GFS 12Z is truly historic this afternoon! 

A lot of discussion prior to the thread reboot regarding GFS not showing the extremity or longevity of heat as it did earlier. 

Chris Fawkes' forecast for the week ahead a short while ago, while the 12z was still rolling out, highlighted the difference between the ECM, which maintained the heat, and the GFS, which shifted it east on Monday. He reiterated the general agreement across England and Wales away from the N and W until about Saturday, maybe Sunday, leaving confidence for 5 hot days. 

The 12z delays the breakdown by another day, with most of England still hot on Monday afternoon; almost as good on Tuesday despite losing the 15°C 850mb isotherm, followed by a recharge until Saturday 19th (so far). Point I am making is what I learned from the posters on here now, almost 10 years ago when I joined two, that a swing in one run shouldn't change the mood on its own. Chris was very honest saying he just didn't know which would be the one. I await the GEFS suite which I can only see to Sunday thus far.

Even with 5 hot days any CET loss will be more than compensated for by this time next week. And 5 hots in August 2020 and 2022 were enough to bring old summer cheer I recall.

12Z manages nine days in a row of 32C+ temperatures (maybe 10 or 11 depending on gridpoint resolution) which is not far off 1976 territory.

GFS 12z has 12 days in a row above 30c

As seems mandatory at the moment there is a bonkers run, P13 this time, which goes 31, 35, 34, 37, 40, 38, 40, 27, 33, 31.

The problem is the core of the high moves so rapidly to Scandi, that the very high uppers dont get a chance to establish,  still hot enough mind.  whether or not pressure can build back from mainland europe is the key to sustaining the hot spell

Hopefully this pattern continues into winter

Hot output continues this morning with the ECM the most extreme this time.  Likely multiple mid 30s days from Saturday to Monday. 

Yes, the ECM is a hot run and even has a high of 32°C in Moray next Monday (with a string of high 20s days here in Aberdeen).

Yes the extent and longevity of the warmth on the ECM is astonishing.

GFS Op - HP once again marching in from the SW for a hot end to the week, but moving on so by Sun 13th it's over Scandinavia with shallow (?thundery) LP moving up from France. That only lasts a day or two; then the HP resumes as a weaker ridge. LP pushes in from both N & S fro the weekend of Sat 19th - but the HP will not be denied and is back a couple of days later.

ECM - like GFS but Hp slower to move on and LP next weekend suppressed to some extent

GEFS - steadily warmer to Sun 13th (ca 5c above norm in S, more in N) then mean with most runs dropping back to near norm with a spread, op much warmer and control much cooler. A little rain in the next couple of days in the S, chances of some more from 15th onwards, those chances much higher in N

GEM and its ENS like ECMWF only more aggressively so. Barely a dip then a reload. 

06z rolling out. Warmer for longer- holds onto 30+ in the south until middle of following week (15th/16th).

Don’t tell Gloomin

Certainly is an absolute belter. ECM is as well. Getting excited now. For me this is the equivalent of snow for coldies  

It's also looks much more nationwide than the previous heatwaves. Infact the highest temps likely further west.

For me they are both equally exciting. However, the bonus is that hot spells are much more likely to materialise.

I like both. It's the boring cool/mild stuff I don't like.

Never fear though - there's a low pressure modelled to arrive at T+348 to keep the doom merchants happy 🙂

And those in the south whose gardens are absolutely parched!!

6Z GEFS looks more solidly hot than recent sets. The number of crazy hot runs has lessened, as you would expect as the time gets nearer although there are still five runs that hit 20C at 850mb in London.

The GFS mean maximum from the 10th to the 21st is now 30, 31, 31, 31, 30, 28, 28, 28, 28, 28, 27, 27 which is a pretty strong signal for a hot spell!

I'm a simple man , hot sunny summers and cold snowy winters please. 

As a mean temperature I would suggest that’s absolutely astonishing?

I remember someone commenting in the last thread several days back that one of the notable things about the model output this summer is that the models have often struggled with the behaviour of the jet stream. I agree with this and is probably why some of last month's hot spells did not last as long over the UK generally as the models (some of them at least) had suggested intially.

For instance, I recall that about three weeks ago, some of the op runs were suggesting the cell from the Azores High which produced the mini-heatwave around the time of the summer solstice would remain over or close to the British Isles well into the following week and possibly beyond. Unfortunately, this didn't come to pass and for most northern areas it has been back to the mostly unsettled and relatively cool pattern that has dominated our weather since the last week of May. If the jet would weaken a bit and move further north, more areas further north would benefit from the much better weather that southern areas have experienced recently.