Model Output Discussion 31/07/14 onwards.

[Frosty.]

Tonight's GEFS 12z mean shows the uk on a slippery slope towards a cooler, windier and more generally unsettled spell by T+72 hours once the atlantic ridge subsides southeastwards, a deepening low swings down from iceland during the weekend, it's the north of the uk which takes a direct hit so the worst of the weather will probably be across scotland, southern uk being least affected but still with a risk of rain and showers. indeed, friday and most of the weekend look decent the further south you are with increasingly dry, bright and fairly warm weather with temperatures into the low 20's celsius thanks to the toppling weak atlantic ridge of high pressure. The trend next week is for a slow improvement from the south west as the trough to the north east slowly loses it's sting, gradually filling and drifting away with winds then falling light although pressure doesn't look high enough to prevent showers from forming, heavy, slow moving and thundery ones likely, which is what most of the uk will have tomorrow. Further into FI we see a north / south split becoming established with high pressure to the south of the uk and persistent lower heights to the north, at least the PFJ retreats well north again later in the month following it's brief visit to the northeast of the uk early next week.

 

The south of the uk could be in for warmer more settled weather again through late august I think.

Edited August 13, 2014 by Frosty.

[damianslaw]

Reliable timeframe all models keep the UK locked on the cold side of the trough with a very amplified pattern, strong heights to the west and north west and low heights to our north east with the country consequently exposed to trough action from the NW. Indeed its the first time this year the UK looks like being locked into a period of sustained cold synoptics delivering colder than average CET values.. so very different synoptics to what we have become accustomed too so far this year.

 

There are tentative hints the azores high will try to build NE towards the end of the month, but it could easily be another thwarted attempt like the upcoming one will be..

 

Pity this isn't the depths of winter for cold and snow lovers, it would be an excellent outlook, in August no use to anyone really, just very disappointing all round, lots of cloud bits of rain from time to time and a nagging cold wind with a definite flavour of early Autumn.

[bluearmy]

Back end of ECM ens looks promising with mean pressure rising above 1020mb across much of the country.

[draztik]

ECM ensembles telling me to get my jacket, may need it for a while. To all those that enjoy cooler fresher conditions, enjoy

ECM ens temp anom days 5-10,8-13

[Frosty.]

I found some good news tonight in the form of the Ecm 12z ensemble mean which shows the azores / atlantic anticyclone building in from later next week onwards, so... gradually becoming more settled with increasing amounts of sunshine and lighter winds, cooler than we are used to this summer with chilly nights and temperatures dipping to single digits celsius overnight but beyond T+240 hours it would likely become warmer by day and night. The first half of next week looks cool, breezy and unsettled, especially the further north east you go, but then it's good news. I think it's good news because I prefer fine and pleasantly warm weather in summer rather than cool and unsettled..I like to make the most of summer before it's gone for another 9 / 10 months.

[William of Walworth]

Of course those 12z ensemble mean charts that Frosty posts from ECM are for the moment only a snapshot possibility for later next week, but charts like that  should provide just a small note of caution to those tempted to assume (as I was over previous days/runs) that trough persistance is bound to win and that any efforts at HP encroachment will inevitably be thwarted. 

 

There've been odd hints of possible returns to more HP influenced conditions at least for the S (albeit in FI) in some runs for  a little while now. Who's to say that such trends might not become a tad stronger than we originally thought? Notice I said 'might'!

 

And of course later runs may well send all that back in the opposite direction too. But beyond the next few days there seems to be plenty still up for grabs (for now). Appreciate that I'm speculating.

Edited August 13, 2014 by William of Walworth

[Mark Neal.]

Back end of ECM ens looks promising with mean pressure rising above 1020mb across much of the country.

 

Also Matt Taylor on BBC news at 10:30 last night said long range indications gave a glimmer of hope towards end of month some potential for settled conditions. 

[SteveB]

Cool and showery best sums up the GFS this morning.

