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

[Derecho]

8 hours ago, Summer Sun said:

17.5c to the 3rd

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

Yesterday came in a bit lower then forecast because minima was a few degrees cooler. Looking at the 12z GFS I've got the following rolling monthly means (with dailies in brackets):

4th: 18.0 (19.7)
5th: 18.4 (19.8)
6th: 19.0 (22.0)
7th: 19.5 (22.7)
8th: 19.8 (21.8)
9th: 20.0 (21.6)
10th: 20.2 (21.8)
11th: 20.2 (20.1)
12th: 20.2 (20.6)
13th: 20.2 (19.9)
14th: 20.1 (18.8)
15th: 19.8 (16.2)

These are just guesses and we can see how they compare as the met office data comes in. 

EDIT: The original post had the 00z CET returns the above have now changed for the 12z which if verified would be staggering. However I think it has gone off on one and cooler air could still come in early next week.

but still...

We will see what happens.

Edited September 4, 2023 by Derecho

[Don]

46 minutes ago, Derecho said:

Yesterday came in a bit lower then forecast because minima was a few degrees cooler. Looking at the 12z GFS I've got the following rolling monthly means (with dailies in brackets):

4th: 18.0 (19.7)
5th: 18.4 (19.8)
6th: 19.0 (22.0)
7th: 19.5 (22.7)
8th: 19.8 (21.8)
9th: 20.0 (21.6)
10th: 20.2 (21.8)
11th: 20.2 (20.1)
12th: 20.2 (20.6)
13th: 20.2 (19.9)
14th: 20.1 (18.8)
15th: 19.8 (16.2)

These are just guesses and we can see how they compare as the met office data comes in. 

EDIT: The original post had the 00z CET returns the above have now changed for the 12z which if verified would be staggering. However I think it has gone off on one and cooler air could still come in early next week.

but still...

We will see what happens.

Increasing chance that June will not be the hottest month of the year after all?!

[Relativistic]

I'd wait till mid-month at the absolute earliest before making any predictions regarding September's possible status as this year's warmest month.

Edited September 5, 2023 by Relativistic

[ItNeverSnowsInWindsor]

As long as it gets cooler for the last week of September when I’m doing the Windsor Half Marathon!

[Summer Sun]

18.2c to the 4th

4.6c above the 61 to 90 average
3.0c above the 81 to 10 average

[Man With Beard]

Of course, claiming the September record won't be guaranteed even if we're 20C by mid month. The rest of the month would still need to average 14C, which it seems to me would still be slightly above average for the second half of September.

Models increasingly converging on an end-point for the heatwave between Sunday and Monday, maybe Tuesday, so probably not 20C by mid month, but likely to be over 20C around the 12th.

[Derecho]

3 hours ago, Man With Beard said:

Of course, claiming the September record won't be guaranteed even if we're 20C by mid month. The rest of the month would still need to average 14C, which it seems to me would still be slightly above average for the second half of September.

Models increasingly converging on an end-point for the heatwave between Sunday and Monday, maybe Tuesday, so probably not 20C by mid month, but likely to be over 20C around the 12th.

Based on this GFS 12z coming in I've got:

5th: 18.5 (19.9)
6th: 19.1 (21.9)
7th: 19.5 (22.0)
8th: 19.9 (22.3)
9th: 20.2 (23.1)
10th: 20.4 (21.4)
11th: 20.2 (19.2)
12th: 20.1 (18.8)
13th: 19.9 (17.3)
14th: 19.4 (13.4)
15th: 19.1 (13.9)

Pretty remarkable, even with the two cool days on the 14th and 15th, the CET would be above 19C at the halfway point. The heat for the weekend keeps upgrading.
 

[Roger J Smith]

EWP has only reached 0.3 mm and the GFS has about 20 mm grid average by 21st. 

I notice the 12z GFS is already softening the blow of the slight cooldown mid-month and returning to quite warm temperatures for about five days 16th to 20th as well, would perhaps prolong the record setting warm averages. 

1898 was on this sort of a tear as well with similar timing if not quite as warm, but got deflated right at the end, falling into the low 15s, whereas 2006 started relatively normal and got warmer mid-month and then stayed up there. 1865 was able to keep most of its gains to the end (in ranking terms, it did lose about 2 C from 20th to 30th). 

