Model Output Discussion 26/08/2012

[mushymanrob]

It has been the wettest summer on record,who got anywhere near forecasting that?

harsh but correct. i didnt see 1 forecast that we would even get a prolonged wet summer let alone the wettest since... with all due respect to forecasters here and elsewhere.

[Gibby]

Good morning. Here’s my interpretation of the 00zs today.

All models this morning show the same pattern as yesterday with the basic pattern of High pressure close to the SW and Low pressure well to the North. A Westerly flow blows across all of the UK with some weak troughs affecting the North while further South a lot of dry weather is expected with some good sunny spells mixed with cloudy periods with the chance of a little rain as weak cold fronts cross SE, this most likely on Sunday and Tuesday. By Wednesday a more notable period of better conditions develop as High pressure builds further North over the UK.

GFS continues the basic synoptic pattern described above late next week and over the weekend with High pressure covering the South though still the occasional front crossing the North. It will be warm and sunny in the South though with light/variable winds. Then in FI High pressure transfers slowly East to the Baltic Sea with a warm Southerly flow wafting North over all of Britain. Pressure falls steadily and fronts off the Atlantic bring a breakdown later with rain at times moving West to East over Britain.

The GFS Ensembles show the operational as a warm outlier after the initial warm period at the start of the new month though overall 850’s do remain above the long term mean, albeit only slightly. Rainfall amounts are generally small and confined to later in the run in the South.

The Jet Stream is currently ridging North through the Atlantic before diving South over the UK. It settles in a position South of Greenland and Iceland over the weekend still diving South over the UK then before blowing West to East near Northern Scotland next week.

UKMO at 144hrs keeps a ridge of High pressure over Southern Britain extending North somewhat through the day with dry, warm and settled conditions through the day. In the NW cloud would likely increase late in the day as a frontal trough approaches from the Atlantic.

ECM as recently places High pressure further North over Ireland at the same time point moving it gently East through the remainder of the week to dissolve over Europe by the weekend at the expense of a new centre in the East of the Atlantic. Warm, sunny and settled conditions would be prevalent for all of the UK away from the very far NW with mist and fog patches overnight and first thing in the morning possible.

In Summary the output looks pretty good this morning. The next 5 days show the pattern as described above before ECM is once more becomes pick of the bunch with High pressure further North over the heart of Britain late next week ensuring a fine, sunny and warm spell develops from midweek. GFS and UKMO keeps high pressure a bit further south so a West or NW flow continues and whilst there will still be a lot of dry and warm weather for the South some cloud cover would feed in off the Atlantic at times further North with occasional rain in the far North. GFS does show a breakdown out in FI while ECM at the close of its run is more gentle on its approach to cooler weather.

[johnholmes]

not greatly impressed with cpc this past week phil. too much variation day to day for my liking. i await 2 days with similar looking output before having any confidence in week 2 modelling.

never ever take 1 days output from whatever source, the 500mb from 3 years of day to day watching need at least 3 days with all 3 showing very similar charts to have a lot of belief in them. Like you say the charts have varied rather too much to be very confident of the actual upper air pattern. Having said that the overall pattern does seem more like rdiging rather than any marked upper trough in the UK area.N

[shedhead]

Absolutely nothing across either the model suite or the teleconnections to suggest September will be anything other than a fine month imo, predominated by high pressure. Clearly there will be blips, with some rain at times for all areas, but the month in general still looks like being a cracker to me...especially in the overall context of the Summer just gone.

[Chris K]

Absolutely nothing across either the model suite or the teleconnections to suggest September will be anything other than a fine month imo, predominated by high pressure. Clearly there will be blips, with some rain at times for all areas, but the month in general still looks like being a cracker to me...especially in the overall context of the Summer just gone.

Looking across the models at the moment, they do all suggest a trend of a 'reloading high pressure' scenario. Occasional blips as you say, but swiftly followed behind by more settled weather. Opposite to the bulk of the Summer really where it was the other way around.

