Model Output Discussion 26/08/2012

[UV-RAY]

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.

Amongst all the hopecasting I see this is what I have been looking at for the past week, first 10-14 days settled and pleasant thereafter heights transferring to our NW and with the jet once again bing pushed Southwards.

[shedhead]

Amongst all the hopecasting I see this is what I have been looking at for the past week, first 10-14 days settled and pleasant thereafter heights transferring to our NW and with the jet once again bing pushed Southwards.

Don't see that happening myself. 1st half of September will be essentially fine and settled and the 2nd half is unlikely to see any major changes imo, apart from a likely cool off due to the increasing lateness of the season.

[mushymanrob]

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

no, its looking like a lovely autumn day

Edited September 1, 2012 by mushymanrob

[Gibby]

Good morning. Here's a look at the rather settled 00zs today.

All models are in agreement on the influence for the UK of High pressure down to the SW of Britain affecting the UK. Further North the weather will be rather cloudy with some occasional rain as troughs pass over though Sunday looks an OK day up here. In the South much more in the way of dry weather prevails with tomorrow and Tuesday the only periods when there is a risk of a little rain as weak fronts cross SE..

GFS then shows little change in the overall synoptic pattern for late next week and the weekend with the best of the dry and warm conditions down in the South with the breezier and occasionally damp conditions reserved for the North. Later in its run the weather turns more unsettled everywhere as deep Atlantic Low pressure winds up to the North with gales and heavy rain sweeping East across all areas in far FI.

The GFS Ensembles are't as good this morning with 850's returning to nearer the early September normal in the South after the first week indicative of High pressure locating SW of Britain. In the North a sine wave pattern to the operational is shown as fronts cross over with much more rainfall shown here than Southern locations.

The Jet Stream is shown moving NE towards NW Scotland over the next few days. As we move into the later stages of next week the flow rides High over Greenland and turns SE towards the NE and North Sea.

UKMO for Friday shows High pressure centred over SE England with fine, warm and sunny weather likely for all. The far MW could see more cloud under a SW flow.

ECM too looks good again this morning with High pressure retreating away East from Britain next weekend to be replaced by a new cell over the North moving slowly East. So very warm and sunny conditions which will cool down later in the weekend and into the new week though still with plenty of sunshine while the NW see more cloud too by the end of the run.

In Summary all output looks set fair. There are minor variations between GFS and ECM with GFS showing a slightly more progressive run with High pressure held on a more Southerly location. This would have a more direct effect on the Northern weather whle the South would see fine weather maintained. The inevitable major breakdown is also shown by GFS later in its run but the Euro's look set for a continuation of fine conditions for many well into the second week.

Edited September 1, 2012 by Gibby

[Gavin Hannah]

Will be interesting to see what happens to this one. Could be the first big storm of the Autumn.

[Frosty.]

The ecm has had it's wobbles recently, just like all the other models but I still think it's consistantly the best performing model and it just so happens it's showing the best looking outlook for the whole of the uk up to T+240 hours with high pressure becoming dominant and further north so scotland and n.ireland can join in with some summery weather in early autumn, beyond T+240 there are signs of a change to something more unsettled from the west but it's a vastly better run than the gfs 00z, which is a fairly disappointing run for northern britain and then develops a very unsettled and possibly stormy period towards mid month, hopefully the calmer and more settled ecm is the model to trust during the next 7-10 days.

[Frosty.]

no, its looking like a lovely autumn day

unless you live in the north of the BI where it's not so lovely, some rain across scotland and n.ireland, heavier rain further northwest with strong winds but tomorrow looks a lovely autumn day further north and not so lovely for the south with a cloudy day and with patchy rain or drizzle around with temps around 19c.

