Model Output Discussion 18z 28/07/13

[bluearmy]

Tough to say anything constructive on this trough. Just amusing to see some of you responding to each run as if its the 'answer'. The 12's and 00z's seem to chop and change to the extent that nothing should surprise on the next run.

Not sure GEM should be viewed as a 'poorer' model than gfs. Anyone post the latest day 5 stats?

[Biggin]

 if mid atlantic becomes more active as things further west kick off ,but thats way in the much longer range .

Yep  in the much longer range, its gotta happen sometime, but oh to pop back in time when one or two people were harping on about breakdowns and an active Atlantic spoiling the whole of August. I hope they can pop back themselves, have a look at the models and explain why and where it all went wrong for their predictions / forcasts. Hopefully they / we can all learn from that.

[johnholmes]

Going back to the post from frosty-and of course he is showing what each model is showing from its 12z run this evening.

But how realistic is it?

The T+240 shows a high sat right over the UK.

Take a look at what its 500mb partner showed for the same day, see below

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Which does one believe?

Or the NOAA 6-10 and 8-14 covering that period, see below

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

 

It would be good if the synoptic ECMWF was correct but I have to say I would favour the anomaly idea, okay its the upper air pattern, but it is pretty near impossible with that upper air to have a surface high where the first ECMWF shows it.

The GFS 12z output for T+240 does not agree with it either, see link below

http://www.wetterzentrale.de/topkarten/fsavneur.html

 

Hard I know when so many want the summer to keep going but it really is best to look at things from a realistic point of view.

to add NAEFS into this. I did a save and copy of its outputs over several days about 3-4 days ago. It showed for the 28th from its start date of 13th August a small +ve anomaly at 500mb over the UK. Its output tonight shows a slight to moderate anomaly west of the UK, not that different from what the ECMWF anomaly shows and the NOAA outputs. So the NAEFS has changed a fair bit in the 6 days. Maybe one day I will do comparison checks including NAEFS to see how it compares with the usual 3 I use.

Edited August 19, 2013 by johnholmes

[john pike]

heres the updated fax chart for saturday

 

certainly looks wet for a bulk of the uk

 

as for monday

 

no idea

[Cloud 10]

Tough to say anything constructive on this trough. Just amusing to see some of you responding to each run as if its the 'answer'. The 12's and 00z's seem to chop and change to the extent that nothing should surprise on the next run.Not sure GEM should be viewed as a 'poorer' model than gfs. Anyone post the latest day 5 stats?

 

Got the six day ones,GEM almost bottom of the pile but all models showing a bit

of a dip at the moment.

 

[The PIT]

A drift away from away from the Hot unpleasant weather to cooler wetter more pleasant conditions. Still hot for Thursday and managing to hold onto it for another day in the SE. All change the next run??

[mushymanrob]

Going back to the post from frosty-and of course he is showing what each model is showing from its 12z run this evening.

But how realistic is it?

The T+240 shows a high sat right over the UK.

Take a look at what its 500mb partner showed for the same day, see below

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Which does one believe?

Or the NOAA 6-10 and 8-14 covering that period, see below

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

 

It would be good if the synoptic ECMWF was correct but I have to say I would favour the anomaly idea, okay its the upper air pattern, but it is pretty near impossible with that upper air to have a surface high where the first ECMWF shows it.

The GFS 12z output for T+240 does not agree with it either, see link below

http://www.wetterzentrale.de/topkarten/fsavneur.html

 

Hard I know when so many want the summer to keep going but it really is best to look at things from a realistic point of view.

to add NAEFS into this. I did a save and copy of its outputs over several days about 3-4 days ago. It showed for the 28th from its start date of 13th August a small +ve anomaly at 500mb over the UK. Its output tonight shows a slight to moderate anomaly west of the UK, not that different from what the ECMWF anomaly shows and the NOAA outputs. So the NAEFS has changed a fair bit in the 6 days. Maybe one day I will do comparison checks including NAEFS to see how it compares with the usual 3 I use.

 

ha ha... i view the charts before coming here to post most mornings (if theres anything to say), i 'saved' charts from this period to use as i didnt 'buy' the ecm's rapidly building azh post weekend.

viewing the ecm, ukmo, gfs, and anomaly charts i reached a similar conclusion.... that there is no real support for a pressure rise (as per 12z ecm) after the weekend. in fact its all looking pretty average... normal.. late summer weather.

