John S2

In answer to the question about comparing July 2020 & July 2023, here in NW England there was a considerable difference between the two. July 2023 is one of the most vile summer months I have experienced. It is the wettest July in the NW England precipitation series [POR=151 years] with 174mm. July 2020 was nowhere near as bad with 110mm which comes in as 36th wettest.

I live in NW England. A good year is a dry one, and it is particularly important to me that March & September are good. So: best year of my lifetime - 1973. honourable mentions - 1997 & 2003, also liked 1969

CryoraptorA303 Regarding your reference to the 'cooling mechanism' of La Nina, my understanding is that it is El Nino that is the cooling mechanism in the sense that some of the excess heat brought to the surface during El Nino episodes is lost to space. The oceans absorb more heat during La Nina episodes. Interestingly the Medieval Warm Period is believed to have been dominated by La Nina episodes, although the MWP was a regional rather than global anomaly.

There appear to be regional differences in summer trends. In the NW England rainfall series [POR=151 years] 9 of the 24 summers this century feature amongst the top 25 wettest, but this trend is not present in the SE England series.

Hadley cell expansion, in isolation, would lead to drier summers particularly in the South - but there is more going on. There is a theory that Arctic Amplification - the fact that the Arctic is warming at a faster rate than the rest of the world - acts to send the jet stream further South. This is a battle between two conflicting influences. Since 2007 there has been an increased frequency in summers with negative NAO, indeed all 18 months in the awful cluster of summers 2007-2012 had negative NAO. It should be mentioned, however, that there are some good summer months with negative NAO so it is only part of the picture.

Could you enlighten us why 1973 is considered an anologue? It had a lovely dry and anticyclonic start to the year. E&W rainfall for 1973: Jan - 46mm, Feb - 45mm, Mar - 23mm

Both 1986 & 1988 had a good June, but as someone who likes my summers dry, there is no contest here for summer as a whole. 1986 is easily the best because it was the driest of the four by a big margin in my region [NW England]. Rainfall figures for NW England for the summers are 1986 - 214mm, 85/87/88 - 324/336/330 1985 was vile and was even worse in Southern Scotland where 1985 had the 2nd wettest July & 2nd wettest August on record contributing to a massive 513mm for wettest summer on record [even worse than 2012]

Rating of summers is controversial because the synoptics leading to a good summer month in areas such as North Lancashire, Cumbria and SW Scotland including Glasgow can be quite opposite to patterns more favourable to SE England & East Anglia. Also opinions vary about what makes a good summer. Personally I want dry weather and a sky that is a proper blue, not the depressing haze that comes with plumes from the South. So, with my bias declared, I nominate the following summers [from my lifetime] as underrated and give their rank in the NW England summer rainfall series [POR=150 years] as evidence. 1984 [7th driest], 2021 [15th driest]. 1996[20], 1969[21]

In answer to the question about causes of sea level rise, the main contributors appear to be: 1) Melting of land based ice 2) Thermal expansion of the oceans 3) Reduction in water held on land - eg reduction in size of lakes and soil moisture I have not been able to find a definitive answer on the percentages due to each of the above. Melting of arctic sea ice should have no immediate effect on sea level, but presumably if the summer trend is downwards then increased heat absorption will be a positive warming feedback.

Addicks Fan 1981 I am puzzled how some of these years are considered to be matches. 1964 is the driest winter in the Central England precipitation series [POR=150 years]. Winter 1973 was also very dry [26th driest]

Deniers have changed their tactics, and unfortunately they are winning in the sense that national politicians continue to make very bad policy decisions. Deniers haven't gone away, but rarely criticize the science these days. They focus instead on short term arguments about costs and jobs. 15 years ago I regularly posted counter arguments with evidence in response to deniers when they were criticizing the science in a Climate section that existed at the 'other place'. My own belief about deniers is that their main issue wasn't with the science even back then, but an irrational hatred of the type of collective action necessary to combat it.

I am not convinced that a significantly cold winter month is now 'long odds', even though the odds will have changed. There is a counter argument that we may see a colder winter at a similar point of the double sunspot cycle that 08/09, 09/10, and the famous Dec 2010 occurred. This would presumably be around 2030 ? Also it doesn't matter how warm the Atlantic is if the wind is blowing from the NE. Nevertheless, a warmer Atlantic and northward displacement of Azores high may help reduce the frequency of winter blocking in locations which bring cold conditions to the UK so it will be interesting to see if solar factors can outweigh this. I would remind members that there was a school of thought about 'modern winters' back around 2005, but only a few years later we had the above mentioned trio.

Agree. A good year countrywide - almost everywhere had above average sunshine, exceptionally so in many areas. Our best chance of something similar to 2003 would be if ENSO simply returned to neutral from the current Nino, but unfortunately a flip to La Nina appears to be statistically more likely. Given the unpredictability of ENSO states, however, it is possible.

For brevity I didn't make it clear what I meant by a 'bad' month. I live in NW England, where July 2023 was the wettest July on record and Sept 2023 had double the average rainfall in some places. Excluding periods of extreme cold, [lack of] rainfall is far more important than temperature in how usable a month is for outdoor activity. In my area [NW England] 2022 & 2023 have been generally poor, contrasting with several months during 2021 [including a controversial summer weatherwise] which were more usable. I trust this paragraph provides sufficient statistical support.

The main concern I have about 2024 is a likely flip from El Nino to La Nina. If a strong transition between these states coincides with summer then this could be bad news. The following is a guess based on the above, possible SSW early January, plus other factors: Significant cold mid-Jan to mid-Feb. Notable heatwaves second half of March plus mid-May. Pressure falls last week of May heralding an unsettled June. July & August nothing special but nowhere near as bad as July 2023, possible brief July 2022 type plume but less exceptional. Decent September - much more anticyclonic than the disappointing Septembers of 2022 & 2023.