Model Output Discussion 31/05/14 onwards.

[William of Walworth]

and i was thinking quite differently - i see a possible temporary respite from high slp and heights before the ridge builds back in through week 2.

I'm not being insane enough to make any real prediction that far into FI.  I'd go no  further than to say that on current output, its not altogether impossible that we MIGHT get a HP dominated (or at least influenced!) week 2, as well as week 1.

 

I think both summer-optimists and breakdown-pessimists should remain very cautious. All still to play for for week 2 at this early stage.

[summer blizzard]

Despite pulling the high west a bit most operationals I've seen in recent days do not bring any below average uppers into the south of the UK, and the GFS 06z is the same, keeping maxima in the low 20's for the southern half of the UK even when the northerly drift is present in FI, before things break down from the west instead (coincidentally with lower uppers for the south).

Not before a couple very warm days on the 06z at any rate:

 

I thought the ensemble means were more reliable than operationals at these time frames though? Seems we are told to use them and disregard operational runs at times, but for a few it's now the other way round and the ensemble means are largely ignored?

 

The ensemble means are quite clear about lower heights to the NW around Greenland too, for now I will be consistent and continue to pay attention to them and not get too hung up on the detail of operational runs beyond a week or so.

 

Operationals do in theory have a higher resolution out to day 8, from day 9 the ensemble mean is probably the better bet.

[Tamara]

There is solid agreement out to the middle of next week circa days 5/6 for High pressure domination, and surface detail as usual is determined by the placement of the centre of High. Guidance across the models fully supports that this will be very close to Ireland and NW Scotland for the whole of this period from the weekend. The ECM EPS ensemble members give a good representation of overall NWP output in this respect with very minimal variation to make a difference at the surface

 

 

Summer anticyclonicity can bring variable conditions at the surface even though it is *usually* uniformly dry when its proximity is very close to or over the UK. Such variability is in terms of sunshine amounts determined by cloud cover and also where onshore winds and sea breezes are most prevalent.

 

In this repect it is the SE quadrant that looks most likely to have the cooler conditions, but mainly on exposed coasts, as winds blow clockwise around the centre of the High. The early part of the week, especially, suggests variable cloud amounts and with the breeze off the North Sea it will feel distinctly cooler here -  certainly compared to today and much of this week gone by.

 

Its a very stagnant pressure pattern on the macro level at the moment into the medium term - and so this anticylonic pattern is advertised to dominate though next week with the High pressure cell staying pretty much in situ overall. On a broadscale micro level across the UK, little change is likely from day to day with the best temperatures inland and towards the entire west of the UK and Ireland  away from coasts in the east and especially south east where onshore breezes look to remain. A lot of very warm weather to be had especially away from the perimeter of the High, under very strong summer sunshine and the very light winds there

 

As others have stated, a cut off low is likely to underpin the ridge in situ for some time and this has obvious bearing on the stability of the pattern. Temperature profiles of increasing extra heat and higher humidity are potentially available to advect further north in time if the orientation of the high and low pressures evolves in favour of this development.

 

Whilst longer term telecommunications might suggest the opposite of such evolvement and support a retrogression of the High NW'rds and pressure to fall to the east and north east, I think that the models have already been shown to be far too progressive with this signal.

 

What is the reasoning behind this? Well, there are reasonable long term indications to suggest that an oceanic/atmospheric coupling may develop as an El Nino pattern increases which might teleconnect to what monthly atmospheric composites suggest and what some FI modelling has been reflecting. The net result of this coupling attained through a tropical forcing signal is to drop pressure over the eastern Pacific and create High pressure downstream towards the eastern seaboard of the US and western atlantic. With such a main higher pressure anomaly developing here, this would have the effect of retrogressing mid latitude ridges even further downstream across the atlantic westwards to be swallowed up into its centre (in this case our UK high)

 

But first there has to be a catalyst for this coupling to occur to enable a response from the atmosphere to shuffle the NH pressure patterns in response to oceanic warming over the Pacific ENSO regions.

 

This is where the MJO equatorial convection forcing signal comes into play and as Mushymanrob rightly suggests we cannot rely on forecasts for this to verify as indicated in terms of its strength, amplitude and progression. Models often overreact in terms of the timing and amplitude of these forcing signals.

