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

[Roger J Smith]

So it would be only the 20th occasion in 355 summers with July cooler than both June and August. The phenomenon seems to be becoming even less frequent in recent times; the most recent events were 1970 and 1965. The other type of July deficit (where one month creates a large surplus and the other one fails to reduce it much) has become the more likely way of creating a July deficit. 

[ItNeverSnowsInWindsor]

Pretty much above normal all the way now.

[Summer Sun]

16.5c to the 16th

0.7c above the 61 to 90 average
0.3c below the 81 to 10 average

[The PIT]

Sunny Sheffield up to 16.7C +0.1C above average. Rainfall unchanged.

[Roger J Smith]

Outlook is quite warm for several days then closer to average last six days of August, can't see the CET getting much past 17.7 during this warmer spell and average is about 15 in late August so that would argue for an outcome around 17.2 to 17.5 C. A warm August but not exceptional if so. I posted a list yesterday of the 19 previous occasions when both June and August exceeded the July CET. This would be the first time since 1970. 

Latest EWP estimate is 51 mm to now and at least 80 mm end of month, further rainfalls of 10 to 50 mm from east to west are predicted. If we do get an outcome around 85 or 90 mm Reef will move up and join current leaders snowray and leo97t in a virtual three-way tie depending on exact details. A chase pack will be back around 10 points lower than those three. Will post some scoring estimates to be adjusted at end of month in a few days if the trends continue as shown. An outcome above 90 mm would lead to almost determined scoring estimates as most of the forecasts are below 90 mm. 

[Don]

30 minutes ago, Roger J Smith said:

Outlook is quite warm for several days then closer to average last six days of August, can't see the CET getting much past 17.7 during this warmer spell and average is about 15 in late August so that would argue for an outcome around 17.2 to 17.5 C. A warm August but not exceptional if so. I posted a list yesterday of the 19 previous occasions when both June and August exceeded the July CET. This would be the first time since 1970. 

One thing I've noticed this year is a number of months have felt somewhat cooler/colder than the CET suggests and that includes the record breaking warm June!  A 17.2 to 17.5C CET would have been seen to be a very warm August back in the 80's for example.  Also, Augusts 2002 and 2013 only managed CET's of 17.0C and to me, they both felt warmer than this month so far!  I'm guessing high minimums have been the main culprit for the warmth in 2023?  A strange year for sure!

[damianslaw]

1 hour ago, Don said:

One thing I've noticed this year is a number of months have felt somewhat cooler/colder than the CET suggests and that includes the record breaking warm June!  A 17.2 to 17.5C CET would have been seen to be a very warm August back in the 80's for example.  Also, Augusts 2002 and 2013 only managed CET's of 17.0C and to me, they both felt warmer than this month so far!  I'm guessing high minimums have been the main culprit for the warmth in 2023?  A strange year for sure!

Yes warmth combined with cloud and rain and mild nights doesnt feel the same as predominantly dry sunny days temps low to mid 20s but cool night cancelling out the high maxima. 

[Earthshine]

3 hours ago, Roger J Smith said:

Outlook is quite warm for several days then closer to average last six days of August, can't see the CET getting much past 17.7 during this warmer spell and average is about 15 in late August so that would argue for an outcome around 17.2 to 17.5 C. A warm August but not exceptional if so. I posted a list yesterday of the 19 previous occasions when both June and August exceeded the July CET. This would be the first time since 1970. 

Latest EWP estimate is 51 mm to now and at least 80 mm end of month, further rainfalls of 10 to 50 mm from east to west are predicted. If we do get an outcome around 85 or 90 mm Reef will move up and join current leaders snowray and leo97t in a virtual three-way tie depending on exact details. A chase pack will be back around 10 points lower than those three. Will post some scoring estimates to be adjusted at end of month in a few days if the trends continue as shown. An outcome above 90 mm would lead to almost determined scoring estimates as most of the forecasts are below 90 mm. 

Hi Roger, how do you estimate the monthly CET?  Do you use forecasted values for a couple of stations?  I'd be interested to know what the projected maximum CET would be for August.  My estimate for the maximum CET for the summer would be the following, dependent on the August value:

August maximum CET / Summer maximum CET / Rank:

21.0°C / 21.2°C / 22nd 

21.5°C / 21.4°C / 20th 

22.0°C / 21.6°C / 16th

A value of 21.0°C for August would amazingly put 2023 ahead of 2013 in terms of the maximum CET (21.1°C) and equal to 1997 (21.2°C).  A value of 22.0°C would give a seasonal maximum CET of 21.6°C, putting summer 2023 ahead of 1984 (21.5°C).  I think a maximum CET of 21.0°C should be reached this month.  Clearly June carrying this summer enormously, putting it amongst some very respectable summers like 1984, 1989, 1990, 2013, etc, even in terms of maximum daytime temperatures and if ignoring the warm nights.

Edited August 17, 2023 by Earthshine

[ItNeverSnowsInWindsor]

It’s flipped to average now! So more like high 16s.

[Don]

5 minutes ago, prolongedSnowLover said:

It’s flipped to average now! So more like high 16s.

Yes, get in with my 16.8C guess!! 

[Dancerwithwings]

I agree Don, the lastest GEFS mean, is going for a cool last week in August, so at most 17c for August is my thoughts

But yes certainty below that is possible for sure

[Metwatch]

16 minutes ago, Don said:

Yes, get in with my 16.8C guess!! 