As others have said, it would be nice to have a pleasant start to autumn to at least make the most it, before darkness sets in even earlier. At the moment it still doesn't get dark until around 8pm so its still decent in my opinion.Even when it does get dark earlier, if it's settled and clear outside its great for anyone who likes a bit of stargazing!

Edited August 31, 2012 by Chris K

[bluearmy]

never ever take 1 days output from whatever source, the 500mb from 3 years of day to day watching need at least 3 days with all 3 showing very similar charts to have a lot of belief in them. Like you say the charts have varied rather too much to be very confident of the actual upper air pattern. Having said that the overall pattern does seem more like rdiging rather than any marked upper trough in the UK area.N

absolutely jh. however, there is a big difference between continuity in the 6/10 day mean ops and the cpc output. whilst the ops require several days at least of consistency to give confidence, it is surprising to see cpc charts varying day to day for so long. (all wrt to 500mb)

[Frosty.]

The GFS 06z shows 7-10 days of mainly fine and warm/very warm early autumn weather for the southern half of the uk but in particular the southern half of england and wales, warming up this weekend but the warmth offset on sunday by a lot of cloud across the southern half of the BI but very little in the way of rain, monday looks sunnier and warmer with temps around 24c, then it gets a bit cooler for a few days with temps nearer 21c but then by friday it's back up to 24c. The northern half and more specifically the northern third of northern britain looks like dipping in and out of the anticyclonic spell with some unsettled intervals as lows continue to track eastwards between scotland and iceland, the 6z indicates a nicer spell for scotland from around or just after midweek for a few days but the further outlook continues to suggest a marked change in weather type to much cooler, windier and wetter spells between 10-15th sept.

Edited August 31, 2012 by Frosty039

[Scorcher]

but the further outlook continues to suggest a marked change in weather type to much cooler, windier and wetter spells beteween 10-15th sept.

Does it? If anything the models have been extending the dry weather, Only a couple of days ago GFS was showing depressions affecting the UK by Friday and these have disappeared in the last few runs. ECM remains much better for sunshine and warmth. Given the current uncertainty I don't think we can pay much attention to anything that far ahead.

[Frosty.]

Does it? If anything the models have been extending the dry weather, Only a couple of days ago GFS was showing depressions affecting the UK by Friday and these have disappeared in the last few runs. ECM remains much better for sunshine and warmth. Given the current uncertainty I don't think we can pay much attention to anything that far ahead.

Yes the 6z shows cooler, windier and rainy spells in FI

[Frosty.]

cooler and unsettled 6Z in FI, much as the gfs has been showing beyond the anticyclonic spell for some time now.

[Scorcher]

Yes the 6z shows cooler, windier and rainy spells in FI

As I said before though, GFS originally showed cooler, unsettled weather for next weekend and that has been put well back now. I don't think we can take something at T+240 that seriously given the changes that have happened at quite close range recently.

[ribster]

As I said before though, GFS originally showed cooler, unsettled weather for next weekend and that has been put well back now. I don't think we can take something at T+240 that seriously given the changes that have happened at quite close range recently.

Maybe only if it showed settled and warm eh? The last few days have been about as Autumnal as it gets, not just here, but down south where I've just returned from, wind, rain and some chilly nights. The models have been hinting at a warm up for next week, for some time now. But to accept that something at 168 -192 is gospel, but totally dismiss something at 240 is quite laughable.

[Scorcher]

Maybe only if it showed settled and warm eh? The last few days have been about as Autumnal as it gets, not just here, but down south where I've just returned from, wind, rain and some chilly nights. The models have been hinting at a warm up for next week, for some time now. But to accept that something at 168 -192 is gospel, but totally dismiss something at 240 is quite laughable.

How come every time you post it's always overwhelmingly negative/dismissing someone else's opinion? You only seem to appear to push your own agenda. Very hypocritical. At what point did I accept that something at 168-192? All you can do is look for trends, and the trend has been to push unsettled conditions back from a couple of days ago, a point which I think I made clearly enough in my posts. Even if I was doing what you suggest, why would it be laughable to believe something at 168 but then not at 240? That's 3 days later which makes a hell of a difference! In addition, what have 'the last few days' got to do with what is showing for next week?

