provisional to 1st


Metcheck                  14.22c    Anomaly    0.50c


Netweather               15.44c    Anomaly    1.45c


Peasedown St John   14.31c    Anomaly   0.03c.






Some people walk in the rain.
Others just get wet.
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ARTzeman
03 September 2021 10:17:05

Met Office Hadley      15.1c      Anomaly      0.3c provisional to 2nd


Metcheck                   14.65c    Anomaly      1.77c


Netweather                15.46c    Anomaly      1.77c 


Peasedown St John   14.76c    Anomaly     0.8c.    






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
Bertwhistle
03 September 2021 17:32:07

Thinking of CET in September for a single day, I wonder if there might be a 21C + day early next week.


The only few of these prestigious days I can find since 1940 are 14.9.2016 (21.3); 21.9.2006 and 2.9.1961(21.4) and 5.9.1949 (22.4)


Earlier ones include (and I didn't check further back in detail but knew of the possibilities here) 21.8 and 22.6 on 1. and 2.9.1906 respectively.


Interestingly most of these years had warm or very warm Septembers, with 3 of 16C +; the one that didn't also had the highest day CET (1906).


This will be hard to do mind- if you think, a 25C max day and 15C min day only give 20, although 2011 reminds us how even right at the end of the month the max can be higher.


Interesting to see what happens.


Add: the 1949 day was blessed by an incredible 18.4 min CET on 5th.


Bertie, Itchen Valley.
Retire while you can still press the 'retire now' button.
Global Warming
04 September 2021 09:04:36

After a cool start the first half of September looks very mild. Still close to 17C by the 18th.


The CET could exceed 20C on 7 and 8 September. At the moment it looks like it will be slightly shy of the date record but it could be close


Date         CET est        CET record mean


7 Sept      20.5C           21.1C  1868


8 Sept      20.8C           21.3C  1898


UserPostedImage


Chart 1


UserPostedImage


Chart 2

Global Warming
04 September 2021 09:58:54

Here is the table of predictions for September


I am going to impose some penalties for late predictions this month. There was a significant shift in the models shortly after the start of the month which means those making very late predictions potentially gained a significant advantage. There are no penalties for those who posted their predictions up to and including 1 September (12 people sent their predictions on the first). 


Those who sent a prediction on the second are going to be penalised by 0.2C (which is Windy Willow, Saint Snow and Duncan McAlister).


Whether Idle sent a prediction at 2236 on the 3rd and will take a 0.4C penalty.


UserPostedImage


Table

Gavin P
04 September 2021 10:45:32


After a cool start the first half of September looks very mild. Still close to 17C by the 18th.


The CET could exceed 20C on 7 and 8 September. At the moment it looks like it will be slightly shy of the date record but it could be close


Date         CET est        CET record mean


7 Sept      20.5C           21.1C  1868


8 Sept      20.8C           21.3C  1898


UserPostedImage


Chart 1


UserPostedImage


Chart 2


Originally Posted by: Global Warming 


Thanks GW! 


Gosh! Imagine if we had a 17C CET September! 


Given September 2006 came out at 16.8 a 17C CET September is certainly possible? 


Rural West Northants 120m asl
Short, medium and long range weather forecast videos @ https://www.youtube.com/user/GavsWeatherVids
ARTzeman
04 September 2021 11:10:31

Met Office Hadley       15.3c       Anomaly       0.5c provisional to 3rd


Metcheck                    14.77c     Anomaly       1.05c


Netweather                 15.66c     Anomaly       1.97c  


Peasedown St John    15.0c      Anomaly       0.72c. 






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
Caz
  • Caz
  • Advanced Member
04 September 2021 18:29:46


Here is the table of predictions for September


I am going to impose some penalties for late predictions this month. There was a significant shift in the models shortly after the start of the month which means those making very late predictions potentially gained a significant advantage. There are no penalties for those who posted their predictions up to and including 1 September (12 people sent their predictions on the first). 


Those who sent a prediction on the second are going to be penalised by 0.2C (which is Windy Willow, Saint Snow and Duncan McAlister).


