Model Output Discussion 30/06/2012

[Thundery wintry showers]

The T+216 and T+240 charts would probably still bring dry weather in my opinion but it would be cool in the east and there might well be a fair amount of cloud. However, it is significant that the onset of cooler cloudier weather has not only been toned down on the latest ECMWF run, but remains confined to the last three frames of the run (T+192 onwards). Thus, apart from a brief interlude on Monday/Tuesday as a frontal system heads SE, it looks like the theme within the realistic/reliable timeframe will be for increasingly dry and sunny weather, with daytime temperatures close to or above the seasonal average after a relatively cool day tomorrow.

[Milhouse]

Would there not be light rain coming down from the north on the last chart,

Maybe some low cloud and occasional drizzle for eastern coasts.

[Frank Trough]

Would there not be light rain coming down from the north on the last chart,

well possibly, but it's at t+240! Even then, that chart has quite a bit more potential than we've seen since May! Add to this the fact we're going to get a decent weekend, excellent week (for the south in particular) next week then i'm a lot happier than i was two weeks ago!

Tonights ECM (yes, i know, FI, one run etc etc) is an improvement on the last couple in that it keeps the high much closer for longer and delays the retrogressing northerly.....it's much more like the GFS tonight at t+240.

Surely this is a time for half full glasses for the majority, isn't it?

[William of Walworth]

Surely this is a time for half full glasses for the majority, isn't it?

All recent updates looking truly excellent for sun and summer-preferrers. Just scanned most of them.

And as for that bit i've bolded above :

Completely full (w cider!) very soon ), since we're going to be at our first music festival (of several mud dominated ones, this so far dismal 'summer') that's going to be mostly, then completely dry, from tomorrow through to Monday .... (it's on the Powys/Herefordshire border)

Edited July 19, 2012 by William of Walworth

[Jason T]

Hellooo,Am I the only one with a childish manner truly over the moon with is current output,2 weeks ago it was wash out low after wash out low. This has been an incredible pain staking 3 month period for Model output. Ecm was truly bliss in comparison, I get the impression some are still not quite content with what is now being shown,How long will it last who Know's.It may not be the ultimate pattern change but it still wins Olympic Gold in my book.

Enjoy.

[Jezzer]

All looking nice and positive, I just wondered can anyone nail down the last Friday when we didn't have a low rattling into us, they were becoming very tedious? This weekend will certainly make a very refreshing change

Edited July 19, 2012 by Jezzer

[Milhouse]

Indeed its looking very good at last. Over the next 2 weeks all areas should see a taste of summer. With the high meandering around the UK we should expect coastal areas to be cooler and cloudier on occasions, but that is the exception to the rule.

[Cloud 10]

All looking nice and positive, I just wondered can anyone nail down the last Friday when we didn't have a low rattling into us, they were becoming very tedious? This weekend will certainly make a very refreshing change

First day of summer.

[Summer Sun]

The ECMWF ensemble continues to support the idea of a pressure rise

Nice to see the ensemble run becoming consistant as well

[chionomaniac]

Having looked at all the models and ensembles and MJO forecasts I am still of the opinion that I had yesterday.

That is that we are about to see a settled spell with Azores ridging becoming more dominant to the end of the month. That at the turn of the month we are likely to come under attack from a trough spilling down the eastern half of the country from the north. And after that the Azores ridge is likely to become dominant again.

This is in fact reinforced tonight by even stronger support in the 6-10 day ECM ensemble anomalies than we have seen all summer.

Any southerly jet stream attack is likely to be repelled strongly by this ( other than on the easterly side)

Furthermore the MJO forecasts are even more favourable.

A lot of faith seems to be shown in the ECM 32 day forecasts from a couple of days ago, but these are liable to change and remember the further out in FI these are the less reliable. The 8-14 day 500mb outlook is good still - and that is halfway through the ECM long range ensemble forecast.

I think I need to see stronger signs that the jet stream will return south before agreeing with the ECM 32 day outlook.

[summer blizzard]

I personally would be quite wary of looking at the high to the west remaining and thinking that sunshine and warmth would be the result, the GFS12z verged on being a mild outlier indicating that the upper air pattern is much more in line with the ECWMF which had the potential of producing a lot of cloud with cool uppers.

Certainly it does look like remaining settled however i fear an August 2008 scenario is upon us however it is late July so there is potential for the sun to have the strength to break through.

