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

[Roger J Smith]

I had a look and found that 1802 also saw July finish in fourth place in CET, and in 1858 it avoided fourth by only 0.1 C. 

[summer blizzard]

6 hours ago, richie3846 said:

What I find particularly interesting about this fact, is that the setup was nothing special really. Yes we had a settled June, but that's not unusual and has happened before. We've had mediocre July and August, and indeed temperatures this time round were not below average by very much. Early September was the only spell that could truly be classified as exceptional or unusual.

So for July to come in 4th seems to boil down to the particular sequence of weather patterns, and timings. A fluke, I guess. 

The mid-May to mid-June spell produced no rainfall here in 29 days, that is something not seen since at least summer 1995 here. So it was exceptional, it was just too early to take advantage of hot uppers. 

But yeah, mid-June to August was just cyclonic, damp and often humid. 

[The PIT]

 Sunny Sheffield down to 17C +2.6C above normal. Rainfall 69mm 104.95 of the monthly average.

There was a spell from the 6th of August to the 10th of September here, where only 39.9mm of rain fell so hardly wet. Then there was that spell from May to June.

[Summer Sun]

17.3c to the 26th

3.8c above the 61 to 90 average
3.1c above the 81 to 10 average

[reef]

8 hours ago, Weather-history said:

July being only the 4th warmest of the year for the CET is truely exceptional

The climatic odds of this happening must be very small. The CET goes back to 1659.

If it has happened in the UK in the last 364 years, then it has occurred at a local level. 

Locally here it has never happened, though 2000 came closest as it had the following means:

June 14.4C
July 14.5C
August 16.8C
September 14.7C

This year is further off as June was 1C cooler than July due to that easterly first 10 days.

[Man With Beard]

Has anyone looked into this? What is the warmest June-September CET combination on record? 

Seeing that June was the warmest for 200 years and September might be the warmest ever, surely 2023 might come close to the top of such a table?

[BlueSkies_do_I_see]

1 hour ago, Man With Beard said:

Has anyone looked into this? What is the warmest June-September CET combination on record? 

Seeing that June was the warmest for 200 years and September might be the warmest ever, surely 2023 might come close to the top of such a table?

It's going to be top by a country mile.

The only years that come close are all within our climate change heated last 20 years:

2021 15.5/16.0

2016 15.2/16.1

2006 15.8/16.9

2005 15.8/15.2

 

Edited September 27, 2023 by BlueSkies_do_I_see

[The PIT]

Never happened here in 80 odd years although it's come close a few times where July has been the 4th warmest month.

[Man With Beard]

1 hour ago, BlueSkies_do_I_see said:

It's going to be top by a country mile.

The only years that come close are all within our climate change heated last 20 years:

2021 15.5/16.0

2016 15.2/16.1

2006 15.8/16.9

2005 15.8/15.2

 

Thanks for the reply! Oops, sorry I meant the 4 month period June, July, August, September (my fault, terrible wording, and I'm supposed to be a university linguist by profession, good grief )

[Roger J Smith]

1 hour ago, Man With Beard said:

Thanks for the reply! Oops, sorry I meant the 4 month period June, July, August, September (my fault, terrible wording, and I'm supposed to be a university linguist by profession, good grief )

Posted during mid-month, 2023 can beat all but 2006 in first list, 17.0 would give an average of 16.625. We would tie 1826 and 1976 with a 16.9 result. For the may-Sep average, 17.0 brings us to 15.80, good for fifth. 

