The 12z GFS Ens were not hugely different to 6Z in terms of overall average 850Hpa and rainfall amounts in the south east. Apologies for the IMBY post ..... 

Yes GFS  continues its struggles.

AIFS ensembles are more solid though. Waves of heat hitting the South. GEM is similar. 

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

Yeah, hot outliers.

A cooling trend in the EMS of sorts.

Still a massive spread though. It shows how sensitive the conditions are to a slight shift in the position of the high. If it nudges west just a small amount then it allows a more northerly drift to push the heat back into France. 

Still, even the cooler options look fairly HP dominated at least for the south. 

Talk about convective.🌩️

According to TORRO the all-time UK record is 578dam, and that was actually in June - June 28 2019. https://www.torro.org.uk/extremes/summary

The 0Z GFS has 579dam around the Herstmonceux region here: https://www.torro.org.uk/extremes/summary

Indeed; 100mm + ppn over parts of central England.

As early as next Tuesday GFS has a 20 degree spread of maxima for London from 18C to 38C. That's only day 7.  Days 4 and 5 have a spread of 7 and 9 degrees...

That's not an honest reflection of the range though is it? If you take out the 3 or so obvious anomalies in the upper temperatures for example they barely have a range of 10, not unusual. The surface maxima will naturally deviate after day 5 and even they barely manage a 15C variation at day 7 once extremes that are not part of a group or have daylight between them and the nearest group are removed.

The trouble at the moment is a tiny shift on a geographical scale of the boundary between the continental heat dome and our more benign warm HP can result in 100s of km difference. Each time a new factor is injected into the models, differences of that scale become likely.

This was the case, the 12 z GFS now has the perfect scenario for UK wide heat middle of next week with high pressure strengthening to the north and east of the UK.

The 12z GFS continues the trend from the 0z in terms of moving the ridging north - which means my area escapes the worst (due to an onshore breeze) and the 20C 850 isotherm is safely kept at bay. 

Don't look at the UKV then - 22C at 850mb over Sheppey on Monday. Although you would get a sea breeze.

TBH the way the models are struggling with the boundary of the frankly tropical airmass versus something very warm instead reminds me very much of winter, when they struggle just as much with say the -10 850 line. In recent years the struggle has always resolved, in winter, in favour of less cold conditions - the same doesn't apply with summer heat.

It does look like there will be an onshore breeze down here from Sunday onwards, and that will keep the far SE that bit cooler. Further inland, though... 

The MetO text forecast mentions isolated thunderstorms, but the UKV output would suggest more general showers - it's lacking the intense rates that you normally see when storms are forecast. The MetO raw has a 60% chance of light rain in the far SE during the early afternoon, it'll be interesting to see which model ends up being correct!

EDIT: The MetO raw now has a 90% chance of rain (at 25C too, which is uncommon), and a good deal more cloud around too (not that I'm complaining). Clearly something's been picked up at the last minute...

GFS Op 0z - Once the hot air has been imported as per FAX it stagnates , even affecting the far N, under the influence of HP covering Britain. From Fri 26th the pressure drops as LP 1015mb moves up from France but still hot (and thundery?) until Wed 1st when the centre of this LP moves east across England and brings in cooler air from the north.

ECM - goes for a much shortened hot spell; after Wed 24th a more active Atlantic pushes the hot air back to the SE and replaces it by cooler W/NW-lies; LP 990mb develops on the Norwegian coast Sat 27th, with trough to SE England.

AIFS - London,  maxima rising to 35C Tue 23rd then staying at 30C to Sun 28th and dry. Mon/Tue 29th/30th much cooler at 20C and wet. Edinburgh, rising to 23C Tue 23rd (there's a temp gradient for you!) after which variable mostly around 17C, rain quite frequent with only a brief dry slot Wed/Thu 24th/25th.

GEFS - in the S, mean temp about 8C above norm to Mon 29th though slow to reach the peak in the SW (quite good ens agreement though not a few even hotter outliers up to 12c above), dropping back to norm or just above from Wed 1st. Very little chance of rain., some in the SW later. In Scotland and England from the Midlands northwards, a pulse of warmth this Sat, then cooler before rising to a mean of  5 or 6C above norm from Tue 23rd and dropping back to norm from the 1st. Chances of rain today & tomorrow and again from Fri 26th always heavier in Scotland.

Still uncertain as to how much heat will be imported from across the Channel, how far north and for how long.

Based on the radar, it looks like the UKV did well. I think it had the ppt too far west, but overall it did a lot better than the other models I saw.

In the end there was a bit of both - the trough (as shown on the "fax" charts, albeit it looked like a small low to me on the radar) started off with heavy downpours moving across down here, some purples on the radar for a time in eastern Kent, then a more general area of rain to follow. There was 1.4mm from it here, about half an hour of rain in total.

No rain here although it did look quite threatening for a while. UKV suggested I was in the firing line but looks like I need to get the watering can out again.

BTW the 12Z GFS is anothe rhot one but then gets quite wet across the south as a slow-moving low wedges itself in between the two HPs.

Post 2022 it just doesn't have the same hype though.

I'm hyped! maybe you should get your hormone levels checked 🙂

Loving the recent trends of the high pushing east and north T 850 temps of 21c in Cumbria? yes please.

https://www.wetterzentrale.de/en/topkarten.php?map=20&model=gfs&var=2&time=204&run=12&lid=OP&h=0&tr=1&mv=0#mapref 

The 12z has the mean 850mb 15°C isotherm from 22nd to 29th.