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

[richie3846]

1 hour ago, LetItSnow! said:

Nighttime temperatures have been boosted due to somewhat of a southwesterly element. A flick through some charts led me to see that we lose this in the coming week and while some nights may be closer to average the days will be cool, especially stuck under any rain. I also think nights could be quite cool between the 18th to the 22nd and I think it could bring us into the upper 15 to lower 16 mark. Uppers are consistently cool plus it looks like me may be going into a northwesterly set up around day 10 but who knows where that will end up. 

I'm not very good with the models, so tend to rely more on forecasts from the met office et al. With that in mind, I'm seeing more showery type weather this week, rather than huge rain dumps like yesterday, so in sunnier spells, temperatures could spike, and maybe reach around average, even if it is coolish for much of the day. We are talking about small differences here really but I suspect we could see 20c days or just under, due to the sunny spells giving short boosts of warmth in the afternoons. That's pretty much what we've been experiencing this July in general. 

But as you mentioned, we may see the wind veering away from the southwest a little, which could impact the nights. All to play for imo, small details make a big difference when we are talking in tenths of degrees!!

[Summer8906]

On 11/07/2023 at 10:37, Roger J Smith said:

It used to be not so rare, but no year since 1970 has produced a warmest June, 1993 was 0.1 below (15.0 vs 15.1 in July).

 

Surprised June wasn't the warmest month in 1992 but I suspect it was once again warm nights in July/August coming into play, cancelling out the suppressed day maxima.

Would be interesting to see if any years since 1970 had June as the month with highest mean max. I'd suspect that would have been the case in both 1992 and 2010.

Edited July 15, 2023 by Summer8906

[Summer8906]

On 10/07/2023 at 22:35, Addicks Fan 1981 said:

I'll say this @damianslawbut I have agreed with you wholeheartedly that this July is a 1997 and 2009 clone it really is.   

July 1997 was rather nice down in the south. Several warm sunny spells interspersed with shorter cooler cloudier spells; ISTR for most southern England locations the month was warmer, drier and sunnier than average albeit not by huge amounts. Better than all but four Julys (and you can probably guess which four) from 2007 onwards.

Edited July 15, 2023 by Summer8906

[damianslaw]

3 hours ago, Summer Sun said:

16.4c to the 14th

0.3c above the 61 to 90 average

0.1c above the 81 to 10 average

Surprised it hasn't fallen more. Mild nights probably reason given cloud. Quite difficult to achieve low minima in atlantic set ups anytime of year. For cool minima need more of a NW / N flow.. signs we will see more of that second half July. Still think we have a good chance dropping into 15s by next weekend. 

Edited July 15, 2023 by damianslaw

[Addicks Fan 1981]

Think @damianslawon the latest GFS 6Z it looks pretty flat to me and I think the CET will flat line now.    

[damianslaw]

9 minutes ago, Addicks Fan 1981 said:

Think @damianslawon the latest GFS 6Z it looks pretty flat to me and I think the CET will flat line now.    

Will see, a below average month will be appropriate given the conditions.

Scotland must be below average now.

[Don]

16 minutes ago, damianslaw said:

Surprised it hasn't fallen more. Mild nights probably reason given cloud. Quite difficult to achieve low minima in atlantic set ups anytime of year. For cool minima need more of a NW / N flow.. signs we will see more of that second half July. Still think we have a good chance dropping into 15s by next weekend. 

Yes, a bit like August 2008 which was an atrocious month (particularly in the south west), but still managed a CET in the 16's.

[reef]

20 minutes ago, damianslaw said:

Surprised it hasn't fallen more. Mild nights probably reason given cloud. Quite difficult to achieve low minima in atlantic set ups anytime of year. For cool minima need more of a NW / N flow.. signs we will see more of that second half July. Still think we have a good chance dropping into 15s by next weekend. 

Going by the max temps here, I imagine it hasn't been too far from average by day in the eastern part of the zone at least. The last 10 days have had the following maxima here:

22.1, 26.6, 24.1, 24.7, 22.3, 20.8, 20.4, 23.0, 18.6, 21.7C.

