LetItSnow!

Summer8906 July 2010 was an odd one. At the time there was extreme heat to our east (Russia had an exceptionally hot summer IIRC) and we were on the periphery of it in July. Looking at the temperature, sunshie and rainfall maps, it was actually an exceptinally hot month in the extreme east. In Scotland the maxima were below the 1961-1990 average so it truly was a grim summer month up there. Ironically, the reverse pattern occured in August 2010 where, though not warm, the north-west was slightly sunnier and drier than average but C England/East was cool (by day) and very wet. Might as well give the anomalies for each month like I did for 2009. June 2010 July 2010 August 2010 Summer 2010 Truly a very mixed bag.

Summer8906 The maxima for large swathes of the south-west in July 2009 were below average even by 1961-1990 averages though interestingly the far north was very warm. Indeed, for the northern Scotland overall it appears July 2009 was very warm.

WYorksWeather I respect that, but in a warming world and with a somewhat plausible chart, I do actually think it is indeed possible and I'd be surprised to not see an attempt at it in the next 5-15 years. All it takes is the right set up. Think back to pre-December 2015 times and pre-February 2019 times when those records seemed unlikely. I do think we're playing with variables we've not encountered in the technological forecasting world. Anyway, back to the forecast and ironically it seems the 6z is less feverish about the scale of the warmth though still manages to get the 10C over the extreme south-east but during the nighttime hours. Despite the southerly influence, it's possible that due to all the cloud and rain associated with these moisture laden southerlies we may not see overly high temperatures. I know you can usually add on a couple degrees but unless there's any sunny spells, probably temperatures pegged into the mid-teens. The C.E.T. will be bolstered by mild, cloudy nights. Further down the line (the 9th) it shows that some really wet weather (and perhaps stormy too) could come from low pressures grinding to a halt due to high pressure to our east. Ironically though on this chart any early spring warmth gets shunted west. I wonder if this will be one of those "C.E.T. disguises the fact it felt poor" kind of months. Wouldn't rule out later cold spells though. Despite the exceptional surge of warmth I'm not sold 100% it's a nailed on super warm April yet. damianslaw @WYorksWeatherJust to add, my thoughts on 30C in April are NOT about the coming April, I meant Aprils in the next 10-20 years or so. No further addition to this in this thread though, just clarifying.

raz.org.rain Considering it was virtually unseen in the UK except on extremely rare events until 2015, absolutely! Sadly, it's become less exceptional since, but for April I dare say it's not been seen in the reliable records. I'm sure someone will post a random chart from like 1982 proving me wrong, but basically yes, the 20C being in our vicinity in April is absolutely unthinkable, remarkable and extreme. Dare I say the equivalent would be the 27-28C line wafting to our south-east in mid-summer?

WYorksWeather October 2001 was wet though, not dry. It didn't have the novelty of October 1969 or October 1995 which, IIRC, were mostly fine and dry.

This 20C line keeps popping up earlier and earlier! Fascinating from a meteorological perspective but also very concerning that it's feasible for the 20C line to be able to reach us so early in the season. Makes me think that 30C in April is achievable some year soon.

To add to that, with some (hopefully) logical and creative liberties, here is what such a month may look like at Heathrow; 1st: 34C 2nd: 36C 3rd: 37C 4th: 36C 5th: 36C 6th: 36C 7th: 35C 8th: 34C 9th: 28C 10th: 28C 11th: 31C 12th: 34C 13th: 27C 14th: 27C 15th: 27C 16th: 30C 17th: 33C 18th: 38C 19th: 41C 20th: 39C 21st: 39C 22nd: 35C 23rd: 32C 24th: 34C 25th: 37C 26th: 36C 27th: 34C 28th: 33C 29th: 30C 30th: 29C 31st: 26C Average max: 33.2C I wonder if this will actually be within the realm of possibility in my lifetime...