Rank ____ CET June-Sep_ Year __________ Rank ____ CET may-Sep_ Year

_01 __ ____ 17.175 ______ 2006 ____________ 01 ___ ___ 16.00 ______ 2006

_02t__ ____ 16.60 _______ 1826 ____________ 02 ___ ___ 15.90 ______ 1947

_02t__ ____ 16.60 _______ 1976 ____________ 03 ___ ___15.86 ______ 2022

_04 __ ____ 16.55 _______ 2022 ____________ 04 ___ ___ 15.82 ______ 2018

_05t__ ____ 16.50 _______ 1846 ____________ 05t___ ___ 15.68 ______ 1868

_05t__ ____ 16.50 _______ 1947 ____________ 05t___ ___ 15.68 ______ 1976

_07t__ ____ 16.475 ______ 1933 ____________ 07 ___ ___ 15.66 ______ 1846

_07t__ ____ 16.475 ______ 2003 ____________ 08 ___ ___ 15.62 ______ 1933

_09t__ ____ 16.45 _______ 1949 ____________ 09 ___ ___ 15.60 ______ 2016

_09t__ ____ 16.45 _______ 2018 ____________ 10 ___ ___ 15.58 ______ 2003

_11t__ ____ 16.35 _______ 1995 ____________ 11 ___ ___ 15.54 ______ 1911

_11t__ ____ 16.35 _______ 2016 ____________ 12 ___ ___ 15.52 ______ 1826

_13 __ ____ 16.325 ______ 2021 ____________ 13 ___ ___ 15.48 ______ 1959

_14t__ ____ 16.275 ______ 1779 ____________ 14 ___ ___ 15.44 ______ 1781

_14t__ ____ 16.275 ______ 1781 ____________ 15t___ ___ 15.40 ______ 1779,1780,1949,1995

________________________________

Note also that list of warm June and Sept combined missed 1846 (18.2, 14.7) which beats 2006 (15.8, 16.9) by .10 C on average. 

======================

Looking at current CET, the average in two decimals is now 17.35 rounded down apparently. (could be 17.33 or 17.34 based on differentials I saw last time I did a two decimal study). So it will take larger drops like days around 14 C to make running mean drop 0.1, and current output suggests 17.0 to 17.1 is now most likely end point. 

Edited September 27, 2023 by Roger J Smith

[BlueSkies_do_I_see]

50 minutes ago, Man With Beard said:

Thanks for the reply! Oops, sorry I meant the 4 month period June, July, August, September (my fault, terrible wording, and I'm supposed to be a university linguist by profession, good grief )

Not to worry.  I enjoyed compiling it even so and seeing the pattern of warm events in recent years when both months are taken together.

[BlueSkies_do_I_see]

3 hours ago, Roger J Smith said:

Posted during mid-month, 2023 can beat all but 2006 in first list, 17.0 would give an average of 16.625. We would tie 1826 and 1976 with a 16.9 result. For the may-Sep average, 17.0 brings us to 15.80, good for fifth. 

Rank ____ CET June-Sep_ Year __________ Rank ____ CET may-Sep_ Year

_01 __ ____ 17.175 ______ 2006 ____________ 01 ___ ___ 16.00 ______ 2006

_02t__ ____ 16.60 _______ 1826 ____________ 02 ___ ___ 15.90 ______ 1947

_02t__ ____ 16.60 _______ 1976 ____________ 03 ___ ___15.86 ______ 2022

_04 __ ____ 16.55 _______ 2022 ____________ 04 ___ ___ 15.82 ______ 2018

_05t__ ____ 16.50 _______ 1846 ____________ 05t___ ___ 15.68 ______ 1868

_05t__ ____ 16.50 _______ 1947 ____________ 05t___ ___ 15.68 ______ 1976

_07t__ ____ 16.475 ______ 1933 ____________ 07 ___ ___ 15.66 ______ 1846

_07t__ ____ 16.475 ______ 2003 ____________ 08 ___ ___ 15.62 ______ 1933

_09t__ ____ 16.45 _______ 1949 ____________ 09 ___ ___ 15.60 ______ 2016

_09t__ ____ 16.45 _______ 2018 ____________ 10 ___ ___ 15.58 ______ 2003

_11t__ ____ 16.35 _______ 1995 ____________ 11 ___ ___ 15.54 ______ 1911

_11t__ ____ 16.35 _______ 2016 ____________ 12 ___ ___ 15.52 ______ 1826

_13 __ ____ 16.325 ______ 2021 ____________ 13 ___ ___ 15.48 ______ 1959

_14t__ ____ 16.275 ______ 1779 ____________ 14 ___ ___ 15.44 ______ 1781

_14t__ ____ 16.275 ______ 1781 ____________ 15t___ ___ 15.40 ______ 1779,1780,1949,1995

________________________________

Note also that list of warm June and Sept combined missed 1846 (18.2, 14.7) which beats 2006 (15.8, 16.9) by .10 C on average. 