Our mean max for the month is 21.7C so far. The 1991-2020 average is 21.0C.

[Addicks Fan 1981]

I would envisage @reefthat they'll be no sign of a let up as things stand.    

[damianslaw]

2 minutes ago, reef said:

Going by the max temps here, I imagine it hasn't been too far from average by day in the eastern part of the zone at least. The last 10 days have had the following maxima here:

22.1, 26.6, 24.1, 24.7, 22.3, 20.8, 20.4, 23.0, 18.6, 21.7C.

Our mean max for the month is 21.7C so far. The 1991-2020 average is 21.0C.

A marked NW- SE divide month on the way I suspect. Maxima here have been below 20 degrees on most days...

[BruenSryan]

1 hour ago, Summer8906 said:

Surprised June wasn't the warmest month in 1992 but I suspect it was once again warm nights in July/August coming into play, cancelling out the suppressed day maxima.

Would be interesting to see if any years since 1970 had June as the month with highest mean max. I'd suspect that would have been the case in both 1992 and 2010.

The following years had June with the highest CET mean max since 1970. (second warmest in brackets)

1993 19.6C (July/August 19.1C)

1992 20.9C (July 20.2C)

1970 21.7C (August 20.4C)

July had a higher mean max in 2010 with 21.4C vs 20.3C.

Edited July 15, 2023 by BruenSryan

[richie3846]

1 hour ago, damianslaw said:

Surprised it hasn't fallen more. Mild nights probably reason given cloud. Quite difficult to achieve low minima in atlantic set ups anytime of year. For cool minima need more of a NW / N flow.. signs we will see more of that second half July. Still think we have a good chance dropping into 15s by next weekend. 

Apart from yesterday, day temperatures have been quite warm, there isn't a huge difference between night and day anomaly at this point, 0.4c difference. Nights have been mild yes, but so have days. 

[summer blizzard]

Rogue perhaps but the GFS12z has Maxima of 14C here on the 21st and 22nd.

[Addicks Fan 1981]

Not convinced @summer blizzardthat it'll be that cold on those days and nothing backs it up.    

[The PIT]

Sunny Sheffield still at 16.3C +0.5C above average. Rainfall 80.8mm 126.4% of the monthly average.

July now our 15th wettest on record and brings out summer back to average rainfall.

[Summer8906]

16 hours ago, richie3846 said:

Apart from yesterday, day temperatures have been quite warm, there isn't a huge difference between night and day anomaly at this point, 0.4c difference. Nights have been mild yes, but so have days. 

Out of the UK at the moment but the BBC forecast temps seem to have been persistently on the low side for both south Hampshire and London (and the 2nd-6th were certainly cool by day back home) so surprised at that - perhaps it's due to Swindon's location being sheltered from SW-lies by various hill ranges?

 

Edited July 16, 2023 by Summer8906

[Summer8906]

17 hours ago, Don said:

Yes, a bit like August 2008 which was an atrocious month (particularly in the south west), but still managed a CET in the 16's.

I do remember August 2008 being very cloudy throughout most of the month, and marked by SW-lies rather than NW-lies. ISTR SSTs also being notably cool that year, so daytime temps were seriously down but the cloud meant nights were often mild and muggy. Hence a particularly unpleasant first two-thirds of the month - though to be fair the 20th-30th was a bit better as a (cloudy but warm) anticyclone took over for a while.

So perhaps, due to the presence of that anticyclone, August 2008 was a little less bad than July 2007, July 2009 and the absolutely worst summer month of recent times by a country mile, June 2012.

Edited July 16, 2023 by Summer8906

[richie3846]

20 minutes ago, Summer8906 said:

Out of the UK at the moment but the BBC forecast temps seem to have been persistently on the low side for both south Hampshire and London (and the 2nd-6th were certainly cool by day back home) so surprised at that - perhaps it's due to Swindon's location being sheltered from SW-lies by various hill ranges?