[chionomaniac]

I personally would be quite wary of looking at the high to the west remaining and thinking that sunshine and warmth would be the result, the GFS12z verged on being a mild outlier indicating that the upper air pattern is much more in line with the ECWMF which had the potential of producing a lot of cloud with cool uppers.

Certainly it does look like remaining settled however i fear an August 2008 scenario is upon us however it is late July so there is potential for the sun to have the strength to break through.

Mean 12z GFS air pressure ensembles keep slp above 1020mb through til August though.

[johnholmes]

A lot of faith seems to be shown in the ECM 32 day forecasts from a couple of days ago, but these are liable to change and remember the further out in FI these are the less reliable. The 8-14 day 500mb outlook is good still - and that is halfway through the ECM long range ensemble forecast.

I think I need to see stronger signs that the jet stream will return south before agreeing with the ECM 32 day outlook

yes I would agree with these comments-still a fair amount of uncertainty but I still feel like a post 24 hours ago, 40% for the ECMWF 32 day outlook (or what I gather it has shown) and the 60% prob as ch suggests in his full post above.

Edited July 19, 2012 by johnholmes

[Cheese Rice]

12Z/18Z is a interesting run.

A few wet days possible for the south with the north seeing the best of the warm/hot sunny weather.

Tuesday-

Wednesday-

It's been showing on a few runs now, 25-27.c possible in Northern England, in comparison the south seeing temperatures ranging from 17-22.c under cloud and rain. This only lasting for two days though (Tuesday/Wednesday) with the south seeing the warmest of the temperatures on Monday and Thursday.

Still I'm pleased to see the rain further south as it at least gives Northern England a good chance of seeing some sunny warm weather.

Edited July 19, 2012 by Cheese Rice

[A Winter's Tale]

Well how about that, you get a shocking first half to the summer then you get some very warm temperatures, widespread sunshine and a high pressure dominated outlook and finally we get to say goodbye to the greenie high...........................for now.....!

Quite a few places today has some sunshine but there plenty of showers around too and across a good part of England and Wales showers will continue well into the night. The north sea coast, parts of central Scotland, good chunks of Ireland and the SW may have good clear skies tonight and minimum temperatures are likely to be at 10C in the north to 15C in the SE. Early tomorrow morning showers will still be present across the southern half of England and Wales so central England could have a cloudy start. Elsehwere, there could well be some good early morning sunshine. As the morning goes on sunshine should become a lot more widespread away from northern Scotland and the shower activity across parts of Western/Central England. And the showers will continue well into the afternoon but everywhere else in Wales, the SW, northern/eastern England, Ireland and also Scotland should have a good sunny afternoon and maximum temperatures across the British Isles should max at 14-18C. The showers should die away in England and a largely dry and clear night for most seems likely away from the light rain in the far north of Scotland. Quite a cool night with typical minimum temperatures of 9-13C.

Saturday looks like being a very decent day again with widespread and plentiful sunshine for a good parts of the country. Scotland may be a little more cloudy with light showers around northern coasts. Maximum temperatures should be 16-22C. Saturday night will again by dry for a good part of the British Isles with plenty of clear skies in the southern half of England. Skies may be a little more overcast in Ireland, northern England and Scotland as we have a cold front moving in from the west so Ireland and Scotland are at threat of getting heavy rain in the night - especially in the western areas of the countries. Minimum temperatures should be 13-15C so a little milder than the previous night.

The majority of England and Wales should have a sunny and warm day on Sunday. Maximum temperatures will be around 17-20C in the north and 21-23C in many areas south of Manchester. Far NW regions of England and Wales and the majority of Ireland and Scotland should be more overcast and western areas of Ireland and northern and western parts of Scotland should experience some heavy rainfall. This band of rain should lose intensity but most of Ireland and Scotland should see some rain as it moves eastwards into the night. Elsewhere, England and Wales again should have a largely dry night away from the far NW and western areas of Wales and the northern third of England may have a cloudy night compared to the clear skies further south and east. Minimum temperatures should 13-16C.

Monday indeed looks like being a very warm and even hot day with maximum temperatures of 25-28C around the London area south of Manchester temperatures will still be warm at 21-24C. In Scotland, Ireland and northern England temperatures of 17-20C are possible. The southern third of England and Wales should have another sunny and dry day but again Ireland, Scotland and northern Wales and England could be cloudy and some damp weather could be possible in western areas. Any damp weather during Monday should become less widespread into the night but again there seems to be a north/south divide between cloud cover and clear skies with Manchester right on the border. Minimum temperatures could be 13-16C.