Looking decent for my 17.1C guess now! 

Not sure about 70mm for EWP though

[Dancerwithwings]

20 minutes ago, Don said:

Yes, get in with my 16.8C guess!! 

I’m 0.1c behind ya

[Don]

8 minutes ago, Dancerwithwings said:

I agree Don, the lastest GEFS mean, is going for a cool last week in August, so at most 17c for August is my thoughts

But yes certainty below that is possible for sure

Trouble is at the moment, the models are flip flopping around as to whether the more intense heat over Europe will make it into the UK.  However, going by the general trends recently, in that the main heat can not quite make it across the channel, then high 16's may be the best bet at this stage?

2 minutes ago, Dancerwithwings said:

I’m 0.1c behind ya

Bring it on!! 

Edited August 18, 2023 by Don

[Summer Sun]

16.6c to the 17th

0.8c above the 61 to 90 average
0.2c below the 81 to 10 average

[damianslaw]

Mmm might June end up the warmest month of the year? Still feel a finish in 17s will be end result, however may be lower end. If a ridge holds and sustains to the west end of the month this could return some chilly nights.

[Don]

35 minutes ago, damianslaw said:

Mmm might June end up the warmest month of the year? Still feel a finish in 17s will be end result, however may be lower end. If a ridge holds and sustains to the west end of the month this could return some chilly nights.

Could well be although you never know, we could get a record breaking September with a CET in the low 17's?!  Not that I'm expecting that, but you never know!

[Roger J Smith]

22 hours ago, Earthshine said:

Hi Roger, how do you estimate the monthly CET?  Do you use forecasted values for a couple of stations?  I'd be interested to know what the projected maximum CET would be for August.  My estimate for the maximum CET for the summer would be the following, dependent on the August value:

August maximum CET / Summer maximum CET / Rank:

21.0°C / 21.2°C / 22nd 

21.5°C / 21.4°C / 20th 

22.0°C / 21.6°C / 16th

A value of 21.0°C for August would amazingly put 2023 ahead of 2013 in terms of the maximum CET (21.1°C) and equal to 1997 (21.2°C).  A value of 22.0°C would give a seasonal maximum CET of 21.6°C, putting summer 2023 ahead of 1984 (21.5°C).  I think a maximum CET of 21.0°C should be reached this month.  Clearly June carrying this summer enormously, putting it amongst some very respectable summers like 1984, 1989, 1990, 2013, etc, even in terms of maximum daytime temperatures and if ignoring the warm nights.

I just look at the projected max and min values daily for the CET zone and go from there. Any comments about a range of outcomes may be governed by comparison to other guidance, or my hunches about whether trends are real or not so real. With this cooler turn after middle of next week, I could see that going either way. But on the current numbers, I would go with lower end of your estimates, mean max today to 31st will only be around 19.5 C. The month could quite easily finish as low as 16.5 at this rate (after maybe making it to 17.3 mid-week). I think low 17s still have a chance if that cooler trend is overdone. EWP also looks to be on its way back down from higher estimates, 75 to 95 mm is the range of estimates I've seen in recent GFS runs. 

[Dancerwithwings]

19 minutes ago, Roger J Smith said:

I just look at the projected max and min values daily for the CET zone and go from there. Any comments about a range of outcomes may be governed by comparison to other guidance, or my hunches about whether trends are real or not so real. With this cooler turn after middle of next week, I could see that going either way. But on the current numbers, I would go with lower end of your estimates, mean max today to 31st will only be around 19.5 C. The month could quite easily finish as low as 16.5 at this rate (after maybe making it to 17.3 mid-week). I think low 17s still have a chance if that cooler trend is overdone. EWP also looks to be on its way back down from higher estimates, 75 to 95 mm is the range of estimates I've seen in recent GFS runs. 

Oh yes of course, we all knew that,

…..Nah not really,  that’s why we leave it to the Roger we know

[Earthshine]

1 hour ago, Roger J Smith said:

I just look at the projected max and min values daily for the CET zone and go from there. Any comments about a range of outcomes may be governed by comparison to other guidance, or my hunches about whether trends are real or not so real. With this cooler turn after middle of next week, I could see that going either way. But on the current numbers, I would go with lower end of your estimates, mean max today to 31st will only be around 19.5 C. The month could quite easily finish as low as 16.5 at this rate (after maybe making it to 17.3 mid-week). I think low 17s still have a chance if that cooler trend is overdone. EWP also looks to be on its way back down from higher estimates, 75 to 95 mm is the range of estimates I've seen in recent GFS runs. 

Brilliant, thanks Roger.  I think I share the view with many others here that your analysis on all things CET and temperature here in the UK is absolutely fantastic and really insightful!

[The PIT]

Sunny Sheffield at 16.8C + 0.2C above average. Rainfall 51.7mm 75.1% of the monthly average.

[Summer Sun]

16.6c to the 18th

0.9c above the 61 to 90 average
0.2c below the 81 to 10 average

[The PIT]

Sunny Sheffield up to 16.9C +0.3C above average, Rainfall unchanged

[Summer Sun]

16.8c to the 19th

1.0c above the 61 to 90 average
Bang on the 81 to 10 average

[Roger J Smith]

EWP projection is now 75-80 mm from current 63 mm. 

CET will continue to drift upward for several days, and later back down, likely ending near 16.7 C. June looking increasingly likely to take top spot but August will still edge out July.