The GEFS will be as utter garbage as they always are and have been all summer. My money is on a largely settled and pleasant September. 

Yes, I would put my money on a mostly fine, dry September, too.

Agreed and looking forward to it.  Plus GFS had been very poor as last week was showing HP, high 20's and settled weather yesterday and it turned out totally opposite with more like mild wet winter day. 

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON TUESDAY AUG 25TH 2015

THE CURRENT GENERAL SITUATION Further troughs of Low pressure will move North and East across the UK today and tonight followed by a more showery SW flow tomorrow.

http://www.wetterzentrale.de/pics/Rtavn001.gif

MODELS-2 WEEK HEADLINE Remaining very unsettled this week with rain at times. Perhaps somewhat drier as we move deeper into September.

THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast pattern this week shows the flow continuing to stream NE across Southern Britain for much of the rest of this week edging slowly North next weekend and realigning North of the UK early next week. The by then weak flow re-strengthens later next week and moves back down to more Southerly latitudes yet again..

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows Low pressure up to the NW for the remainder of the week with a frontal boundary lying close to the SE from Thursday with showers for many and the threat of more prolonged rainfall for the far South and SE for a time. Then temperatures recover a little at the weekend when shallow showery Low pressure remains in control before a gentle build of pressure from the West early next week settles things down across England and Wales for a time before unsettled weather under Atlantic Low pressure returns to all areas to end the period.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

THE GFS CONTROL The GFS Control Run today shows a similar sequence of events over the period though the period of High pressure early next week is somewhat more dominant for a time than on it's operational brother. It's breakdown from the fine and warmer pattern for the South next week comes from the NE as High pressure recedes SW and allows cooler and showery Northerlies to spread down over the UK lasting to the end of the run when High pressure is ridged over NW Britain and lower pressure lies to the East and SE.

THE GFS CLUSTERS(14 Days) The GFS Clusters this morning show a bias of 80%/20% in favour of Westerly winds blowing across the UK. Not all members make this an indication of unsettled weather as a fair few show High pressure from the SW ridged towards the South with any rain from Atlantic systems more likely for the North. The 20% group indicate High pressure over all of the UK with fine if not overly warm weather for all.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO UKMO today shows a a showery SW flow for the rest of the week from tomorrow with slack pressure gradients developing for the Bank Holiday Weekend. With warm air to the SE and a frontal boundary their it looks like the threat of some heavy and thundery showers or rain at times looks a very real one dor the SE while some heavy and slow moving showers look possible elsewhere too.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts this morning keep High pressure at arms length over the period preferring to maintain an influence of rather more unstable air across the UK. While showery troughs are shown to move East across the UK at times in a slack flow at the weekend careful attention will have to be focused on the stalled front to the SE as well as it could move back further to the NW at times.

http://www.weathercharts.org/ukmomslp.htm#t120.

GEM GEM today has backed away from it's suggestions from yesterday that High pressure could develop over the UK next week. Instead this morning's offering favours escalating conditions at the weekend from a deepening depression moving North from the SW with thundery rain then sunshine and showers looking likely in rather cool conditions for much of next week too.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM looks a little indecisive this morning in regard to where we move from the coming weekend. While on the face of it no deep pressure areas are shown low or high the air is slack and unstable for much of the time with showers always a possibility and while it may become warm and humid briefly in the SE at the weekend generally cooler conditions look more likely.

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

ECM ECM this morning still shows improvements as we move through next week but the pace of such change is agonizingly slow. This week shows the weather as before with sunshine and showers and some longer spells of rain locally before things warm up a bit in the SE at the weekend. With unstable air across the UK showers look like continuing over the Bank Holiday and for that matter much of next week too. However, with cool High pressure edging into the West and NW of the UK then showers will become more and more restricted to more Eastern and Southern areas while Northern and Western areas become largely dry but with very chilly Autumnal nights and the risk of frost and fog increasing.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN The ECM 10 Day Mean Chart  from last evening shows a growing trend to build High pressure North, probably just to the West of the UK leaving the UK under a weak Northerly flow and cool, gentle early Autumn conditions for most.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models maintain the theme of a very unsettled and windy spell this week. There is little cross model agreement that improving conditions on a grand scale are likely next week now.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM. This morning's verification statistics show ECM leading the way at 3 days with 96.1 pts followed by UKMO at 95.9 pts and GFS at 94.8 pts. At 5 days UKMO is king at 86.8 pts followed by ECM at 86.3 and GFS at 83.3 pts. Then at 8 Days ECM still leads at 61.3 pts over GFS's 55.2 pts. Finally at Day 10 ECM leads GFS at 43.1 pts to 37.5 pts from GFS.
 