[bluearmy]

The ecm has had it's wobbles recently, just like all the other models but I still think it's consistantly the best performing model and it just so happens it's showing the best looking outlook for the whole of the uk up to T+240 hours with high pressure becoming dominant and further north so scotland and n.ireland can join in with some summery weather in early autumn, beyond T+240 there are signs of a change to something more unsettled from the west but it's a vastly better run than the gfs 00z, which is a fairly disappointing run for northern britain and then develops a very unsettled and possibly stormy period towards mid month, hopefully the calmer and more settled ecm is the model to trust during the next 7-10 days.

but its not terribly good beyond 6 or 7 days, just like all the other operationals. as JH and many others advise, look at the 500mb and ens output to get a better idea of where we go days 7 to 10.

[Frosty.]

look at the 500mb and ens output to get a better idea of where we go days 7 to 10.

I do look at the 500mb etc but I was just commenting on a good ecm operational run compared to the mixed gfs 00z

[mushymanrob]

unless you live in the north of the BI where it's not so lovely, some rain across scotland and n.ireland, heavier rain further northwest with strong winds but tomorrow looks a lovely autumn day further north and not so lovely for the south with a cloudy day and with patchy rain or drizzle around with temps around 19c.

fair comment

the 06z gfs within a reliable-ish timeframe still stubbournly keeps the azh centered to our southwest later in the week keeping us in a northwesterly, whilst the ecm insists it drifts across us bringing eventually some continental warmth. who will be proven correct?

[Summer Sun]

Will be interesting to see what happens to this one. Could be the first big storm of the Autumn.

That storm keeps getting pushed further and further away into FI

It was first shown to arrive on the 11th 2 days ago

Then yesterday it got pushed back to the 16th

And now its the 17th today

[bluearmy]

I do look at the 500mb etc but I was just commenting on a good ecm operational run compared to the mixed gfs 00z

however the 00z ecm op is an outlier re uppers next weekend so at this stage its fi placement of the block is suspect. not picking on you in particular as you aren't one for doing this too often but too much dissection and analysis of fi op runs can be quite misleading for those less knowledgeable who may come on here looking for some guidance re week two.

[Frosty.]

fair comment

the 06z gfs within a reliable-ish timeframe still stubbournly keeps the azh centered to our southwest later in the week keeping us in a northwesterly, whilst the ecm insists it drifts across us bringing eventually some continental warmth. who will be proven correct?

yes mushy hopefully the ecm op run will be proven correct with a good spell for all.

[Frosty.]

however the 00z ecm op is an outlier re uppers next weekend so at this stage its fi placement of the block is suspect. not picking on you in particular as you aren't one for doing this too often but too much dissection and analysis of fi op runs can be quite misleading for those less knowledgeable who may come on here looking for some guidance re week two.

Fair point bluearmy, i was just looking on the bright side of life with a corking ecm 00z op run although I realise when you look deeper, you find more problems although the ensembles are sometimes wrong, the alternative gfs version is rather poor in comparison to put it mildly.

[johnholmes]

Fair point bluearmy, i was just looking on the bright side of life with a corking ecm 00z op run although I realise when you look deeper, you find more problems although the ensembles are sometimes wrong, the alternative gfs version is rather poor in comparison to put it mildly.

hi Frosty and others

Again no dig intended but just to show how much the GFS Op run does change regularly bookmark the link below and have a look yourselves for the variations for 10 days time, over the past 24 hours let alone any further.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&CONT=euro&MODELL=gfs&MODELLTYP=1&VAR=prec&WMO=&ZOOM=0&RES=0&PERIOD=&PANEL=0&ARCHIV=0&BASE=201209010000%26HH%3D246

It really does show how ALL the models chop and change at that distance, ECMWF as well as the others out that far. Even closer say at T+144 see how sometimes, not necessarily the past 24 hours, how the main 3, GFS, ECMWF and Met also change.

I find it a first class way of doing a quick check on how the what I call synoptic models are treating any predicted weather feature. Then compare them with the 3 500mb anomaly charts I witter on about so much.

Its hard to give marks without any bias but if I was asked to compare the synoptic outputs at T+240 I doubt I would rate them over 40-50%, the anomaly charts are currently working out, since the checks started in February this year, at just under 70%.

[ICETAB]

I know it's a bit early in the year for this, but I hope we start seeing this type of chart in the 144 time range come November.

