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

[Metwatch]

53 minutes ago, BlueSkies_do_I_see said:

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.

Coventry still yet to see 30C since 1911.

Reached 29.8C 2 years ago today, and again above 29.0C today, but not 30C. Maybe Saturday it happens here. Numerous date records both minimums and maxima have been broken this week though.

Edited September 7, 2023 by Metwatch

[Roger J Smith]

I edited into my previous posted table two new CET records for 6th, new max (28.1) and daily mean (21.1) both at the expense of 1898 which kept its high min record. Will try to keep up that table although as mentioned will not be around much as we go on a road trip starting tomorrow. 

The latest GFS guidance does not look promising for the idea of a record warm month, it turns cooler in stages and some of the days are quite cold, looks more like 1906 than 2006. Near term we do likely soar to about 20 or even higher by Monday 11th after which it all crumbles away, 1906 with its record warm start ended up 13.9 and saw no return to warmth after holding the lead in running CET to 8th. 1880 which had some similar daily values also dropped a long way to 14.6 although it was a bit warmer than average again in the last third. 

1906 by daily values:  ___ ___ 1880 for comparison 

1-10 _ 11-20 _ 21-30 ________ 1-10 _ 11-20 _ 21-30

22.0 __ 11.8 __ 11.9 _________ 16.7 __ 15.8 __ 12.1

22.3 __ 12.9 __ 13.1 _________ 19.9 __ 13.8 __ 14.7

19.3 __ 15.9 __ 10.2 _________ 19.8 __ 13.1 __ 15.8

16.7 __ 13.5 __ 12.0 _________ 20.1 __ 12.3 __ 13.7

15.3 __ 12.4 __ 10.6 _________ 19.3 __ 12.9 __ 14.0

17.7 __ 10.9 ___ 9.9 _________ 14.9 __ 14.1 __ 15.4

18.3 __ 13.0 ___ 9.8 _________ 13.6 __ 13.3 __ 14.8

16.6 __ 14.7 ___ 9.7 _________ 12.8 __ 12.5 __ 13.4

15.2 __ 13.6 __ 10.2 _________ 14.8 __ 10.1 __ 12.1

12.0 __ 14.2 __ 11.0 _________ 17.1 __ 11.1 __ 12.8

By 9th of September, 1898 held the lead in running mean, it was able to keep a fairly high average to about the 23rd before a cool last week brought it down to 15.2. 1865 took over the lead by 12th and held it to 23rd, and despite some very ordinary looking daily means in second half, never falling way behind (16.3) the eventual leader 2006 (16.9) or the unknown daily details of second place 1729 (16.6). 1795 was similar to 1865 but never quite as high up in the ranks. 1949 was always lurking in the top ten to finish at 16.3 and had quite a good warm spell 22nd to 29th that averaged 16.6 for eight days. 

Meanwhile on the EWP front, nothing much to report yet, but eventually the south gets very wet and the grid average by 23rd is around 60 mm with as much as 120 mm in west Norfolk, for a change the north sees less rain than other regions, not much over 30 mm in the northeast. All of the output is probably low to medium confidence, what happens if Lee takes a track to reinforce the eastern Atlantic ridge? (or if the eastern Atlantic ridge forces Lee into a track towards Iceland). These trends could all change. 

[The PIT]

Sunny Sheffield up to 19.6C +3.3C above normal. Rainfall 0mm 0% of the monthly average.

[Nick L]

18 hours ago, BlueSkies_do_I_see said:

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.

And those who deny the climate is warming can't even trot out the gormless line of "it's called summer!".

[Summer Sun]

19.7c to the 7th

6.1c above the 61 to 90 average
4.6c above the 81 to 10 average

[reef]

Yesterday was 23.3C aswell, breaking the old date record of 20.9C by quite a margin.

1st-7th September is also almost a full degree above the previous warmest (1906). That averaged 18.8C.

[Roger J Smith]

Not only the date record but 23.3 is a new high mean daily value for September, the old ones being 22.4 (5 Sep 1949) and 22.3 (2 Sep 1906, formerly 22.6 in CET legacy). 