 

The chart below could represent any day from Sunday onwards

[Frosty.]

I hope this brightens up your day   the Gfs 00z op run saved the best until last with high pressure building in and intensifying over the uk during low res, now this is not cherry picking because the longer term signal is for the weather to settle down and warm up again later in the month.. it could actually become very warm by the turn of the month if this carried on further...so it will hopefully be a fitting end to a very good summer overall...cheers

 

PS..honestly I did put these charts in the correct order but the computer said no

 

 

Edited August 14, 2014 by Frosty.

[IDO]

After the south has the temporary ridge over Fri-Sat temps drop to below average for 4-6 days in London if the GEFS mean is correct. Cooler still further north:

With the flow from the north and uppers from 0-4c country wide for a while it will also feel cool especially out of the sun:

The GFS op run has weak heights trying to build from the SW around D8 and after a bit of a battle by 27^th August a ridge of higher pressure spreads north:

GEM has discarded its optimistic pressure build from the west and now is in sync with GFS with a tentative pressure rise from the south around D8:

ECM also showing a cooler flow at D7 with again signs of slight improvement in the south as pressure rises and the flow is from a less cold direction:

The GEFS after D9 are in 3 equal clusters, one building pressure over the UK, another bringing a trough back into play and the other a N/S split on a westerly flow. The mean:

ECM at D8 delays the pressure rise:

The NOAA 8-14 day highlights that the UK will be in between heights to the west and the Scandi trough:

The D10 ECM op represents a variation on the NOAA theme:

So from Sunday, next week looks a write off as far as Summery weather is concerned. After that potential for improvement.

Edited August 14, 2014 by i'm dreaming of...

[knocker]

I hope this brightens up your day   the Gfs 00z op run saved the best until last with high pressure building in and intensifying over the uk during low res, now this is not cherry picking because the longer term signal is for the weather to settle down and warm up again later in the month.. it could actually become very warm by the turn of the month if this carried on further...so it will hopefully be a fitting end to a very good summer overall...cheers

 

PS..honestly I did put these charts in the correct order but the computer said no

 

That rather depends on how you define cherry picking. I tend to think selecting a couple of charts 14 days down the road from one run satisfies the definition. After all I could pick some charts from the same week and say the situation is quite fluid and the high is probably transitory. Equally meaningless at the moment.

[Frosty.]

That rather depends on how you define cherry picking. I tend to think selecting a couple of charts 14 days down the road from one run satisfies the definition. After all I could pick some charts from the same week and say the situation is quite fluid and the high is probably transitory. Equally meaningless at the moment.

it's the longer term signal for the weather to become more summery again no matter what you say, so it's fair enough to show it. I hope the evolution is as the Gfs 00z op run shows, eventually get rid of that horrible trough to the north east and bring back summer! Edited August 14, 2014 by Polar Maritime
To remove unnecessary comment.

[Summer Sun]

Back to the models and the ECM ens is again showing something more settled developing just in time for the bank holiday weekend with pressure steadily rising from the 22nd

 

[IDO]

A difference of opinion is hardly a personal dig and no need to bother the mods as I won't bother posting in this thread in future.

Hi. Don't do that Knocker. Really appreciate your Input and those charts you post are very useful.We are heading for a cool 5-7 days from Sunday whatever your preferences. Then less certainty with several options on the table with the GEFS having no clear signal yet. So still time for a warmer period but we need more time for that to resolve.FWIW EC winter update suggests tentative signs of Northern blocking in Jan and Feb, though currently Dec looks more zonal.

 

Weather warning for the SE this afternoon: http://www.metoffice.gov.uk/public/weather/warnings/#?WT.mc_id=Twitter_Warnings_Rain&tab=warnings&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1407970800

Edited August 14, 2014 by i'm dreaming of...

[Polar Maritime]

I have had to delete some posts, Can we all please get on and respect others opinions.

