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 back yard.  

August has been a slightly above average month overall. 

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

The deadline for predictions is 2359 tonight (Saturday evening). 

Now on to some data for September

Historic CET summary for September

1971-2000 13.7C (30 years)  

1981-2010 14.0C (30 years) 

1999-2018 14.4C (last 20 years)  

September last year was average with 13.7C with 13.5C in the previous year. 2016 was very warm with 16.0C whereas 2015 was cool with 12.7C. 

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

Direct link to chart

Latest model output 850hPa and T2m temperatures - 28 Jul (12z) 

SHORT RANGE (2 weeks)

GEFS (12z) - mean is below average but huge scatter

https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=2&run=12&lid=ENS&bw=

T2m temperatures are really quite cool

https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=5&run=12&lid=ENS&bw=

GEM ENS (00z) - Similar to GFS

https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gem&var=2&run=12&lid=ENS&bw=

T2m's on the cool side  

https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gem&var=5&run=12&lid=ENS&bw=

The 00z ECM ENS T2m temperatures for De Bilt are also cool.

http://cdn.knmi.nl/knmi/map/page/weer/waarschuwingen_verwachtingen/ensemble/detail/ensemble-verwachtingen-detail10.png

LONGER RANGE

Met Office contingency planners outlook  

Probability is for higher than average temperatures to be the most likely option.

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

Monthly outlook at BBC website

Cool first half but potentially warmer towards the latter part of the month

https://www.bbc.co.uk/weather/outlook 

JMA 

Cool start returning to average

http://ds.data.jma.go.jp/tcc/tcc/products/model/map/1mE/map1/img/R07_1/Y201908.D2812.png

http://ds.data.jma.go.jp/tcc/tcc/products/model/map/1mE/map1/img/R07_2/Y201908.D2812.png

http://ds.data.jma.go.jp/tcc/tcc/products/model/map/1mE/map1/img/R14_3/Y201908.D2812.png

ECM 

After a cool start it gradually turns warmer with potentially slightly above average conditions by the end of the month

https://www.met.hu/img/meTz/meTz20190829_0000+26400.png

https://www.met.hu/img/meTz/meTz20190829_0000+43200.png

https://www.met.hu/img/meTz/meTz20190829_0000+60000.png

https://www.met.hu/img/meTz/meTz20190829_0000+76800.png

Beijing Climate Centre  

Slightly above average for the UK

https://cmdp.ncc-cma.net/download/Prediction/MD2gen/20190830/figure/md2019091gl_t2m1_2.gif

CanSIPS

Close to average perhaps slightly above in the east of the UK

https://www.tropicaltidbits.com/analysis/models/cansips/2019080100/cansips_T2ma_global_2.png

Here is the list of predictions for September

Full sized table

Thanks GW. An interesting spread of predictions there. Col could open up a significant lead if a decent September heatwave manifests. 

That's what I'm counting on. I feel that summer hasn't finished with us yet and like the past few months there will be a dose of heat towards the end of the month. This  line of thinking paid off in August and I'm hoping the weather pattern continues and it pays off in September as well. It is something of a gamble though, it could go badly wrong and if one of my closest rivals has a good month I could lose my lead entirely!

Met Office Hadley            12.4c.         Anomaly      -1.6c.

Metcheck                         13.6c          Anomaly      -0.12c

Netweather                      13.99c        Anomaly       0.3c

PSJ                                  12.74c        Anomaly      -1.98c. 

A strong warm spell is certainly plausible with the background drivers bearing some similarity to Sep 2011 for example.

I've factored that in too, but couldn't drum up enough confidence to anticipate a long and strong enough warm spell to do more than neutralise the CET anomaly after the unusually cool opening 10 days or so.

Perhaps I'll regret that - after all, anticipating a big turnaround worked well in July & August.

The 00z ECM looks promising for a mid-month very warm spell, but the 00z FV3/GFS could hardly be more different. The two models have been at odds for several 00z/12z runs now.

Same here SC. I'm spotting the potential mid month heatwave but I can't ignore these first 10 days. Nigh time temps are starting to drop into single digits with increasing frequency.

I didn't dare go above 14.32 as a result.

Met Office Hadley            13.5c.       Anomaly     -1.4c. Provisional to 2nd.

Metcheck                         14.15c      Anomaly      0.43c

Netweather                      14.46c      Anomaly      0.77c

Peasedown St John           13.8c.       Anomaly      -0.92c  Using a 6-year average.            

Met Office Hadley            14.5c.        Anomaly          -0.4c. Provisional to 3rd.

Metcheck                         14.86c       Anomaly          1.14c

Netweather                      15.33c       Anomaly          1.64c

Peasedown St John            14.8c        Anomaly          0.08c 

We finally have a GFS run that depicts a big mid-month warm-up, albeit only lasting a week.

It's enough to rocket a rough CET estimate upward from just 13.4*C as of 10th to 14.7*C as of 18th. 

So, it goes to show how rapidly the 'flavour' of the month can change.

Worth noting the seasonal cooling trend with time though; applying long-term average from 21st onward temps thereafter results in the CET estimate dropping from the mid-14s as of 20th (end of FV3 run) to the low 14s as of month's end.

