August 2024 C.E.T. and EWP forecast contests

[WYorksWeather]

 Don It would require something we don't often see though, which is a late burst of heat in August. August seems to really under-perform its potential in the second half.

We would need both an absence of any particular cool spell, and another period of hot or very hot weather in order to be in with a chance. Either a Coningsby-level heat spike in the second half achieving two or three more days in the mid 30s, or a much more sustained heatwave spell which records a number of days of widespread high 20s.

The difficulty this summer for recording very high CETs has been getting sufficiently high returns from Stonyhurst - it's very difficult to record many 20C means if Stonyhurst struggles to reach much above low to mid 20s by day. You're then relying on Rothamsted and Pershore to really do a lot of heavy lifting.

 

[Don]

5 minutes ago, WYorksWeather said:

It would require something we don't often see though, which is a late burst of heat in August. August seems to really under-perform its potential in the second half.

I think this last happened in 2019 which had the hottest August Bank holiday on record?

[The PIT]

Sunny Sheffield up to 17.9C +1.2C above average. Rainfall 10.7mm 15.6% of the monthly average.

A very very slow rise this week looks to be on the cards.

Edited August 13, 2024 by The PIT

[Derecho]

Latest from the 00z EC control. Looks like we will hold up in the mid to high 17s as we get towards the end of the month. 

High minima is often the cause of the CET only dropping slowly. The control was on the warmer side of the mean, but there are other ensemble members that bring in hot conditions at times which suggests the window may be open for another plume at some point.

The scope is there for an August CET above 18C IMO.

[Scorcher]

Yes I think 17.5C+ is odds-on now and a decent chance of 18C+. Definitely a trend to warmer Augusts (with the exception of last year) it seems.

[Summer Sun]

18.5 to the 12th

2.8c above the 61 to 90 average

1.6c above the 81 to 10 average

[Don]

 Scorcher 17.4C could be in with a chance still?! 

[Roger J Smith]

Yesterday's values did not break (12 Aug) date records from 2020, nor second place max and mean values set later in 2022, and are similar to mean values from 1911 ... as 1911 temps peaked next day, I included 13 Aug 1911 values below 12 Aug in table. Probably all of data reflect the fact that Stonyhurst was not at same daytime levels as other locations yesterday.

YEAR ______ max _ mean _ min

2020 ______ 32.0 __ 25.2 __ 18.5

2022 ______ 31.4 __ 23.0 __ 14.6

1911 ______ 29.3 __ 22.2 __ 15.1

2024 ______ 27.2 __ 22.1 __ 17.1

1911 (13)__ 30.5 __ 23.9 __ 17.4

also, 2022 highest min of spell was on 15 Aug at 16.9.

11 Aug 1997 min was 18.8 and 10 Aug 1997 max 30.5 (12 Aug 1997, 27.7, also beat 2024).

 

[WYorksWeather]

 Don You need that cold spell you wanted at the end of August to then lead into a sub-15C CET September 

[damianslaw]

A warmer than average August against 61-90 high odds, but I'm not confident whether it will finish in the 18s or 17s finish, largely due to uncertainty thanks to hurricane activity.

[Don]

 WYorksWeather Too flppin right, particularly wrt to a sub 15C September!! 

[WYorksWeather]

 damianslaw Yeah very hard to be sure at this stage. Probably need to wait until about the 20th.

[CryoraptorA303]

 Don Highly doubt it this year with summer being backended, you want a 2017 or 2010 style summer to get a cool September.

I can't even remember when the last below average September was, it must've been 2017. It in particular seems to be a very hard month to shove below average these days even with a cooler spell like in 2022 - But of course many months are starting to fall into this category as we're using an outdated climatology now. By 2001-2030 Sept 2022 would likely be below average overall.

Edited August 13, 2024 by CryoraptorA303

[WYorksWeather]

 CryoraptorA303 You can get a CET just below the 15.0C threshold even if it's 0.5C above 1961-1990, so something like that could still happen. I don't actually believe there's anything to it by the way - I think the September 15.0C threshold is just more of a coincidence than anything.

Anyway, I'll say no more on here because this belongs in the September thread when it launches!

[Don]

31 minutes ago, CryoraptorA303 said:

Highly doubt it this year with summer being backended, you want a 2017 or 2010 style summer to get a cool September.

Not necessarily, September 1995 was bang on the 61-90 average following the hottest August on record.  September 2022 had a CET of 14.4C and that also followed a hot August.  I agree that a cool September is probably unlikely, but that doesn't mean to say a very warm month is on the cards.

Edited August 13, 2024 by Don

[Summer Sun]

18.4 to the 13th

2.7c above the 61 to 90 average

1.5c above the 81 to 10 average

[Roger J Smith]

Also, 1.2 C above 1991-2020 average. 

EWP is now around 15 mm and GFS only foresees 20-25 additional, a 3-5 event underway on 30 Aug at end of 06z run, so would speculate 40 mm is the estiimate for end of August. (have seen dry outlooks reversed a few times in past tracking).

CET estimate also from 06z GFS would be around 17.5 C by nearly end of August. A few rather cool days around 25th but also quite a few before that in 17s or low 18s to keep average up. 

If you missed it, I posted a complete summary of all years (1772-2023) with CET values at or above 18.0 in second half of August, posted Sunday. Anyway, list has 25 years (plus two likely additions in 1736, 1747) with a value of 18 in period 15 to 31 Aug, of which four were not at 18 on 15 or 16 Aug but peaked later. Also there were about a dozen years with peaks in 17.6 to 17.9 range late in August. If we are at around 18.2 on 15 and 16 Aug, that would rank t-18 warmest of 253 (and possibly t-20 of all time). Quite a few years on list end up falling off into 16.6 to 17.2 range by end of August. 

[The PIT]

Sunny Sheffield up to 18C +1.3C above average. Rainfall 13.8mm 20.1% of the monthly average.

[Don]

3 hours ago, Roger J Smith said:

CET estimate also from 06z GFS would be around 17.5 C by nearly end of August.

Hopefully the 06z GFS was on the money.....

[Durham Weather]

First half of August at Durham. Very pleasant summer conditions.

Mean : 17.5C

Mean Max : 22.0C

Mean Min : 13.9C

Abs Max : 26.0C on 2nd

Abs Min : 11.6C on 14th

Rainfall : 12.6mm

Wettest Day : 2.3mm on 4th

[Summer Sun]

18.3 to the 14th

2.5c above the 61 to 90 average

1.4c above the 81 to 10 average

[The PIT]

Sunny Sheffield down to 17.9c +1.3C above normal. Rainfall Unchanged.

So it s going to be a dry warm start to the month.

 

[damianslaw]

A warm core summer period, suspect running mean 15 July - 15 Aug could end up the warmest of the year, apt timing for most heat in high summer period. Not expecting any rise hereon now, but late Aug could see a tick upwards. Stonyhurst is going to drag the CET down somewhat with quite a cool persistant westerly flow.

[The PIT]

Sunny Sheffield down to 17.8C +1.2C above average. Rainfall 14.5mm 21.1% of the average.

A slow drop for the next few days looking at things.

At the moment it's looking like summer will come out close to average temperature wise with below average rainfall for here at least.

 

[Summer Sun]

18.2 to the 15th

2.4c above the 61 to 90 average

1.3c above the 81 to 10 average