[Frosty.]

It's fairly clear that next week is going to be anticyclonic in the southern half/third of the uk so FI doesn't even start until the fine weather breaks down (between T+168 but probably nearer T+240 hours), the gfs in particular has been indicating a marked change in weather patterns when the high pressure spell ends but of course the settled spell could persist for longer. FI can sometimes start at T+48 so it's not such a difficult time for weather forecasters to predict the next 7-10 days, to sum it up, fairly benign in the south and a mixed bag up north.

Edited August 31, 2012 by Frosty039

[ribster]

How come every time you post it's always overwhelmingly negative/dismissing someone else's opinion? You only seem to appear to push your own agenda. Very hypocritical. At what point did I accept that something at 168-192? All you can do is look for trends, and the trend has been to push unsettled conditions back from a couple of days ago, a point which I think I made clearly enough in my posts. Even if I was doing what you suggest, why would it be laughable to believe something at 168 but then not at 240? That's 3 days later which makes a hell of a difference! In addition, what have 'the last few days' got to do with what is showing for next week?

Not sure about an agenda, I don't have a commercial interest and I'm looking forward to some warm days. It's others that seem to chase one weather type or another (or at least models showing it). In the meantime a warm up is on the cards, which is just as well because it isn't today. Although Sat/Sun look a bit cloudy here. We shall see what next weekend brings. I haven't seen any rules about positive posts only

[Summer Sun]

Monday is looking like a lovely summer's day with plenty of warm sunshine around

As the week goes on high pressure continues to keep things dry and settled for most of England and wales, Scotland looks prone to rain at times

As we go further into FI high pressure continues to keep things mainly settled at dry apart from the spell of light rain here and there

Its not until deep FI that there is anything unsettled and stormy

So a good run from GFS tonight with ample high pressure around with Monday looking like the pick of the lot

[Gibby]

Good evening. Here is tonight’s look at the 12zs of the big three.

All models tonight continue the pattern illustrated in earlier output as High pressure stays close to the SW while Lower pressure to the North of Britain allows occasional troughs SE in the flow. The North will see a lot of rather cloudy conditions between now and midweek though Sunday looks an OK day here. In the South the weather will be dry for much of the time though there may be some drizzly rain overnight tonight as a warm front crosses and a little more on Sunday and Tuesday as weak cold fronts cross SE over all parts.

GFS changes little beyond midweek with the general synoptics of High pressure ebbing and flowing between influencing the weather for all or just for the South as Low pressure continues to throw occasional troughs across the North with some rain at times between the drier spells. Further South after Tuesday’s light rain a sustained dry spell looks likely as High pressure stays close by. There will be some warm sunny spells and with light winds at times. Some misty nights are possible. Late in the run some major storm systems pass East north of Scotland extending an unsettled and sometimes windy theme to all areas.

The GFS Ensembles show 850 uppers above the seasonal normal for all areas for most of the next 2 weeks translating into some fairly warm conditions. Under the influence of High pressure for much of the time there is little chance of any significant rainfall until late on in the run in the South. The North though sharing in the mildness there will be some rain at times throughout.

The Jet Stream is forecast to move North to the NW of Scotland over the next few days where it persists for the coming week or so tilting slowly from a SW-NE axis to NW-SE axis later next week.

UKMO is set fair tonight at 144hrs with High pressure centred over Southern Britain with fine and settled conditions for all with temperatures comfortably above normal by day but with the chance of mist and fog patches near the dawn hours of each day.

ECM too shows High pressure anchored over Southern Britain next Thursday extending its influence over all of the UK later next week with fine, warm and sunny conditions in very light winds. As with UKMO light winds at night under clear skies mean fog patches are likely clearing quickly after sunrise each day. The end part of the run shows high pressure receding away East before a reload moves in from off the Atlantic to maintain the fine and warm theme going in the South at least.

