Model Output Discussion

[Swave Snow]

and your town as asked please?

Sure NW London

John,

Just realized,

I have it already in my signature.

Edited June 30, 2011 by Swave Snow

[johnholmes]

Sure NW London

John,

Just realized,

I have it already in my signature.

ta-I never have the sigs shown so my apologies-reason, some folk have extremely long and somewhat repetitive ones. I'll remember NW London

[Swave Snow]

ta-I never have the sigs shown so my apologies-reason, some folk have extremely long and somewhat repetitive ones. I'll remember NW London

No Worries

[Alex]

Something to note is the GFS is at the bottom end of the ensembles with most members showing higher temps.

[Buzzit]

I do have to laugh a little - GFS op progs a current temperature for Heathrow of 11c feeling like 12c when the current temperature is 17c

[Derp Patrol]

Looking decent for England and Wales for the next week or so in the reliable frame. We are now entering the time when traditionally I find that the temperatures 'stabilise' to about 22-24C on average here and it's rare to get below 20C, so any cool weather for here now is off the cards as the warmer air masses are moving northwards. We are not under an exactly warm airmass yet we are predicted night minima of 14-17C here and there will be plenty of sunshine so it is not a bad outlook at all unless you're in Scotland or Ireland.

[damianslaw]

Looking decent for England and Wales for the next week or so in the reliable frame. We are now entering the time when traditionally I find that the temperatures 'stabilise' to about 22-24C on average here and it's rare to get below 20C, so any cool weather for here now is off the cards as the warmer air masses are moving northwards. We are not under an exactly warm airmass yet we are predicted night minima of 14-17C here and there will be plenty of sunshine so it is not a bad outlook at all unless you're in Scotland or Ireland.

Not sure about those minimas - temps look positively cool in the next few days with clear skies and the not particularly warm airmass - low teens in central London and high single digits elsewhere- cooler in sheltered northern parts. BBC said we are about to see 'infill' conditions or something along those lines - first time I have heard them use this term - i.e. clear skies overnight with clear skies in the morning but as the land warms cloud builds midday clearing later as land cools again - a recipe for some cool nights I think.

[Slowpoke]

18z is baffling

If we're stuck with this Greenland high crap all Summer then it best stay for winter.

Edited June 30, 2011 by Slowpoke

[NorthernRab]

Looking decent for England and Wales for the next week or so in the reliable frame. We are now entering the time when traditionally I find that the temperatures 'stabilise' to about 22-24C on average here and it's rare to get below 20C, so any cool weather for here now is off the cards as the warmer air masses are moving northwards. We are not under an exactly warm airmass yet we are predicted night minima of 14-17C here and there will be plenty of sunshine so it is not a bad outlook at all unless you're in Scotland or Ireland.

I don't know if we're looking at different charts, but it looks really quite dry and sunny in Scotland and Ireland, especially compared to the last couple of weeks! Warm too, certainly up from the fairly deflated temperatures as of late.

[Slowpoke]

18z would give us a well below average July...

[SP1986]

18z would give us a well below average July...

I fear your disappointment has clouded your judgement. Firstly the charts don't show the whole of July.

Secondly, there is a trend in the model outputs for poor setups to be shown which then modeify into good setups recently. Next week is one of them.

Therefore the assumption that July will be poor because of the downward spiral in FI is not really a valid one.

[snowlover2009]

What are some people talking about judging runs and saying that July will come in as below average, I am seeing upgrades and it looks cracking to me, the 18z prolongs the very warm settled conditions to the end of next week, which is reliable enough time frame and anything beyond that is not important as the warm spell has upgraded on the 18z till the end of next week. That would take us to the 8th July, with some missing out on rain for the first 8 days if it was to verify, a totally different July from the last 4 which just seem to be repeatedly none stop showers for the entire month. I remember July 2009 almost every day has some measurable rain with the odd 2 to 5 days dry. Sp if the 18z came off it would be a big improvement on all the last Julys as I don't remember one week of decent weather in any of them, not on the scale of the upcoming one with temperatures in the mid 20s possibly and I believe that 18z FI is nothing to worry about and will change. It looks a cracking start to July. Perfect temperatures bang on what I like, I wouldn't say no to the recent temperatures but it is going to feel very warm in the sun.

Edited June 30, 2011 by snowlover2009

[Buzzit]

I fear your disappointment has clouded your judgement. Firstly the charts don't show the whole of July.

Secondly, there is a trend in the model outputs for poor setups to be shown which then modeify into good setups recently. Next week is one of them.

Therefore the assumption that July will be poor because of the downward spiral in FI is not really a valid one.

In addition I would say that the daily difference in output after the 8th of July in this run looks to me like it has got tired of processing the data and gone off on one

On the 10-12th every 6am has 1024 over greenland and every 6pm has 1018 with quite different isobars - seems strange to me ?

[Costa Del Fal]

Until about the 10th July at least a very pleasant 18z GFS with at least 20c every day next week for Central and Southern areas and not bad elsewhere either. Cloud maybe an issue at times but when the sun is out it will feel very very nice. Almost perfect really, not too hot but by far not cool except in the core overnight period maybe.

[chionomaniac]

Is there? looks like just slightly above average to me. http://ds.data.jma.g...e/pole30_n.html

looks like about 2C above normal to me..

I'm not as knowledgeable as some like chionomaniac for example, but surely a 2C above normal temperature will not have much of an effect. I might be wrong but I thought major warmings only really happened in winter?

On a different point I've noticed runs like the GFS seem to have gradually upgraded 850hpa and surface temps for this weekend/early next week. the 10C 850hpa line comes across the south briefly now.