 

I think for purposes of this thread and the likely over anticipation of NWP within the context of what the 'longer term' global teleconnectic pattern implies (which on these pages is realistically much shorter in relative terms) then these signals are best taken with a pinch of salt for the time being as the models for the time being are likely to continue to be too keen to over egg them and misread the amplification of the jet stream.

 

I think that the most likely outcome before any of that (might) happen is a migration of the High (eventually) a little way slighly eastwards with perhaps some thundery weather as heat and instability encroaches from the south and west to introduce an attempted breakdown to less settled weather further north and west. At the same time the highest temperatures could transfer from the NW to the SE as perhaps a NW/SE split develops for a while. But this is all some way off and open to usual caveats of long term uncertainties and best we all enjoy the rare spectacle since way back to last year of what looks to be quite a prolonged anticyclone over the UK

 

Edit: Its worth being cautious of individual operationals as the ECM longer term ensembles indicate that possibility of a warming trend with time. Some spread there as would be expected, but a good cluster of solutions there that are warmer towards day 10 than this mornings ECM operational and even this keeps the High closer to the UK than some other operational output available today which want to take it further west.

 

http://www.weathercast.co.uk/meteo/eps/ensemble-tt6-london.gif

Edited June 13, 2014 by Tamara תָּמָר

[mushymanrob]

i don't see any high uppers next Wednesday...dry with average temps certainly doesn't look hot to me.

 

really? cherry picked charts for thursday, heat starts building tues/wedns.

 

 

 

there, can you see them now?...lol.

Edited June 13, 2014 by mushymanrob

[mushymanrob]

and i was thinking quite differently - i see a possible temporary respite from high slp and heights before the ridge builds back in through week 2.

 

i agree, thats the feeling im getting over the current pattern. it was like that in 76, cooler cloudier interludes as the high drifted around, but either way - theres no sign of a monsoon washout! 

 

 

 

yet....

Edited June 13, 2014 by mushymanrob

[cheeky_monkey]

really? cherry picked charts for thursday, heat starts building tues/wedns.

 

Rtavn1442.gif

 

next week.gif

 

there, can you see them now?...lol.

this is weds max temperatures struggling to see 90f anywhere here?

[mushymanrob]

this is weds max temperatures struggling to see 90f anywhere here?

 

who said anything about 90f ?

 

i said high uppers, and the 10c+ isotherm is high. IF we avoid the cloud, those uppers should certainly give daytime max's of mid to upper 20's c . those temp prediction charts are notoriously inaccurate.

[mushymanrob]

one thing i cannot do is guess the cloud cover off the expected synoptics.ok, when we have a drift off the north sea its usually cloudy (but not always). how effective the sun is at burning it back i cannot even try to understand. clearly if this remains a dirty high, at least for the eastern half of the uk it will impact on daytime max's despite how high the uppers are.  last july, in the middle of the heatwave, here we had a whole weekend of cool dull cloud off the north sea.... but last year, after a bitterly cold spring the north sea was much colder then usual.im guessing that with the expected higher pressure, closer by, and lighter breezes the strong sun, nearly at its zenith, could well burn back the cloud for most of us inland areas quite readily. .... i might be wrong, if anyone with greater knowlege (shouldnt be hard, lol) can pour some light onto this i for one would be grateful.

[Mokidugway]

this is weds max temperatures struggling to see 90f anywhere here?

Irelands recently had all the storm activity lately , now looks like its going to get all the heat , could do with it shifting further east as my daughter gets married a week Saturday !!....

[Summer Sun]

Still high pressure dominated from UKMO though we have more of a north to northeasterly flow by Thursday on this afternoons run

 

 

850's only available at t96

 

[IDO]

JMA@T192:   NavGEM@T180: 

 

GEM@T240:   GFS Control@T240: 

 

GFS op@T240:   ECM@T240: 

 

ECM keeps the faith with UK HP; no surprise there. The rest bring some sort of breakdown (nothing too bad) during week 2.

 

ECM Op probably another outlier; the uppers at D10 are v. nice: 

 

Compared to the GEFS mean:   Hadrian's Wall 8c higher on the ECM op!

[knocker]

Looking at the back end of the ECM ops run there seems no obvious reason for the end of the fine spell. In fact it's quite warm. The 500mb anomaly shows the quite intense HP west and over the UK with the cold air stretching eastern seaboard/Greenland/Scandinavia. The cut-off low west of Spain remains just that. Surface remains under HP with a front edging towards N. Scotland. Very respectable temps apart from N. Scotland.

