C'mon.

Message omg. The GFS on it's own for Thursday 26th June to Friday 27th June 2014, will the SE tracking N Atlantic Low with Sub 546 dam air win as per 12z UKMO and ECMWF runs, the High Pressure still dominates on Wednesday 25th with some very warm sunshine, but after that Cooler and breezy with 1000 - 1005 millibar Cyclonic UK Low approaches by Late Wednesday and particularly by Midday Thursday, thundery showers and a band of heavy rain is expected if ECMWF and UKMO Models are together on bringing this relief Summer hailstorms / thundery rain hail showers.

Looks like the West and SW could see some flash flooding albeit for a day or two!.

Is the last week of June 2014 looking like that of 2009 I must think, or was it 2008 Re: hail and thunder showers even in London 26-27 June it was in memory lane.

Well the weather of Junes and July's at the 25 June to July 07time periods I have taken look at the differences between years 2008 and 2009 and also looked at 2013 last year and compared the differences - the UK weather has more often been dry very warm or just warm and sunny ish, that varies with differing temperatures but some years though less often taken from the above two sets of two years each twinned up, for space out of 5-6 years of UK weather at 500 hPa pressure pattern, there also are some very wet and cool periods at this specified period with fairly large and extensive plus deeper Low's having affected us in some years.

Last year was really warm very warm and sunny but some June Low Pressure with heavy rain or showers and strong winds also came along for a time, but it was dry and sunny for longer.

The GFS Model on it's own right now, but maybe the ECMWF that backed today's Active Low pressure Thursday and Friday which the GFS is having none acceptance that they will verify- I think the High Pressure and dry warm sunny periods of GFS May by Tomorrow need UKMO and ECMWF to back it up which is quite easily the more credible possible outcome- still not clear cut, the charts appear to have a funny High Pressure Zone that covers our part of the world in the next Week coming- it is still in the realms of having an effect just as GFS and ECMWF led the UKMO at mid June this year what went on with very warm sunshine but a thundery breakdown did occur- I am talking about pre- Tuesday 12th June there happened to be a 5 day spell at least of very warm humid sunny spells and this June has been very good at times with that but there has been about two weeks of fairly dull and or cloudy weather in two long spells of the cloudy and very cool conditions in London and SE England.

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Bloody glad someone mentioned that one - A sunshine summer deficit of 500 hours since 2007. I think that can be applied to most of us really since. Now that will take some impressive synoptics to rectify that one.  

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HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY SUNDAY JUNE 22ND 2014.

THE CURRENT GENERAL SITUATION. A slowly weakening area of High pressure lies just to the West of Ireland with a strong ridge maintained over England and Wales.

GFS The GFS Ensembles today shows a lot of slack pressure gradients across the UK over the next 10-14 days. As a result the current period of light winds will persist. With no specific weather feature over the UK these light winds will continue to promote a lot of dry and bright weather with sunny spells and being we are approaching mid Summer it will feel warm. With some upper air troughs across the UK at times showers may become more of a feature with time and though scattered these could be heavy and thundery at times. It's not until later in the run when a more definitive SW flow is shown with more organised rain at times likely then in the North and West while the South and East stay largely dry, bright and warm.

UKMO UKMO shows Low pressure gradually sinking SE across England later this week and away to the SE by the start of next weekend. There would still be a fair amount of dry, bright weather around but in association with this Low pressure scattered thundery showers would become an increasing possibility later this week and the start of the weekend gradually focusing more towards the SE.

GEM The GEM operational today is also showing a spell of cooler uppers over the UK with upper troughs increasing the risk of showers later this week and next weekend in light winds. Late in the run a more definitive retraction of the weather into windier and wetter weather is shown with a deeper Atlantic depression crossing East over the UK bringing temperatures back down to average for all.

NAVGEM NAVGEM today shows a slow fall of pressure as weakening low pressure areas aloft trundle across the Uk from the west later this week. The dry and fine weather currently would become more punctuated by a greatly increased risk of showers by midweek and thereafter though general rain and stronger winds look unlikely with further sunny spells in between the showers.

