General summer chat

[CryoraptorA303]

 raz.org.rain This is how I'm expecting this summer to go: A June that isn't special, a dry and warm to hot July and a very hot and dry August and September, and a dry autumn after that. I wouldn't rule out a September annual maximum again, although even higher than last year and possibly breaking the 35.6°C record.

[Addicks Fan 1981]

 Summer8906 however 1994 like 2023 had the east QBO and el niño combination but I think last year's July was very similar to 2009 to be honest, August though had things in common with August 1994.    

[raz.org.rain]

 CryoraptorA303 I could imagine a repeat of June '23 if the LRFs are to be trusted, but I could imagine it being benign and average. Average temperatures and perhaps a few very warm days.

[CryoraptorA303]

 raz.org.rain That's not too far into the realms of imagination, perhaps if there's a particularly strong easterly Wales could see the highest temps of June. Maybe Porthmadog could break Wales' June record of 33.7°C from 2000.

Any extreme heatwaves will likely come from mid-July onwards. August is in prime condition to break the historic run without an annual maximum this year. Otherwise September will pull off a second consecutive annual max.

Edited March 4 by CryoraptorA303

[LetItSnow!]

 East Lancs Rain Love Gavin's videos but these analogue forecasts aren't really worth the time and effort in my opinion. You can put all the closest matching previous months together in terms of rainfall and temperature but the global pattern for those analogues could be completely different. You can have, say an August that is cool and wet, but it can be cool and wet in multiple different patterns, same with hot. Then there's the added influence of CC. Even with matches to El Nino's etc you still have different types of EN's and LN's, plus no weather pattern will likely ever be the same. It reminds me of a poster on here whom I thought was excellent for making a list of all the years that had the most similar weather events globally to try and create the ultimate analogue and it still didn't end up being accurate. I think when it comes to forecasting, the less precision the better. You can make general assumptions of what weather patterns will likely be in certain areas due to things like El Nino, ENSO etc, but to try and fine point it is futile.

[WYorksWeather]

 Summer8906 None of those summers would be anywhere near warm enough to qualify. You're talking about a summer with an overall CET in the 17s.

Looking through the list of summers that would qualify, probably a close analogue for what the CFSv2 is showing would be a summer like 1983, based on my reading of the historic weather data.

Again, not saying the CFSv2 is right with what it is showing, and in any case it'll probably show something different when I next look at it. But interesting to think what a modern version of 1983 might look like. In short, we'd be looking at a bit of something for everyone - a fair few heatwaves but some great thundery breakdowns, but broken up with periods of cooler and more unsettled weather.

Here's Trevor Harley's write up:

Quote

June. Mostly cloudy and cool. A very dry month in the south but with some notable thunderstorms.

July. The hottest July of the century (19.5C), and indeed the hottest month since records began (until July 2006). Also mostly dry and sunny, but with some severe thunderstorms.

August. Hot (17.3) and dry. There was a cool, showery start before it turned warm and sunny.

The CFSv2 is probably wrong in any case. But a summer like 1983 would be closer to what it is showing I think than 2023, for instance.

[WYorksWeather]

 CryoraptorA303 The key as usual will be to watch the temperatures across southern and central Europe through spring and early summer. The lesson I think from 2022 and 2023 is that even in a relatively unfavourable pattern for heat like in 2023, there will almost always be at least one or two occurrences of very hot weather, as it's usually impossible to have a summer completely devoid of any wind directions between east and south.

[LetItSnow!]

 WYorksWeather The rapid warming of northern Africa compared to other places in the world is meaning that our hot southerlies that once would have brought 10-15C uppers are now bringing 15-20C uppers, plus urban heating as well means that our Spanish plumes are no longer and are now African plumes in a way. You can sort of see this how when we’ve had hot spells that are more homegrown/from the east they’re not as intense for ultimate maximums, like summer 2018 and June 2023. However those types of patterns were always much harder to come by by default. I’ll be keeping a close eye on the heat and drought situation to our south. Considering that parts of Spain were seeing heatwaves as early as January it’s not a great sign. Also will be interesting to see if the wet theme continues into the spring. If it does and we retain moist soil into the summer then that may limit the maximum temperature capacity though that could easily be undercut by very hot uppers and a drought stricken continent. 

[Metwatch]

31 minutes ago, WYorksWeather said:

None of those summers would be anywhere near warm enough to qualify. You're talking about a summer with an overall CET in the 17s.

9 hours ago, Summer8906 said:

think a lot of recent summers have come out that way. Warm by CET, but rather wet, with the warmth primarily from night minima plus heat spikes and/or short transient heatwaves in the midst of prolonged unsettled weather (good examples being August 2020 or July 2021).