So certainly a much drier next few days with lots more sunshine but a north/south divide is likely in terms of cloud/sun. Some very warm temperatures are likely in the south come Monday. The settled conditions may slowly edge it's way further north next week but the far south again will see the best of the settled and warm weather. The Azores high moving north eastwards is responsible for the developing settled weather in the next few days but during next week the models are showing high pressure out in the middle of the Atlantic and this may move further eastwards to build on the settled conditions already established so even northern areas could join in. I wouldn't look beyond the end of next week as first and foremost we know that settled conditions will develop in the south over the next few days and that high pressure out in the atlantic will have an influnce but the timing, movement and positioning are all crucial in mapping out on what will precisely happen as any subtle changes could be the difference between how hot it gets and how long and widespread the settled spell will be. The realms of FI show the high pressure leaving the British Isles as it moves eastwards but I wouldn't worry about that and for a spell of less settled weather to follow is very normal. The Greenland High doesn't look like making a comeback yet and with the Azores High still present at the end of the run, what COULD POTENTIALLY happen in August is that we see interludes of warm, settled conditions and cooler, showery and wetter conditions which is very typical British summer weather.

[Snowy Easterly]

12Z/18Z is a interesting run.

A few wet days possible for the south with the north seeing the best of the warm/hot sunny weather.

Tuesday-

Wednesday-

It's been showing on a few runs now, 25-27.c possible in Northern England, in comparison the south seeing temperatures ranging from 17-22.c under cloud and rain. This only lasting for two days though (Tuesday/Wednesday) with the south seeing the warmest of the temperatures on Monday and Wednesday.

The 500 SLP pressure charts or whatever they are called are really starting to annoy me now, they give a false illusion of nice warm sunny weather, with high pressure, but the chart you posted for next Wednesday shows rain over the south, you wouldn't think it by looking at a chart like this

http://cdn.nwstatic....141/h500slp.png

you have to be wary and check other things like 850's and precipitation in situations like this as it could quite easily fool people, and it fooled me tonight, why can't the weather in our country ever be straight forward

Also even though the ECM looks nice it might not be if cloud filters into the east in FI from a northerly, but again you wouldn't think it as the charts look nice,and it doesn't tell the real story http://cdn.nwstatic..../ecm500.216.png

Edited July 19, 2012 by Snowy Easterly

[reef]

The 500 SLP pressure charts or whatever they are called are really starting to annoy me now, they give a false illusion of nice warm sunny weather, with high pressure, but the chart you posted for next Wednesday shows rain over the south, you wouldn't think it by looking at a chart like this

http://cdn.nwstatic....141/h500slp.png

you have to be wary and check other things like 850's and precipitation in situations like this as it could quite easily fool people, and it fooled me tonight, why can't the weather in our country ever be straight forward

Also even though the ECM looks nice it might not be if cloud filters into the east in FI from a northerly, but again you wouldn't think it as the charts look nice,and it doesn't tell the real story http://cdn.nwstatic..../ecm500.216.png

Thats the problem when when it is assumed that high pressure = warm and sunny. Being an island even at this time of the year when the sun is strong and seas relatively warm we're still very much reliant on wind direction, air source and lack of air modification being favourable.

This is the main issue with Azores high ridging, its just not a totally reliable way of getting warm, sunny and dry weather. If the high is too far out in the Atlantic then cloud and drizzle can be dragged around eastern flank of the high (as above) with passing features. Likewise if the ridge is too far north then heights drop over Southern areas and this can drag in cloud and showers. By far the best setup in summer for warm/hot and sunny weather is when the Azores high throws a ridge into Europe which then breaks away and we drag in a warm (and more importantly) dry flow from the continent. Modification isnt an issue over the sea as the track to the UK is relatively short, so warm sunshine usually results.

[Snowy Easterly]

i really hope the 18z has gone off on one, as the control run shows the high going too far west into the atlantic by thursday, and we know how much high pressure loves to retrogress west in summer but im not ignoring it just because its not what i want to see, FI for me is T120

Edited July 19, 2012 by Snowy Easterly

[Thundery wintry showers]

That trailing front on Monday-Wednesday may well cause us some more forecasters' headaches over the next couple of days. Until this morning it looked like it was going to take until late Tuesday to get south of the Scottish border and probably fizzle in the process, this morning it looked like it would move south more quickly, and now the GFS 18Z has a persistent trough pepping up the rain belt over southern areas on Tuesday and Wednesday.