The max of 28.8 and min of 17.7 are daily records but neither is an extreme value for the month in CET, those are 31.2 (1 Sep 1906) and 18.4 (5 Sep 1949). I have updated my table of records back in the thread. 

Will soon be on the road and away from the internet. If anyone wants to copy that table and show further updates in real time, be my guest, but I will eventually update it and bring it forward into the thread later in the month. 

[Earthshine]

Saw a stat on Twitter that the first week of September, in terms of maximum CET, was the 8th hottest of ANY month on record.  That is absolutely nuts for September, almost 3 months after peak solar insolation. 

 

[LetItSnow!]

10 minutes ago, Earthshine said:

Saw a stat on Twitter that the first week of September, in terms of maximum CET, was the 8th hottest of ANY month on record.  That is absolutely nuts for September, almost 3 months after peak solar insolation. 

 

Perhaps a not so subtle indication at the potential heatwaves we could see in the future. Unless dramatic changes in weather patterns actually occur like are being theorised, who knows when we could see our first 30-32C in October.

[ItNeverSnowsInWindsor]

6 hours ago, Summer Sun said:

19.7c to the 7th

6.1c above the 61 to 90 average
4.6c above the 81 to 10 average

Absolutely bonkers!

Let’s hope we get a beast from the east this winter to give us some proper cold for a change!

Edited September 8, 2023 by prolongedSnowLover

[Derecho]

An update on the CET projections based on the 12z GFS, which sends the CET cascading, mainly due to cool nights. However this is a work in progress and it may be off:

8th: 20.1 (22.9)
9th: 20.4 (22.4)
10th: 20.5 (21.5)
11th: 20.3 (18.0)
12th: 19.7 (13.9)
13th: 19.2 (13.2)
14th: 18.8 (13.7)
15th: 18.5 (13.8)
16th: 18.1 (11.8)
17th: 17.7 (12.3)
18th: 17.4 (11.9)
19th: 17.0 (10.2)
20th: 16.7 (10.9)
21st: 16.4 (10.9)
22nd: 16.2 (11.1)
23rd: 16.0 (11.6)

However the prediction I made 5 days ago held up fairly well:

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)

Still the warmest first half to September on record but I wouldn't bet on the warmest September on record overall. Tropical storms may throw up surprises and the EC does look much warmer however.

[Shillitocettwo]

1 hour ago, Derecho said:

An update on the CET projections based on the 12z GFS, which sends the CET cascading, mainly due to cool nights. However this is a work in progress and it may be off:

8th: 20.1 (22.9)
9th: 20.4 (22.4)
10th: 20.5 (21.5)
11th: 20.3 (18.0)
12th: 19.7 (13.9)
13th: 19.2 (13.2)
14th: 18.8 (13.7)
15th: 18.5 (13.8)
16th: 18.1 (11.8)
17th: 17.7 (12.3)
18th: 17.4 (11.9)
19th: 17.0 (10.2)
20th: 16.7 (10.9)
21st: 16.4 (10.9)
22nd: 16.2 (11.1)
23rd: 16.0 (11.6)

However the prediction I made 5 days ago held up fairly well:

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)

Still the warmest first half to September on record but I wouldn't bet on the warmest September on record overall. Tropical storms may throw up surprises and the EC does look much warmer however.

Yes a very warm start but a very warm first 3rd won't carry a record monthly value with average temps for the other 20 days!

[Frigid]

1 hour ago, Derecho said:

An update on the CET projections based on the 12z GFS, which sends the CET cascading, mainly due to cool nights. However this is a work in progress and it may be off:

8th: 20.1 (22.9)
9th: 20.4 (22.4)
10th: 20.5 (21.5)
11th: 20.3 (18.0)
12th: 19.7 (13.9)
13th: 19.2 (13.2)
14th: 18.8 (13.7)
15th: 18.5 (13.8)
16th: 18.1 (11.8)
17th: 17.7 (12.3)
18th: 17.4 (11.9)
19th: 17.0 (10.2)
20th: 16.7 (10.9)
21st: 16.4 (10.9)
22nd: 16.2 (11.1)
23rd: 16.0 (11.6)

However the prediction I made 5 days ago held up fairly well:

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)

Still the warmest first half to September on record but I wouldn't bet on the warmest September on record overall. Tropical storms may throw up surprises and the EC does look much warmer however.

