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...!  

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. 

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.   

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.

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.

 

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.

HadCET has 17.95C for the 1st 8 days of this month as provisional data

When I analysed my Access DB for daily CET Mean I got some higher ones for Sept1-8

2005 17.96

1999 17.98

1795 18.01

1898 18.35

1906 18.68

(Haven't desk checked them though !)

But this last week has been up there (but if you look at the September predictions you might see why I have not quite treated it like the pleasant surprise it is )

 

HadCET has 17.95C for the 1st 8 days of this month as provisional data

When I analysed my Access DB for daily CET Mean I got some higher ones for Sept1-8

2005 17.96

1999 17.98

1795 18.01

1898 18.35

1906 18.68

(Haven't desk checked them though !)

But this last week has been up there (but if you look at the September predictions you might see why I have not quite treated it like the pleasant surprise it is )

 

I think my maths, eyesight or ability to read have gone Martin (or more probably, all three!)

Edit: just looked at 1906 again and realised I was scanning down the August column in Hadley- it was a near but not quite! Need to go back now as I think I may have done that for the others. Double

Met Office Hadley       18.1c     Anomaly       3.6c provisional to 9th

Metcheck                    17.21c   Anomaly       3.49c

Netweather                 17.99c   Anomaly       4.3c

Peasedown St John    17.52c   Anomaly       3.24c.  

 

I think my maths, eyesight or ability to read have gone Martin (or more probably, all three!)

Edit: just looked at 1906 again and realised I was scanning down the August column in Hadley- it was a near but not quite! Need to go back now as I think I may have done that for the others. Double

Looking like a 16c+ CET is pretty much nailed on now.

Looking like a 16c+ CET is pretty much nailed on now.

You can be forgiven Bertie and the first ten days may prove to be a record.  The mild, muggy nights are doing me no favours with sleeping. At this rate, we’ll have all gone too low with our predictions. 

I believe you are right Caz- although the usual adjustment will no doubt knock half a degree off. Last night continued the run of warm nights- a 3rd consecutive with a min > 16C so we might still be around the 18C mark- I'll check Art's update later. But we're not at half month yet and after the model swing at month's start, I wouldn't be surprised at anything!

Gosh, CET actually went UP another 0.1C yesterday! 

I really am starting to wonder if a new record 17C CET September could be possible?

Would love an update from our guru GW soon! 

Gosh, CET actually went UP another 0.1C yesterday! 

I really am starting to wonder if a new record 17C CET September could be possible?

Would love an update from our guru GW soon! 

To do that would take some meaty hot days in the last week of the month. Don't forget that by the 21st we're in the autumn solstice and the days are drawing in at quite a rate.

Met Ofice Hadley        18.2c       Anomaly      3.7c  provisional to 10th

Metcheck                    17.32c     Anomaly      3.60c

Netweather                 18.05c     Anomaly      4.36c

Peasedown St John    17.53c     Anomaly      3.27c.       

 

To do that would take some meaty hot days in the last week of the month. Don't forget that by the 21st we're in the autumn solstice and the days are drawing in at quite a rate.

 

Provisional CET for 1st-10th was right up against the record high for the period (1898): https://twitter.com/peacockreports/status/1436777893766569988

Actual is probably two or three tenths lower, mind.

Still, this is proving to be a staggeringly warm month. Far more so than the models were indicating as of August's end. Good of GW to apply penalties for entries after 1st. Even on 1st there was arguably some advantage so I wish I'd held on now!

Anyway, a curious feature of this month has been GFS periodically producing a batch of runs featuring extraordinary warm spells. The 06z of today went full late Sep 2011 on us, while the 12z is more laidback but, through sheer persistence of very warm days and mild nights, gives an even higher CET estimate to 27th (dashed line on the 2nd graph in the tweet).

Usually I'd toss them aside as crazed ravings, but here's the thing - GFS spotted the big plume of early this week ahead of all the other models. Not consistently, by any means, but then, it's not being consistent this time around either.

So maybe it's onto something.

There is one key difference, though. Before this week's hot spell, ECM was bringing changeable westerlies. Currently, it has an increasingly cool easterly (from a warm starting position in the middle of next week). So, if GFS' last success was bias-related, it might not enjoy such good fortune this time.

I have a bit of a conflict of mind on the matter. On the one hand, I could do with the CET coming right down to my prediction for obvious reasons. On the other, I enjoy exceptional warmth a great deal when it happens in spring or autumn, especially March-April or September-October. I'm also a big fan of impressive monthly stats. The warmest September for over 100 years, let alone on record, would be amazing to reflect on.

Just like to say that my prediction on 31st August was purely and totally based on nothing other than a funny feeling- it just got lucky, equal to the many unlucky ones previously!

Met Office Hadley        18.2c       Anomaly     3.7c provisional to 11th

Metcheck                     17.2c       Anomaly      3.48c

Netweather                  18.04c     Anomaly      4.35c

Peasedown St John     17.17c     Anomaly      2.59c.