ECM The ECM operational today completes the common ground between the models in showing showery Low pressure moving across the UK later this week with slack pressure gradients following next weekend before a warm frontal systems edges up from the SW early next week. So showers are likely scattered about from Tuesday onward, heavy in places with thunder possible. This lasts through the weekend with the risk continuing towards the end of the run with more general cloud cover by then and perhaps more general rain into the SW by Day 10.

MY THOUGHTS  This morning continues to show the models struggling to handle the synoptic pattern as we move through this week. The general consensus is for pressure to fall somewhat and the risk of showers increase from as early as tomorrow on. However, there is no clearly defined Low pressure areas shown this week with just upper atmosphere disturbances moving gently ESE across the UK creating an increasingly volatile atmosphere and making it become the breeding ground for heavy showers especially towards the East and away from the coasts. In these slack patterns in Summer many areas maintain predominently dry and warm weather at the surface and I see no reason why this won't still be the main focus of the weather for most even at the end of the week. Further on into Week 2 things may turn more generally windier and cooler as more of an Atlantic based Westerly breeze is hinted at developing but my thoughts remain that any effect from this will only be towards the North and NW where rain at times could become much more of a feature while the South and East see warm and bright weather with some sunshine and little chance of significant rain as pressure builds close to the South.

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Looks like heavy convective shower risk by Thursday with a risk of thunder continuing into next weekend.

Beyond that difficult to tell.

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It's a bit hard to comprehend the models at the moment;

 

The past 48 hours has seen a considerable reduction in the modelled Atlantic jet strength.

The models have then been trying to figure out what will actually happen as a weak jet stream wafts a shallow trough in our direction.

The results have been very varied indeed, with the toning down of the jet differing from model to model.

There has, though, been a net movement towards the idea of a trough sliding SE... or at least trying to.

 

UKMO has a relatively clean evolution, where the trough crosses the far SW on day 4 and then develops slightly in the Channel on day 5, before moving swiftly on to lie to the SE of the UK by day 6. A decent ridge builds across the UK and over the top of the trough, seemingly destined to find a foothold across Scandinavia.

GFS seemed to be following UKMO at first, but then came up with a wild card - a second trough develops near the Azores, and interaction with the first trough causes that one to stall rather than slide SE. The trough near the Azores then takes over procedings, gradually moving in from the west, with a weak ridge ahead of it bringing some very warm conditions with afternoon showers for next weekend and into the following week.

The Atlantic jet then ramps up massively through lower-res (FI), which obviously should be viewed as an extreme case scenario based on the way GFS likes to behave.

GEM hasn't toned down the jet as much as the above two models yet, and as such there is still a bit of an 'Atlantic train' scenario portrayed.

 

Soon we can find out whether ECM and JMA are also seeing this weak sliding trough scenario or not.

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A fascinating ECM 12z op run has rolled out...!

https://max.nwstatic.co.uk/ecmimages/20140622/12/ecmt850.120.png

At day 5, it's similar to UKMO, and I reckon there's a bit of a split-jet situation to the west of the UK, which explains the troubles the models have been having;

 

At the split point, the jet breaks into two 'arms', one tending to run NE and the other SE. The one going NE tends to favour troughs progressing eastward and flattening ridges, while the one going SE favours troughs sliding south/southeast and heading beneath (by which I meant to the south of) ridges of high pressure, which then allows those ridges to build into strong features.

At the mid to long range, the models nearly always have the northern arm too strong and the southern arm too weak. Corrections on future runs then weaken the northern arm and may strengthen the southern arm too, though not always (ofteb the overall jet strength is reduced and most of this loss taken from the northern arm).

Over the past four ECM and UKMO runs, such an adjustment has taken place. The ECM 12z is a very good example of what tends to occur when most of the energy goes south but without there being all that much energy overall.