Wow, 13th onwards looks very chilly for September on the 12z.. could we get the coldest second half alongside the warmest first half. 

Edited September 8, 2023 by Frigid

[Derecho]

55 minutes ago, Frigid said:

Wow, 13th onwards looks very chilly for September.. could we get the coldest second half alongside the warmest first half. 

I suspect the minima is too cold on the 12z GFS and it'll be slightly below average rather then notably so. If the EC comes off the CET will be much higher.

We are getting to that time of year where high pressure may not sustain warmth (unlike from April - June) instead the warmest daily means are often those where we have cyclonic type conditions and a very warm air source.

Edited September 8, 2023 by Derecho

[Don]

5 hours ago, LetItSnow! said:

Perhaps a not so subtle indication at the potential heatwaves we could see in the future. Unless dramatic changes in weather patterns actually occur like are being theorised, who knows when we could see our first 30-32C in October.

Perhaps in 4 weeks?! 

[summer blizzard]

Looks to me like the Euro would however produce significant rainfall. 

At any rate, Autumn should arrive.

[Summer Sun]

20.0c to the 8th

6.4c above the 61 to 90 average
4.9c above the 81 to 10 average

[Frigid]

1 minute ago, Summer Sun said:

20.0c to the 8th

6.4c above the 61 to 90 average
4.9c above the 81 to 10 average

[reef]

17 minutes ago, Frigid said:

There's isn't much more you can say is there! Ridiculous heat for September.

Yesterday was 22.0C so thats five consecutive 20C+ days now. Another date record for the mean on the 8th aswell.

Edited September 9, 2023 by reef

[The PIT]

Sunny Sheffield 19.9C +3.7C above average. Rainfall unchanged

14 hours ago, summer blizzard said:

 

At any rate, Autumn should arrive.

It arrived on the 1st and lasted for a day. We've skipped winter and spring and now back into summer.

[Scorcher]

If someone had told me this was going to happen even 2 weeks ago, I'd have laughed in their face.

An absolutely extraordinary weather event- especially after a relatively poor July and August.

[reef]

5 minutes ago, Scorcher said:

If someone had told me this was going to happen even 2 weeks ago, I'd have laughed in their face.

An absolutely extraordinary weather event- especially after a relatively poor July and August.

I'm not too surprised. The heat has been there to the south all summer, its just the synoptics didn't allow it to be blown up this way. Odds were always that it would reach us at some point.

It just show how potent it was when we're hitting temperatures like this in almost mid-September.

[Scorcher]

59 minutes ago, reef said:

I'm not too surprised. The heat has been there to the south all summer, its just the synoptics didn't allow it to be blown up this way. Odds were always that it would reach us at some point.

It just show how potent it was when we're hitting temperatures like this in almost mid-September.

I don't think anyone could have predicted something of this magnitude in September though. This is one of the best spells I can remember at any time of year in terms of duration of the heat.

[snowray]

1 hour ago, reef said:

I'm not too surprised. The heat has been there to the south all summer, its just the synoptics didn't allow it to be blown up this way. Odds were always that it would reach us at some point.

It just show how potent it was when we're hitting temperatures like this in almost mid-September.

That's why I went so high in August's competition, thought a late August heatwave was very possible, never expected this in September, came from nowhere really with the models compared to the August forecast warm ups all coming to nothing. If only it had turned up a week earlier.

[Don]

2 hours ago, reef said:

I'm not too surprised. The heat has been there to the south all summer, its just the synoptics didn't allow it to be blown up this way. Odds were always that it would reach us at some point.

It just show how potent it was when we're hitting temperatures like this in almost mid-September.

This is what I've been alluding too, in that we were very close to having another hot summer (although I've been snapped at to suggest this!), but the synoptics didn't quite align to allow that until now!  

Edited September 9, 2023 by Don