Whether Idle sent a prediction at 2236 on the 3rd and will take a 0.4C penalty.


UserPostedImage


Table


Originally Posted by: Global Warming 

I think that’s very fair! 


At this point it looks very much like we’ll get a high month but then we all know how quickly things can change. 


Market Warsop, North Nottinghamshire.
Join the fun and banter of the monthly CET competition.
Whether Idle
04 September 2021 18:35:46


Here is the table of predictions for September


I am going to impose some penalties for late predictions this month. There was a significant shift in the models shortly after the start of the month which means those making very late predictions potentially gained a significant advantage. There are no penalties for those who posted their predictions up to and including 1 September (12 people sent their predictions on the first). 


Those who sent a prediction on the second are going to be penalised by 0.2C (which is Windy Willow, Saint Snow and Duncan McAlister).


Whether Idle sent a prediction at 2236 on the 3rd and will take a 0.4C penalty.


UserPostedImage


Table


Originally Posted by: Global Warming 


Thats fair enough - youre the boss.  Mine was down to insane work scedules but hey ho.


Dover, 5m asl. Half a mile from the south coast.
Saint Snow
04 September 2021 23:09:38

Mine was due to having a full message box that wouldn't allow me to send, then forgetting to clear a couple 'later' as I intended (and only just remembered on the 2nd!)


Not really a big issue, though, and I can see your reasoning. 



Martin
Home: St Helens (26m asl) Work: Manchester (75m asl)
A TWO addict since 14/12/01
"How can wealth persuade poverty to use its political freedom to keep wealth in power? Here lies the whole art of Conservative politics."
Aneurin Bevan
springsunshine
05 September 2021 08:54:55

After watching Gav`s 10-14 day forecast its in the relms of possibility we could have the warmest September on record this year. It looks like all being dependant on what happens with hurricane Larry.Very uncertain after this time next week with some models going for a marked decent into autumn instead. Nevertheless this coming week looks like being one of the warmest weeks of the summer.


Ive sat on the fence with a near average prediction of 14.25c but fully expect this to be way too low.

Bertwhistle
05 September 2021 09:40:00


After watching Gav`s 10-14 day forecast its in the relms of possibility we could have the warmest September on record this year. It looks like all being dependant on what happens with hurricane Larry.Very uncertain after this time next week with some models going for a marked decent into autumn instead. Nevertheless this coming week looks like being one of the warmest weeks of the summer.


Ive sat on the fence with a near average prediction of 14.25c but fully expect this to be way too low.


Originally Posted by: springsunshine 


Not out of the question although it would have to work hard in the second half to match 2006. That year to 18th averaged just under 17.1C; GW has mentioned that this year looks as if it may be around 17 at 18th. Apart from 21st in 2006 (which was very warm) and 24th, the other days were below 17. I'll watch Gav's again with this in mind I think.


Bertie, Itchen Valley.
Retire while you can still press the 'retire now' button.
ARTzeman
05 September 2021 10:31:29

Met Office Hadley       15.5c        Anomaly       0.7c provisional to 4th


Metcheck                    14.87c      Anomaly       1.15c


Netweather                 15.69c      Anomaly       2.0c


Peasedown St John     15.2c      Anomaly       0.92c.    


 






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
ARTzeman
06 September 2021 10:45:07

Met Office Hadley        16.0c      Anomaly       1.3c  provisional to 5th


Metcheck                     15.31c    Anomaly        1.58c


Netweather                  16.08c    Anomaly        2.39c


Peasdown St John     16.1c        Anomaly      1.9c.   






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
Stormchaser
06 September 2021 19:28:43

Been quite the run of days for CET projections. For a while there were some bonkers GFS runs giving me estimates of more than 18.0°C for the middle days of the month. Not for the daily returns, the mean-to-date! Would be record high for that point in the month.


Anyway, since then GFS has freshened up the weekend and has only intermittent very warm weather thereafter, so CET estimates aren't so eye-watering. They're still notably high though, owing to the impressive very warm / hot spell we're currently in and a lack of sustained switch to a cool pattern in most runs.