======================

Looking at current CET, the average in two decimals is now 17.35 rounded down apparently. (could be 17.33 or 17.34 based on differentials I saw last time I did a two decimal study). So it will take larger drops like days around 14 C to make running mean drop 0.1, and current output suggests 17.0 to 17.1 is now most likely end point. 

Thanks Roger. Well spotted RE 1846.

Really interesting that taken over the 4 months, 2023 will rank so highly. Most here will only remember their cool summer holiday in July/Aug (myself included) and forget the very warm months preceding and succeeding.

[Derecho]

It looks like the cooler night on the 29th will help drop the CET for the month into the 16s. Both the EC and GFS 12z OPS have the CET finishing at 16.9. A very slightly warmer following days could tip the final CET to 17.0 though.

That's the difference between the joint warmest with 2006 and the warmest on record. Would be quite an achievement if both June and September had a CET of 17C in the same year.

[Earthshine]

Definitely the most bizarre summer in my lifetime (since 2000).  Could you imagine two 17°C CET months with neither being July or August?  Perhaps we won't have to imagine soon!

[Scorcher]

11 hours ago, Derecho said:

It looks like the cooler night on the 29th will help drop the CET for the month into the 16s. Both the EC and GFS 12z OPS have the CET finishing at 16.9. A very slightly warmer following days could tip the final CET to 17.0 though.

That's the difference between the joint warmest with 2006 and the warmest on record. Would be quite an achievement if both June and September had a CET of 17C in the same year.

Is it really going to drop 0.4C over 3 days though? I'd say it's very borderline whether it will drop into the 16s. I'd say if it does, it could still be a rounded 17C. Another warm night across the CET zone last night with none of the stations dropping below 13C. Tomorrow night doesn't look all that cold to me and it will be cloudier further north. Saturday is the final day of the month so the 'following days' doesn't apply here.

[BlueSkies_do_I_see]

When I predicted an evens chance of getting the record, I incorrectly assumed we would get another plume that would push large parts of the country into low 20s max.

That hasn't happened, outside the SE. But we have had wind and cloud from the south and west that has given us some mild nights and I see now that those conditions are every bit as big an influence on boosting the daily values as we head further into Autumn.

 

[Derecho]

2 hours ago, Scorcher said:

Is it really going to drop 0.4C over 3 days though? I'd say it's very borderline whether it will drop into the 16s. I'd say if it does, it could still be a rounded 17C. Another warm night across the CET zone last night with none of the stations dropping below 13C. Tomorrow night doesn't look all that cold to me and it will be cloudier further north. Saturday is the final day of the month so the 'following days' doesn't apply here.

Been pretty consistent from the models. Only discrepancy could be timings (ie. I've been basing it on 24 hour means from midnight to midnight. if the met office do it a different way then there may be some deviation).

The GFS again lands on 16.9 to end the month (06z OP). Here are the anticipated returns:

27th: 14.5C (17.24C) - Based on observations yesterday in the CET zone, minima at the start of this period was around 11C
28th: 15.2C (17.16C)
29th: 14.0C (17.06C)
30th: 12.9C (16.92C)

You've misunderstood where I mentioned 'following days'. This wasn't referring to October, more the September days remaining following my post. The slightest change and it could end up on 17.0C and I think the calculations I've done throughout the month were reasonable.

To highlight how much of a close run thing this is, if one of the CETs from the 27th-30th comes in a degree higher with the rest remaining the same, the CET would finish at 16.95C which I presume would be rounded up with the record being beat. So it is possible.