Sep 2011 was, however, an extremely strong reminder that the seasonal trend doesn't always apply! 

Met Office Hadley             14.7c.       Anomaly      -0.1c. Provisional to 4th.

Metcheck                          14.63c      Anomaly      0.91c

Netweather                       15.44c      Anomaly      1.73c

PSJ                                   14.85c      Anomaly      0.13c

Met Office Hadley           14.5c         Anomaly      -0.2c  Provisional to 5th.

Metcheck                        14.35c      Anomaly       0.63c

Netweather                     15.0c        Anomaly       1.31c.

Peasedown St John          14.18c      Anomaly       -0.54       

GW..

Can you help me (or anybody please?)

Whenever I view  a posting of yours - nothing shows. The posting is totally blank.

If I reply  (as per this note) then I am able to see your posting, but not able to access any of your links outside of this forum.

If I access your profile I can then 'see' the last 10 postings of yours.

I was trying to ensure that my entry for this months competition was OK, but I am unable to see the table you have shown above.

It must be some 'option' somewhere, but I am lost as to where to start to resolve the issue. I wondered if I had accidently blocked you but can find no evidence of it..

Anyone else had the same problem?

Grandad 

Edit...

Just found a shoe/hide option at the end of your post.

If I click on 'show' the post appears. So how do I turn the 'hide' feature on/off is probably the question I need to ask? 

Oh no.... now I cannot see this post?     Can anyone else?

PS  I can see everyone elses posts OK>>>

PSS... Problem solved.....

I have found a 'show' all user  posts if I access the profile for Global Warming or anyone else.

I was not aware the option existed and must have turned it to 'hide' when I sent the PM for Sept CET  to you over2 weeks ago, before my hols.

I have just got back from holidays and I could not see any of my own (or more importantly) your posts.

Grandad  

Met Office Hadley           14.5c.      Anomaly      -0.2c. Provisional to 6th.

Metcheck                        14.20c     Anomaly      0.47c

Netweather                     14.81c     Anomaly      1.12c

Peasedown St John           14.38c     Anomaly      -0.34c   

Met Office Hadley         14.4c.      Anomaly       -0.2c Provisional to 7th.

Metcheck                      13.79c     Anomaly       0.07c

Netweather                   14.58c     Anomaly       0.89c

Peasedown St John        13.94c     Anomaly       -0.78c. 

GFS 00z possibly showed us the ultimate warmest possible outcome for mid-Sep with a prolonged southerly delivering a dozen days of increasingly impressive warmth. This catapults a rough CET estimate of mine up to 15.6*C as of 22nd, to the sound of much gleeful chuckling from Col in my overactive imagination.

Even exactly average conditions thereafter would land the final CET around the 15*C mark.

The 06z is more restrained, but still suggests that the CET may be a good way through the 14s by 23rd. ECM shows good support for the precursor UK high setup D6-D10.

Starting to wonder if I'll regret punting for a total balance of cool and warm this month.

I did see that run and to be honest couldn't quite believe what I was seeing. It was apparently very much a warm/hot outlier though. So no 'gleeful chuckling' here at camp Col, at least not yet. It's more of a cautious optimism, after all the forecast warm weather is still a week away.

Met Office Hadley         14.1c.       Anomaly        -0.6c.   Provisional to 8th.

Metcheck                      13.67c      Anomaly        -0.05c

Netweather                   14.21c      Anomaly        0.52c

Peasedown St John        13.8c       Anomaly        -0.92c. 

Ouch! That's quite a drop, presumably primarily due to low overnight minima. It will take another hit today as well, this time mainly because of low maxima. After that I expect it will make a general steady rise, hopefully for some time to come!

Met Office Hadley           13.9c.     Anomaly       -0.6c  Provisional to 9th.

Metcheck                        13.53c    Anomaly       -0.19c

Netweather                     14.07c    Anomaly        0.38c

Peasedown st john           13.98c    Anomaly        -0.74c.           

Well, I imagine Col nearly keeled over when the 12z GFS of yesterday rolled out. The 00z of today wasn't much better either, but the 06z has upped the temperatures markedly for the 2nd half of next week onward.

This takes it toward the ECM 00z, which itself is warmer than the preceding 12z from that model, which was already much warmer than a downright chilly 00z before that.

So overall, we've been a big downward dip in the temp signals for late month - with a CET well down in the 13s being put on the table - followed by a considerable resurgence, with the GFS 06z giving me a rough estimate in the high 14s for the CET to 25th.

The ECM 00z looks to have less of a fresher interlude during the middle part of next week, so would likely yield an even higher CET estimate if I had the time for that.

I daresay Col has little reason to worry at this time (now just watch the 12z runs all align to the northerly outcome for mid-next week...!).

Yes indeed, that did come as something of a shock! However the stunning previous charts were still for a week away and I've watched enough cold spells on the MOD thread unravel at that timeframe or shorter to know that nothing is remotely 'nailed on' at that distance. Conversely of course (as has happened to some degree) there is still time for the output to make it's way back again.

Thing is though due to the predictions of my closest rivals, I don't even have to be extremely close to preserve my lead. Even in the high 14s I will extend it.