In Summary the models look good again tonight if it’s fine weather you’re after. If you live in the South there’s a more than a 50/50 chance of not seeing appreciable rain for some while once the weak troughs of the coming few days have passed. Temperatures will also be comfortably above normal with plenty of warm daytime sunshine to enjoy. If you live in the North fine weather is much more temporary with some rainy and windy spells at times though even here some better periods could occur.

[Milhouse]

I dont like summarising runs in one word but the whole 10 days on the ECM 12z are basically high pressure dominated with the chance of some patchy light rain moving southeast at times ahead of the next approaching high. Whats more remarkable is at day 10 we are no closer to knowing where any breakdown is going to come from with any low to the north of the UK in FI not looking like it will trouble the UK at all. Temperatures will remain very warm in the south throughout but tending to fluctuate between average and above average in the north.

[Summer Sun]

I don't like summarising runs in one word but the whole 10 days on the ECM 12z are basically high pressure dominated with the chance of some patchy light rain moving southeast at times ahead of the next approaching high. Whats more remarkable is at day 10 we are no closer to knowing where any breakdown is going to come from with any low to the north of the UK in FI not looking like it will trouble the UK at all. Temperatures will remain very warm in the south throughout but tending to fluctuate between average and above average in the north.

shedhead's thought's over the past few day's are now becoming clear in the models, the basic pattern at the moment is for high pressure to dominate for at least the first half of September with above average temperatures and very little rain away from the north

[East_England_Stormchaser91]

Tbh I cannot wait for winter now as we got down to 4c last night! Cant believe I was seeing vapour when I breathed out for the first time since early March probably! If we were to get something settled, no way will we be seeing extreme warm values now as it is far too late. Bring on the gales, rain and them dark blue and violet isotherms!

[Summer Sun]

Tbh I cannot wait for winter now as we got down to 4c last night! Cant believe I was seeing vapor when I breathed out for the first time since early March probably! If we were to get something settled, no way will we be seeing extreme warm values now as it is far too late. Bring on the gales, rain and them dark blue and violet isotherms!

Erm what about last September when 29. something was recorded and early October also saw temps way into the high 20's, its not too late at all for extreme warm values far from it.

Those wanting gales ect are going to have to be very patient this year there is only small hints way out in FI for Gales but that keeps getting pushed back

[Milhouse]

shedhead's thought's over the past few day's are now becoming clear in the models, the basic pattern at the moment is for high pressure to dominate for at least the first half of September with above average temperatures and very little rain away from the north

It was a bold call to make but with GP lending his support i can see this prediction coming true for at least the first half of September to be mainly warm and settled.

[Milhouse]

Recent mean outputs at day 10 have shown winds turning more northwesterly. Now its showing good support for high pressure to remain close by, or even over the UK.

[pottyprof]

One or two posts are drifting away from the topic. Can you please try and keep to topic in this thread please? There are other threads for discussing your preferences and what happened last year...

Ta muchly.

[damianslaw]

For the foreseeable future it looks a typical north - south split. The north will hold onto more cloud and wind with temps slightly above average, though nearer average under any rain or showers, whereas the south will be under the influence of the azores high meaning predominantly fine weather with decent sunshine at times and temps appreciably above average though not completely immune to any showery outbreaks should the atlantic wage greater influence. By no means will the next few days bring completely dry sunny warm weather - you need heights overhead or just to our east for that, and the set up isn't conducive to this.

The first 10 days of Sept on average bring settled conditions and often quite warm conditions, early sept on average is just as warm as late June. In recent years it very much has felt like a summer month compared to an autumnal one. However, I am expecting the azores high to quickly come under attack from low pressure to the NW and once this occurs probably as we enter the second week of the month, we will then see heights transferring to our west/northwest pulling in a much cooler NW/N flow with the trough once again restablishing itself in the position its been mostly locked in since early April i.e. over us, the next week being a temporary blip just like we saw in late May.