WYorksWeather

CryoraptorA303 I think very low chance of true heatwave territory. A very tall order so early in the year. As your heatwave thread shows though - not completely unprecedented. The thing I've actually noted more so than any intense heat is that most of the ensembles just show temperatures to just be persistently warm on average. Not necessarily even all that warm by day, but if we get e.g. maxima near 18C or so and minima near 10C that's all you need for a very warm start to the month. I do think we may see an intense heat spike (in my prediction for May I pencilled that in for the last third of the month), but I think persistently moderately warm and humid with a fair bit of showery rain is probably the likely option for the next 10 days or so. I do think there will be drier interludes though especially next week.

Summer8906 Sun strength making a big difference. Now equal to mid-August. Of course nowhere near as warm temperature wise so doesn't really feel like it.

Similarly not a horrendous day here. After an absolutely shocking late morning and early afternoon with heavy rain and a strong breeze, increasingly bright with much lighter cloud later on. It has shown up in the temperatures as well, even UKV's 15z model tonight ended up being significantly wrong for the late afternoon temperatures. Temperatures supposed to be limited to perhaps 13C at most and many areas 10-12C, but in fact a number of stations crawling their way up, with an absolute max around 15C in the late afternoon. Closer to home not so much - temperatures around 10-11C only but still felt better as the afternoon wore on with more in the way of sunshine. Overall still has to go down as a poor day for late April. Felt better because I had zero expectations, but in truth still only about a 3/10 kind of day weather-wise.

GFS 12z was on the cooler end of its ensemble from about day 5 to day 12. General consensus around the idea that despite potential for wind and rain at times it will turn much warmer than it has been of late. Contrary to what some say about warm rain I do find at this year changeable weather feels much better than it does earlier in the spring, and though there is rain about at times it's unlikely to be of the heavy frontal variety very often. Temperatures generally above average for the first half of May by the looks of things, albeit with huge uncertainty beyond next weekend. As I mentioned yesterday a few cooler runs but now quite a number of very warm runs appearing. In terms of the daytime temperatures there's nothing absolutely astounding appearing but the consistent warmth with double-digit lows is quite impressive. This should at least put an end to the need to use heating! For the shorter term, here are UKV afternoon temperatures for the next 5 days (Mon-Fri): I couldn't blame those of you in Wales or SW England for feeling a bit disgruntled with this forecast, but for most other areas it looks like a very big improvement on this week. Helpfully as well the warmth isn't focused in the same place every day so those who miss out on a certain day will have other chances. Something for everyone really away from the aforementioned areas. Big questions still around exactly how warm - absolute max is forecast to be around 22-23C but if we did get some clearer skies I wouldn't be massively surprised if we got a random 24-25C somewhere. Beyond May Day the trend is still as the above charts show for something on the warmer side of average, but exactly how warm is the key question, and that won't be answerable for some time yet.

Based on the temperature ensembles it looks like we are getting a more notable warmup into the middle part of next week. Beyond the bank holiday weekend a bit of a cooldown is forecast but a lot of uncertainty around that. UKV 03z somewhat higher with the temperatures than the means shown above though - a spot 20C on Tuesday, and after a cooler day on Wednesday a spot 23C on Thursday. Usually worth adding a degree or so to these for the absolute maximum.

B87 What if we're a bit more optimistic and assume say a moderately sunny May (120% of average or thereabouts)? Summer contributes disproportionately, so where would we be if we averaged 120% for May to September? I'm assuming that would put us back to average at least?

Final post for tonight, but worth posting yet another anomalous warm run - this one a near record-breaker from the 12z ECM, P33. Just a mere 28C. First 30C of the year anyone (in practice, with usual under-reading)? Again, not to be taken too seriously! But you never know...

Both GFS and ECM 12z continuing to prolong the warm spell.

B87 There might be, but not coming from me! I suppose the point I'm making is that though this late April spell has been poor, it's not been to such an extent that the opposite would be any sort of record breaking or worrying. Shunter That's the mean temperature, and compared to 1961-1990. Compared to 1991-2020 and only considering daytime max temperatures it's near average, and may even finish below average.