 

July average max temp for Heathrow (to date), 23.2c. Bournemouth, not too far from Hampshire 21.4c. Brize Norton not too far from Swindon (and more representative of Swindon temps imo, than the very rural Lyneham)  21c. 

These are not very far below average temperatures. Maybe a touch below for Brize, but splitting hairs really. There does seem to be a tendency this time of year, for the forecasting to be a little below actual temperatures for some reason. 

[Addicks Fan 1981]

16.4 to the 15th

0.4 above the 61-90 average 

0.2 above the 81-10 average 

Edited July 16, 2023 by Addicks Fan 1981

[Summer Sun]

16.4c to the 15th

0.4c above the 61 to 90 average

0.1c above the 81 to 10 average

[Addicks Fan 1981]

54 minutes ago, Summer Sun said:

16.4c to the 15th

0.4c above the 61 to 90 average

0.1c above the 81 to 10 average

Thanks for putting me right.

[Don]

5 hours ago, Summer8906 said:

So perhaps, due to the presence of that anticyclone, August 2008 was a little less bad than July 2007, July 2009 and the absolutely worst summer month of recent times by a country mile, June 2012.

I spent two weeks in Cornwall that month and it was dreadful, the worst I've ever known it down there.  However, it was less bad for other parts of the country.

[Summer8906]

31 minutes ago, Don said:

I spent two weeks in Cornwall that month and it was dreadful, the worst I've ever known it down there.  However, it was less bad for other parts of the country.

The first 19 days or so were dreadful even in Hampshire but it did improve after that. We did however have anticyclonic SW-lies after that however, so while merely cloudy (Sc sheets) and muggy at home I can imagine it might have been an utter drizzlefest in the far SW.

Edited July 16, 2023 by Summer8906

[Don]

15 minutes ago, Summer8906 said:

The first 19 days or so were dreadful even in Hampshire but it did improve after that. We did however have anticyclonic SW-lies after that however, so while merely cloudy (Sc sheets) and muggy at home I can imagine it might have been an utter drizzlefest in the far SW.

There were a couple of decent days in Cornwall around the 22nd/23rd, but apart from that, the rest of the fortnight was an absolute washout!

[Roger J Smith]

From the table I posted on 1st or early 2nd  (page four of thread), note that the running mean for CET is similar in 1991-2020 compared with 1981-2010 until this point in the month. It was 16.3 after fifteen days in both intervals. It has been the second half of July that bumped up the 30-year average (by 0.17, from 16.63 to 16.80 in v2.0). 

The difference between these two in mathematical terms is one-third the difference between two decades, 2011-2020 compared to 1981-1990. That's because two thirds of both averages come from the same 20 years 1991-2010. 

So if the second half of the month is 0.3 warmer, then the two decades were 0.9 different in that interval (roughly, second decimals would change some comparisons, for example, 0.33 would work out to 1.0, 0.27 would work out to 0.8). 

You'll see that I have tracked both daily means and running means. So from 1st to 5th, 1991-2020 runs a bit warmer. From 6th to 15th, 1981-2010 has warmer or equal daily averages nine out of ten days. Then 1991-2020 has the edge from 16th to 27th (except for 21st), with 1981-2010 taking three more days 28th-30th, but thanks to 2020 the 31st goes to 1991-2020. The largest increase comes on the 23rd (17.5 vs 16.8) while the biggest margin in favour of 1981-2010 is 0.3 on four different dates (8, 11, 13, 15). The overall comparison shows 19 days warmer in 1991-2020, 10 days warmer in 1981-2010, and two days tied. 

Since it's really those two decades being compared, the differential is coming from heat waves in 2016, 2018 and 2019 (2022 does not factor in). Once the 1983 heat wave petered out, that decade only had 1989 and 1990 working towards a high finish and a lot of years in the 1980s were a bit on the cooler side. 

The highest running mean to 15th was 21.0 in 1976, and the lowest 12.5 in 1879. Those become 20.8 and 12.5 for today, and 20.6 and 12.6 for 17th (all of those in the same years 1976 and 1879). 

 

Edited July 16, 2023 by Roger J Smith