It is now

Please stay OT. I've removed a number of posts this morning already. 

Yes looks like the heat haters might be getting off pretty lightly this time. A few days of high 20s hopefully combined with relatively cool nights and low humidity shouldn't be too bad hopefully.

I'm not sure ECM is an outlier.

Yes I think realistically that's about as cool as we could get now and I hope that prediction turns out correct.

It does baffle me when people treat potential signals deep in FI as gospel, like it is inevitable it will happen. Who exactly needs an apology? Even if we get a less settled, more average second half of July we'll still be comfortably above the average CET. Moomin's cooler July just isn't going to happen. A cooler second-half of July is possible, perhaps even likely if we get a less-favourable blocking high, but then it is not at all a stretch to predict that given how warm/hot the first half is looking nationally.

When I read longer-term analysis from very knowledgeable posters and forecasters (like the longer-range Met outlook, etc), they emphasis the uncertainty, because small changes in the pattern can make a huge difference to our little island in terms of rainfall distribution and where the warmest conditions will be. We're struggling for any real consistent signal into next week, with the usual suspects taking every operational as a given with knee-jerk posts (over on NW forums too) so why on Earth are we writing off the second half of the month if the models can't even resolve next week?

We're going to see a number of different options ahead for next week and beyond. Operationals are going to be all over the place; some hot outliers that need treating with caution, some cooler outliers like last night's GFS 18z, that have caught a few out that should know better. Ensembles are only going to be so much help because of the scatter into FI, and the ECM clusters may well play around with a few scenarios in the longer term as well. It's going to be fascinating and frustrating to try and pin down how we go forward from this forthcoming heatwave (that we need to not lose sight of and enjoy!), but it's safe to say it won't be as bad as some will have you think (note, average is not bad!).

Do you realise just how cool it would need to be in the final 10 days of the month, given the preceding heat, to get to that kind of range. Do you also realise that there is no suggestion of such cool (well below average) temperatures being suggested in the model output? If there are, as you seem to imply, I would be pleased to see the charts showing that scenario (of cooler than average for a protracted period). I keep asking this but it just seems to be opinion rather than model output.

The CET is currently just over 18°C for the month so far. Given the extended period of very warm weather this is likely to increase significantly. What do you and Moomin see in the current output that will counteract that to bring the CET for the month to a degree below where it is currently? I’m genuinely baffled as even the extended outlook after the upcoming heat looks around average at coolest? It’s a bit tedious seeing all these claims about cool weather then when asked for evidence being completely ignored. Try to prove it’s not trolling by adding some output showing a consensus for cooler than average conditions for the latter stages of the month. It is very likely the latter parts of July will be cooler than the next ten days, in fact it would be amazing if it wasn’t, but cool?

There is virtually zero cool weather predicted on any model on any ensemble set this morning.  Just bizarre comments from some. The AIFS ensembles some it up. Hot to just very warm for London. 

https://www.wetterzentrale.de/en/show_diagrams.php?geoid=49069&model=aifs&var=2&run=0&lid=ENS&bw=1 

GEM is awful for you sweat lovers.  I hope its wrong as I like warmish sunny weather, but not hot humid nights which seems common in the modern era. We never had that in the 80s and 90s (apart from 95)

I'd say the GEM 0Z and the GFS 6Z shows a definite marked cool down. The GEM is really quite unsettled, and the updating GFS continues the trend towards a much cooler and more changeable period.

At present, it's out at day 10, so unreliable of course, and the ECM 0Z still looks fine...but will be interesting to see if the trend towards a cooler and more unsettled second half if July continues. 

Can't call it a clear trend out at day 10, but will be watching closely to see if it comes into the reliable time frame, which will be interesting. 

The FI part of the 06z GFS is something we don't want to see in terms of hoping for sustained warmth and dry over the UK as we go into "high Summer" - the dreaded northern blocking set up which tend to ruin many a summer as low pressure is forced southwards. Of course, this is only one run and is centuries away in forecasting terms. The ECM is even showing a similar thing with the northern blocking set up in FI but still manages high pressure over the UK anyway.