 

The northern/southern arm modelling tends to waver about a bit across the runs, so the output could easily swing back to more of an 'Atlantic train' scenario again tomorrow, but I for one am hoping that it doesn't!

 

...so what about the rest of that ECM 12z op run then? Well...

https://max.nwstatic.co.uk/ecmimages/20140622/12/ecmt850.192.png

There is a huge transfer of energy across the U.S. days 6-7, bringing a sudden increase in the strength of the upstream jet stream.

Both ECM and GFS have a trough near Greenland on day 6, but ECM is the only one to combine that feature with the one crossing the U.S.

This is important because if the troughs combine, a lot of energy is expended by the resulting intense low pressure system, whereas if they don't, much more of it moves on into the Atlantic and develops storms that can track towards the UK, with GFS managing to throw them right at us with unseasonable ferocity.

 

The way ECM evolves is truly excellent for longer-term prospects:

https://max.nwstatic.co.uk/ecmimages/20140622/12/ecm500.240.png

A weakening trough is cut-off to the SW, with no means of tracking towards the UK, while there is a strong trough complex extending between Greenland and Canada, which is pretty much the best place to have it when looking for decent summer weather 

 

We do need a lot to come together to achieve something like that ECM run though - best not to set your hopes that high, but there's plenty of reason to have higher levels of hope than 24 hours ago 

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i think the general opinion is that early july will be o.k. it is the final2/3rdsthat is not looking so good with longer range models showing a fairly deep trough over the u.k. with the current high sea temps any feed of colder air is going to develop areas of low pressure.

The Friday update of the EC-32 day run last week had a more unsettled first week and then a fortnight under a strong ridge of high pressure, so it depends which model you look at.

I've seen plenty of CFS runs bringing a fine couple of weeks in July too... so by and large I'm seeing good signs for that month to be at least reasonable when considered as a whole.

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The GFS 18z op run is in line with the ECM 12z op run and the 12z UKMO op run to day 6.

The mid-Atlantic trough doesn't make a lot of progress east days 6-12, with intense heat building across Europe and the UK on the periphery - above average temperatures, hitting the mid-20's or so at times, but with some hefty rainfall around.

Then, the pattern backs west a bit, and it turns settled and becoming very warm.

 

That's a nicely familiar story that fits in well with the tendencies of the summer so far... could this be the true solution emerging at last? With the key developments taking place in the 5-6 day range, I'm feeling optimistic, but also wary of it all being shattered tomorrow morning! 

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HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY MONDAY JUNE 23RD 2014.

THE CURRENT GENERAL SITUATION. A ridge of High pressure continues to lie from the Azores to Ireland while a weak trough slips SE down the North Sea through today and tonight.

GFS The GFS Ensembles today shows showery Low pressure developing over England and Wales later this week and through the weekend with higher pressure persisting to the North of the UK. Next week shows a better period as High pressure again ridges up from the SW across most parts but this in itself proves relatively shortlived as further Low pressure brings a return to showery weather late in the period.

UKMO UKMO shows a broad and ill defined surface High pressure ridge lying NE across the UK next Sunday but with upper instability a few showers could defy this ridge though there s still a lot of dry and bright weather shown across the UK even though temperatures will of falllen back somewhat by then.

GEM The GEM operational today shows the main theme of High pressure down to the SW with the UK lying in nomansland at times while at others shallow Low pressure areas slip down from the NW delivering an increased risk of showers at times while at other times dry and bright weather will predominate.

NAVGEM NAVGEM today shows a slack Low pressure area across the South later this week and into the weekend with sunshine and showers the likely pattern of events while High pressure down to the SW remains interested in returning a ridge NE towards western Britain by early next week.

ECM The ECM operational today is in unison with other output in the short term bringing showery Low pressure across the UK later this week and into the weekend with some heavy showers in places. Winds are then shown to settle into a Southerly quarter as pressure falls to the West and SW with Low pressure likely to push North and East across the UK early next week.

