As usual all CET predictions to be sent to me via PM please

Deadline is 2359 on Monday evening (3 September).

August was a bit of a frustrating month. A hot start followed by somewhat cooler but still very warm conditions. The last 9 days saw a steep drop in the CET which left us only very slightly above average and ensured that summer 2018 finished in fifth place in the all time rankings rather than third.  

September has a recent track record of being very warm. The Met Office contingency planners forecast is continuing to show increased probability of warmer than average conditions right through to the end of Autumn. We may have missed out on a record breaking summer CET but what odds a record breaking Autumn CET this year? Eyes down for another interesting season I think. And after that we have a solar minimum winter to come. It won't be dull thats for sure.

Historic CET summary for September

1971-2000 13.7C (30 years)

1981-2010 14.0C (30 years)

1998-2017 14.4C (last 20 years)

After a run of very warm Septembers in the early part of this century the last 11 years have seen an average CET of 14.0C with only 2016 finishing above 15.1C. Last year was a little below average at 13.5C but 2016 saw a figure of 16.0C

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

Direct link to larger version of the CHART

Current model output

GFS (12z) - 850hPa temperatures generally somewhat above average but nothing exceptional.  

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

GEM (12z) - similar to GFS

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

Multi Op - generally looking fairly mild. ECM12z seems to have gone off on one - very out of sync in the latter part of the run

http://www.wetterzentrale.de/de/show_diagrams.php?model=multi&var=2&geoid=49069&lid=OP&bw=

Met Office contingency planners outlook 

Looking like a continuation of the warm weather is the outcome with the highest probability fo this Autumn. They seem to have stopped providing a chart for the month ahead and now only show the next 3 months combined.

https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-son-v2.pdf

Recent data for September

https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/ncic-temp-maps-son.pdf

Out of interest the precipitation forecast is close to average.

Temperature analogues

The last time we had a run of very warm months prior to September was in 2003. The September of that year was relatively warm at 14.3C.

1976 is of course another analogue and in that year September was a little below average at 13.4C

If we look at other hot summers we have 1983 with 13.7C, 1995 also with 13.7C, 2006 with 16.8C (record) and 1826 with 13.6C.

So actually apart from 2006 most other years where the summer has been hot have seen a fairly average September between 13.6C and 14.3C.

Another year that is an analogue for July and August 2018 is 2013 when the September CET was 13.7C.

So the analogues would suggest a September close to average is the most likely scenario.

First look at September temperature tracker

Slightly above average but not by very much. Looks fairly consistent with the analogue analysis above.

So the exact opposite of last September? 

<Bump>

I assume some kind person will sticky this

These threads until now have always been stickied, so I'm surprised that this one hasn't been so far.

The year to date and more especially summer seems to have been quite like 2006; even so, I'm concerned about HP moving N of us and sticking there so I'm hedging a bit- eating my words from the MOD a couple of days ago!

Prediction posted.

Post a requested for Stormchaser (James).

It doesn't always adjust down, so we'll see. Not at all confident that it won't, though, given GW's estimate!

Anyway, to distract myself from the ridiculously large late-stage crash in August CET, we have some entertaining September model output to admire. Next week is generally indicated to be warmer than average, but the midweek period is varying a lot between runs depending on the exact direction of flow and extent of cool air aloft circulating around from the Atlantic (i.e. how much of a gap between ridges we see just E of the UK for 2-3 days). For example, the 00z GFS gave me an estimate of 16.9*C to 7th which is over 1*C above the LTA, but the 12z GFS gave me one of just 15.8*C to that date, barley half a degree above the LTA.

Beyond that, the warm signal is actually more consistent, especially for the 8-14 day range. The 00z GFS produced 'moderate' levels of warmth (widely low-mid 20s) to lift the estimate very slightly; into the low 17s as of 14th September. The 12z GFS, by contrast, delivers some exceptionally high temperatures via an almost optimal positioning of high pressure (dependability alert!), rocketing the estimate into the low 17s by 11th and to very near 18*C as of 14th. That'd be quite some going!

Locally for me, that 12z GFS produces a 7-day (and counting as of run's end) stretch of mid-high 20s maximums following mid-teens minimums, which would leave me local mean very close to 19*C as of 14th. Oh what I'd give to secure that outcome, it would be something to remember for years to come!

When the September CET thread opens I'll move this across - or I might forget, in which case hello mods, please feel free to do that for me... .

Met Office Hadley          16.2c.      Anomaly    1.4c. Provisional to 1st.

Metcheck                       15.97c     Anomaly    2.25c

Netweather                    17.66c     Anomaly    3.97c

Alton                             13.6c       Anomaly     -1.66c

Clevedon Weather           18.6c       Anomaly     2.48c

Mansfield Woodhouse      17.3c       Anomaly     0.54c

Peasedown St John         16.6c       Anomaly      1.63c

Mean Of My 10 Stations    16.46c.

ALL  GONE UP A DEGREE .....

Met Office Hadley        17.4c       Anomaly     2.5c.  Provisional to 2nd.

Metcheck                     16.88      Anomaly      3.16c

Netweather                  17.98c     Anomaly      4.29c

Cheadle Hulme             19.2c       Anomaly      4.98c

Clevedon Weather         19.2c       Anomaly      3.8c

5 Year Mean Of My 10 Watched STATIONS    17.46c.     

Worth posting here as well , despite our obsession with this wonderful competition it was in fact the hottest ever summer for England. Stand aside 1976 we have a new King 2018

https://www.bbc.co.uk/news/uk-45399134

Some very different results for the CET stations over the past few days. With clear skies in the east Rothamsted has been recording minimums around 8C, similar to many southern and eastern parts of England. Conversely Stonyhurst and Pershore College have recorded some very high minimums under cloud cover. On the 2nd Stonyhurst had a minimum of 17C and Pershore 16.5C. Overall a reasonably warm start to the month.