Edited September 1, 2012 by ICETAB

[Thundery wintry showers]

It's dry and cloudy over most of the country today and I expect more of the same tomorrow, associated with the moist westerlies on the northern flank of the high pressure, but on Monday the supply of moist tropical maritime air will be cut off over England and Wales as the high extends further north and this is likely to allow the sun to come through more widely, particularly to the east of high ground.

From Tuesday onwards, the ECMWF run looks like a standard precursor to a spell of dry sunny anticyclonic weather- the polar maritime incursion on Tuesday/Wednesday will help to shift any cloud away from our shores and then we have a high building right over us. It would be cooler initially due to the polar maritime airmass, especially overnight, but it would soon warm up as the high pulls away eastwards bringing warm air up from the continent.

The outlook on the GFS is rather more complicated as we get high pressure centred to the west and this allows a weak front to move SE on Thursday and Friday giving 24-36 hours of cloud and maybe the odd spot of drizzle, and so while it would mean a dry week, sunshine amounts may be relatively limited in the north in particular. Following behind, next weekend would probably be sunny and dry but rather chilly in the polar N/NW airstream.

The ECMWF ensemble mean is not really sending out any conclusive signals to me, although the UKMO operational run looks a lot more similar to the ECMWF run than the GFS and would give most of us at least three dry sunny days with rising temperatures, and the NOAA's 8-14 day forecast looks more similar to the ECMWF operational run with high pressure sat right on top of us. For these reasons I'd back the UKMO/ECMWF operational runs over the GFS, but not with very high confidence at this stage.

[snowstorm445]

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!

Agreed. This week brought the first sub-zero temperatures of the season to parts of Scotland and Northern England. Its nice that we are getting a heatwave during the week but after about mid-September I really find it quite unseasonable.

It would be nice to see a seasonal Autumn this year, with nice cool weather later on. If this type of weather pattern continues then I feel it will be a complete repeat of last year, which ultimately saw a very mild, mucky winter. Hopefully we will see a return to normal weather soon.

[Frosty.]

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!

Agreed, although I would like one last warm and anticyclonic spell first before we go into a colder and stormier pattern. The latest models are showing a fine and warm spell for the south but continue to look more mixed further north with more limited warmth and sun.

Edited September 1, 2012 by Frosty039

[Iceaxecrampon]

Isaac inbound - any cause for concern as yet?

[AWD]

Isaac inbound - any cause for concern as yet?

Nope, waaaaaaayyyyy too far out yet!

The trend for the next 10 days is for high pressure domination, especially the further south you are, but not exclusively.

After that, I do notice a trend from the GFS to slowly drop pressure around about the 11th, but nothing more than a trend. I'm not talking stormy, gales etc, just pressure dropping enough to allow shower activity to develop as the AZH drops South. Long way off yet anyway! Enjoy the sun those you can, those like me working, let's hope for a decent weekend next weekend. This weekend is rather spoilt by the front moving South.

[Summer Sun]

Isaac inbound - any cause for concern as yet?

No, by the time its shown to arrive in the UK its nothing really to worry about

A typical Atlantic depression really

[Frosty.]

A very settled Gfs 12z operational run until well beyond T+250 hours in the south with high pressure in control and even the north of the uk looks like improving after tuesday but the southern half of the uk is in for a summery spell with temps well into the 70's and lots of sunshine and light winds, the north looks like being breezier and cloudier at times with a moister atlantic flow around the northern side of the high, there is no breadown until the very depths of FI and the polar front jet remains well to the north of the BI for at least the next 10-12 days, the only threat of a significantly cooler polar airmass appears to be reserved for ne scotland but only a low risk.

[Iceaxecrampon]

No, by the time its shown to arrive in the UK its nothing really to worry about

A typical Atlantic depression really

....thanks Mr Fish

Edited September 1, 2012 by Iceaxecrampon

[summer blizzard]

Isaac inbound - any cause for concern as yet?

Issac is already dead and no remnants of him remain.

Given the date whatever storm that is has not even been declared an invest yet.