B87 Heathrow ticked up to 11C recently as did Kew. Still looks like it won't get much higher I'd imagine so probably 5C or so below average. Still a pretty chilly day, though in that sense not particularly remarkable, because the equivalent the other way would be about 22-23C. In Absence of True Seasons It's about 5C below average now, not 8C, and actually I've seen multiple posts by the Met Office talking about frost risk / how cold it has been for late April. And the corresponding equivalent on the warm side would be 22-23C, which again wouldn't be particularly remarkable either.

The GFS 00z ensemble has now fully eliminated the cooldown in the mean - temperatures now looking consistently near or above average. Looking at precipitation it seems like we'll struggle to keep things entirely dry though - a fair few precipitation spikes. But certainly nothing there screaming extremely wet pattern - the mean rainfall is pretty low which suggests it'll be dominated by infrequent showers rather than heavy frontal rainfall. Sea level pressure tells the same story as well - mostly on the rise after this weekend's dip. All in all - not too bad. It's also interesting how the number of warm outlier runs is beginning to increase again - an odd run taking the temperatures above 25C, like P20 of the GFS, with a broad area of high pressure over the UK and centred to our south east. Also looking at the dam lines a very strong high for the time of year - the 584 line into the SE of the UK. By the end of the run some very hot air just to our south as well, so the pattern may have continued beyond the end of the run. The first heatwave run of the year - taking into account a usual under-read of 1C or so many areas would surpass the Met Office heatwave thresholds with this. Again, only one option and a very long way away, highly unlikely to verify. But as many of us have been saying we need to be on the lookout for these very warm outliers and see whether they gather any further ensemble support. Most of the time they do fall away again but sometimes they keep gathering momentum... Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5061824

Bit of a late night update - did the ECM 12z follow the GFS 12z with a warmer spell in FI? The control (OP doesn't run far enough) says no - the whole pattern is a few hundred miles to the west, and we're actually stuck under cool and cyclonic northerlies. To be fair, the control was amongst the coldest runs. One pattern that we do notice though is that the downward trend in temperatures after the warmup early next week has been downgraded to more of a return to average, similar to the GFS 12z ensemble. Still no sign of anything particularly warm though on the mean, but still looks a fair bit warmer than of late overall. Next is the GFS 18z. Ensemble isn't out and I'm not waiting up for it, but does it follow the 12z? The answer, much as with the ECM, is no. The pattern is not as far west as the ECM, but the high is over and to the south of the UK, which is badly positioned for any real warmth. Nothing overly cold, and should be largely dry, but I'd hesitate to call it warm. All in all, not the most inspiring late night update after the earlier optimism. I imagine the models will still go back and forth a bit around May Day and beyond as we still have a fair way to go. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5061787

Scorcher This morning's UKV has come even more out of nowhere - a sudden heat spike to 25C as early as next Wednesday!

The GFS 00z ensemble has now fully eliminated the cooldown in the mean - temperatures now looking consistently near or above average. Looking at precipitation it seems like we'll struggle to keep things entirely dry though - a fair few precipitation spikes. But certainly nothing there screaming extremely wet pattern - the mean rainfall is pretty low which suggests it'll be dominated by infrequent showers rather than heavy frontal rainfall. Sea level pressure tells the same story as well - mostly on the rise after this weekend's dip. All in all - not too bad. It's also interesting how the number of warm outlier runs is beginning to increase again - an odd run taking the temperatures above 25C, like P20 of the GFS, with a broad area of high pressure over the UK and centred to our south east. Also looking at the dam lines a very strong high for the time of year - the 584 line into the SE of the UK. By the end of the run some very hot air just to our south as well, so the pattern may have continued beyond the end of the run. The first heatwave run of the year - taking into account a usual under-read of 1C or so many areas would surpass the Met Office heatwave thresholds with this. Again, only one option and a very long way away, highly unlikely to verify. But as many of us have been saying we need to be on the lookout for these very warm outliers and see whether they gather any further ensemble support. Most of the time they do fall away again but sometimes they keep gathering momentum...

