General summer chat

[CryoraptorA303]

14 hours ago, Metwatch said:

One of the reasons I am not seeing a classic warm dry summer that likely this year is the fact it's been too soon since summer 2022. Usually there is a return period of those classic warm dry summers in the UK to happen every couple of years.

1975 and 1976 happened back to back. Let's not forget that the July 2019 and August 2020 heatwaves were back to back and only 2-3 years before 2022 as well. 1989 and 1990 happened back to back as well.

A return period is just an average after all.

[MP-R]

Yes if anything I’d say it’s not unusual at all to have good/great summers back to back.

There’s always one less good one out of a pair. If May and June last year had been in June & July then we had August (& September although not summer), it could’ve been the ‘less good but still good’ one of a 2022/2023 pair.

[Addicks Fan 1981]

Forgot to add to my other post into this thread that last year's summer had some things in common with 1997 as well especially in July and to an extent September as well.   

[damianslaw]

 Addicks Fan 1981 Lets hope for no Summer 98 repeat then. May delivered a very good spell of warm dry sunny weather, but the summer was very wet, little warmth and often cloudy. Winter 23-24 has shown similiarity with winter 97-98 mind.

Edited February 26 by damianslaw

[Metwatch]

European summer weather linked to North Atlantic freshwater anomalies in preceding years

WCD.COPERNICUS.ORG

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Abstract. Amplified Arctic ice loss in recent decades has been linked to the increased occurrence of extreme mid-latitude weather. The underlying mechanisms remain elusive, however. One potential link occurs through...

Interesting article with a focus on north Atlantic fresh water anomalies and impact European summers.

A lot to unpack in that paper, but the general consensus if I understand it correctly is that enhanced freshwater anomalies in the far north of the Atlantic in winter can lead to hotter and drier European summers, promoting high pressure to be more dominant in central Europe. So a more anticyclonic in response to the increased north-south SST gradient. They used the preceding summer NAO to infer freshwater anomalies, but actual salinity data is inadequate, there isn't exactly data to check anomalies for that to the best of my knowledge.

Skip to the conclusion and from section 4.6, that explains the link fully I found.

Edited March 2 by Metwatch

[raz.org.rain]

 Metwatch it's informally known as the cold-ocean-warm-summer feedback. The atmospheric response to a more pronounced cooling of the North Atlantic results in a high pressure blocking regime over Western Europe, which leads to hotter and drier summers. It's generally assumed that this would be the outcome to a slower or collapsed AMOC.

[Earthshine]

 MP-R if we had June and September's anomaly (+2.9°C and +3.4°C respectively) in July and August it would have been an absolute classic.  An 18.8°C July and 19.2°C August, would have thought it would be the hottest July-August period on record.  

[WYorksWeather]

 Earthshine I've checked the July-August records and there's nothing that would exceed a 19C average for July and August.

The absolute maximum possible would be the two record holders - July 2006 and August 1995, which would have averaged 19.5C in the same year.

1995 does come fairly close, however, with an 18.5C July and a 19.1C August, for a combined average of 18.8C.

I think the chance to break this would probably be to have a record-breaking month that pushes the envelope on max CET - either the first 20C July, or an August in the high 19s, combined with a top-10 warm month for the other month.

 

[MP-R]

 Earthshine Yeah that would have been an absolute classic! I meant if we just erased last July lol, and May happened in June, June happened in July, then August and September were as they were. That would have removed the bogey month and perceptions of the summer overall would be much better. 

[Addicks Fan 1981]

 damianslaw I'd say it's had more in common with 2006-07 to be honest, the only difference though is we have a different QBO evolution.   

[WYorksWeather]

The long-range forecasts are still suggestive of a warm summer. However, not necessarily a dry one.

Precipitation from CFSv2:

Temperature:

All I can think to explain such a warm and dry pattern in combination (these temperatures are relative to 1991-2020, not 1961-1990) is that we have periods of heavy and/or thundery rain and cooler conditions, interspersed with very extreme heat spikes.

To give some examples, for the CET region, this would require a June between 15.6C and 16.6C, a July between 17.7C and 18.7C, and an August between 17.6C and 18.6C.

This would almost certainly mean a top 10 warmest summer for the CET, but without being particularly dry, and looking at those precipitation anomalies for central England on the charts above, possibly even slightly wetter than average. Has this ever happened before? If not, what would the closest analogue be (in other words a summer that was fairly warm but average to wet, or extremely warm but nearer average)?

[B87]

 WYorksWeather 2019 was warm and wet. 2014 was warm and wet while also being very consistent. 

[Addicks Fan 1981]

 WYorksWeather I'd say 1995, 2005 and 2016 are probably the nearest analogues to this summer at the moment in the sense of declining el niño and west QBO although 2005 actually was an East QBO summer.   However saying that you have to look at other variables as well.    

