September 2023 C.E.T. and EWP forecast contests

[Don]

Just now, Derecho said:

17.6C

Thanks for the info and somewhat lower than the first 10 days of this month are forecast to be!  I imagine the first days of September 2020 were very warm (albeit probably less warm than the next 10 days), as that too had a very warm start to the month.

[J10]

14.7c and 70mm

 

[Don]

1 minute ago, J10 said:

14.7c and 70mm

 

 I would snap your hand off for that right now! 

[summer blizzard]

1 hour ago, Don said:

Of course it would be, considering the 17C June this year was the warmest on record.  That said, a 17C September would only narrowly beat the current warmest on record which is 2006, having a CET of 16.9C.

The CET was 17C and not the warmest on record. It was the UK average that was hottest and that will have been a little different. 

[Don]

1 minute ago, summer blizzard said:

The CET was 17C and not the warmest on record. It was the UK average that was hottest and that will have been a little different. 

Sorry, my bad!  Yes, there have been higher CET's for June, the warmest being 18.2C?  However, it would still be remarkable if September was to be the warmest month of the year, considering how warm June was.

[Roger J Smith]

I posted some interesting (to me) stats about warm Septembers or at least Septembers warmer than any summer month, in the August thread and will migrate that over here soon. There has never been a CET summer where June and September ranked 1-2, and in fact there was only one (1890) where September ranked 1st, so the fact that July 1890 was second means that if any such years existed, they would have to go in the order June 1st and September 2nd. This summer could manage it for the first time, if September is 16.5 to 16.9. It could go tied or the other way round if September does break the 2006 record. 

Also there has never been a summer where September was warmer than only July, and only one (1891) where it was only warmer than August. There have been summers where September was warmer than July but those were always in cases where September beat June as well to finish second. There have been almost seventy years with a warmer September than June, on the other hand there were 24 years with a May warmer than September, most recently 1992. It has been 216 years since October was last warmer than September (1807) and it only happened one other time (1672 when like 1807, both May and October were warmer). 1729 and 1865 were years with notably warm Septembers that could not quite fend off a summer month. 1795 and 1895 also gave it a run. But the chilly summer of 1890 remains the only year where September is champ (14.6 vs 14.5 July). 

Summer Sun, if you look in on 2nd September for the usual running CET data, it's already posted quite a few posts back from here due to all this chatter about warmth. J10, I will add your forecast to the table of entries soon. 

 

 

[RJBingham]

17.2c 47mm

[Midlands Ice Age]

On 31/08/2023 at 08:23, Midlands Ice Age said:

15.1C and 59mms please

MIA

Is it too late to change to 16.7c and 50mms please.?

For better  or worse.!!!!

MIA

[LetItSnow!]

In a perverse sense I do think that if this September is going to be very warm, why not do it in style and go freakily warm… having said that, I will also be praying for beefy northerlies to arrive very soon. 32C in the first half and early snowfall in the second half will do just fine

 

then I woke up 

[Earthshine]

Could rolling CET reach as high as 20°C sometime next week?  Would be a first!

[Roger J Smith]

1 hour ago, Midlands Ice Age said:

Is it too late to change to 16.7c and 50mms please.?

For better  or worse.!!!!

MIA

As long as you realize you will get nailed for a two-day late penalty. That would be a lot smaller than the points gain especially on temperatures, you aren't moving your EWP guess very far but you would gain maybe ten scoring levels if you are correct. 

Please check with J10 re CET contest permission to do this, I have allowed similar changes for EWP contest in the past. 

I'll see what decisions are made about it later today before editing the table yet. 

 

[Summer Sun]

17.1c to the 1st

3.5c above the 61 to 90 average
1.7c above the 81 to 10 average

[Midlands Ice Age]

8 hours ago, Roger J Smith said:

As long as you realize you will get nailed for a two-day late penalty. That would be a lot smaller than the points gain especially on temperatures, you aren't moving your EWP guess very far but you would gain maybe ten scoring levels if you are correct. 

Please check with J10 re CET contest permission to do this, I have allowed similar changes for EWP contest in the past. 

I'll see what decisions are made about it later today before editing the table yet. 

 

J10

Is this allowed? I realise I would lose  lot of points of it goes wrong..

MIA

Edited September 2, 2023 by Midlands Ice Age

[ItNeverSnowsInWindsor]

Why couldn’t this heatwave have happened in August ?

[Summer Sun]

17.6c to the 2nd

4.0c above the 61 to 90 average
2.2c above the 81 to 10 average

[LetItSnow!]

5 hours ago, prolongedSnowLover said:

Why couldn’t this heatwave have happened in August ?

I imagine a set up with slack southeasterlies and 20C uppers for several days would have brought a August 2020 style heatwave if not maybe a bit more potent. I'm thanking my lucky stars it's come a bit later as that would be too much for me and my flat to handle!

[Man With Beard]

I've seen GFS analysis today suggesting the CET might be around 20C by mid month - unlikely but wow!

[LetItSnow!]