 

what makes this mornings runs even worse, is that the 'heat' appears to have been downgraded to one day... friday... for most of southern uk (southeast should get more) IF this mornings bbc forecast proves correct. saturday might be warm, but with a low sat right ontop of us, its not going to be totally dry with heavy thundery showers about.

 

i struggle to believe that so many runs that promised so much are set to fail to deliver so dismaly.

Edited August 20, 2013 by mushymanrob

[Frosty.]

Every cloud has a silver lining, the Gefs 00z mean is showing a warm cyclonic weekend with sunshine and heavy, thundery showers with temperatures into the low to mid 20's celsius, the showery trough slowly fills and migrates away northeastwards and weak ridging from the azores/atlantic anticyclone begins to push towards and across the south of the uk. This eventually sets up a north-south split next week with the northern half of the uk being unsettled for most of the time with rain and showers and average temperatures but also some drier, sunnier and warmer interludes, the southern half of the uk and more particularly the southern third, wales, midlands, east anglia and southern england/se england start showery but then gradually improving with a lot of dry, fine and pleasantly warm weather with temps in the low 20's celsius, there are signs that through early september the PFJ will start to push further south towards the uk.

Edited August 20, 2013 by Frosty039

[Man With Beard]

UKMO and ECM kind of agree this morning, the trough pushes through fairly quickly on Saturday, perhaps still around in the east on Sunday but well clear by Monday. So maybe the bank holiday will be a "getting better" one. UKMO is looks most inviting for next week with pressure nudging into the south, though far from completely settled. 

GFS on the other hand has completely ditched the stalled low to the south-west and now has a real nasty-looking low for Saturday/Sunday.

[shedhead]

The overnight runs suggest pretty average conditions now across most parts of the UK, but the SE will become warm, locally very warm for a time on Friday. Into the BH weekend low pressure looks set to dominate, bringing showers or longer spells of rain to all areas, some of which will be thundery for a time across the south in particular on Sat. Even into next week there is no guarantee that the weather will settle down, but the south should see at least a few dry days, with temps near or a little below the seasonal average. 

 

Whichever way you try to cut it, the models that promised so much look set to deliver so little.

[johnholmes]

One only has to compare the ECMWF output this morning at T+216 with its T+240 12z yesterday.

Not chalk and cheese but not really very similar I would suggest.

It matters not which model any of us use. If there is no contiuity from output to output for the same day then one cannot give any reliability to that model. Even with such continuity the model can still be wrong but with muc less chnace of it being wrong. By the very nature of the way the synoptic models operate one must expect swings and round a bouts from them. Other models are less prone to all this chopping and changing. I am no computer expert so you need to ask someone who is and also has a deep meteorological knowledge to ask why this is.

Turning to nearer matters the BH weekend, I repeat that the Fax charts and the Met O text outputs will be as close to what happens at T+xyz as anyone else on the web. Their latest Fax chart now for T+120 produced last evening keeps the low over southernmost counties as it fills and moves roughly east from the position close to SW Eire at 12z Friday, a change from the previous prediction of off southern Eire. Continue to see fairly small changes to its track over the coming days as they get more information on it.

Summing up the anomaly outputs from last evening and this morning, ECMWF-GFS link below, and I have written this

sorry forgot the link, here it is

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

 

Tue 20 aug

Ec-gfs

Changes from yesterday, ec much less meridional, both now have some +ve heights west of uk and flow is a bit n of west on both, more like noaa really; the Iberia area trough is now a shallower and more elongated affair well sw of Iberia

There is at one and same time no real continuity between the models but they do tend to keep the idea of a 500mb flow being n of west with +ve heights w of the uk and a trough e of the uk

Edited August 20, 2013 by johnholmes

[Walkinglad2013]

Looks like all the models over the past week were totally wrong !I have lost my trust in the GFS models that were predicting a 7 day heatwave! Not good! Why the massive change since last night?

Current weather in Leeds - a lot of medium level cloud but clearer skies to South. Due to be in low 70s today

[snowking]

UKMO and ECM kind of agree this morning, the trough pushes through fairly quickly on Saturday, perhaps still around in the east on Sunday but well clear by Monday. So maybe the bank holiday will be a "getting better" one. UKMO is looks most inviting for next week with pressure nudging into the south, though far from completely settled. 

