Turning much fresher later next week after a very warm/hot and humid thundery breakdown

on the UKMO run the and the majority gfs ensembles.

My guess is it wont last long and the heat will soon be back, something similar to run 12 from the gfs is my bet

http://modeles.meteociel.fr/modeles/gens/run/gens-12-1-216.png?12

The 12z ECM still shows the breakdown a little bit later than GFS, but after next Friday, it becomes particularly unsettled. I think it's pretty much nailed on for a cooler, unsettled spell now, but still not sure how long this will last.

Today's trend has been a shift west in the location of the trough from the middle of next week. This could reflect the models having over-reacted to the signal for a longwave pattern shift, but on the other hand, the models have also trended towards quicker development of the trough, which could also be placing it further west.

Kudos to UKMO, which hasn't had to trend quicker at all, having already been there yesterday

Interesting to see plenty of slack conditions on the UKMO and ECM runs up to day 9. Should continue to feel plenty warm enough especially in the sunnier spells.

ECM produces a bomb for day 10... would be an interesting event but at that range a trivial feature given how many things could change such as the position and intensity of the 500mb trough and the strength of the jet stream.

Hi everyone. Here is tonight's review of the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for tonight Friday July 19th 2013.

All models show High pressure over Northern Britain with a cooler Easterly flow giving some relief from the heat to Southern and Eastern Britain over the next few days with low cloud night and morning. The NW will see the highest temperatures in the sunniest and least breezy conditions. Through the early days of next week the High weakens and slips even further North with airflows over the UK becoming slack, hot and very humid with a slow fall of pressure being a catalyst for showers and thunderstorms to break out over Southern and Western areas early next week.

GFS then shows Low pressure developing close to SW Britain with a complete change to cooler and more changeable weather from midweek with the thundery weather swept away with cooler and cloudier conditions with rain and fresh winds for all. Through the second half of its run tonight the Atlantic takes control of the UK weather with cooler Westerly winds bringing average temperatures and rain at times, heaviest in the North and West with some dry and brighter spells to the South and East.

The GFS Ensembles show a complete change moving up from the SW midweek and lasting then through the rest of the period with showers or longer spells of rain following a short thundery breakdown in the middle of the week.

The Jet Stream is coming South from midweek next week as it loses it's identity up to the NW and relocates across the Atlantic towards the UK from the end of next week onward.

UKMO tonight shows Low pressure trundling slowly North to the West of the UK. The hot and thundery conditions of the middle of the week will steadily be displaced by cooler if light Atlantic winds filtering East across Southern and Western areas after Wednesday with cooler weather and scattered showers likely.

GEM tonight shows Low pressure becoming prevalent to the West of the UK with a thundery breakdown moving North over the UK through the middle of the week followed by cooler and fresher conditions arriving by the weekend.

NAVGEM tonight shows Low pressure developing to the West of the UK with a short thundery period followed by cooler and more breezy conditions with rain at times to end the week.

ECM shows a slow decline in conditions too through next week. Following several days of hot and humid weather with thunderstorms scattered about the trend is for things to cool later in the week as Atlantic winds in response to Low pressure close to NW Britain late in the run brings occasional rain and cooler weather well in time for next weekend with a really inclement end to the run as a vigorous Low moves in close to the SW.

In Summary it looks very much like the models are firming up on a significant change by the end of next week. GFS has shown such a change for some while now and if it comes off all credit to it as the other models appear to be falling into line with it tonight though details between the models differ somewhat. Nevertheless, we have firm commitment from the models tonight of a change around the middle of next week with a period of hot and thundery weather followed by cooler Atlantic winds with occasional rain and nearer to average temperatures throughout the UK which does look like lasting for some while.

This is only based on gut feeling and don't have anything to back this up, but somehow I can't help but wonder if perhaps the ECM is overcooking the LP to the west on the 12z run. It seems to go from being a standard summer-type trough to something rather more potent, and seems to be somewhat stronger that it is on the UKMO run. It would certainly be a big shock to the system given what we've had in the last fortnight, but I can't help but feel that ECM may be overdoing the return of unsettled weather, a bit like last weekend in one run when it showed a potent LP system moving down from the NW early next week which it then dropped.

To be honest thou ecm does not look to bad a run for s and s/e bit of a n/w s/e split develops on ecm

other than last chart but then again it would be intresting cause the high could roll over the top its happened before.

one thing ive noticed over the years thou model watching thou and I have aspergers which means very poor in some parts but brillant in others is that they all tend to hit a default pattern after a certain amount of time seems to vary from run to run but her self gfs has been bad for that over the years ive noticed.

Thanks very much Martin

Thanks Gavin a intresting read as ever I admire also the effort u put in.

The only worry Matty is all the models are pretty much in agreement now.

I hate using the phrase "be careful what you wish for", and I know it winds other people up as well, but all I will say is I hope and pray that any upcoming cool unsettled spell doesn't last too long.

I don't think I could handle another dank, dismal, cool August.

At risk of going significantly off topic, the first half of last August was pretty decent for many!

The first full week of August (the 2nd week of the Olympics) was a decent week where I live. Unfortunately it was the only reasonably summery week we had throughout the whole sorry affair that was last summer!

That's true, but I don't think it lasted for much longer after the Olympics ended. I seem to recall that when the PL football season started a week or so later, a game at Sunderland was called off on either the first or second Saturday of the season as the pitch was sodden after torrential rain in the north-east. That must have been almost unheard so early in the season beforehand.

Yes I remember on a number of occasions it being sunny and very warm/hot in the SE yet up here was dull and cool with temps around 18 or so, there was a proper NW/SE split at times.

Yes "NW/SE split" was one of the buzz phrases of last year. Jiries bemoaning the lack of nationwide hot temps giving very poor heat duration etc...

Meanwhile 18Z GFS blasts away the heat even quicker than 12Z...

http://www.wetterzentrale.de/pics/Rtavn962.png

Once again giving the lie to the oft touted myth that "once HP is established it's very difficult to blow away". Rubbish - it can be and is destroyed in 24 hours in winter or summer. Remember that mega block last winter that was meant to repel the Atlantic attack? It ended up rolling over faster than a Chelsea striker on the edge of the penalty area.