Bit of a late night update - did the ECM 12z follow the GFS 12z with a warmer spell in FI? The control (OP doesn't run far enough) says no - the whole pattern is a few hundred miles to the west, and we're actually stuck under cool and cyclonic northerlies. To be fair, the control was amongst the coldest runs. One pattern that we do notice though is that the downward trend in temperatures after the warmup early next week has been downgraded to more of a return to average, similar to the GFS 12z ensemble. Still no sign of anything particularly warm though on the mean, but still looks a fair bit warmer than of late overall. Next is the GFS 18z. Ensemble isn't out and I'm not waiting up for it, but does it follow the 12z? The answer, much as with the ECM, is no. The pattern is not as far west as the ECM, but the high is over and to the south of the UK, which is badly positioned for any real warmth. Nothing overly cold, and should be largely dry, but I'd hesitate to call it warm. All in all, not the most inspiring late night update after the earlier optimism. I imagine the models will still go back and forth a bit around May Day and beyond as we still have a fair way to go.

damianslaw Which is of course why some of the late season warm spells feel so odd. September 2023 being perhaps the weirdest major heatwave I've ever experienced. Such an incredibly warm week, one day after another, and yet simultaneously incredibly weird with sunset before 8pm, and the sun at the 'wrong' angle for that sort of heat, and yet it happened anyway. The few times we get notable warmth in October are even weirder, of course. Anyway, back to daylight hours so as not to derail things - at my location today (Saturday now) will be the first day with sunset at 8.30pm or later. Other milestones coming up soon include the first 15 hour day (Monday).

jonboy Read the post again. I didn't say if your opinion differs to mine you're a denier. But if you're off the opinion that either a. the Earth isn't warming, or b. it is but not mainly due to human activity, then I would call that denialist. The reason being that the evidence for it is about as solid as the fact that if I were to throw a rock off a building, it would hit the ground rather than levitating up into the sky. The reason I have very little time for 'it's natural' or 'the Earth isn't warming' as an argument is because it's frankly boring. I mean you can hit me with an argument for either of those positions if you like - if it's a new one I've not heard before I'll take an interest. But the issue has been absolutely done to death - the scientific debate on whether the Earth is warming and on the cause ended decades ago for a reason. Here is just a brief, non-exhaustive list of factors that have been considered as alternative explanations for the main part of the warming, all of which have been examined and rejected: Solar activity Internal variability Milankovich cycles Ocean currents ENSO Volcanoes Urban heat islands Those issues make up easily 90% or more of the talking points I read online, probably more than that. And every one of them takes about five minutes to debunk. That's the reason there's no point debating it any more. I mean, if you have a brand new contribution on the issue I've not heard before, I'm happy to reopen the discussion. In terms of the use of the term denier, the reason it is used is in contrast to the term sceptic - you could perhaps more neutrally call them those with a non-mainstream view on climate change, but of course that doesn't roll off the tongue. The reason to use the term denier is that sceptic implies scepticism in the scientific sense - which is perfectly natural and healthy. But if scepticism goes beyond demanding evidence, double checking data, and interrogating sources and so on (all perfectly normal in science), and instead proceeds to casting aside all the data, alleging grand conspiracies without evidence, or even in the most egregious cases just making stuff up or misrepresenting the mainstream science, then it is often referred to as denial. I'm afraid that I don't think that's particularly unfair.

sunny_vale Yeah I suppose it depends on whether we talk about warmth or heat. Consistent warmth has happened as you say in 2018, but I don't think we've yet had consistently hot weather dominating from May to September.

raz.org.rain I think four months of summer is theoretically possible - if we assume the envelope at which 30C is reasonably plausible (barring freak heat spikes) runs from mid-May to mid-September. In the future, this will probably extend to the first half of May and second half of September as well. EDIT: meant to add - not likely though!

Some work days I'm up around 6am so it's been great the past couple of weeks to be waking up in daylight. Lighter evenings are brilliant as well. Unfortunately not been able to make as much use of them as I'd like as they've been very cold! For me, the arrival of summer is the first evening I can go somewhere after work and it's still warm enough to sit out in shorts and a T shirt. Rarely happens before mid to late May here.