[MP-R]

 Addicks Fan 1981 well at least all those years had good Augusts, which has often been a bogey month in recent times. 

[In Absence of True Seasons]

 WYorksWeather 2020 summer was overall warm but also quite wet. 

Less wet in my area but on the whole, definitely warmer and wetter than average for many parts of the country.

[Summer8906]

 B87 2014 and 2019 summers were quite different though. 2014 had a fine, warm and sunny June and July followed by a cool and rather wet August.

2019 was more consistently unsettled though July was fairly dry, and IIRC was much cloudier than 2014 with no months being significantly above average for sunshine, versus both June and July for 2014.

Edited March 4 by Summer8906

[Summer8906]

14 hours ago, WYorksWeather said:

This would almost certainly mean a top 10 warmest summer for the CET, but without being particularly dry, and looking at those precipitation anomalies for central England on the charts above, possibly even slightly wetter than average. Has this ever happened before? If not, what would the closest analogue be (in other words a summer that was fairly warm but average to wet, or extremely warm but nearer average)?

I 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).

IIRC, 2015, 2017, 2019-21 and 2023 were all warm but dull and wet summers so any suggestion of a repeat would definitely not be welcome as I despise pretty much all those summers!

A rather warm and rather wet combination rings alarm bells for me personally more than a potential cool summer would do, in the sense that it would suggest dull and damp southwesterlies delivering warm nights and lots of rainfall, with brief hot spells when the wind occasionally backs southerly. Sadly it seems to be becoming our new normal.

Cool summer months by contrast at least might have some bright N-lies or NW-lies from time to time, as in August 2014.

Wouldn't it be great to have a warm-by-day, cool-by-night, very dry and very sunny summer for a change? Sadly such summers are probably in the same rarity category as snowy winters.

Edited March 4 by Summer8906

[Summer8906]

 MP-R Interesting that the shift you mention would have a profound effect on people's perception. From an appalling summer to something rather like 2006 or 2014 (two good months and one rather poor one).

On 26/02/2024 at 00:50, Addicks Fan 1981 said:

 I'd say 1994 was nearish too to last year as well.   

Perhaps if you shift it by a month. July 1994 and July 2023 could not be more different.

Edited March 4 by Summer8906

[MP-R]

 Summer8906 Probably better tbh as last August really wasn’t that bad, the weather just misbehaved at weekends. During the week it was sunny and warm.

[Rich_Clements]

4 minutes ago, MP-R said:

During the week it was sunny and warm.

I had forgotten about that, you are absolutely spot on.

[B87]

 Summer8906 Summer 2019 had almost exactly average sunshine here. Roughly 180 hrs in June, 220hrs in both July and August. 

2019 was a warmer summer than 2014.

Edited March 4 by B87

[East Lancs Rain]

An interesting summer update from Gavsweathervids looking at the top 10 wettest and mildest Februaries and the summers that followed (unsurprisingly, February 2024 was in the top 10 mildest and top 10 wettest on record).

 

 

All Junes combined following top 10 mildest Februaries:

 

All Julys combined following top 10 mildest Februaries:

 

All Augusts combined following top 10 mildest Februaries:

 

All Summers combined following top 10 mildest Februaries:

 

All Junes combined following top 10 wettest Februaries:

All Julys combined following top 10 wettest Februaries:

 

All Augusts combined following top 10 wettest Februaries:

 

All Summers combined following top 10 wettest Februaries:

 

Overall, quite a good signal looking at the summers following the top 10 mildest Februaries. The summers following the top 10 wettest? Not so much…

[MP-R]

 East Lancs Rain So to conclude… we ain’t got a clue

[Summer8906]

 MP-R

3 hours ago, MP-R said:

During the week it was sunny and warm.

Does look like it was regionally dependent though. The South Hampshire area seemed to come out cooler, duller and wetter than normal: https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/summaries/mwr_2023_08_for_print_v1.pdf

The 1st-8th, 12th-14th, 19th and 25th-31st all looked cool in this area according to the same document.

Edited March 4 by Summer8906

[raz.org.rain]

 East Lancs Rain so far the most plausible analogue still seems to be 1995. Gav's summary seems to suggest the following combo; Mixed June, some warm to hot spells but also a lot of rain and largely unsettled. Southerly flow, low pressure to the west, high to the east. A settled July but no strong signal to suggest what temperatures to expect. A settled and potentially very hot and dry August.

 

@CryoraptorA303 is still tracking the analogues I think. I would assume there's still strong analogues to suggest a warm and dry summer with potential for notable heat.

Edited March 4 by raz.org.rain