I actually tried to answer my own question. I stitched together different daily C.E.T. means from Julys of 1976, 2006 and 2022. I took the C.E.T from the 1st to the 14th of July, 1976 and added a degree to account for global warming. I then took the C.E.T. for the 15th to the 19th of July, 2022 and adjusted a couple of the cooler means to fit in the weather pattern. I then used the daily means from the C.E.T. from the 20th to the 31st of July, 2006 and adjusted them upwards to account for the hypothetical pre-existing weather pattern. With this it suggests a July C.E.T. of 22.4! What would @B87and @SunSeanmake of that? I'd also imagine in this hypothetical month that the maximum of 40.3C would be higher and probably as high as 41 or 42C and that perhaps this heat would stretch for several days. Perhaps from the 18th to around the 26th being constant highs between 35-40C. Absolute hell. Sounds like a @CryoraptorA303theory gone mental.

Methuselah A July 2022 style heat spike could occur within a hotter overall month though. Using Heathrow as an example, if you take out the 18th and 19th then only two other days exceeded 30C and most days were between 22C and 29C. July 2006 for example had more days over 30C and was hotter, so if you had that sustained level of heat and then the same synoptic pattern, then you could easily get a C.E.T. of 20C for July. We've already seed 20+C C.E.T. inter-monthly periods in 1976 and 1995. As for January 1963, it's a beast of a month but there have been about five colder Januaries. Again, if you had the persistent cold synoptics of January 1963 but containing a brutal spell like January 1881 you could probably get into the -3s and maybe even break the record of -3.1C set in January 1795. Good luck at that happening in our lifetimes, childrens lifetimes, grandchildrens etc not accounting for an unforseen event.

Earthshine You were really on the ball with this one! Both of them occurring the following year. Interesting topic to revive. And to add to it, we beat this one in January 2024!

Not too dissimilar to what would happen 100 years later, a cold winter over Scandinavia but we never quite bit the cherry. Interestingly, 1923 had a near miss for both extreme heat and extreme cold for the UK as the summer of 1923 had blistering heat at times across the continent and as the chart shows, some brutal cold later too. Only in November did we tap into it.

Metwatch Enraging article, for two reasons; One is that it is ridiculous to suggest such measures would need to take place but also two, the state of water infrastructure is indeed a shambles… but that is just ridiculous. I know things are probably different but the country managed fine in 1995 and 2003, two dry and hot summers that came off the back of notably wet periods. It’s just infuriating to me to suggest such measures would be necessary because I don’t think they would be, but even more infuriating if they actually would be.

Peep a pocket of 20C air not that far away from us on the 6z by the 6th. It does actually bring the 15C line flirting with the south-east coastal regions in the early hours. However it moves through extremely quickly on this run so by daylight hours the air becomes cooler.

I do remember the month was running pretty exceptionally cold in the first half. Loved it from a meteorological perspective. There was one day pretty late in the month that was very wet and very windy and it felt pike November. Shame that it was scuppered from from a sub 10 finish. That spring is why I don’t listen to anyone who says that below normal months can’t happen anymore. Sure does feel a lifetime ago now though.

The stats June 2009 July 2009 August 2009 Trevor Harley writes about August 2009's unusual contrast in rainfall between the south-east and the north-west; "Parts of Norfolk saw only 5 mm of rain, the lowest since 1947, while several spots in the NW had record amounts of rainfall for August: Eskdalemuir had 394 mm (over 15 inches!) of rain, four times the average amount. The England and Wales rainfall total was 65 mm (90% of average), while Scotland saw 193% and Northern Ireland 205%.". It appears for the extreme east such as Norfolk and Suffolk August 2009 was quite a good one with temperatures over 1C above average, very dry and sunny too. My own personal memories are very limited being that I was only 8 years old. I remember early July having thunderstorms. I remember the 7th being a convective day of sunshine and heavy showers but that is the only memory I can for sure date to summer 2009.

WYorksWeather And those warm anomalies may fuel further lows if the pattern persists as the natural temperature contrast remains large from the north and the south at this time of year. I feel instability in this region could persist though whether the zonal south-westerlies last all month or whether it may promote a more blocked UK high/Azores low set up later down the line is another question. Perhaps a possibility though.

B87 If I had a couple wishes I would definitely erase the global warming and bring back the snowy winters and mild summers I never knew. Maybe I'll take up the dark arts to restore balance! It's important to use old averages though to make sure as to not forget or undermime how much things have changed. And also, the 1980s was just as icy as the 1960s at times.