Increasingly likely that at least the first half of September will be off the scale for warmth. The question is now how high can it go and can it go down that much. A C.E.T. of about 20C mid-month means that even a rather cool second-half wouldn't be anywhere near enough to get even somewhat close to normal. I'm fascinated to see where we end up. 

[Derecho]

2 hours ago, Man With Beard said:

I've seen GFS analysis today suggesting the CET might be around 20C by mid month - unlikely but wow!

If the warmth can hang on it is definitely possible. Based on the GFS 12z I've got the following for the CET up to the 15th. Running mean CET is given for each day with the daily mean in brackets:

3rd: 18.0 (18.8)
4th: 18.5 (19.9)
5th: 18.7 (19.4)
6th: 19.3 (22.9)
7th: 19.9 (23.6)
8th: 20.2 (22.3)
9th: 20.3 (20.9)
10th: 20.5 (22.1)
11th: 20.5 (20.3)
12th: 20.0 (15.2)
13th: 19.6 (14.0)
14th: 19.1 (12.8)
15th: 18.8 (14.6)

The CET for the 6th to 10th is going to be remarkable. My previous estimates have been a bit under so far so I've tried to account for that. 

It's worth noting that the GFS OP however is one of the slowest members to push the heat away. The UKMO also starts bringing in cooler air on Sunday.

Edited September 3, 2023 by Derecho

[Roger J Smith]

11 hours ago, prolongedSnowLover said:

Why couldn’t this heatwave have happened in August ?

Blame rests with Pope Gregory. 

[Frigid]

My CET looks laughingly low now, and that's after a modest uptick. I know it's only the 3rd but I genuinely believe the CET will be record breaking, perhaps higher than 2006. 20C by mid month, would require a freezing second half to bring it to average. 

September is looking more extreme than the June gone past, can't believe I'm saying that...

[Earthshine]

Feeling better about my last minute 17.2°C guess now

[Frigid]

6 minutes ago, Earthshine said:

Feeling better about my last minute 17.2°C guess now

If the second half is anything like 2011, then you could be too low

[Roger J Smith]

Current top ten for running CET values (10th to 20th, adding 25th, end of month)

__ based on v2.0.1.0 daily values.

Info on 1st to 9th is found in notes below table for 1906 and 1898.

^ _ End of month contains some years before daily data (started 1772) and may have had values in the top ten earlier, most notably 1729. Reasonable assumption would be 1729 was somewhere near top of table from 10th to 25th as well. 

Ranks ___ 10 ___ 11 ___ 12 ___ 13 ___ 14 ___ 15 ___ 16 ___ 17 ___ 18 ___ 19 ___ 20 ____ 25 ____ end

_ 01 ____ 18.4 _ 18.2 _ 18.1 _ 18.1 _ 18.1 _ 18.1 _ 18.2 _ 18.0 _ 17.9 _ 17.7 _ 17.7 __ 17.1 __ 16.9

__ year _1898 _1898 _1865 _1865 _1865 _1865 _1865 _1865 _1865 _1865 _1865 _2006 __ 2006

 

_ 02 ____ 18.0 _ 18.0 _ 18.0 _ 17.7 _ 17.7 _ 17.7 _ 17.7 _ 17.9 _ 17.8 _ 17.4 _ 17.4 __ 16.8 __ 16.6

__ year _1865 _1865 _1898 _1795 _1898 _1898 _1898 _1898 _1898 _1898 _1898 _1865 __ 1729^

 

_ 03 ____ 17.9 _ 17.9 _ 17.8 _ 17.6 _ 17.6 _ 17.5 _ 17.4 _ 17.1 _ 17.1 _ 17.0 _ 17.0 __ 16.6 __ 16.3

__ year _1795 _1795 _1795 _1898 _1795 _2016 _2016 _1780 _1780 _2006 _1795 _2021 __ 1865

 

_ 04 ____ 17.9 _ 17.9 _ 17.7 _ 17.5 _ 17.4 _ 17.3 _ 17.2 _ 17.1 _ 17.1 _ 17.0 _ 16.9 __ 16.5 __ 16.3

__ year _2021 _2021 _2021 _2021 _2005 _1795 _2021 _2006 _2006 _2021 _2006 _1795 __ 1949

 

_ 05 ____ 17.8 _ 17.6 _ 17.5 _ 17.4 _ 17.4 _ 17.3 _ 17.1 _ 17.1 _ 17.0 _ 16.9 _ 16.8 __ 16.4 __ 16.1

__ year _2005 _2005 _2005 _1949 _2016 _2005 _1780 _2016 _2016 _1780 _2021 _1949 __ 2016

 

_ 06 ____ 17.6 _ 17.5 _ 17.5 _ 17.3 _ 17.3 _ 17.2 _ 17.1 _ 17.1 _ 17.0 _ 16.9 _ 16.7 __ 16.4 __ 16.0

__ year _2022 _1999 _2022 _2005 _2021 _2006 _2006 _2021 _2021 _1795 _1780 _2016 __ 2021

 

_ 07 ____ 17.5 _ 17.5 _ 17.4 _ 17.3 _ 17.3 _ 17.2 _ 17.1 _ 16.9 _ 16.8 _ 16.8 _ 16.7 __ 16.2 __ 15.9