[Midlands Ice Age]

1 hour ago, Roger J Smith said:

EWP has only reached 0.3 mm and the GFS has about 20 mm grid average by 21st. 

I notice the 12z GFS is already softening the blow of the slight cooldown mid-month and returning to quite warm temperatures for about five days 16th to 20th as well, would perhaps prolong the record setting warm averages. 

1898 was on this sort of a tear as well with similar timing if not quite as warm, but got deflated right at the end, falling into the low 15s, whereas 2006 started relatively normal and got warmer mid-month and then stayed up there. 1865 was able to keep most of its gains to the end (in ranking terms, it did lose about 2 C from 20th to 30th). 

Roger

Any news of my request for a change on the 2nd / 3rd?

Your orig table still has me not updated.

For an excuse - I broke my PC on the 1st when I wanted to change but managed to get a new one up and running on the 2nd.

MIA

 

[Don]

4 hours ago, Derecho said:

Pretty remarkable, even with the two cool days on the 14th and 15th, the CET would be above 19C at the halfway point. The heat for the weekend keeps upgrading.

And I'm rather dubious when the heat will actually break down?!  First it was the weekend, then it was early next week and now it's looking like it maybe mid week and whose to say it won't delay even further with more heat upgrades?!

[Summer Sun]

18.7c to the 5th

5.1c above the 61 to 90 average
3.6c above the 81 to 10 average

[The PIT]

Sunny Sheffield at 18.8C +2.3C above normal. Rainfall 0mm 0% of the monthly average.

[Metwatch]

21 hours ago, Derecho said:

Based on this GFS 12z coming in I've got:

5th: 18.5 (19.9)
6th: 19.1 (21.9)
7th: 19.5 (22.0)
8th: 19.9 (22.3)
9th: 20.2 (23.1)
10th: 20.4 (21.4)
11th: 20.2 (19.2)
12th: 20.1 (18.8)
13th: 19.9 (17.3)
14th: 19.4 (13.4)
15th: 19.1 (13.9)

Pretty remarkable, even with the two cool days on the 14th and 15th, the CET would be above 19C at the halfway point. The heat for the weekend keeps upgrading.
 

I think we can get to 21C for next Monday's value, let's see. 

[summer blizzard]

20 minutes ago, Metwatch said:

I think we can get to 21C for next Monday's value, let's see. 

From a pure GFS6z point of view, the last 20C CET day is probably Sunday. At my location the maximum on Monday is 19C and we are only a little north of Sheffield (CET station). 

[Derecho]

22 minutes ago, summer blizzard said:

From a pure GFS6z point of view, the last 20C CET day is probably Sunday. At my location the maximum on Monday is 19C and we are only a little north of Sheffield (CET station). 

Yup the cooler air has been coming in a bit quicker in todays runs, unless that reverses over the next 24 hours then I think we can confidently say the 10th /11th will be the last of the hot days over a good area of England. All 3 main models are moving closer to this now.

CET will probably drop below 19C by the 15th.

Edited September 6, 2023 by Derecho

[Metwatch]

38 minutes ago, summer blizzard said:

From a pure GFS6z point of view, the last 20C CET day is probably Sunday. At my location the maximum on Monday is 19C and we are only a little north of Sheffield (CET station). 

Yes Sunday likely the last warm day but the figure for Sunday comes the next day; Monday, hence Monday will have the highest value as the previous day is counted.

[Roger J Smith]

On 05/09/2023 at 11:45, Midlands Ice Age said:

Roger

Any news of my request for a change on the 2nd / 3rd?

Your orig table still has me not updated.

For an excuse - I broke my PC on the 1st when I wanted to change but managed to get a new one up and running on the 2nd.

MIA

 

I was waiting to see if J10 gave you a response on your request. Maybe I will p.m. him about that. I imagine it will be okay, then I can adjust the table of entries. 

General note to all, plan to be on holiday and not on line very often for about two weeks starting Friday. I have posted tables of record high running means back in the thread in case that question comes up. 

[SqueakheartLW]

After just 5 days of the month on the provisional CET September 2023 is already ranking ahead of all of the top 10 Septembers on the CET record between 1772 and 2022 as shown in the table below.

Positive anomalies show 2023 ranking warmer than the year whilst negative ones show 2023 cooler.

As can be seen we are already above all of these Septembers.