Edited June 13, 2014 by knocker

[Summer Sun]

Bar a slight blip for the east later next week ECM is looking very good for a prolonged settled spell

 

Edited June 13, 2014 by Summer Sun

[IDO]

The ECM op uppers was indeed a massive outlier. The mean 850s at D10: 

 

The mean 500hPa is far less confident of a UK high in FI, with the breakdown more in line with other models.

 

D7: 

 

The NOAA 8-14 dayer is a bit irrelevant today: 

 

It consists of 65% ECM mean (40% of yesterdays 12z and 25% today's 0z). The rest is from GEM. They have ignored the GFS. Confidence despite that remains as 2 out of 5!!!  Offers a nice positive UK surface anomaly that I suspect that will be binned tomorrow.

 

IMO confidence after D6 remains low but the 12z have moved towards a pressure fall in week 2, though as Knocker says, for the UK, the outlook is still reasonable. It may all flip back tomorrow so more runs needed.

[knocker]

The ECM ens is similar to the ops apart from dropping the 850 temps a bit. The 500mb anomaly is essentially the same.

Edited June 13, 2014 by knocker

[johnholmes]

T

 

The NOAA 8-14 dayer is a bit irrelevant today: 814day.03 (15).gif

 

It consists of 65% ECM mean (40% of yesterdays 12z and 25% today's 0z). The rest is from GEM. They have ignored the GFS. Confidence despite that remains as 2 out of 5!!!  Offers a nice positive UK surface anomaly that I suspect that will be binned tomorrow.

 

 

 

Not sure  why you say it is irrelevant today as it clearly shows the probability of the upper ridge persisting even out to 14 days from now. It is consistent as well over the last few days with this idea. Likewise the 6-10 fits well with the EC-GFS pattern of upper ridge and associated +ve heights in the UK area with -ve heights and an upper low south of it, again this has been a consistent idea from the 6-10 for several days.

All seems fairly logical to me and the most likely upper pattern through 5-about 12-15 days?

 

I would add that the NOAA comments from an experienced forecaster on how they see the 500mb charts using a mix of models , in their region, but with implications downstream, are one of the reasons why the NOAA 6-10 and to a slightly less extent the 8-14 is so often close to the actual chart. My data suggests the 6-10 is 70% of the time about right for the upper pattern and the 8-14 maybe 60-65%. Others of course will disagree but it gives me a good deal of confidence when looking beyond the 3-5 day period.

Edited June 13, 2014 by johnholmes

[J10]

Not sure  why you say it is irrelevant today as it clearly shows the probability of the upper ridge persisting even out to 14 days from now. It is consistent as well over the last few days with this idea. Likewise the 6-10 fits well with the EC-GFS pattern of upper ridge and associated +ve heights in the UK area with -ve heights and an upper low south of it, again this has been a consistent idea from the 6-10 for several days.

All seems fairly logical to me and the most likely upper pattern through 5-about 12-15 days?

 

I would add that the NOAA comments from an experienced forecaster on how they see the 500mb charts using a mix of models , in their region, but with implications downstream, are one of the reasons why the NOAA 6-10 and to a slightly less extent the 8-14 is so often close to the actual chart. My data suggests the 6-10 is 70% of the time about right for the upper pattern and the 8-14 maybe 60-65%. Others of course will disagree but it gives me a good deal of confidence when looking beyond the 3-5 day period.

 

Indeed those upper charts have kept showing a upper ridge over or close to the UK in the 6-10 range for most of June.

 

http://forum.netweather.tv/topic/80198-glastonbury-wed-25-to-sun-29-june-2014/page-3?p=2988621 shows these charts so far this month if anyone is interested.

[Costa Del Fal]

The ECM op uppers was indeed a massive outlier. The mean 850s at D10: EDM0-240 (5).gif

 

 

Was it definitely a massive outlier?

 

Surely at D10 which is quite a way out, the spread from the range of predictions from other members is rather naturally going to appear to water down the uppers a bit. Still, if the mean has the 8c upper over S England, its going to be pretty damn warm regardless in the sun.

 

Thus, to be honest, anything at Day 10 is very often going to look cooler because of the greater spread and uncertainty in comparison to the warm spell we will be entering.