Looking through seasonal CET and summer's EWP plus the graph from RoostWeather to compare different variables to each other, there does appear to be an increasing number of summers which can be classed as warmish but also fairly wet.

For central and southern England region below we've got 2023, 2020, 2019, 2017, 2004 and 1997. A few more which aren't particularly dry but neither overly wet and still warmish include 2021, 2016, 2014 and 2010.

Quite hard to get single months which are warm and wet though, if say 1 summer month is warm and dry and the other 2 are wet and near average temperature wise, the summer will still finish warm but wet, 2023 a good example. August 1997 seems to be an outlier, not dry, but very warm so probably quite thundery. June 1982 similar.

Edited March 4 by Metwatch

[WYorksWeather]

 LetItSnow! To be fair the urban heating has a fairly modest effect. Even extremely rural stations in parts of south and east Yorkshire recorded 38-39C during July 2022, so I don't think it'll make much difference.

The ground moisture is probably a bigger factor, and is probably why e.g. September 2023 didn't set a record after the very wet July and August, if I had to name one factor.

In terms of what you're saying about upper air temperatures, worth noting that though I haven't been paying too close attention, southern and eastern Spain gets briefly tagged with the 20C isotherm in mid-March on today's GFS 12z.

[WYorksWeather]

 Metwatch Yeah it is interesting though that actually none of those years qualify. In other words, we don't have an analogue for a summer that combines e.g. the heat of 1995 with also being near-average for rainfall, let alone wetter than average.

Depending on how exactly the rainfall was distributed, it raises a lot of interesting questions as to how that could even work. You could have extremely mild nights I suppose with lots of very humid south-westerlies. You could alternatively have classic unreliable British summer weather with flat westerlies, but punctuated with extraordinary heat spikes. You could also have fairly reliable weather overall, but with fairly frequent thundery breakdowns. Few rain days, but large overall rainfall totals.

In short, I think the point I'm trying to make is that no summer we've had previously corresponds very well to this sort of scenario, as only about 10-15 summers ever (and only 5-6 in modern times) qualify on heat grounds, and none of those were wet enough.

Not to worry though in any case, the CFSv2 will end up being wrong in one way or another, these long range models are entirely for a bit of fun. If I post it again in a couple of weeks it'll show something completely different.

[LetItSnow!]

 WYorksWeather The urban heating effect was one of the lesser points but it definitely makes a difference from being in a country field to the heat of the city. Experiencing 40C in the city with no air con in a brick built load of apartments was genuinely terrible. When these apartments were constructed in 1993 the annual max wasn’t even 30C, oh how times have changed. A lot of Britain’s homes were built in times when 40C was impossible and really not likely to ever happen so it will be interesting to see how we adapt. But this isn’t the chat for that. 

I really would just like a normal summer without any weird extreme weather. If we could have decent anticyclonic spells but have a lack of far fetched southerly winds then that would be nice, but often with unsettled spells to keep soil moisture and gardeners happy. Probably a summer with a displaced Azores high, though that would run the risk of northerlies, and that can at worst lead to conditions like the second half of July 1987 where lows become stuck and a lot of grey gloomy weather becomes immovable over the country.

Summer 2001 seems like a good one that I wouldn’t mind a repeat of. Every month had a bit of everything to keep everyone happy and I think every month reached 32C. There was also a lot of thunder at times and sometimes there were cool nights. May 2001 was also dry and fine but with some spectacular storms (It would fit to have a summer like that as we’re in a similar situation rainfall wise to that time. May 2001 finally broke the run of unprecedented rainfall but the following summer wasn’t a dry one).

[reef]

I think looking at analogue years based on temperature is flawed these days. 1989 had a CET mean of 16.4C and 2023 had a mean of 16.5C but they were vastly different summers.

The upcoming summer may have a CET of 17-18C like the forecasts suggest, but that doesn't mean it will be another 1976 or 2018. It could just as well be another 2023 but with temperatures 0.5-1.0C warmer but with the same crap weather.

Its difficult to find any summers that are 17C+ and wetter than average as they haven't happened yet. However with the background warming taken into account, such summers that were 16C and wetter than average not long ago are probably the closest fit to this, but with temperatures a little higher.

I think it'd be a good bet that 2024 will be one of these two: warm and wet (like 2023) or very warm and dry (aka 2018/2022). I think getting any summer (wet or dry) much below average (16C) is probably difficult now and sub-15C (1C below average) out of the question.

[In Absence of True Seasons]

13 hours ago, LetItSnow! said:

When these apartments were constructed in 1993 the annual max wasn’t even 30C, oh how times have changed. A lot of Britain’s homes were built in times when 40C was impossible and really not likely to ever happen so it will be interesting to see how we adapt. But this isn’t the chat for that. 

Britain recorded a 30c or 30c+ temp at some point in most years in the last 100 years. The frequency of such days is what's increasing now. 