Below we have how 2023 is comparing to these top 10 Septembers day by day. The top 5 rows already have the provisional CET values on the left highlighted in yellow. Below this I have included the average GFS, ECM and GEM 2m temp mean mins and maxes averaged for each day across all 3 models and this predicted CET value is a mean of all 3 models put together.

It has predicted a CET mean daily value for today (6th) of 20.1C. I feel this could be a slight underestimate however and the high running means around the 10th to 12th over 20C could end up even higher when we do get to these.

The other notable thing here is how far 2023 is predicted to get ahead of the top 10 Septembers if the models prove correct. However we start falling back towards the top 10 by the 21st but still have a rolling value of 17.710C if these models runs are spot on.

[Roger J Smith]

List of all September maximum CET records in v2

... we already broke two daily max values 4 and 5 Sep ... 

Date _____ Daily Max ___ Daily Mean ___ High Min ____ new 2023 __ (other 2023 in brackets)

01 Sep __ 31.2 (1906) __ 22.0 (1906) __ 16.4 (1984) ____ 20.9 (17.1) (13.3)
02 Sep __ 31.1 (1906) __ 22.3 (1906) __ 16.4 (1939) ____ 22.8 (18.1) (13.3)
03 Sep __ 26.0 (1906) __ 19.8 (1880) __ 16.6 (1939) ____ 24.4 (17.4) (10.4)
04 Sep __ 27.4 (1880) __ 20.6 (2005) __ 15.4 (2022) ____ 28.1 (20.2) (12.3)
05 Sep __ 26.5 (1999) __ 22.4 (1949) __ 18.4 (1949) ____ 27.7 (20.6) (13.4)

06 Sep __ 25.6 (1898) __ 20.9 (1898) __ 16.2 (1898) ____ 28.1 _21.1 _(14.1)
07 Sep __ 28.3 (2021) __ 20.9 (1868) __ 16.3 (2016) ____ 28.8 _23.3 _17.7
08 Sep __ 29.4 (1911) __ 21.6 (1898)^_ 16.0 (1898, 2009)_ (28.6)_22.0_(15.4)
09 Sep __ 25.7 (1895) __ 19.5 (1781, 1898) _ 15.5 (2021) _ 28.9 _22.8 _16.6
10 Sep __ 26.5 (1959) __ 19.1 (1865, 2011) _ 16.0 (2011) _ 27.1 _21.6 _16.1

11 Sep __ 27.2 (1919) __ 20.2 (1999) __ 15.9 (2021) ____(22.6) (19.9) 17.2
12 Sep __ 25.4 (1891) __ 20.3 (1945) __ 17.2 (1945) ____(19.2) (17.0) (14.7)
13 Sep __ 26.3 (2016) __ 20.7 (2016) __ 16.0 (2006) ____(19.3) (13.7) ( 8.2)
14 Sep __ 26.4 (2016) __ 21.3 (2016) __ 16.2 (2016) ____(20.2) (15.7) (11.2)
15 Sep __ 27.4 (2020) __ 20.1 (2020) __ 14.5 (1947) ____(22.5) (16.7) (10.9)

16 Sep __ 26.2 (1898) __ 19.6 (1961) __ 16.1 (1961) ____(20.0) (15.6) (11.2)
17 Sep __ 27.1 (1898) __ 20.1 (1898) __ 15.0 (1926, 1945)_(19.2) (16.8) (14.4)
18 Sep __ 25.6 (1926) __ 19.8 (1926) __ 14.9 (1945) ____(17.3) (16.0) (14.7)
19 Sep __ 27.1 (1926) __ 20.9 (1926) __ 15.0 (2014) ____(18.0) (14.2) (10.5)
20 Sep __ 22.8 (1970) __ 18.4 (1947) __ 15.8 (1947) ____(17.6) (16.5) (15.3)

21 Sep __ 27.1 (2006) __ 21.4 (2006) __ 15.8 (2006) ____(17.4) (13.2) ( 9.0)
22 Sep __ 22.9 (1956) __ 18.7 (1956) __ 14.7 (2006) ____(16.1) (11.7) (7.3)
23 Sep __ 23.4 (1895) __ 18.3 (1956) __ 15.1 (1956) ____(17.0) (12.1) (7.3)
24 Sep __ 25.7 (1895) __ 18.5 (1895) __ 15.0 (2006) ____(19.9) (15.2) (10.3)
25 Sep __ 24.5 (1895) __ 19.2 (1895) __ 14.5 (1936) ____(19.9) (16.6) (13.3)