MY THOUGHTS  The model output this morning show a slow decline in conditions through the week to come with a highly increased risk of showers. This risk looks to be greatest across the South and East later in this week with parts of Scotland becoming or staying largely dry and bright. There will still be a fair amount of bright, warm and useable weather around for outdoor activities. In the mid to longer term things are still very unclear with some output suggesting a return of the ridge from the SW at least for a time next week while ECM looks more threatening with Low pressure eventually setting up just to the West and SW with rain spilling NE at times for some. However, this needs to be seen in context with it's ensembles released later this morning before much credence can be given to this evolution. No output this morning suggests anything notably chilly and when the sunshine breaks through between the showers it should continue to feel reasonably warm in what should be very light winds throughout.

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I've just taken a look at the MetO surface pressure charts, and what a change compared to yesterday!

Instead of fronts and low pressure attacking us from the W/NW there's a 'slider' on the SW approaches.

If only it was winter etc etc...

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Heavy scattered showers more than anything rather than persistent rain.

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As usual, the apparent clarity of last night has been lost in a fog of uncertainty.

 

ECM and GFS now have the sliding trough clearing away a bit more slowly and then developing more substantially once located some way to our east, which interferes with the development of the ridge ahead of those Atlantic storms later next week.

ECM then has enough upstream amplification to send the jet diving south while well west of the UK. This produces a large trough to the SW of the UK, ahead of which a ridge of high pressure holds on, potentially becoming a blocking feature if the trough to our E/SE lends support (an omega block, where the jet follows a pattern similar to the Greek Letter omega.)

GFS just fires the jet straight across the Atlantic and through the UK. This almost always gets adjusted to a more amplified (i.e. wavy) solution on later runs, so I'm not paying it too much attention. Alas, the FIM model also has this super-flat jet going on.

UKMO and GEM still have the faster sliding trough from yesterday, and show a more decent ridge building in behind. GEM then has the increase in Atlantic jet energy blasting NE, which works out well for us as it encourages further ridging of high pressure through the UK.

 

In conclusion, the situation beyond Friday is all to play for!

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Hi all,

Here's today's video update:

Fine Weather Breaking This Week, But For How Long?

www.gavsweathervids.com

Using Brian's CFS monthly anomalies today for the first time!

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http://www.wetterzentrale.de/pics/Rukm961.gif

http://www.wetterzentrale.de/pics/Rukm1201.gif

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

Sunshine and heavy, thundery showers from the Met/o 12z this evening.

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Some large differences between the models in the placement of that LP on day 4... getting a bit tired of their shortcomings to be honest!

ECM places it furthest SW, UKMO/GEM the furthest NE.

 

GFS gradually clears the LP away east and has a faint sort of ridge before the Atlantic lows steam across in FI.

UKMO appears to be along similar lines.

ECM continues to develop a more amplified upstream pattern, with the Atlantic LP dropping south to lie to our SW, working in combination with a ridge through the UK to bring a potentially hot few days starting 11 days from now. Yeah - 11 days, so not worth thinking about much at this stage!

GEM... yikes. That model manages to stall the trough right over the UK for several days, before finally clearing out on day 9.

 

Little consensus to work with from the weekend onwards, really! 

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The latest fax chart has that low as a nasty feature crossing Southern England on Saturday.

I think we could get some heavy rain and thunderstorms out of that with the best weather in Western Scotland and some very cool conditions on the east coast.

It's all going down hill lads!

Andy

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As James said last night, conditions remain difficult to call going forward.

Friday looks like a waterfest though, especially down here.

The key will be how quickly this cut-off feature moves on and how strongly pressure builds in behind it.

ECM continues to show a low approaching in FI which could inflate a ridge allowing some heat :)

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY TUESDAY JUNE 24TH 2014.

THE CURRENT GENERAL SITUATION. A ridge of High pressure continues to lie from the Azores to Ireland which will weaken slowly as a trough of Low pressure affects the far NW.