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig
 
MY THOUGHTS The weather patterns across the UK remain stubbornly complex and unconforming this morning if it's a prolonged and fine warm spell your after. The models refuse to release the troughing near the UK albeit under very slack synoptics with all models now showing a reluctance in allowing High pressure to make a large impact for any length of time on conditions across the UK next week. A few members do show some decent weather about then under some degree of High pressure but it never looks overly convincing. We also have a Bank Holiday Weekend approaching and while it doesn't look like a washout it looks like we are at least going to have to cater for some showers almosy anywhere and while I'm sure some will fair well and have a decent weekend others may see a fair amount of heavy thundery rain in a short space of time under any slow moving showers. Also though warm and humid in the SE to start the weekend it looks like becoming average at best temperature wise thereon with some jolly chilly nights in the North with a risk of frost especially if ECM's sequence verifies. However, despite all that there is no particularly active early Autumn storms shown likely to affect the UK over the next few weeks and it wouldn't take much more of a build of High pressure than that shown at the moment to override the projected trough dominance to deliver something much more pleasant than what's on offer this morning. So in a nustshell it's the changeable pattern as before to take us from Summer into Autumn and while nothing particularly bad is looking likely over the next few weeks I can't help but feel a little deflated on the synoptics shown as I feel they could be an awful lot better too.

Next update from 09:00 Wednesday Aug 26th 2015

BBC forecasts last night were pretty bullish about the prospects for high pressure building over the UK as the weekend went on. The charts this morning don't seem too keen on this, with high pressure initially building in from the east but then quickly being eroded by lows to our south & northwest.

Damn!

That Euro low has gained some support this morning, but remains a weak feature on most model output, with some very warm air drifting across the SE while frontal rain affects areas further north. There could be thunderstorms across the S and SE as things destabilise, but so far GFS has shown little appetite to develop anything much - perhaps due to a strong capping inversion meaning that, like we saw last Saturday, some high surface temperatures will be needed to set off any storms.

In the much shorter term, there's a fairly typical spell of rain moving across southern parts during the middle part of the day, by which I mean the expected totals are nothing special at 5-10 mm for most, perhaps 15 mm in some spots.

Tomorrow could be a different story for some, waves of heavy precipitation move NE in associated with a weak disturbance along the polar front, meaning we could see some areas receiving as much as 40 mm while others see little more than 5 mm. This pattern shows up well on the 00z Euro4 accumulated precipitation chart for the coming 42 hours (after which the front has cleared to the SE):

As for Thursday, the model consensus currently keeps an area of heavy rain - with some large totals - just SE of the UK, associated with a small area of low pressure. Some runs (e.g. GFS 00z operational) have it close enough to bring peripheral rain to the far south - intermittent with variable intensity.

Any adjustment north could spell trouble for the south given how much rain has and will have fallen across the preceding 5 days. An adjustment south could allow for some fair weather at times with sunny spells and a few showers. Place your bets... 

As a side note, has anyone else found themselves staring wistfully at the pool of -10*C 850hPa temps over Svalbard on the ECM day 8 chart? It's funny to see it cropping up there already when we have struggled so much to import such a cold airmass even during the heart of recent winters 

ARPEGE has tomorrow's rain much further northwest and largely missing the southeast corner, with the heaviest totals up in the Midlands. Will be interesting to see how it pans out.

http://modeles7.meteociel.fr/modeles/arpege/runs/2015082506/arpegeuk-1-30-0.png?25-10

Cluster analysis groups the GEFS runs based on similarities between them, usually producing a range of scenarios for a given weather event. It's a neat tool but I can only find it on one site at the moment (weatheronline)

Top left is a cluster composed of 15% of the runs, in which the low develops enough to track across SE England and bring a very wet day. Top right is a cluster that represents the 'majority vote', being composed of 45% of the runs. It shows a glancing blow from the low, enough to bring a wet day to the far south, wettest in the far southeast, but nothing severe.