26 Sep __ 25.4 (1895) __ 18.4 (1895) __ 14.1 (1967) ____(20.3) (15.7) (11.1)
27 Sep __ 25.7 (1895) __ 19.7 (1895) __ 14.6 (1913) ____
28 Sep __ 25.0 (1895) __ 18.9 (2011) __ 15.0 (1948) ____
29 Sep __ 26.4 (2011) __ 19.7 (2011) __ 15.4 (1908) ____
30 Sep __ 27.2 (2011) __ 20.0 (2011) __ 14.8 (1923) ____
____________________

__ ^(also 21.4 2021) 

 

Edited September 27, 2023 by Roger J Smith

[Roger J Smith]

1 hour ago, SqueakheartLW said:

After just 5 days of the month on the provisional CET September 2023 is already ranking ahead of all of the top 10 Septembers on the CET record between 1772 and 2022 as shown in the table below.

Positive anomalies show 2023 ranking warmer than the year whilst negative ones show 2023 cooler.

As can be seen we are already above all of these Septembers.

Below we have how 2023 is comparing to these top 10 Septembers day by day. The top 5 rows already have the provisional CET values on the left highlighted in yellow. Below this I have included the average GFS, ECM and GEM 2m temp mean mins and maxes averaged for each day across all 3 models and this predicted CET value is a mean of all 3 models put together.

It has predicted a CET mean daily value for today (6th) of 20.1C. I feel this could be a slight underestimate however and the high running means around the 10th to 12th over 20C could end up even higher when we do get to these.

The other notable thing here is how far 2023 is predicted to get ahead of the top 10 Septembers if the models prove correct. However we start falling back towards the top 10 by the 21st but still have a rolling value of 17.710C if these models runs are spot on.

Your table appeared to be missing a lot of years. I can see you're using CET legacy values which only makes for a slight adjustment and does not explain missing years. Then I realized you were probably comparing 2023 to years that ended up with top ten means and not to all years. So here's a list of all years no matter how they finished the month, compared to 2023.

Three years were actually warmer than 2023 to 5th, and I will use legacy values with v2.0 in brackets if different ... 1880 was 19.32 (19.16), 1906 was 19.30 (19.12), and 1991 was 18.82 (18.76).

Rank_YEAR _ CET 1-5 (v2.0, legacy)

 _ 1. 1880 _ 19.16 (19.32)

 _ 2. 1906 _ 19.12 (19.30)

 _ 3. 1991 _ 18.76 (18.82)

 _ 4. 2023 _ 18.68 (no legacy)

 _ 5. 1824 _ 18.64 (18.64)

 _ 6. 1999 _ 18.36 (18.46)

 _ 7. 1949 _ 18.22 (18.24)

 _ 8. 2005 _ 18.18 (18.22)

 _ 9. 1780 _ 18.16 (18.16)

 _10. 1961 _ 18.10 (18.10)

 _11. 1958 _ 17.90 (17.88)

 _12. 2022 _ 17.88 (no legacy)

 _13. 2006 _ 17.86 (17.86)

 _14. 1939 _ 17.84 (17.86)

 _t15. 1865 _ 17.78 (17.84)

 _t15. 1973 _ 17.78 (17.78)

_17. 1795 _ 17.34 (17.34)

_18. 1929 _ 17.24 (17.30)

_19. 1818 _ 17.06 (17.06)

_t20. 1868 _ 17.02 (17.04)

_t20. 1898 _ 17.02 (16.84)

_t22. 1872 _ 16.92 (17.04)

_t22. 1940 _ 16.92 (16.94)

_24. 1914 _ 16.86 (16.88)

_t25. 1798 _ 16.86 (16.86)

_t25. 1911 _ 16.86 (16.74)

_t27. 1802 _ 16.82 (16.82)

_t27. 1941 _ 16.82 (16.78)

_29. 1867 _ 16.80 (16.94)

_30. 1849 _ 16.78 (16.78)

_t31. 1947 _ 16.68 (16.92)

_t31. 2004 _ 16.68 (16.68)

_33. 2013 _ 16.64 (16.64)

_34. 1821 _ 16.60 (16.60)

_35. 1861 _ 16.52 (16.60)

_36. 1843 _ 16.48 (16.48)

_37. 1779 _ 16.46 (16.46)

_t38. 1899 _ 16.40 (16.60)

_t38. 1936 _ 16.40 (16.46)

_________________

(2016 was 16.04 in both)

I noticed on my work 1816 low running CET just 8.2 C !