ECM was going for warmer but more unsettled outcomes than GFS yesterday but has moved close to it today. Sunday morning could feel decidedly cool as some polar maritime air moves though on a light breeze.


It soon warms up the following week, though. Generally I'm not seeing anything that would force a sustainably cool or very cool pattern to establish within the next fortnight. I'm starting to suspect I may have estimated too low for this month - but then again, I thought that about halfway through last month and...!  


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2023's Homeland Extremes:
T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
Keep Calm and Forecast On
Col
  • Col
  • Advanced Member
07 September 2021 04:59:50


After watching Gav`s 10-14 day forecast its in the relms of possibility we could have the warmest September on record this year. It looks like all being dependant on what happens with hurricane Larry.Very uncertain after this time next week with some models going for a marked decent into autumn instead. Nevertheless this coming week looks like being one of the warmest weeks of the summer.


Ive sat on the fence with a near average prediction of 14.25c but fully expect this to be way too low.


Originally Posted by: springsunshine 


Same here. I deliberately went bang on average as I thought it was going to be a non-descript month. There can have been few months when my prediction has gone so badly wrong at such an early stage in the month. Of course there could still be a very cold final 3rd of the month that would pull the figure back down, but how likely is that, really?


Col
Bolton, Lancashire
160m asl
Snow videos:
http://www.youtube.com/channel/UC3QvmL4UWBmHFMKWiwYm_gg
ARTzeman
07 September 2021 10:44:31

Met Office Hadley      16.7c     Anomaly      2.0c  provisional to 6th


Metcheck                   15.92c   Anomaly      2.19c


Netweather                16.69c   Anomaly      3.0c


Peasedown St John    16.9c    Anomaly     2.62c.   






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
Hungry Tiger
07 September 2021 13:31:39


Been quite the run of days for CET projections. For a while there were some bonkers GFS runs giving me estimates of more than 18.0°C for the middle days of the month. Not for the daily returns, the mean-to-date! Would be record high for that point in the month.


Anyway, since then GFS has freshened up the weekend and has only intermittent very warm weather thereafter, so CET estimates aren't so eye-watering. They're still notably high though, owing to the impressive very warm / hot spell we're currently in and a lack of sustained switch to a cool pattern in most runs.


ECM was going for warmer but more unsettled outcomes than GFS yesterday but has moved close to it today. Sunday morning could feel decidedly cool as some polar maritime air moves though on a light breeze.


It soon warms up the following week, though. Generally I'm not seeing anything that would force a sustainably cool or very cool pattern to establish within the next fortnight. I'm starting to suspect I may have estimated too low for this month - but then again, I thought that about halfway through last month and...!  


Originally Posted by: Stormchaser 



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


ARTzeman
08 September 2021 10:22:33

Met Office Hadley       17.4c      Anomaly     2.7c


Metcheck                    16.50c    Anomaly     2.8c


Netweather                 17.36c    Anomaly     3.66c


Peasedown St John    17.51c    Anomaly     3.23c. 






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
ARTzeman
09 September 2021 10:51:21

Met Office Hadley         18.0c       Anomaly      3.3c provisional to 8th


Metcheck                      17.07c     Anomaly      3.34c


Netweather                   17.86c     Anomaly      4.17c


Peasedown St John      17.48c     Anomaly      3.2c.   






Some people walk in the rain.
Others just get wet.
I Just Blow my horn or trumpet
Bolty
09 September 2021 15:36:58
Still early days, but could this be another instance where September is warmer than the August before it? The last time it happened was in 2014: August was 14.9 and September was 15.1.
Scott
Blackrod, Lancashire (4 miles south of Chorley) at 156m asl.
My weather station 
Bertwhistle
09 September 2021 17:59:23

Still early days, but could this be another instance where September is warmer than the August before it? The last time it happened was in 2014: August was 14.9 and September was 15.1.

Originally Posted by: Bolty 


I've popped through some of the hot early Septembers and I can't see one since 1868 with a hotter first 8 days- I'm sure someone else can spot one- mean daily CET that is. As we saw early in the month it can change at the drop of a hat though.


Bertie, Itchen Valley.
Retire while you can still press the 'retire now' button.

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