WYorksWeather

Right, latest UKV update. I'm back at work tomorrow (I picked a good week to be off!) so won't be around for too many of the evening model runs, but have time to do tonight's UKV. Starting with tomorrow, we have a warm day to come for eastern areas but much cooler further west due to a band of rain. Much cooler on Tuesday overall, though some western and south-western areas will have a warmer day than Monday. Absolute maximum is 21C in northern Scotland but very localised. Most places will see mid-teens. Wednesday looks better away from central and eastern areas, with temperatures quite widely into the high teens or low 20s. Again Scotland the warmest spot with a localised 24C. Thursday is showing widespread high teens or low 20s, with an absolute max of 22C. Friday is similar with fairly widespread high teens and low 20s, and an absolute max of 23C. Summary Overall, tomorrow looks like the worst day for southern and western areas. Tuesday the worst overall day for most areas. Tuesday and Wednesday worst for many central, eastern and northern areas (away from Scotland). Overall though - it's not looking like a horrendous working week, more of a mixed one. A fair bit of rain around, but it doesn't look anywhere near as bad as it looked a few days ago.

Roger J Smith Likely 14.1C or 14.2C after tomorrow I think. Key will be the next few days whether the surface conditions and timing of any rain/cloud are conducive to rises or falls. If we get cloudy days and clear nights CET will head down, vice versa it will head up. In order for a record-challenging month to happen we probably need CET to be at minimum mid-14s by this time next week, and then we would need a very warm or hot final ten days to seal it. More likely though I think is a finish in the 14s which would be of course the second warmest May ever recorded.

Mark Walker Yeah you're right from the looks of the radar, maybe more straight N which would put it more Tadcaster / Wetherby area.

Mark Walker If that one heads N or NNE and keeps going you'd think maybe York in its sights perhaps?

summer blizzard Yep, bit of a waiting game I think. Lots of storms around just whether any make it over this way.

In any case it is irrelevant - Iver has topped that with 27.0C (rounded to 1dp, actually 26.98C technically!). Not sure if anywhere else has topped that - am sure that Met Office will report later on with the highest. markyo Yeah it will still be cooler next week - but not as cool as had been forecasted. Previously it was thought the wind direction might be more westerly but it now looks like predominantly southerly to south-easterly through the early part of next week at least.

LetItSnow! I think it's more complicated than that. From my understanding of discussions online a couple of years ago, it is a case of how the models deal with soil moisture content. In generally wet areas like the UK, the bias is towards underprediction. But in much drier regions, and on rare occasions you'll see this in the UK after exceptionally dry spells like July 2022, particularly in the case of the GFS, you can start to see overprediction. E.g. some rogue GFS runs predicted 48C for NW France and 43-44C for the UK if I remember rightly, which was never really feasible. In contrast, the UKV, being a Met Office model and at a more local scale for the UK and its immediate surroundings, is tuned to conditions in the UK, and of course is run at a much higher resolution feeding in from the UKMO. It therefore has a much better ability to predict temperatures, but of course has the disadvantage that it is limited to the UK only. Very happy to be corrected on this by the pro forecasters on here if I've missed something important or got something wrong - this is solely based on my memory of the comments of a number of forecasters on Twitter in the run up to the July 2022 heatwave.

Is it just me or from the looks of things does it seem like the earlier forecasts were better? It seems like the forecast was more western parts only up until yesterday, then some chatter about possibly further east, and verification looks closer to the more westerly solution? Seems unlikely looking at the radar that any storms will make it here unless I'm missing something?

Addicks Fan 1981 You are right in fact though as it seems that Iver has reached 27.0C (rounded to 1 dp). In any case probably splitting hairs a bit at this point - overall not a bad performance from UKV hovering between 26C and 27C. I'd only really call it a miss if we'd seen 28C or 29C, or vice versa if we'd seen 24C or lower.

Derecho Thanks - I've tried using Meteociel for the temperature tables and they're not as good - will have a go with Wetterzentrale later. I'll probably pick something eye-catching off the 12z runs and see what I can come up with.

TwisterGirl81 Yeah it's not surprising it's wrong in a few areas - it tends to be to be honest even at very short notice. But overall I do think UKV is much better for on the day temperatures than most of the other models. GFS and ECM are absolutely chronic for under-reading.

Derecho Was going to ask actually - what's your methodology for compiling these (i.e. which site do you use for the raw data and to obtain values for the CET stations - the maths isn't an issue)? Just asking because I'd be interested in trying to do something similar for some of the more extreme ensembles that are popping up - in other words to try and see if some of the hotter ensemble outliers would be enough at this stage. At the moment my feeling is that only the very hottest ensemble members are likely to do it, but it would be good to check my working.

Earthshine And your location has close to the worst of it. Even with a slight overnight downgrade the UKV this morning shows absolute UK maxes of 23C tomorrow, 20C Tuesday, 22C Wednesday and 21C Thursday. All in all as you say not a horrendous first few days to come, just less good than this week.

Just comparing Meteociel's temperatures from today to yesterday at the same time: Most areas further north and west are cooler, but in terms of absolute maximum the south is getting a good start on heating up today. The key is whether thunderstorm development scuppers the last degree or two of heating in the afternoon. Theoretically there's no reason we can't reach 27-28C, but we'd need no sea breezes and no significant cloud development in the hottest areas before 2pm or 3pm.