There's also a cluster composed of 20% of the runs which appears to be a faster version of that majority outcome, but also one that spares the SW from most of the rain. The remaining 20% have the rain only really affecting the far SE.

Another way of looking at things is the usual GEFS graph plot, in this case for London:

...which reveals that only a few runs bring the heavier rain as far north as the Capital.

Meanwhile selecting the Isle of Wight using the map feature reveals that 4 or 5 runs bring substantial rainfall:

...which is not far from 20% of the ensemble suite, tying in well with the cluster analysis.

Keep em coming James. Your posts are excellent and informative.

In the past 20 years, you would tend to favour warm and dry conditions for September, but I'm just wondering about that cold pool in the Atlantic. We've not seen anything like it since the early 1990's and that was a period when we had a run of cooler/wetter Septembers (and Autumn's generally)

27 Aug. 1994, with a low centred north of the British Isles, as in those GEFS posted above for 27 Aug. 2015:

http://www.meteociel.fr/modeles/archives/archives.php?day=27&month=8&year=1994&hour=0&map=1&mode=0

Mid Sept. 1994 and a low centred on the Western Approaches:

http://www.meteociel.fr/modeles/archives/archives.php?day=14&month=9&year=1994&hour=0&map=1&mode=0

Not a forecast for 2015. Just perhaps illustrating what Gavin P. has in mind for how things were in the early 1990s and MIGHT be this year.

Sunday could end up being hot depending on the timing of the rain and the next plume.  Here is the 12z GFS with +20 850s for a few hours for some and widely 15+ for the S and E.  Worth a watch to see if it continues and to see if it does, how the timing changes. 

Spotted the peak of the heat, so to speak:

...shame it's 9am in the morning and making a rapid beat for the North Sea!

Any adjustments S or W of the developing low over Europe could lead to a more notable waft of heat, similar to last weekend.

As it stands, GFS is has the low furthest SW on Sunday, with ECM and UKMO taking it further east. It's a complicated setup though, the pace and track determined by how quickly the jet stream weakens and buckles between Saturday and Sunday:

Its over Justin's House, again!

Meanwhile at midday Sunday ECM has the heat heading eastwards but still 18c 850s just a mile or two from the Kent coast

and cue Jires... 😄

Could be quite a cool start to September this year:-

GFS has a strong flow of chilly uppers moving down the country. ECM not a million miles away although more HP influence (cold nights):-

Could be quite a low CET return for the first 5 days or so 

Fortunately the extra 170 metres usually delivers a degree or two less heat and a cooling breeze compared with the cauldron down the bottom 

Bank holiday weekend now within MetO fax range and it isn't looking too good.

A weak ridge might give the Midlands a fine day on Saturday while the SE and NE is cool and cloudy but by Sunday it's cool and showery everywhere under a north westerly flow with a depression close to NW Scotland.

Monday might be a bit better in the SE but most areas will remain under the influence of the same low especially in the NW. Scotland (along with NI and Cumbria) look like having a very poor weekend finishing off a terrible summer.

i am glad summer is almost over now, it's been appalling and made worse by the lovely conditions across the SE.

At least in autumn I expect it to be miserable.

Andy

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON WEDNESDAY AUG 26TH 2015

THE CURRENT GENERAL SITUATION A trough of Low pressure will clear erratically East today followed by a showery SW flow. A further trough will affect the far South tomorrow as it runs along the English Channel.

http://www.wetterzentrale.de/pics/Rtavn001.gif

MODELS-2 WEEK HEADLINE Gradually becoming less unsettled for a time with longer dry spells and some sunny spells next week.

THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast pattern this week shows the flow streaming NE over the South of the UK currently. The flow moves more South to north towards the weekend still across the UK. then over the weekend a trough complex in the flow crosses the UK and once away the Jet flow collapses and becomes ill defined for a time next week. In the longer term it looks to realign South of the UK through the second week.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows rather changeable and often complex synoptic patterns over the coming two weeks. The SW flow which takes us up to the weekend weakens and is superseded by a developing Low pressure cell to the SW over the weekend which moves NE and deepens to become situated over Northern districts enhancing a further spell of breezy and changeable weather for a time next week. then in the second week very slack airflow patterns take hold with a lot of dry and benign weather but with the risk still of occasional showers. After a warmer and more humid blip in the SE this weekend it looks like temperatures are shown to be average or maybe a little below at times especially by night later.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

THE GFS CONTROL The GFS Control Run today shows a similar sequence of events over the period with Low pressure over the North early next week migrating East with pressure trying to build from the West. This sets up a Northerly flow with scattered showers, these mostly to the East. then as High pressure dominates to the NW Northern areas will see a lot of dry weather for a time before Low pressure moves into the SW and extends slowly north and East across all of the UK late in the run.

THE GFS CLUSTERS(14 Days) The GFS Clusters this morning show a bias of approximately 65%/35% in favour of High pressure across or near the UK in 14 days time. The other 35% of members go for a more mobile Atlantic based pattern under Low pressure to the North and Westerly winds across the UK.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO UKMO today shows a slowly improving picture but it may be too late to rescue the Bank Holiday weekend which may turn out to have a wet spell over Saturday night and Sunday morning as Low pressure moves NE across the South. Pressure builds very slowly behind with High pressure not far from the South come Tuesday.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts this morning show a lot of slack pressure patterns over the UK come the weekend and start to next week with a basic Westerly drift carrying a lot of dry, bright weather with just scattered showers, these chiefly across the North while a spell of more prolonged rainfall looks likely for many midway through the weekend as a small developing Low moves NE across the UK.

http://www.weathercharts.org/ukmomslp.htm#t120.

GEM GEM today shows pressure building behind the weekend rain event as Low pressure moves off to the North and NE while pressure builds from the SW. So next week may see a lot of fine and benign conditions for a time before the High decays away at the expense of further showery Low pressure edging across the UK from the West by the end of the week as it turns rather cool again.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM also shows a small bt significant Low moving up over the UK from the SW over the weekend renewing rain and showers for all for a while. Pressure then builds from the South with several fine and bright days likely away from the far north before things synoptically begin to look more fragile again from the West by soon after  midweek.

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

ECM ECM this morning still likes the idea of it's slack Northerly next week following the indifferent weekend of some sunshine and occasional rain and showers as Low pressure complexes move away to the NE early in the week. The slack northerly then steadily gives way to calm conditions later in the week as the High pressure centre to the west edges across the UK with fine, settled weather for all with reasonably warm days but very chilly nights with frosts in the North possible.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN The ECM 10 Day Mean Chart  from last evening endorses the prospect that the UK could lie close to or under High pressure in 10 days time

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models maintain the theme of changeable conditions for a while yet. The prospect of better conditions under High pressure next week has gained some momentum this morning.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM. This morning's verification statistics show ECM leading the way at 3 days with 96.2 pts followed by UKMO at 96.0 pts and GFS at 94.8 pts. At 5 days UKMO is king at 87.1 pts followed by ECM at 86.3 and GFS at 83.3 pts. Then at 8 Days ECM still leads at 61.2 pts over GFS's 55.2 pts. Finally at Day 10 ECM leads GFS at 43.9 pts to 38.0 pts from GFS.
 