B87 Yep definitely shows how much difference a relatively short distance between us makes. Can't go back as far as you without finding a different source but using Ryhill for the last three years, I get: 2023: 17.4C 2022: 17.1C 2021: 14.3C Minimum of around 1C cooler than yours and more typically 2-3C lower. I would say that Ryhill tends to be about 1C lower than my experienced temperatures though as I live in a more built up area, so it probably exaggerates things somewhat. Ryhill is in a really rural spot.

B87 I meant more universally in terms of how it feels to me, which doesn't really depend on time of year between about the start of May and mid-August as the strength of the sun is relatively similar. In terms of how unusual it is, you're right that 20C days are pretty common at your location. I'm guessing in May 2020 when the average was near 19C for the CET region you were possibly even averaging 20C or higher? Of course up here it's quite different - we generally learn a slightly higher tolerance to cold. Anything about 18C and up if it's not either windy or raining, you'll see plenty of people out and about in shorts and t-shirt walking, sitting out at cafes, etc. I guess we have to make the most of it a bit more! If summer-type activities up here were limited to properly warm days of say 22C or higher, it'd be pretty grim.

B87 I suppose it depends on conditions. 20C in May with sun is properly warm in my book. Cloudy and with a strong breeze, then no. I think 20C is right around the cusp where it does very much depend on the surface conditions as to whether I'd consider it warm or not. Personally, assuming relatively typical surface conditions (let's say for argument's sake, a light breeze, sunny intervals, and moderate humidity), my personal warmth scale would be something like this: 20C - neutral 22C - warm 25C - very warm 28C - hot 32C - very hot 35C - extremely hot Obviously, it's very person-dependent, and conditions could vary this massively. A stiff breeze could make a 20C day feel quite cold for shorts and T shirt - there were quite a few days like that last May here. Equally I remember a 27C late afternoon last June when I was leaving work which actually felt very hot with the humidity. As it turned out, weather apps were showing feels like 32C, so it wasn't just me.

Tonight we seem to not have a great outlook in the short to medium term. After we get the current cool cyclonic period out of the way over the weekend (unfortunately a pretty dreadful one for most), into early next week we have a warmer pattern developing for Tuesday and Wednesday, but nothing particularly impressive. Raw maxes of 17C on Tuesday and 20C on Wednesday, perhaps in practice 18-19C and 21-22C. Exact figures probably dependent on timing of cloud and rain. Wednesday possibly a new warmest day of the year, but nothing out of the ordinary for the start of May. However, further into May we have a significant pattern change on the GFS tonight. In the extended range, the 12z at around day 12-14 sets up a high over and to the east of the UK. It's not the strongest, but especially eastern areas you would think stay mostly dry under that. The temperatures are nothing spectacular to be fair as the core of the resulting heat plume is away to our south, but a number of days with very pleasant afternoon temperatures in a row. Of course, this is a long way off. In terms of the ensembles, the GFS still isn't that interested, but it has mostly erased the cooldown after the initial warmup around the middle of next week, and a bit of a signal to follow the GFS OP later on to a lesser extent, so I guess already an improvement on what was showing 2-3 days ago. Summary Still a long way from any sort of heatwave or anything particularly notable, but the pattern on the GFS 12z OP would be pleasant enough. Certainly a welcome improvement. From a personal perspective, I'll be paying close attention to forecasts for May Day and the following week (commencing 6th) as I've booked it off work. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5061632

sundog What's always interesting about these people is how little they actually know about the scientific theories they challenge. I've genuinely never encountered a single denialist argument that can't be debunked with a few minutes of basic fact-checking. To be clear here, by denial, I mean here anyone who would disagree with the following statement: the Earth is presently warming, primarily due to human emissions of CO2 and other greenhouse gases from the burning of fossil fuels. There are plenty of arguments to be had about the political side on what we do about it, and also the speed of warming, exact severity of consequences and effects, etc, and I don't mean to call anyone who disagrees with me on any of those a denier.