And knocker don't get put off from posting!

Many Thanks, PM

[knocker]

Right a look at the Bank Holiday weekend with GEFS, GEM and the ECM. It basically boils down to the strength, position and orientation of the upper trough, and how far east the Greenland high pushes. The trough seems to be edging east which on the surface allows the Azores ridge to nudge into the UK which could well give some settled weather. The downside is below average temps although the GEM isn't quite so bullish with this.

 

Apologies as the charts don't seem to have loaded in the correct order.

ECM

GEFS

GEM

Edited August 14, 2014 by knocker

[mushymanrob]

it's the longer term signal for the weather to become more summery again no matter what you say, so it's fair enough to show it. I hope the evolution is as the Gfs 00z op run shows, eventually get rid of that horrible trough to the north east and bring back summer!

 

hi karl....(or indeed anyone)  may i ask what long term signal?... i cant see anything tangible that would suggest any settling down. the 06z gfs is having non of it which makes your earlier chart redundant. theres no sign on the anomaly charts that theres anything settled.

im sure that after the expected below average/cool spell we appear to be getting, at some point things will return to more average in terms of temps, but i cannot see any signal that it might settle down in the near furture, and its highly unlikely this month/ summer . imho.

[IDO]

The latest JMA anomaly till the 20th sits nicely with all the usual models: 

 

Week 2 ties in with the GEFS with a retreating Scandi trough with the Greenland/Atlantic anomalous high edging in from the west:

 

 

The continued sign for late August into September also showing up on the week 3-4 anomaly mean: 

 

No conclusive evidence from the 06z GEFS though still a cluster of UK higher pressure runs, but this is way out in FI so its just a case of looking for a trend in the next 3-5 days. 

 

[Chris K]

hi karl....(or indeed anyone)  may i ask what long term signal?... i cant see anything tangible that would suggest any settling down. the 06z gfs is having non of it which makes your earlier chart redundant. theres no sign on the anomaly charts that theres anything settled.im sure that after the expected below average/cool spell we appear to be getting, at some point things will return to more average in terms of temps, but i cannot see any signal that it might settle down in the near furture, and its highly unlikely this month/ summer . imho.

 

I think some people are misinterpreting Frosty's posts, thinking that he is saying a return to summery weather is a definite outcome...

All I am reading is someone who enjoys discussing outputs and possibilites that may bring more settled weather. Yes I doubt anyone reading this thread would rely on charts that far out, but outputs at the far range of the runs are a type of longer term signal nonetheless.

 

There have been for a few runs now showing a push of higher pressure from our W towards the end of August. It is too unreliable to consider at this stage so as others have said, we will need to wait a few days at least before it becomes clearer on whether it is likely/unlikely to happen. Just like when unsettled weather is shown that far out...just as unreliable right?

 

I am not exactly seeing washout synoptics that we have been accustomed to in other recent Augusts either. At least we don't have depressions diving to our SW and then bringing frontal rainfall again and again as it swings back up over the UK.

Edited August 14, 2014 by Chris K

[johnholmes]

it's the longer term signal for the weather to become more summery again no matter what you say, so it's fair enough to show it. I hope the evolution is as the Gfs 00z op run shows, eventually get rid of that horrible trough to the north east and bring back summer!

 

But until the upper air pattern shows the necessary pattern for that to occur then it is very unlikely to occur?

[Frosty.]

hi karl....(or indeed anyone)  may i ask what long term signal?... i cant see anything tangible that would suggest any settling down. the 06z gfs is having non of it which makes your earlier chart redundant. theres no sign on the anomaly charts that theres anything settled.im sure that after the expected below average/cool spell we appear to be getting, at some point things will return to more average in terms of temps, but i cannot see any signal that it might settle down in the near furture, and its highly unlikely this month/ summer . imho.

