Model Output Discussion 18z 28/07/13

[J10]

well, even with higher pressure, the EPS model showed showers/rain affecting the UK. North & South.

 

EPS model ?

[Methuselah]

well, even with higher pressure, the EPS model showed showers/rain affecting the UK. North & South.

Pity the Met - who have much more model output available than either you or I - don't seem to share your view?

[Frosty.]

But the mean did not support a northwesterly at all, rather it had high pressure building and suggested warm and dry more especially for the southern half of the UK.

 

This evenings GEM has high pressure building throughout next week. Its all too far out to be sure.

 

You make a few very good points there Milhouse, firstly about the Ecm ens mean, I posted the 00z charts this morning and they looked warm and settled apart from the coming weekend.. and regarding the Gem, yesterday it had a very cool and unsettled spell from the weekend onwards but today it looks much better, I reckon this ecm op run will be one for the...

[summer blizzard]

As nice as the GFS12z is in FI it depends on a 965mb low over Canada and a tropical storm recurving and being deep enough to support a ridge.

 

Probably a write off..

 

[Captain Shortwave]

As nice as the GFS12z is in FI it depends on a 965mb low over Canada and a tropical storm recurving and being deep enough to support a ridge.

 

Probably a write off..

 

Got to love the GFS 

I know there are people wanting summer to continue and some who want autumn to drive through and blow all the leaves off the trees. By the output I just can't help but feel that both parties will end up rather underwhelmed.

The pattern looks pretty mobile, especially the ECM, westerly which suggests alternating periods of tropical and polar maritime airmasses. The longevity of each dependent on where the jet lies. But at the moment the odds seem to favour the warm sector type weather being more dominant. This could change if the GFS/GEM move towards the ECM, We will see in due course. 

Edited August 26, 2013 by Captain shortwave

[ANYWEATHER]

The ecm has the most mobile theme, up to t+168, so in terms of good weather, the gfs steals the show tonight, the charts below show this.....  

Edited August 26, 2013 by ANYWEATHER

[Milhouse]

The ECM mean is neither here nor there really in FI. Not as settled looking as this mornings 0z mean but not supporting the blustery and cool ECM op.

 

[syed2878]

tonight's model Analysis by gibby.  Good evening folks. Here is my look at the 12 noon outputs for today Bank Holiday Monday August 26th 2013.

　

All models show a ridge of High pressure across the country giving ground temporarily to a weakening front moving SE over the UK over the coming 18 hours or so. A dry night is likely before cloud and rain dissipating to scattered showers moves down from the NW through tomorrow not reaching the SE. By Wednesday high pressure re-establishes itself to give a fine and warm day before the next front takes a similar route as tomorrows in moving NW to SE over the UK with some rain for a time before a change to slightly cooler and fresher NW winds sets itself up over the weekend, especially in the North.

　

GFS then builds High pressure back in close to the SW late next weekend and more especially in the week that follows, extending it's influence to all of the UK as the week progresses with warm and settled weather developing over all areas with light winds and sunny spells. High pressure then shows no sign of losing control over the rest of the run just drifting slightly West and allowing a slightly cool NW flow to develop over the UK. Night's could see some mistiness with cool weather in rural locations.

　

The GFS Ensembles tonight show a warm set of members tonight with a short and very noticeable cool blip next weekend as a brief flirtation with Autumnal NW'lies affects the UK for a while. Thereafter there is sound support for warm and largely settled conditions to return especially in the South.

　

The Jet Stream is predicted to maintain it's position for a day or two more before it diverts SE across the UK at the weekend as the cooler NW flow moves in. It isn't long though before it is pulled back North again close to Iceland towards the end of the period.

　

UKMO tonight shows a cool NW flow at the weekend most prolific in the North and East where occasional showers are likely. Towards the South and West High pressure will be building back late in the weekend with lighter winds and sunny spells but chilly and perhaps misty nights.

　

GEM tonight shows a sustained period when winds will be blowing from the NW. They would be quite strong for a time through the weekend and the start of next week but fall lighter as High pressure edges in with weekend showers in the North and East easing to drier conditions from the SW. Temperatures would remain close to average but cool for a time in the North and East at the weekend.

　

NAVGEM shows the chillier feel at the weekend too as Low pressure develops to the North moving East with a cooler showery NW flow over the North and East in particular before a secondary feature crosses SE in the flow at the end of the run with some rain for all for a time.

　

ECM tonight shows some strong early Autumn storms whipping up to the North of Britain with a double whammy of cool and strong West or NW winds in the North at the weekend and again early next week with enough punch to throw cloud and some rain all the way down to Southern Britain at times. Although the first Low doesn't affect the South much on this run the second one next week would with a squally cold front bringing a band of rain followed by showers to all areas in cooler early Autumnal West or NW winds.