__ year _1780 _2022 _1949 _2006 _1949 _1949 _1795 _1795 _1795 _2016 _2016 _1898 __ 1795

 

_ 08 ____ 17.5 _ 17.4 _ 17.3* _ 17.3 _ 17.2 _ 17.2 _ 16.9 _ 16.8 _ 16.6 _ 16.5 _ 16.4 __ 16.1 __ 15.7

__ year _1906 _1780 _ 1780 _2022 _1780 _2021 _1949 _1949 _1949 _1949 _1926 _1780 __ 1760

 

_ 09 ____ 17.5 _ 17.4 _ 17.3 _ 17.2 _ 17.2 _ 17.1 _ 16.9 _ 16.9 _ 16.5 _ 16.4 _ 16.4 __ 15.9 __ 15.6

__ year _1949 _1949 _1999 _1780 _2006 _1780 _2005 _1795 _1929 _1926 _1947 _1898 __ 1999

 

_ 10 ____ 17.5 _ 17.3 _ 17.2 _ 17.1 _ 17.1 _ 16.8 _ 16.7 _ 16.6 _ 16.3 _ 16.3 _ 16.4 __ 15.7 __ 15.6

__ year _1973 _1933 _1929 _2016_2022_2022_1929 _1929 _1947,58 _1929,47_1949 _1825,1929 _1780

                                                  

* tied 1999, which drops out of top ten but ends month at 15.6 again tying 1780.

(note top ten end of month follow order of CET tables with second decimals determining rank, otherwise I have arranged them in chronological order for ties in the table values)

Following below are some added values for years that entered after 10th Sep, or dropped out soon after. Otherwise you can follow the various top ten years through the table as they occasionally rise or fall to new ranks. 

____ ___ (1933) ______________ 2005 17th-20th, 25, end_16.4 _ 16.2 _ 16.1 _16.1 _ 15,7 _ 15.2 

2006 10-12 _16.8 _17.0 _17.1 _ (then into table above) 1911 also 17.1 on 12th (t11).

2016 10-12 _17.0 _16.7 _16.7 _ (then into table above)

2022 sank well below the top ten after 15th (was 15.7, 15.2, 14.4 last three checkpoints)

1865 was 17.5 17.2 17.0 21st-23rd, passed lead to 2006 on 23rd.

1895: warm spell late in month too late to make an impact on table but was 14.9 25th _ 15.4 end

1898: in table to 25th then fell to 15.2 final value.

1906: warmest running means 1st-8th were 22.0, 22.2, 21.2, 20.1, 19.1 (5th 19.2 1880 intrudes), 18.9, 18.8, 18.5 (tied 1898) (18.2 9th with 1898 then in lead at 18.6), dropped fast after 10th, ending 13.6. 1880 fell faster and was 16.9 by 10th, ended 14.5.

1929: 17.3 17.2 17.2 17.1 10-13 and continued near or just below top ten warmth to end (15.3, 12th warmest) 

1947: 15.5 on 25th and 14.9 end of month. 

_____________________________________

Tracking the consistent top ten values by rank in table: 

YEAR ___ 10 _11 _12 _13_14_15_16_17_18_19_20 __ 25 __ end

2006 ____ -- __ --_(11) _ 7 _ 9 _ 6 _ 6 _ 4 _ 4 _ 3 _ 4 __ 1 ____ 1

1865 ____ 2 __ 2 __ 1 __ 1 _ 1 _ 1 _ 1 _ 1 _ 1 _ 1 _ 4 __ 2 ____ 3 (1729 2nd)

1949 ____ 9 __ 9 __ 7 __ 5 _ 7 _ 7 _ 8 _ 8 _ 8 _ 8 _10 _ 5 ____ 4

2016 ____ -- __ -- __ -- _10 _ 5 _ 3 _ 3 _ 5 _ 5 _ 7 _ 7 __ 6 ____ 5

2021 ____ 4 __ 4 __ 4 __ 4 _ 6 _ 8 _ 4 _ 6 _ 6 _ 4 _ 5 __ 3 ____ 6

1795 ____ 3 __ 3 __ 3 __ 2 _ 3 _ 4 _ 7 _ 7 _ 7 _ 6 _ 3 __ 4 ____ 7

1780 ____ 7 __ 8 __ 8 __ 9 _ 8 _ 9 _ 5 _ 3 _ 3 _ 5 _ 6 __ 8 ___ 10 (1760 8th, 1999 9th)

1929 ____ -- __ -- __10 _ -- _ -- _ -- _10_10_9_10 _ -- _ 10 ___ 12 (1895 11th)

1898 ____ 1 __ 1 __ 2 __ 2 _ 2 _ 2 _ 2 _ 2 _ 2 _ 2 _ 2 __ 9 ___ 16

2022 ____ 6 __ 7 __ 6 __ 8 _10_10 

Edited September 4, 2023 by Roger J Smith

[Summer Sun]

17.5c to the 3rd

4.0c above the 61 to 90 average
2.2c above the 81 to 10 average