[The PIT]

Sunny Sheffield at 19.2C +2.8C above average. Rainfall 0mm 0% of average.

Apart from the heat it's been fairly dry round here with only 33mm of rain in the last 32 days.

[SqueakheartLW]

12 hours ago, Roger J Smith said:

Your table appeared to be missing a lot of years. I can see you're using CET legacy values which only makes for a slight adjustment and does not explain missing years. Then I realized you were probably comparing 2023 to years that ended up with top ten means and not to all years. So here's a list of all years no matter how they finished the month, compared to 2023.

Three years were actually warmer than 2023 to 5th, and I will use legacy values with v2.0 in brackets if different ... 1880 was 19.32 (19.16), 1906 was 19.30 (19.12), and 1991 was 18.82 (18.76).

Rank_YEAR _ CET 1-5 (v2.0, legacy)

 _ 1. 1880 _ 19.16 (19.32)

 _ 2. 1906 _ 19.12 (19.30)

 _ 3. 1991 _ 18.76 (18.82)

 _ 4. 2023 _ 18.68 (no legacy)

 _ 5. 1824 _ 18.64 (18.64)

 _ 6. 1999 _ 18.36 (18.46)

 _ 7. 1949 _ 18.22 (18.24)

 _ 8. 2005 _ 18.18 (18.22)

 _ 9. 1780 _ 18.16 (18.16)

 _10. 1961 _ 18.10 (18.10)

 _11. 1958 _ 17.90 (17.88)

 _12. 2022 _ 17.88 (no legacy)

 _13. 2006 _ 17.86 (17.86)

 _14. 1939 _ 17.84 (17.86)

 _t15. 1865 _ 17.78 (17.84)

 _t15. 1973 _ 17.78 (17.78)

_17. 1795 _ 17.34 (17.34)

_18. 1929 _ 17.24 (17.30)

_19. 1818 _ 17.06 (17.06)

_t20. 1868 _ 17.02 (17.04)

_t20. 1898 _ 17.02 (16.84)

_t22. 1872 _ 16.92 (17.04)

_t22. 1940 _ 16.92 (16.94)

_24. 1914 _ 16.86 (16.88)

_t25. 1798 _ 16.86 (16.86)

_t25. 1911 _ 16.86 (16.74)

_t27. 1802 _ 16.82 (16.82)

_t27. 1941 _ 16.82 (16.78)

_29. 1867 _ 16.80 (16.94)

_30. 1849 _ 16.78 (16.78)

_t31. 1947 _ 16.68 (16.92)

_t31. 2004 _ 16.68 (16.68)

_33. 2013 _ 16.64 (16.64)

_34. 1821 _ 16.60 (16.60)

_35. 1861 _ 16.52 (16.60)

_36. 1843 _ 16.48 (16.48)

_37. 1779 _ 16.46 (16.46)

_t38. 1899 _ 16.40 (16.60)

_t38. 1936 _ 16.40 (16.46)

_________________

(2016 was 16.04 in both)

I noticed on my work 1816 low running CET just 8.2 C !

I know other years that started warmer are missing but when looking out for a possible top 10 September the best years to include are the top 10 CET mean Septembers. After all its not how the month starts on the rolling mean but where we are late in the month that counts.

How we compare to 2006 is what I'll be particularly looking at for a record warmest chance.

Edited September 7, 2023 by SqueakheartLW

[Summer Sun]

19.1c to the 6th

5.5c above the 61 to 90 average
4.0c above the 81 to 10 average

Edited September 7, 2023 by Summer Sun

[Earthshine]

23 minutes ago, Summer Sun said:

18.7c to the 6th

5.5c above the 61 to 90 average
3.6c above the 81 to 10 average

Actually 19.1°C now!

[BlueSkies_do_I_see]

Well there's another record gone.  4 consecutive September days over 30C.  We managed 3  days in succession  in 1898, 1906, 1911 and 2016.

To put it another way, we had not had three consecutive 30C days for over 100 years, and we've now had it happen twice in the last 7 years.

Edited September 7, 2023 by BlueSkies_do_I_see