　

In Summary the weather appears to be heading for a sustained period when winds will be blowing down from the NW. As a result some of the warmer conditions we have seen of late could start ebbing away if the trajectory of the deepening Atlantic depressions crossing East to the North of the UK move a little further South than suggested. As it is the North is likely to become a good deal windier with rain at times for here while the South holds on to dry, bright and relatively warm daytime conditions for a while yet. GFS on the other hand goes all out to keep the UK in summer mode well into September.

http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm

[BlueHedgehog074]

Thanks for posting that. Has been a while since Gibby posted on here, but the quality of his model analysis appears to be of the usual high quality. I wonder if he'll ever come back here and post again? Like with other fab model posters we have on here, he did add some sparkle to the model thread. But I'm guessing he's likely busy with other missions and I suppose we do have his website to keep an eye on his latest model summaries. Who knows, though, maybe he might still come back for a surprise visit.

 

Broken link to Gibby's model summaries posted above also fixed (which I'm sure was obviously a mistake): http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

 

It'll be amusing to see whether the GFS can put the ECMWF under a spell and make those Low Pressure systems for next week less of a feature. Since the 12Z ECMWF Ensemble mean does have High Pressure quite influential to the South, with the pressure not looking terribly Low to the North, I wouldn't be surprised if it was the ECMWF who starts to follow the shadows of the GFS.

 

This would, no doubt, be bad news if you want something more unsettled, unless we find that the GFS ends up following what this evenings 12Z ECMWF had shown tonight.

 

I think, at least, what seems pretty clear now is that this weekend will very likely be dominated by a North-Westerly flow, which all models seem to agree on. The 12Z JMA is probably on its own with its more North-North-Westerly flow....

 

 

.....rather than the North-Westerly/Westerly-North-Westerly flow most other models show for Sunday. But I shouldn't think it would make too much difference to the weather (though it could mean any precipitation could become more concentrated to the Eastern part of the UK). As mentioned by others, though, it should be the driest to the South or South-West - the areas closer to the High Pressure and a bit more less settled further North, for the weekend. The GFS UK Precipitation charts seem to think along similar lines, too:

 

An example from the GFS for 12pm both Saturday and Sunday

(One thing I've just noticed about this one is the 18Z GFS does show a small area of precipitation down near the far South of England early on Saturday, but probably would end up being much at all).

 

 

Expect (slight) variations of this from run to run with some moderate tweaks, in regards to the weather, still likely for that period.

Edited August 27, 2013 by DiagonalRedLine

[mushymanrob]

no wonder the ecm 12z suggests a more mobile pattern emerging after the weekend...

 

 

its outlook has moved away from a possible settled spell (that the gfs on the right has) and has moved towards an atlantic dominated regime. of course this is 1 run, but i wouldnt be surprised if the gfs follows suit. pity, its moved  towards the previously progged settled spell over us.

 

its clear though that theres no concesus as to the emerging pattern after friday nights coldfront passes through introducing cooler brisker northwesterlies.

Edited August 27, 2013 by mushymanrob

[ANYWEATHER]

Good Morning! Looks as though the projected cooler spell for this weekend looks pretty much nailed on now, but some sparkling early autumn sunshine looks likely too in that very clean airmass. Thereafter, the gfs has sided for now, with last nights ecm, with a more mobile set up, with spells of rain and sun just about for all, although the north and west bearing the brunt of this,,,, Looks a fairly typical early autumn set-up, with still some fair weather at times to be had....

[johnholmes]

no wonder the ecm 12z suggests a more mobile pattern emerging after the weekend...

 

test8.gif

 

its outlook has moved away from a possible settled spell (that the gfs on the right has) and has moved towards an atlantic dominated regime. of course this is 1 run, but i wouldnt be surprised if the gfs follows suit. pity, its moved  towards the previously progged settled spell over us.

 

its clear though that theres no concesus as to the emerging pattern after friday nights coldfront passes through introducing cooler brisker northwesterlies.

the 3 anomaly charts have not been totally consistent either with themselves or each other but the overall pattern has stayed the same, +ve height anomalies west or WSW of the UK and a mainly W'ly flow across the Atlantic into the UK. The idea of a ridge has never really been a major feature if you watch these things daily and take an overall view of what they show.

[Frosty.]