It rather reflects what Reef was saying above- in this case the complication is arising from a significant Atlantic influence on the northern flank of the ridging Azores High, something that rarely happens when we get a "breakaway" high situated over central/western Europe sending in a sluggish import of dry continental air (incidentally a setup that the ECMWF had been showing a couple of days ago, before revising the high pressure positioning somewhat further west). It doesn't rule out a generally warm sunny spell of weather for most parts of the country, but it does mean that it's now far from straightforward.

Similarly for the long-term it is not straightforward as sunshine and warmth are on a knife edge when the high pressure is centred to the west. The GFS 12Z showed how we can still get a generally warm and sunny spell from that setup, but the GFS 18Z shows us how it can end up very different with just a slight change in the orientation of the high- the cooler cloudier conditions with light showery rain heads down the eastern side of Britain rather than the North Sea.

Despite the uncertainty it still looks unlikely to be as cloudy, and certainly not as wet, as most recent weeks have been, whatever happens.

[Lincs Observation]

Morning all. Just checked out the models this morning and its so frustrating to see that Azores high just sitting and meandering right at the end of our fingertips. Its so close to the Uk you can smell it however that pesky jet is like a Bakery shop window, You can see the cakes, smell the cakes but the glass wont let you touch the cakes. LO

Edited July 20, 2012 by Lincs Observation

[Jezzer]

The 00Z isn't what I wanted to see when waking up. Everything looks a bit too far west for my liking. This is starting to get very frustrating.

Models certainly seem to have tweaked things over the past 24 hrs

[Roger J Smith]

I suspect the models may be underdoing the extent of ridge-building that will develop over western Europe and that the eventual outcome will be stagnant high pressure over the UK and Ireland with a hot southeast surface flow in southern England and virtually no wind for days in some central regions. In other words, a heat wave. The GEM is leaning towards this outcome and has been quite good all month on developments in North America with the extreme heat (not to say the other models have been poor).

We shall see, but I'm predicting the evolution of a heat wave that might last quite some time as they tend to do at this time of year. It would be ironic if it turned out too hot for the Olympics (in Britain), although I suppose the track athletes will be loving it. Sailing might need a bit more of a gradient wind than appears possible on some long-range charts.

[Alex]

Apparently the GFS 00z is showing 23mm of rain on Wednesday in Chelmsford, Essex. You having a giggle with me GFS?!

The models are over doing the cold front, however I think that it may get stuck across central areas and produce 2 days of cloud for some.

Onto teleconnections, the MJO is showing a move into phases 4/5, angular momentum is steady and the GWO is moving into phase 3, a continuation of the more north/south divide looks likely with perhaps the ridge more east with time covering a greater part of the country.

Edited July 20, 2012 by Alex

[Alex]

I suspect the models may be underdoing the extent of ridge-building that will develop over western Europe and that the eventual outcome will be stagnant high pressure over the UK and Ireland with a hot southeast surface flow in southern England and virtually no wind for days in some central regions. In other words, a heat wave. The GEM is leaning towards this outcome and has been quite good all month on developments in North America with the extreme heat (not to say the other models have been poor).

We shall see, but I'm predicting the evolution of a heat wave that might last quite some time as they tend to do at this time of year. It would be ironic if it turned out too hot for the Olympics (in Britain), although I suppose the track athletes will be loving it. Sailing might need a bit more of a gradient wind than appears possible on some long-range charts.

Quite possibly, problem is that it has little support from any of the GFS ensembles. Will be interesting to see the ECM ones.

[shedhead]

Something of a switch around this morning on the 00 runs . GFS is now being pretty bullish about a much cooler, more unsettled breakdown from the north as early as T+168hrs, whilst ECM which was singing from a similar hymnsheet this time yesterday now maintains relatively high pressure, with the more unsettled stuff heading into S Scandinavia. That said the trend does now look set for this type of evolution, the main questions being can we keep the rubbish far enough east to allow another quick rebuild of pressure, or will this signal the start of significant retrogression and the return of cooler, generally unsettled (tho nowhere near as unsettled as of late) conditions? Personally I still feel the latter is more likely.

Edited July 20, 2012 by shedhead