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig
 
MY THOUGHTS There is a gentle consensus between the models that improvement in the weather may be just around the corner as High pressure attempts to make inroads to dislodge the trough over the UK. There is still some way to go before we get there though and it may not be in time to give the UK a weekend of entirely fine weather with a small but significant Low pressure in humid air developing to the SW and deepening as it moves NE over the second half of the weekend. So while the start of the weekend might not be bad with just a few showers around a band of potentially heavy and thundery rain looks like crossing NE over the middle of the weekend displacing the temporary warmth and humidity that develops over the SE on Saturday. Then after a showery Westerly or Northerly flow for a day or two it looks like Atlantic High pressure could visit our shores towards the middle of next week with some fine, dry and in places sunny conditions looking likely for nearly all of the UK from some of the models and Southern areas at least from all. The air in association with the High looks inherently cool and some chilly nights could lead to grass frost over the North at times but compensated by some fine and sunny days. Then we have to look into the less reliable period from Post 7 days to see High pressure collapsing from the West and SW which GFS seems to lean towards however with the backing of ensemble data and from GFS and the ECM 10 day mean it does suggest that High pressure could continue to play a role over the UK well out into the second week. So while I can't predict a late Summer or early Autumn heatwave again this morning I am more optimistic that things will turn rather better next week and beyond with far less rainfall for all and some fine and bright weather to enjoy too and while it may not last for long lets enjoy it while it is here as the nights are closing in fast now at  minus 2 minutes of daylight night and morning each day now.

Next update from 09:00 Thursday Aug 27th 2015

It wasn't lovely here since early July and it been going downhill to now 2007-2012 levels this month.  That the danger of modern summers when you get something good then a bad one come and will destroy everything on the path without any recovery or good weather attempt to fight back failed until September that end this problem.  Models now pointing a good September start and this Sunday just 1 day quickie heat since is a modern summer quick hot few hours spell, uppers going up to 20C in the morning to high teens uppers by noon so low 30's if conditions are right like 31-32C was recorded last Saturday. 

When we will see a return of 90's to mid 00's hot spells? Probably gone for good.  Quickie heat does no good or usable at all.

You mean like a couple of years ago in 2013 when virtually the whole of July was hot? With 19 consecutive days over 28C? Yeah, summers are dreadful these days 

That under exceptional hot summers with 2006,2003 and so on. but on other normal summers prior to 2005 had a weekly heatwaves and proper settled spells which had long disappeared and now only a quickie hot spells from 2007 onward which GFS showing it for Sunday, far too short for my liking.

Compare GFS (left) with ECM (right) and it's clear that even at 4 days range the weekend is a long way from sorted. GFS has already cleared the rain and warm air away from the south by Sunday morning - faster than most recent runs - while ECM appears to have the boundary stuck over Southern England.

I'm not entirely sure where precipitation would lie on the ECM run, as it's different to any previous GFS run. It does have support from UKMO but the rainfall charts for that model are no longer on public display. So maybe a chance that the far SE sees a very warm day, otherwise the risk of a very wet day seems more concerning given the recent deluge across southern parts.

We actually come very close to some exceptional late-summer heat this weekend. If the jet stream was weakening sooner and digging further south, we'd have a pretty epic plume on our hands. That'd take an insanely large adjustment at such short range though, so it's safe to anticipate a weekend of fairly average temps at best for the most part, maybe nudging into the mid-20's in the SE on at least one of the two days, and with that risk of heavy rain that we seem to be having a hard time shaking off for more than a few days at a time.

Next week could well change the game though, as a strong ridge of high pressure slowly advances from the west. It may take it's time to bring a total break in the rain though - with relatively cool air aloft and a good chance of some sunshine to warm the ground each morning, the first two or three days of the week threaten some heavy afternoon showers.

After that, we need to hope that the clash of that cool air with the hot air over parts of Europe doesn't lead to low pressure development close to our shores. Good thing is, there's been little evidence of that from recent model output, and in fact there are signs that LP may develop well south of the UK and 'prop up' an area of high pressure over us, prolonging the dry spell at least a little.

Another possibility is that the high pressure retrogresses to Greenland instead of progressing to the UK. ECM and GFS have trended away from this over the past two days, but GEM continues to practice for the silly season:

For anyone who's new here and hasn't experienced the late autumn and winter shenanigans, the above chart is the sort of thing that drives the place nuts - it's a way of bringing deep cold from Siberia while destabilising it at least a little... it's not hard to guess what that can bring! It's not usually all that effective until late December, though, so put those ski boots away