This is an important point that seems to be overlooked. The 6z GFS continues to hint for the time being at a less warm set up going further into next week. The media (BBC weather) is starting to be influenced but only by easing down the heat from the high to mid twenties in Winchester for example. 

After yesterday the CET may well be a little under 18- HadCET data may be published quite soon. But a rough estimate for the second week based on the 6z comes in around or slightly above 20 I reckon, including a cooler today and an earlier cooling of the Lancashire station.

That leaves us not far off 19 for the almost first half of the month. The rest of the month would need to be below 15 to get a few points below 17 at the end. Hardly a cool month.

The GEFS are out to Wednesday- the mean can't be taken on its own but whether there is clustering in the output or divergence at this point, there are enough members going high to give that mean its weighting. As somebody mentioned, the Op is only one of all those possibilities. Temperatures still very warm across large parts of England on Wednesday 16th. On Monday 14th much of England still in high twenties.

The GEFS 06Z shorts for London.

ECM ENS 00Z also looks continues to look consistent. PPT here:

https://www.theweatheroutlook.com/twodata/ecmhrens.aspx?chartname=ecmwfenspreciprate&chartlocation=london 

(Remember it's the grey numbers you should be checking)

Not always. Take 6th, 9th and 10th August 2003- it was that shift that actually opened the gates to the 20+ uppers.

We shall see what the models produce over the coming days in FI. However at the moment, there is precious little if any evidence from recent runs of a notably cooler spell in the offing any time in the near future, although one can never second-guess the models.

Yet just what, 50 miles away max across the estuary there was just 6.3mm in  the last 24!

I won't rely on the temperature figures almost 12 days out as I'm sure you wouldn't! Nevertheless after a few pleasant days of respite I will be bracing myself for the next 4 or 5 days of extreme heat later in the week. After that the ensembles become less sure as ever but the mean for London is still making me think it will be low to mid 20's which in most summers would be considered at least warm as no doubt there will be the odd 26-27C in there. Of course the real standout for us in the East of our respective regions is no rain and that is what Guy Fawkes should be going on about.

That is way I said 'realistically that is about as cool as it could get' but you obviously don't read the comment properly.

I'm not saying it's likely but it's still plausible that the overall monthly CET ends up below 18c and maybe even as low as under 17.5c. I think it is also ridiculous to completely write off that scenario at this point in time and just assume that the entire month will be an endless heatwave.

What seems more likely at this point is a reasonable heatwave Thursday - Sunday and then a spell of average more unsettled weather which could end up being cooler than average at times and we shall then see from there what happens.

So it's an option, but in the minority (at the moment).

Err yes, but it is an internet forum so there will be the wide range of opinions from as "good as a pro" to the "downright daft"

It would be rather boring any other way , well thats my opinion.😎

I read your comment fully before replying and your implication is clear that you believe that 17 to 17.5°C is a realistic end of month CET. I and Bertie have both explained why, based on current output, that scenario is rather implausible. Nothing of course is impossible. As for average after Sunday, I’m not sure I would refer to 29-30°C across the SE as a spell of average? It looks like being a good deal above average until around the Q6th or so (and quite possibly beyond that).

Trying to defend the suggestion the month is likely to (not “could” but will probably) end up as a cool month overall is an interesting hill to die in in the face of such strong evidence to the contrary. 

There is precious little evidence of the weather being cooler than average never mind by enough to make a 17 to 17.5°C July CET plausible:  

London 06z GEFS data 

Things of course could change but they would need to change a lot and unless someone can see models that the rest of us cannot then that looks unlikely. It could end up a colder than average month but I could also win the lottery.

And no Fairweather I am not taking temperature values at 10+ days out at face value rather using them as an exemplification of the overall pattern in the output I.e. warm especially in the south.

Things will warm up this week, with heatwave criteria being reached in parts of the UK by the end of the week.

Temperatures could climb into the low 30s, although the heatwave isn’t expected to see temperatures quite as high as the one experienced at the end of June/early Jul

When will the heat end?

There are signs that less hot, or fresher, conditions may arrive from the west into the start of next week, but exactly how quickly this transfers eastwards is uncertain. It’s certainly possible that hot conditions may persist for a while longer, especially towards the south and east.