Edited June 13, 2014 by Blizzards

[Captain Shortwave]

It does look likely that we will see a cut off low developing to the west of Portugal next week. I must admit the response over Europe to this looks lackluster at the moment. GFS 18z as an example.

Again a large bias towards the ridge in the Atlantic and pulling the UK high further west. I do wonder whether the models will begin to increase the influence of this low and hence start to develop heights over Southern and central Europe over the next 24-48 hours. If this happens then the pattern should correct east. Though it's more gut feeling than anything else. 

 

Very strange to see an Arctic northerly developing, but yet also see the 12C isotherm creep into the south of the UK. Oddly contrary to many posts here tonight, I thought the ECM was actually a reasonable solution for the cut off low with heights being maintained over the UK.

Edited June 13, 2014 by Captain shortwave

[Man With Beard]

So with the block looking secure for, say, the next 7/8 days at least, attention turns to the temperatures. I very much suspect that within 4 days, the SE and E coast will be the only places experiencing average temperatures, no matter what GFS says. It's mid June, HP very nearly centred over us, I would expect all but those areas to be well above average by Wednesday. Once temps get there, they may stay there some time.

[knocker]

Taking a peak into the future and the GFS is going for a breakdown of the HP/warm scenario by early next week.

 

Following the evolution of the 500mb anomaly Tuesday of this week has the warm air Greenland to a ridge just to the west of the UK with a trough in the western Atlantic.

 

There then follows a fairly rapid transition in the next few days. The warm air over Greenland weakens and moves south with a weak ridge mid Atlantic. An upper low forms mid Atlantic and moves east to a position west of Spain whilst the same time the cold air over Scandinavia intensifies and moves west north of the UK.

 

On the surface this has the affect of moving the HP westwards with a low west of Spain. This develops further by the beginning of the following week with low pressure adjacent in northern France. By Tuesday the low is over Cornwall with moderate rain. Just as well this won’t verify.

Edited June 14, 2014 by knocker

[IDO]

The GEFS have been picking up an incursion from the NE around next Thursday for a few runs. It has been a trending development and the 0z continues with this:

 

 

Even though that has been a strengthening signal the members have been unable to agree how the pattern develops from there, with numerous possible outcomes. So falling pressure from the NE and initially a W-E split in our region whilst the members sort out a solution is my best bet.

 

GEM also picking up on this:   

 

They also have the cut off upper Iberian Low link up with the N.Europe lower heights to form a weak trough from Scandi to Iberia by D7+.

 

Neither GFS or GEM would be anything but a return to more average temps and a slightly higher risk of rainfall (apart from the unlikely GFS op at D11).

 

This morning's ECM op has reluctantly spotted the possible change but delays it till T192: 

 

By T240 the centre of the heights is back over the Azores: 

 

As expected an 8c difference in uppers compared to last night's outlier 12z for the Hadrian's Wall area: 

 

I suspect the ECM will continue to backtrack on sustaining the UK high next week, but uncertainty remains after D5, so I wouldn't bet on that; though likely west is best from mid-week onwards.

 

 

 

 

[summer blizzard]

Operationals vs Ensemble means.

 

Both ensemble means keep pressure high.

 

All operationals have at least a temporary breakdown (Euro at day 8, GEM and GFS at day 10)..

 

[knocker]

The ECM ens 500 anomaly not so bullish with the western movement of the eastern cold air or the the incursion from the south with a ridge still in place to the west of the Uk. The jet is shooting around this ridge to the north. perhaps a build up of heights from the SW in time for Glastonbury. That's my punt anyway but off to consult Joan the Wad for confirmation.

Edited June 14, 2014 by knocker

[mushymanrob]

another day, another option for the highs departure.weve had it drift across us, weve had it retrogress and join the greenland high, now its expected to retrogress and join a strengthening azores high .  theres still plenty of time for yet another option to emerge, or to go back to a previous one.the models all agree though that in the reliable timeframe the hiogh will sit just to the west of scotland/north of ireland this week and intensify. some of us are in line for some splendid, warm sunshine, whilst others will be frustrated by cloud, but it will be dry and warm even under the cloud. favoured places could get hot weds-fri.then the high is expected to drift away westwards... but where it goes and what effect itll have on us is far from clear atm . but currently the options dont favour a return of the rains. so the rest of june should be largely dry, and theres plenty of scope for something hot and sunny to develop as we enter july. so many of us MIGHT miss out on the sun/heat this time, but classic hot spells often start in july.