Regarding the 40c, as soon as it happened in 2022, many people seemed to think it'd be some sort of "new normal" and would happen in 2023. Summer 2023 showed that our climate is still very capricious and maritime-driven regardless of climate change. We could easily not see another 40c for years and years. Or we we may see one this year. Who knows. Either way, such temps are certainly not going to become the norm, not any time soon anyway, so in terms of "adapting", I don't think there's much - if any - adaptation that will be made to accommodate for random, extreme outlier heat spikes like that. A bit like how we also don't invest in accomodations for heavy snow/cold in the same way as, say, Norway or Sweden do, because it's too irregular to warrant proper investment in. 

The main investment imo needs to be made into better dealing with the wetter climate that we seem to be moving towards. That is having, and will have, a far more significant impact on our communities, our landscapes and our agricultural industries than the odd day of 38c, 39c or 40c once a year. 

[LetItSnow!]

 In Absence of True Seasons I am aware that 30C was commonplace. In fact, 30-35C was commonplace. It was just a remark how much our climate has changed since that time and how a lot of our infrastructure may be rather uncomfortable in the future. 

And summer 2023 did indeed show us that, whilst also providing the warmest June (UK wide) and September on record with the longest spell of 30C weather in September ever. Meanwhile the 40C we saw only came 2 years after nearly 38C (from a heat spike) then a multiple day long heatwave of 34-36C in 2020 and the year before that the then-record went in 2019.

While these past couple of years may turn out to be a fluke, I think the global situation and the past few years has shown that it could very well be becoming a norm. I hate to say it but I would be surprised if we don’t tackle the 40C again in the next ten years, maybe even five. I hope it is a fluke! I’m excited to see what summer 2024 has in store… and scared too!

Edited March 5 by LetItSnow!

[WYorksWeather]

 In Absence of True Seasons Unfortunately it's more complicated than that. I agree that the 40C-level heat is so far a one-off - we may not see that again for a few years.

To give just one example though, 35C heat is sufficient that current railway infrastructure requires speed restrictions, regardless of any mitigations.

According to Trevor Harley's site, there have been 17 days that have seen temperatures of 36C or higher in the period for which we have reliable records. There were only six in the entire 20th century (including some early 20th century readings that could be disputed). That was a low enough rate that it could effectively be written off, much as we do the risk of extreme cold / snow e.g. 2010 or 1962/63. You're talking about one day every ten years or less.

However, things are not staying the same. The other 11 days were this century, so now one day every two years, and signs are there that there may be a further acceleration in recent years.

We are getting to the point where significant disruption due to heat is now more likely than not on at least one day in a given year.

[kold weather]

The other thing that isn't really being talked about is the increase of 'tropical nights' which has a really detrimental impact on health if sustained. In a world with higher sea temperatures and an atmosphere with more moisture this maybe an underestimated problem as it does not stand out quite as much as 35-40c days.

[*Stormforce~beka*]

 kold weather This is a very fair point!

[Cheshire Freeze]

EC has lost its HP dominated signal for summer and suggests a mean Scandi trough

[In Absence of True Seasons]

 kold weather what's the definition of a tropical night? Just a night that is warm and humid? 

[Cheshire Freeze]

 In Absence of True Seasons overnight minima fall no lower than 20C

[Addicks Fan 1981]

I've just looked at world climate service on X/twitter and it seems like 1973 is the strongest analogue of the lot for summer of this year with the combination of el niño into la niña, the negative PDO and the west QBO that summer, march is going the same way of 1973 as well.   1998 was also mentioned but the signals for 1998 were weaker.    

 

https://twitter.com/WorldClimateSvc/status/1763329286755479897?t=n-OlL1cA4Sx4HZAXtBsAag&s=19

Edited March 8 by Addicks Fan 1981
To elaborate basically.

[Addicks Fan 1981]

Have been doing the maths on summer 1973 and it would imply that we would have the coolest summer this year since 2015.   

[B87]

1973 looks like a front loaded horrible summer, looking at the Heathrow stats.

June with near normal temps, sunny and wet (through thunderstorms).

June: 21.9c av max,  254 sun hours 68.8mm rainfall

July was a horror show, cold, dull and slightly wetter than average.

July: 21.4c av max, 174 sun hours, 49.1mm rainfall

August had average temps, slightly duller and drier than average.

August: 23.7c av max, 190 sun hours, 40.9mm rainfall

 

We have had enough dull summers in recent years.

Edited March 8 by B87

[reef]

 B87 That was not a terrible summer back then though. You cant compare 50 years ago to current averages. The same synoptics now would be much warmer and probably sunnier - along the lines of perhaps 1.5-2.0C warmer with perhaps 15-20 hours more sun per month. It would be a very warm and sunny June, average July and very warm August.