WYorksWeather Well, I don't really think the weather (or indeed the universe) really has a balance that could make sense to (relatively) pea-brained humans. The Earth's time-scale is incredibly large, way larger than our existence let alone our records. What we percieve as an unusual frequency may not be unusual if we had a larger scale of monthly records we could analyse over tens of thousands, even hundreds of thousands of years. Then there's the fact that we tend to search for patterns to make sense and of course the planet doesn't have a brain like we do. What we think is random tends to probably be far more organised than we realise. There are only global drivers and I suppose chance that steer the weather. Perhaps their was a particular thing going on that promoted excessive wet weather between 1875 and 1883 despite lower global temperatures. Likewise, there may come a time when there may be something that promotes persistent high pressure over a similar time frame may promote high pressure over and around our shores despite warmer global temperatures and a predisposition for wetter weather.

B87 -1.9C below the 1991-2020 average, but completely equal to the 1961-1990 average, as stated. Heathrow (Greater London) UK climate averages WWW.METOFFICE.GOV.UK Heathrow UK climate averages Fascinating to see the changes over time, isn't it?

Something interesting on the latest run of the GFS is how close the 15C line is from us. A slight adjustment could see the UK under some truly very warm air. Interesting that the 15C line is usually associated with the hot spells in the iconic summers of the 20th century so to see that it's flirting with us in early April is a little concerning! Times truly are changing... No doubt this very warm air is fuelling the low pressure due to the temperature differences. April power showers...

WYorksWeather I mean, yeah. I was only looking at the raw figures though, not talking about my perceptions. I didn't categorise summer 2023 as poor as I don't like humid, oppresive heat so it never bothered me. I'm happier when it rains than when it doesn't.

B87 Funnily enough the Heathrow average maxima for April 2021 is only exactly average to the 1961-1990 average but -1.8C below by night.

To be fair, the extreme SST anomalies even for the current climate meant that the month was far warmer than the same synoptics would have been even a year or two earlier. This point is also made a little void by the fact most of July 2020 was cool with the C.E.T. hovering in the 14s/low 15s for most of the month. It's just that expanding heat/heights to our south make those southerlies pack so much more of a punch that it's hard to escape their influence as the mean westerly flow in summer is now probably becoming more south--westerly as the Hadley Cell expands. But if we saw the same Atlantic dominated synoptics of July 2023 repeat in the 2025-2030 timeframe with more normal SSTs then I think it would be cooler than 16.1C. But as stated, pressure from the south is making it more and more difficult to avoid southerlies in the summer.

Summer8906 I haven't finished scrolling through the data but for the overall UKP series, there was a 13-month period from January 1872 to January 1873 where every month was above average, most notably so, though different decadal average may mean some teeter around average. January 1872 140.2 February 1872 88.2 March 1872 84.9 April 1872 69.1 May 1872 66.2 June 1872 100.0 July 1872 122.9 August 1872 80.8 September 1872 104.1 October 1872 149.5 November 1872 140.7 December 1872 138.3 January 1873 109.1 1873 and 1874 proved to be dry years meaning that the rest of 2024 or at least 2025 and 2026 are likely to be less wet, though in the warmer, wetter era perhaps less likely to swing to notably dry, but it is possible. Also for extra information, that was just before the extremely wet period I spoke about before that lasted from 1875 to 1883 which actually averaged a little wetter than the past ten years which have been unusually wet. It shows that just because you have one period of extreme rainfall it doesn't mean it won't keep swinging that way. You could argue that the atmosphere swinging to an unusual extreme for the time shows than swinging to an unusual extreme of the other type, aka for us, dry, could happen - or it could compoud the likelihood for a similar spell to persist into the rest of the 2020s and early 2030s but even more excessively wet due to extra moisture. The ultimate answer is that no one knows. We know the forces at play but we don't know how they'll play. It's sort of like sports really; you might know who's playing but you don't neccesarily know who's going to win. Coming from someone aversed to sport that is.

raz.org.rain Scary that +2.5C above normal feels average nowadays! I don't have sunshine statistics at hand but March 2024 feels grimmer than March 2023. I'm also unsure of rainfall anomaly distribution so far but is it one of those times where even though last year was wetter for the UK overall that this March is wetter down south? Apparently Heathrow is about 5mm away from beating the March rainfall record set in 2001.