GFS on the other hand has completely ditched the stalled low to the south-west and now has a real nasty-looking low for Saturday/Sunday.

Certainly agree on the last part but to me UKMO and ECMWF are actually fairly different in terms of their eventual outcome for the UK - adding even more to the confusion!

 

 

The UKMO far more keen to push the influence of the trough in across the UK, signalling a rather unsettled day on Saturday for all, where as the ECMWF holds the trough further North-West, with Southern and Eastern areas escaping with a mostly dry day. Here's the synoptic setup with precipitation overlay:

 

 

 

So I think its becoming a case of whether its an all UK rainy bank holiday special, or whether we can hold off the worst of the conditions for some.

 

As for the GFS and its yo-yo'ing, it's safe to say I'm not paying too much attention to its operational suggestions right now

 

SK

 

EDIT:

 

And as I waffle on, the ECM ensemble mean giving good support for the operational suggestion:

 

Edited August 20, 2013 by snowking

[Walkinglad2013]

Bank Holiday showers and becoming cooler too Conditions are going to be turning more unsettled into the Bank Holiday weekend. There wil be some showers and outbreaks of rain around, although where, when and how much rain there will be is still unclear. Indications are that we are into a showery for next week, most of them in more northern areas, with the east tending to stay drier. Becoming cooler at the weekend too.

For the weather for the next few days click here Friday 23/8/13 An area of low pressure just west of Ireland on Friday. A front will be edging eastwards taking cloud and rain with it. This rain reaching western Scotland, Wales and western England through the afternoon. Showers breaking out in central and southern England later these edging northwards as the day progresses. An increasing breeze too. Highs at 17 to 27C.

Saturday 24/8/2013 A trough through the UK and Ireland on Saturday brings generally more unsettled day to all. However, confidence in the detail of the forecast is very low. There are likely to be some showers and these could become heavy at times. Some areas will be dry. A much cooler day at 15 to 20C.

Sunday 25/8/13 The trough remains through the UK and Ireland on Sunday. This brings showers and some outbreaks of rain through Scotland and Northern Ireland, with a few showers in northern England too. A few showers may affect western coasts of England and Wales, but other areas should be dry with sunny spells. Highs at 16 to 24C.

Monday 26/8/13 Low pressure remains t the north of Scotland on Monday, continuing to influence the weather across the UK and Ireland. There will be further showers or long spells of rain in Scotland, although more showery conditions further south. Highs at 15 to 22C. Tuesday 27/8/13 Little change through Tuesday. Low pressure stays to the north of Scotland. All parts will have a mix of sunshine and showers, the heaviest and most frequent of them tending to be in Scotland and Ireland. Highs at 16 to 22C. Wednesday 28/8/13 There will be sunny spells and showers for most again through Wednesday. These are going to be heavy at times in Scotland, but more scattered further south. Some eastern parts of England may stay dry throughout. Highs at 17 to 23C

[Walkinglad2013]

Im gutted that there isnt going to be a heatwave! Cold and wet all bank holiday weekend - what a washout!

[shedhead]

Im gutted that there isnt going to be a heatwave! Cold and wet all bank holiday weekend - what a washout!

To be honest walkinglad there was always a large degree of uncertainty over any potential heatwave, with some wise sages on here frequently pointing to the lack of support for one from the 500mb anom charts.  Despite the clear disappointment for you and I'm sure many others, there's also nothing to suggest that the up coming BH weekend will be a cold, wet washout either....so my advice is keep watching.

[Frosty.]

 Cold and wet all bank holiday weekend - what a washout!

OTT in the extreme, sunshine and heavy showers and pleasantly warm to rather warm in the sunny spells, monday looks dry with sunny spells across the southern half of the uk with showers confined to northwest britain, hardly a washout!

[Steve Rob]

Im gutted that there isnt going to be a heatwave! Cold and wet all bank holiday weekend - what a washout!

 

gutted too... off to dorset for a week camping on thursday... have packed shorts and suntan lotion, looks like i'll have to replace them with wellies and waterproofs 

[shedhead]

The 06GFS is even more progressive with Friday's rain, meaning Thursday will be the only warm/very warm day across the vast majority of England and Wales.