GFS The GFS operational model today sees the UK under shallow areas of low pressure lasting from 48 hours time until well into week 2 of the run. This is also endorsed by the ensemble charts as well making for a strong chance that the weather will become much more showery in nature with temperatures gradually becoming more suppressed to average levels. Late in the period both the operational and ensemble pack show a trend for the most unsettled weather to shift further North to the North and West while Southern areas could become drier and warmer again.

UKMO UKMO today shows Low pressure over Southern Britain at the weekend with plenty of showers and thunderstorms possible in places while the North are less likely to see widespread showers. The close of the run shows this Low pressure only slowly exiting east from East Anglia still bringing showers to many parts of the South in particular.

GEM The GEM operational today shows a belt of Low pressure once formed stretching across the UK from the end of the week until the end of the run when a more potent area of Atlantic Low pressure down to the SW replaces the showery theme of much of the run with stronger winds and rain by the end sweeping up from the SW.

NAVGEM NAVGEM today shows Low pressure hugging the South of the UK later this week, through the weekend and start to next week bringing a heady mix of bright intervals and showers and temperatures much closer to average than of late.

ECM The ECM operational today also shows that once showery low pressure arrives later this week it is reluctant to clear away anytime soon with the weather at Day 10 still a basically showery one as an unstable WNW flow blows across the UK with temperatures declining to average levels.

MY THOUGHTS  The models show a lot of common ground this morning in as much as they all show that once the showery theme of Low pressure arrives later this week there seems a lot of support for keeping the risk of showers very much alive for all areas thereafter. If I had to pick a favoured area to stay drier then I would choose the far North as well as coastal regions elsewhere as always in Summertime with convective showers capped in these areas due to sea breeze influences. With shallow Low pressure shown by all models for a lot of next week most places will see at least a little rain while others may see rather more with thunder a possibility. In the far reaches of the output this morning there is a weak signal for pressure to want to recover to the South of the UK and should this occur then the risk of rain would retreat to NW Britain while the South could become drier and warmer.

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Thank you Martin for the output. Showery activity will be welcome for the garden.

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Thanks Gibby.

At least it's not going to be zonal although with more if a northerly drift next week I imagine it will be cooler than earlier in June when we had a similar showery theme.

Andy

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Surprise!

A very slack LP sat right over us is now the consensus for next week.

Good thing is, the airmass within doesn't look to be too cool, so temperatures could still be climbing into the high teens to low 20's across many areas, which with light winds would feel pleasant enough out of the showers.

The flipside is lots of slow moving downpours which could bring some issues with high rainfall accumulations in short periods of time.

 

Beyond that, still very uncertain. The Atlantic push appears to have been toned down a bit on ECM and GFS, with hints that it might not make it as far east as the UK, which is encouraging and seems more 'fitting' now that we have that UK trough scenario for next week.
A blocking high appears to try and develop to the north of the UK trough as it drifts into the continent, which could explain the Atlantic being held back more.

GEM and FIM have the Atlantic trough coming along faster, causing it to slide SE to the UK, which is not a nice sight - looking for those westerlies to be toned down as usual! 

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So the outlook is a convective one.

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Hi all,

Here's today's video update:

Unsettled Weather Being Upgraded Next 8-10 Days

http://www.gavsweathervids.com

Will be interesting to see how long this unsettled goes on for as we move through high summer. Sometimes when the pattern changes like this it never completely settles again, but early July is often an unsettled period, so hopefully by second week of July we'll be back to HP.

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...and now the LP is moving along more quickly again.

UKMO and GFS both have it on the way out on day 5, with a ridge arriving from the west through day 6.

Then with a marked trough developing in the Greenland area, it seems that the main eastward progression of LP should cease somewhere in that area, with those storms then either heading off NE or sliding SE to pass west of the UK.

Yes - I do say west, rather than to the NE as GFS shows, because that model often sends sliders way too far east at the 7+ day range.

 

My thoughts are in fact close to what ECM was showing on yesterdays runs. Today's 12z could potentially revive that theme.
GEM sort of has it this evening, though not in the same way.

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