Edited September 28, 2023 by Derecho

[Polarwesterly]

2 hours ago, Scorcher said:

Is it really going to drop 0.4C over 3 days though? I'd say it's very borderline whether it will drop into the 16s. I'd say if it does, it could still be a rounded 17C. Another warm night across the CET zone last night with none of the stations dropping below 13C. Tomorrow night doesn't look all that cold to me and it will be cloudier further north. Saturday is the final day of the month so the 'following days' doesn't apply here.

Friday night min will only be around 7c forecast. That’s enough to take us into the 16’s

[Scorcher]

1 hour ago, Polarwesterly said:

Friday night min will only be around 7c forecast. That’s enough to take us into the 16’s

Where? The Met Office have a min of 10C for Pershore, 9C for Rothamsted and 9C for Stonyhurst. Actually an above average night for this stage of the month.

[Scorcher]

1 hour ago, Derecho said:

You've misunderstood where I mentioned 'following days'. This wasn't referring to October, more the September days remaining following my post. The slightest change and it could end up on 17.0C and I think the calculations I've done throughout the month were reasonable.

I don't think I misunderstood- I may be splitting hairs here, but there is only one day of the month left after Friday. Following 'days' made me think you meant multiple days after Friday.

[Scorcher]

1 hour ago, Derecho said:

Been pretty consistent from the models. Only discrepancy could be timings (ie. I've been basing it on 24 hour means from midnight to midnight. if the met office do it a different way then there may be some deviation).

The GFS again lands on 16.9 to end the month (06z OP). Here are the anticipated returns:

27th: 14.5C (17.24C) - Based on observations yesterday in the CET zone, minima at the start of this period was around 11C
28th: 15.2C (17.16C)
29th: 14.0C (17.06C)
30th: 12.9C (16.92C)

You've misunderstood where I mentioned 'following days'. This wasn't referring to October, more the September days remaining following my post. The slightest change and it could end up on 17.0C and I think the calculations I've done throughout the month were reasonable.

To highlight how much of a close run thing this is, if one of the CETs from the 27th-30th comes in a degree higher with the rest remaining the same, the CET would finish at 16.95C which I presume would be rounded up with the record being beat. So it is possible.

 By my calculations, yesterday was warmer than 14.5C. I've calculated 16.55C at Rothamsted, 15.3C at Pershore and just under 15C at Stonyhurst. It will be interesting to see what the figure actually is. Unless you're actually using the data from the CET stations, the figures aren't going to be that precise with the estimates.

[richie3846]

6 minutes ago, Scorcher said:

 By my calculations, yesterday was warmer than 14.5C. I've calculated 16.55C at Rothamsted, 15.3C at Pershore and just under 15C at Stonyhurst. It will be interesting to see what the figure actually is. Unless you're actually using the data from the CET stations, the figures aren't going to be that precise with the estimates.

Do they knock off 0.4c to account for urban warming?

[BlueSkies_do_I_see]

34 minutes ago, Scorcher said:

Where? The Met Office have a min of 10C for Pershore, 9C for Rothamsted and 9C for Stonyhurst. Actually an above average night for this stage of the month.

It's the BBC Forecast that is showing 7C Fri min for me and Met Office showing 9C.  

[Derecho]

34 minutes ago, Scorcher said:

 By my calculations, yesterday was warmer than 14.5C. I've calculated 16.55C at Rothamsted, 15.3C at Pershore and just under 15C at Stonyhurst. It will be interesting to see what the figure actually is. Unless you're actually using the data from the CET stations, the figures aren't going to be that precise with the estimates.

Yes, looking at the obs yesterday at those 3 stations, the mean should come in at around 15.3C. I took a more generic station in the middle of the CET zone which had a cooler minimum then Pershore and Rothamstad.

Taking the GFS data at the grid points of those 3 stations, the daily means for the remaining 3 days of this month are 14.6C, 13.6C and 12.4C which means the final value should be 16.89C, unless the GFS has a cool bias of some sort.

[The PIT]

Sunny Sheffield down to 16.9C +2.6C above average. Rainfall 69.3mm 105.3% of the monthly average.