Hi mushy, or indeed anyone else...the long term signal is how the ensemble mean from ecm and gfs has been looking in recent days with another push from the azores high anticipated once the scandi trough fills and departs the scene, also the met office and bbc forecasters have been hinting at a more settled and warmer late august..I sincerely hope they are right...hope i'm not slated for being too optimistic.  

[Frosty.]

But until the upper air pattern shows the necessary pattern for that to occur then it is very unlikely to occur?

i'm only going by what the models have been showing john

[Blessed Weather]

I think some people are misinterpreting Frosty's posts, thinking that he is saying a return to summery weather is a definite outcome...

All I am reading is someone who enjoys discussing outputs and possibilities.....

 

I thoroughly enjoy this thread and the terrific posts from many members (too many to list). But I do get disappointed when people who have posted their interpretation of model output (even if it is in FI) get impolite comments from others.  

 

So today's "discussion"  amongst posters causes me to ask a model output related question please. I read many posts that refer to "upper air pattern" and comments along the lines of "until the upper air pattern indicates X", then model output suggesting Y should be ignored. But don't the numeric weather predictions of the models take into account the upper air patterns in their mathematical calculations to predict the weather??

 

Ready to be shot down...

[mushymanrob]

Hi mushy, or indeed anyone else...the long term signal is how the ensemble mean from ecm and gfs has been looking in recent days with another push from the azores high anticipated once the scandi trough fills and departs the scene, also the met office and bbc forecasters have been hinting at a more settled and warmer late august..I sincerely hope they are right...hope i'm not slated for being too optimistic.  

 

yes sir, but thats only 1 set of data.. and its pretty much fi.i accept that its a possibility that the azores might ridge in close enough to settle things down, but surely its only a long shot atm. its far from certain that there will be a settling down, indeed it might not settle at all.  im fully behind john on this, until the upper air pattern allows it, its not going to happen (other then breif odd days here and there)

 

I thoroughly enjoy this thread and the terrific posts from many members (too many to list). But I do get disappointed when people who have posted their interpretation of model output (even if it is in FI) get impolite comments from others.  

 

So today's "discussion"  amongst posters causes me to ask a model output related question please. I read many posts that refer to "upper air pattern" and comments along the lines of "until the upper air pattern indicates X", then model output suggesting Y should be ignored. But don't the numeric weather predictions of the models take into account the upper air patterns in their mathematical calculations to predict the weather??

 

Ready to be shot down...

 

impolite comments?... you mean me questioning where frosty gets his pretty strong conviction that things will change for the better?.. no sir, im questioning it because theres no tangible evidence off the models that theres going to be a settling down. now im not saying it wont, im not saying frostys wrong, im saying that theres no support for it in reality just yet, nothing certain anyway just a few odd runs.the upper air pattern determines what the surface air pattern we get. the anomaly charts which when in agreement over several runs (which they are) give a pretty accurate prediction of what the upper air pattern will be. the current concensus across the board is that the upper air will see a large/strong high over to our northwest, and a trough over our northeast. this pattern is expected to last most of the rest of the month, at least, and thatll produce a cool, northerly scourced airflow.

 

heres the latest.... see the trough? see the high? and thats the expected 8-10 day mean.

 

 

that is the most likely upper air pattern that transferres to the surface as a cool, showery, northerly scourced air.

 

to get a settled spell, the green lines would need to 'bump upwards' and grow apart over or near to us. like what these charts show between greenland and iceland. unfortunately they dip down over us, meaning that we are likely to be trough dominated, and thats a long way from being 'settled'. .... hence my scepticism at posts ramping up possible settling down. until these charts support it...it will not happen.

[phil nw.]

It's quite simple really if it's in the outputs it's ok to give your views-that's what this thread is for.

If however a view is more of hope than data based then maybe the other thread ie Model moans and ramps, is the one to post in.

 

Members will have different interpretations sometimes and that's fine but all posts should remain respectful to others.

 

Ok then on with discussion,the 12z runs will be out soon.

 

Thanks all.