UKV has backed off again at the last go - 26C the max on this morning's chart for this afternoon. Probably a nowcast at this stage.

Don I guess the SSTs probably prevented July 2023 from being below average, for example. Scorcher Especially when you consider that another spell like this one in two weeks time would by definition be hotter. So rather than temperatures maxing in the 24-26C range most days you'd have maybe 26-28C.

Don I think we still don't have enough of a sample size yet to know how rare below average 1961-1990 months are now. Up until recently I was thinking 10%, about one per year. If we don't get one by the end of this year though, I might have to reassess. Possibly you'd have to start saying 5%. It's definitely going to happen at some point - the middle of January and second half of April this year prove we can still get significantly below average spells of weather - we just need one to be sufficiently prolonged to enable a below average month and to not be counteracted by a strongly above average spell at another point in the month. Very difficult to predict when it might happen, though. It's just that the odds indicate that it pretty much must happen at some stage, since I can't really believe that we've moved so far in the last two years that e.g. a December 2022 repeat will never happen again. Even if you added a bit on to the anomaly it'd still be below average if the same synoptic had repeated last winter. As always, more data needed. If we go another full year or two with no below average months on 1961-1990 I'll have to revisit this question.

Derecho Looks like the EC control backs up my early look at the UKV. Key as always will be surface conditions with next week's low I think. Should have a good chance of staying above 14C to the two-third point (becoming only the second year to be above 14C at that point) and then as you say anything can happen. A benign end with a slow drop into the mid to high 13s, a sharper drop into the low 13s or upper 12s, and frankly sky-is-the-limit if we get one of the insane plumes that seem to just come out of nowhere these days. There are still ensembles throwing out mid to upper 20s beyond day 10 at the moment. As long as that is showing up it really feels like it'd be crazy to ignore the possibility. In terms of probability I'd put a 14s finish at maybe 50% going off the latest output and given the lack of any real cold signal. 13s and below gets 40%. 15s and above gets 10%. The 10% I think is a reasonable educated guess based on the number of ensemble members at the moment that go very warm / hot in the final week to ten days, which is what we'd need for that sort of finish.

Unfortunately had an early start this morning so couldn't stay up. Hoping for a chance tonight.

danm The question is whether we will beat it tomorrow? 27C is possible, but all depends on the timing of thunderstorm development - an hour or two earlier than forecast would be enough to scupper it, an hour or two later could allow a sneaky 28C, maybe.

damianslaw Tonight's UKV also rapidly dropping any chances of a drop. Not even sure that we'll see a drop at all up to Thursday. Here are maxima from Monday to Thursday: Just taking a glance at that, you'd expect maxima to average 20C for the CET, at the low end. Here are minima for the early hours of Tuesday through Thursday: Again, from this, minima probably also above average for the period, near 10C or so. If you combine with a 20C average maximum, that gives a CET average, possibly even on the slightly conservative side, of 15C. Of course surface conditions make a massive difference to this even at relatively short range, but I'd now expect that the CET will hold through the first half of next week looking at this, or maybe even rise slightly.

Having had a look at a couple of Hampshire weather stations (not knowing the area), your feel may well be right! It looks like most stations in Hampshire beat yesterday by around half a degree or so.

Locally or nationally? Nationally it definitely was with 25.9C at Herstmonceux being the highest I'm aware of. May be beaten tomorrow - UKV is sticking to 27C.

And the 15z UKV which is the penultimate run before tomorrow is sticking to 27C. More early-mid afternoon though - presumably thunderstorm development will limit any late climbs in the temperature. For CET watchers worth noting that the 27C spot is near Pershore. Beyond that, into Monday we see that despite tomorrow's thunderstorms the heat holds on in the east with 24C. By Tuesday the heat is much less widespread but still 23C in East Anglia. Warm all the way to Wednesday as well though - similar to Monday. A random 25C in NE Scotland as well, must be some crazy Foehn effect being predicted! And on and on we go - Thursday as well! What a change this is. Looking at the causes, it seems that UKV is developing far fewer showers than some of the other models over the next few days. It looks like eastern areas may escape frontal rainfall on Monday and after that there will be scattered showers and possibly thunderstorms. Here are the precip forecasts for mid-afternoon for the next 5 days: A fair few cloud breaks, not huge amounts of rain, and warm, locally very warm conditions. I really don't think even the early part of next week is going to be half as bad as it looked a few days ago.

In Absence of True Seasons I think what was remarkable about that period was how consistent it was in avoiding anything below average. You can see it on the CET chart below. Obviously some locations will have had a very different year to the CET but for many of us it's a decent proxy. From late January to mid April there were virtually no below average days at all on the 1961-1990 average. Admittedly this is the older average which is somewhat cooler, but it's still bonkers. Worth showing the min and max charts above as well - you can also see here that contrary to what a lot of people have been saying it hasn't been driven particularly by mild nights either. Almost equally mild by day and night. So far this year for the CET we have max anomalies of: 1.1, 4.1, 2.4, 1.6 and 2.5 (May to date) Mean anomalies of: 0.9, 4.0, 2.5, 1.7 and 2.3 (May to date) Min anomalies of: 0.7, 3.8, 2.6, 1.9 and 2.1 (May to date) In short, no months with a significant difference either way, not even half a degree difference in the max and min anomalies for any month so far.