 

 

 

 

 

As most of us know GFS has a propensity to undercook maxima, but it has to be said the kind of values being advertised across the BH weekend are a little disappointing..at least compared to what looked on offer not that long ago.

 

 

Sat

Sun

 

Mon

 

 

 

Edited August 20, 2013 by shedhead

[Frosty.]

The Ecm 00z ensemble mean shows a recovery during the course of next week for the southern half of the uk with weak ridging from the azores/atlantic anticyclone bringing largely fine and dry weather and temperatures back to respectably warm levels in the low 20's celsius and closer to the mid 20's celsius for southern/se england at times, this is not to say there won't be any rain, there will just be a lot less than further north with longer spells of fine and warm weather between. For the northern half of the uk, those areas don't really recover overall, it stays more unsettled with rain interspersed by sunshine and showers but with occasional drier, sunnier and warmer days here and there. In the meantime, becoming very warm and humid across the southern half of the uk on thursday and especially friday with mid 20's celsius, nearer to 27-29c 83F for the southeast of england where it will be hot and sultry, a lot of very warm hazy sunshine on thurs/fri but a growing risk of a few thundery showers later on friday, saturday looks warm, muggy and showery with some heavy and thundery downpours with mid 20's celsius for england and wales, low 20's celsius for n.ireland & scotland. Sunday becomes cooler and fresher after a band of rain clears through and sunny spells become more widespread with just a few showers dotted around, early next week, still some showers around, mainly further northwest but most of southern britain being dry with sunny spells and pleasantly warm in the low to mid 20's c, the warmest weather across the southeast corner, the coolest weather across northwest britain, thereafter, a north-south split developing with pressure rising somewhat across southern britain with more in the way of fine and warm weather, more average and breezier conditions as you go progressively further to the north, not bad at all.

Edited August 20, 2013 by Frosty039

[draztik]

Fear not Shed, the trusted gfs in fi takes us into an Indian summer...

lol

[Buzzit]

Fear not Shed, the trusted gfs in fi takes us into an Indian summer...

We are going to have an Indian summer but the high is going to be centered further East. With respect to the chart you have posted, these synoptics only last on the GFS op for a couple of days so hardly representative of an Indian summer.

 

The synoptic features over the UK in the model output have changed frequently this month - but if you compare the GFS in far FI of two weeks ago with this mornings 6z output for 23rd August, the significant difference is the movement of the feature lows further East. But the broad overall pattern remains very similar. We may have a washout for some this weekend but that is the luck of the draw.

 

Edited August 20, 2013 by Buzzit

[shedhead]

Fear not Shed, the trusted gfs in fi takes us into an Indian summer...

lol

Yes indeed Draztik, I too am convinced there will be one...in India

[johnholmes]

Sticking to the BH weekend all 3 models now seem to want the actual surface low to be further north than previously. ECMWF has followed this line more than the other two. Both GFS and Met tended to fill the feature and drop it into France. If you look at the timed issues of the Fax charts from Exeter you can already see where the low is on their chart, and check this with an infra red sat picc from sometime after 0400 this morning. Exeter have the centre a bit further north than they had predicted it be when around 50 west and hence its position in the UK area is now expected to be a good deal further north and deeper than their predictions of 24-48 hours ago.

 

Not a bad idea to compare all 3 models treatment of this low and see which is the closest come Saturday 12z?

Edited August 20, 2013 by johnholmes

[Frosty.]

Well what an interesting Gfs 06z op run we have here, firstly, the atlantic low bulldozes it's way southeastwards a full 24-36 hours sooner than the 00z models show and 48-72 hours faster than yesterday! quite amazing how the upstream signals can fluctuate so much in such a short space of time, however, the main point of interest to me is the eventual domination of the azores/atlantic anticyclone on this run, it shows that it still packs a mean punch and this run would produce a stunning end to summer and start to autumn. As it is, the 6z next week looks very plausible since it almost mirrors what the ecm 00z ensemble mean is showing next week with azores ridging across the south of the BI after a bit of a sticky start but slowly warming up and drying up with long sunny spells and any frontal activity would be weak and insignificant, as time goes on, the azores/atlantic anticyclone gains ever more of a foothold and builds in across the uk, eventually settling the weather down across the north too, it turns into a stunning superb run..short term pain, long term gain, and i'm BANKING it for that reason. 

Edited August 20, 2013 by Frosty039