There is still some uncertainty about the impact of the weekend depression as to whether it hits scotland full on or just brushes past the far northeast of the mainland but whichever it does, it will force the azores/atlantic ridge to pull back and bring a cooler and less settled weekend for all with at least a nw'ly breeze and possibly gales for scotland, it's still in the balance. Beyond the weekend, the GEFS 00z mean shows a gradual improvement spreading from the southwest as high pressure builds in again and early september is still looking fine, warm and settled across the south of the uk, especially for the southern half of england and wales, the northern half of the uk probably more changeable and unsettled across the northwestern corner of the uk where it would be cool. The Ecm 00z shows a more amplified upstream pattern which eventually brings in a cool and unsettled spell through early september, however, although the T+240 chart looks poor, it would just be a mix of sunshine and a few showers after a band of rain has cleared through with temps in the mid to high teens celsius..not so bad after all, it's bark is worse than it's bite.

Edited August 27, 2013 by Frosty039

[summer blizzard]

Oh my, as Autumn model runs go that is a lovely Ecwmf.

[Summer Sun]

Looking at this mornings UKMO run and the low seems to be slightly further north with only the northern Isles seeing the tail edge of it at the weekend

 

 

At this the continued signal from UKMO is for high pressure to push north wards again apart from turning cooler at the weekend most of the country will be staying largely dry maybe some scattered showers in the north on Saturday but that's all

 

[Yarmy]

The GFS op FI has gone from a ridge magnet to, well, whatever the opposite of that is in the space of 12 hours, e.g.

 

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2013082612-0-252.png?12

 

http://modeles.meteociel.fr/modeles/gfs/runs/2013082700/gfs-0-240.png?0

 

 

A salutary reminder to self not to pay attention to anything that far out (there is a reason UKMO only goes to T144 publicly), even for "trends". I still think we can squeeze out a few more weeks of settled, warm conditions though based on nothing other than my sense that a lot of Atlantic progged breakdowns have failed to materialise this year. 

[Yarmy]

Looking at this mornings UKMO run and the low seems to be slightly further north with only the northern Isles seeing the tail edge of it at the weekend

 

 

At this the continued signal from UKMO is for high pressure to push north wards again apart from turning cooler at the weekend most of the country will be staying largely dry maybe some scattered showers in the north on Saturday but that's all

 

 

 

Yep, for example this is yesterday's 0Z for next Sunday:

 

http://www.meteociel.fr/ukmo/archives/2013082600/UW144-21.GIF?26-00

 

...and this morning, we have...

 

http://www.meteociel.fr/ukmo/runs/2013082700/UW120-21.GIF?27-07

[draztik]

think we can squeeze out a few more weeks of settled, warm conditions though based on nothing other than my sense that a lot of Atlantic progged breakdowns have failed to materialise this year.

the difference being we are about to enter September, autumn is ready to say hello to the UK.

[Summer Sun]

Yep, for example this is yesterday's 0Z for next Sunday:

 

http://www.meteociel.fr/ukmo/archives/2013082600/UW144-21.GIF?26-00

 

...and this morning, we have...

 

http://www.meteociel.fr/ukmo/runs/2013082700/UW120-21.GIF?27-07

 

Yeah I thought it had moved further north thanks for posting yesterdays 00z chart to back that up

 

[TonyH]

the difference being we are about to enter September, autumn is ready to say hello to the UK.

If you believed some on here you would think Autumn started in June, while for others a non stop heatwave since July!

Edited August 27, 2013 by TonyH

[No Balls Like Snow Balls]

Oh my, as Autumn model runs go that is a lovely Ecwmf.

 

Yes all models are looking increasingly unsettled and autumnal, especially the further North you go.

About time in my opinion :-)

[Captain Shortwave]

the difference being we are about to enter September, autumn is ready to say hello to the UK.

It was autumn for about 9 months last year. It can stay away 

GFS mean this morning beyond day 7 is similar to yesterdays ECM

ECM mean beyond day 7 is starting to resemble the ECM op aka welcome to Autumn.

Oh well life goes on even if the weather is pants

[No Balls Like Snow Balls]

IMO it looks as though the LP takes a more SE track on the GFS 6Z. certainly fresher feeling this weekend if GFS were to verify.

 

 

 

 

 

 

 

 

[Yarmy]

Return of the ridge

 

 

Now, what was I saying earlier about ignoring anything that far out... 

[shedhead]

IMO it looks as though the LP takes a more SE track on the GFS 6Z. certainly fresher feeling this weekend if GFS were to verify.

 

 

Indeed, as I suggested yesterday the weekend LP is starting to correct a little farther SW'wards and I think we will all notice a distinct change of air by Sunday IF this comes to pass.

 

 

 

 

Before that though we're still looking at a pretty decent week to close out meteorologial summer 2013, especially across the south, with temperatures near or above normal for much of England and Wales.

 

Into next week the slide towards something rather autumnal might start to gather pace, but we have seen some huge swings in FI across the last 3 or 4 runs, so it's clearly a little early for over confidence.

Edited August 27, 2013 by shedhead