My CET calculation to the 2nd was 17.30C so 0.1C below Hadley.

Cooler today mainly due to slightly lower minimums and a much lower maximum at Stonyhurst.

Running mean now stands at 16.92C.

Turning really quite chilly later this week - Thursday to Saturday in particular. After that a slight recovery to something a little above average.

Current estimates suggest a CET of just 14.64C by the 17th which is just 0.03C above the 1981-2010 mean.

Some of my 10 stations have dropped a degree since yesterday.  Mean of my 10 today 16.78c.

Thanks GW 

All to play for for September at the moment then! 

Met Office Hadley          17.4c.       Anomaly        2.5c. Provisional to 3rd. 

Metcheck                       16.45c.     Anomaly        2.73c    

Netweather                    17.58c      Anomaly        3.89c 

Peasedown St John         17.2c.       Anomaly        2.23c.

Mean of 10 stations  16.78c.   

Met Office Hadley        16.7c       Anomaly        2.0c. Provisional to 4th.

Metcheck                     15.92c     Anomaly        2.19c

Netweather                  16.94c     Anomaly        3.25c

Hexam                         14.7c       Anomaly        1.0c

Mount Sorrel                 15.5c       Anomaly        1.26c

Mansfield Woodhouse     16.8c       Anomaly        3.02c

Peasedown St John        16.2c       Anomaly        -1.23c

Mean of 10 stations   16.40c.            

Met Office Hadley         16.3c.      Anomaly    1.6c. Provisional to 5th.

Metcheck                      15.59c     Anomaly     1.87c

Netweather                   16.6c       Anomaly     2.91c

Hexam                          14.8c       Anomaly     1.64c

Mansfield Woodhouse      15.0c      Anomaly     2.72

peasedown St John          15.9c     Anomaly      0.93c

Treviskey Redruth            16.4c     Anomaly      1.66c

Mean of 10 stations        16.04c

Signals are all over the place at the moment, with the El Nino continuing to struggle and the atmosphere wobbling around in the neutral zone.

Even almost a week into the month, I have little confidence in where the final CET will land.

For what it's worth, an estimate based on the GFS 06z has the CET near 14.8*C as of 14th, after which point the run shows that a finish in the 15s is still within reach, but via some truly exceptional charts in the late stages... so the inspirational estimate I get of of near 15.7*C is to be treated as wildcard territory I'm afraid!

The GFS 00z was much cooler, with the CET having a hard time even staying in the 14s.

For those looking for a final CET at least 0.5*C above average, your best source of hope is some hints of the Atlantic trough being held up further west during mid-late next week as a result of hurricane Florence amplifying the upstream pattern. This could allow a Euro-UK ridge to set up shop.

On the other hand, it comes with the risk of the trough out west being replaced by a ridge at some point, which would have a very downward effect on the CET.

We live in interesting times .

Having rather recklessly gone for 15.5C this month, I'd certainly need something exceptional at some point to get anywhere near that.

There was enough in the modelling back at the end of Aug and start of Sep to justify such an adventurous estimate IMO. The collapse in major Euro-Scandinavian high building signal was very dramatic - and, of course, it took place just after the deadline for CET estimates. Typical eh?

However... even now, with the ongoing cooler interlude dragging the CET a long way down, the ECM 12z for example would leave you feeling a lot more hopeful; it gives me a CET estimate near to very a healthy 16.0*C for 1st-16th. 

It's among the very warmest outcomes on offer this evening within the 10 day range, but you never know!

I think those of us in the high 14s and higher have had some good fortune already in that the cut-off low currently approaching us isn't looking to make it as far south and west as was once the consensus, and also looks to depart a bit sooner, allowing Sat-Sun to be milder than could have happened. About time some things went that way as the final week of August saw several that went the other.

Met Office Hadley            15.07c.       Anomaly       1.0c  Provisional to 6th

Metcheck                         15.06c        Anomaly       1.34c

Netweather                      16.04c        Anomaly       2.35c

Canvey Island                  15.8c          Anomaly       1.28c

Hexam                             13.6c         Anomaly        0.44c

Mansfield Woodhouse        15.5c         Anomaly        0.53c

Peasedown St John           16.17c        Anomaly       1.2c.

Mean  of  10 stations     15.71c.            

Yes, it did look very good at one stage. Thing is, for August it also looked good but then I resisted the temptation to get carried away with that and I ended up being 2nd in the August competition, albeit 0.4C away. This time I decided to go with the forecasts!

It will need more than just warm conditions to get to 15.5C, it will take some serious plumage at some point to get there. Just that was being shown on some GFS runs yesterday around the 20th, don't know if they are still there but if the models are playing with the idea then there must at least be some potential there.

Met Office Hadley        15.1c.    Anomaly    0.5c. Provisional to 7th.

Metcheck                     14.73c    Anomaly    1.01c

Netweather                  15.51c    Anomaly    1.82c

Alton                           14.4c      Anomaly    -0.86c

Clevedon Weather         17.1c     Anomaly     0.98c

Hexam                          13.5c    Anomaly     0.34c

Mansfield Woodhouse    15.4c    Anomaly    1.62c

Peasedown St John   15.85c   Anomaly    0.88c.

Mean of my watched 10 stations    15.23c.  

Fairly impressive CET collapse again in the past four days! 

I went for 15c but had to get my ‘guess’ in before I went away on 23rd August, so I wasn’t at all swayed by forecasts or the the MO.  I doubt it’s made a difference to my chances of getting it right though!  My guesses are always guesses!