One has to remember that the mean zonal winds turn easterly for the summer after the final warming. These fluctuate slightly but are in the order of around -7m/s at 30 hPa and vary only by a couple of m/s over summer. To compare this to winter, then the average for January is around 30m/s with a variance of that allows the winds to increase up to 50m/s and reduce to negative if a warming occurs. From this, it can be suggested that once the stratospheric temperature has settled down for the summer, stability is introduced and slight temperature changes are unlikely to have any noticeable affect on the troposphere.

[mushymanrob]

I don't think this will be a "cloudy" high by any means, but it will be weak enough to allow some convection to sprout up, leading to broken cloud and sunny intervals, and a wide scattering of showers (most places staying dry though). Some areas of the country might end up with relatively cloudy afternoons due to the old issue of convective cloud encountering a cap and spreading into stratocumulus, but I'll be surprised if any lowland areas (bar perhaps Shropshire, which sounds like it's particularly prone) have three cloudy afternoons out of three. So, don't expect wall-to-wall sunshine, but don't expect anything approaching anticyclonic gloom either.

oh i fully agree, which is what i was refering to in my reply to conor, sorry if i gave the impression that it could be a dirty high.

the ecm is having non of the siberian/scandinavian block the gfs is still championing into fi... the ecm still paints a disappointing picture with low pressure being locked in over us for some time. the gfs however would produce some splendid summer weather IF fi became reality. atm it look like very pleasant weather from now until the middle of next week with temps slowly rising. the 'uppers' from sat - thurs are decent and should translate into at least average temps but above average for most.

[Gibby]

UKMO shows slack high pressure in control of the UK weather between now and Tuesday with reasonably warm weather with cloud coming and going and very light winds. Temperatures in the low 20s in the south and east with time. By Tuesday and Wednesday Low pressure edges in from off the Atlantic with rain then showers and somewhat cooler conditions for all.

GFS this morning is much less disturbed than last night with the Low pressue breakdown next week fairly temporary in the south as the Azores High pushes a series of ridges across before High pressure takes control again in FI. As it stands there would be a few unsettled, showery days next week before the south becomes mostly settled, dry and eventually very warm as High pressure builds over the UK deep in FI. Any rainfall from Atlantic troughs would be reserved for the NW with a few thundery showers in the south at the end of the run.

ECM shows quiet weather out till Tuesday of next week when low pressure comes in close to NW Britain generating showers through the remainder of next week as it slowly fills in situ. Some dry, bright and warmer spells with fewer showers seem likely towards the south and east at times though by the same token some of the showers would be heavy and thundery where they occur. This theme lasts until the end of the run.

This morning sees a marked division in the runs as GFS has flipped this morning giving southern regions a much more summery look after next weeks brief showery spell. However, UKMO looks little different from last night bringing Low pressure over the UK by next Wednesday. ECM is much like last night though the Low pressure seems less energetic allowing the far south and east to see fewer showers at times. All in all a slightly less pessimistic look about the overall output for southernmost areas but little change for northern and western regions.

[casparjack]

Just looked at the ECM 00z and to me it looks an unlikely outcome.

The suggestion that a low will arrive then sit W/NW of Ireland from T96 to T240 with very little change in central pressure, 8mb or so, it seems to deepen, fill, deepen then fill again - I don't doubt that scenario to start with, I just can't see it lasting out to day 10 with little or no real change, I suspect subsequent runs might show a different evolution, maybe allowing a little more influence from the high to the SE at last.

[Ben_Cambs]

GFS 00z this morning was an outlier or top of the range at best in terms of SLP from around T+168 onwards;

http://www.netweathe...bridgeshire.png

Though in the short term it is looking dry and increasingly warm, temperatures could get up to the mid-20's in the South by Tuesday and even getting into the low 20's up into Southern Scotland.

Edited July 1, 2011 by Ben_Cambs

[Eugene]

This morning sees a marked division in the runs as GFS has flipped this morning giving southern regions a much more summery look after next weeks brief showery spell

Not supported by its own ensembles though, i think i'll go with ECM 00Z as being the most likely scenario.

[shedhead]

Just looked at the ECM 00z and to me it looks an unlikely outcome.

The suggestion that a low will arrive then sit W/NW of Ireland from T96 to T240 with very little change in central pressure, 8mb or so, it seems to deepen, fill, deepen then fill again - I don't doubt that scenario to start with, I just can't see it lasting out to day 10 with little or no real change, I suspect subsequent runs might show a different evolution, maybe allowing a little more influence from the high to the SE at last.

I can't see any real reason to suggest the 00 ECM outcome is 'unlikely', other than wishful thinking perhaps, and if so I'm with you there! However it is clearly at the worse case senario end of the scale, with GFS close to best case given the overall set up, so I suspect we'll probably end up with something of a half way house. The UKMO at 144hrs does look of concern to me though, struggling to see a quick root back to anything warm and settled from there.

[Methuselah]

As per usual there's (as one has come to expect) nothing concrete in the models this morning; and, certainly, there's no particular run that seems to be in any way better than the majority...So, I'd guess at a gradual evolution away from what we currently have towards something a little different (most likely warmer and drier, though not necessarily so)...Anyhoo, attempts to write off the whole of July based on today's runs seem ridiculous in the extreme...

[casparjack]

I can't see any real reason to suggest the 00 ECM outcome is 'unlikely', other than wishful thinking perhaps, and if so I'm with you there! However it is clearly at the worse case senario end of the scale, with GFS close to best case given the overall set up, so I suspect we'll probably end up with something of a half way house. The UKMO at 144hrs does look of concern to me though, struggling to see a quick root back to anything warm and settled from there.

I don't do wishful thinking in meteorology, experience tells me it has very limited effect on the outcome!

All I was saying was that I doubted that the modelled low would stay in the same spot for almost a week.

It may, it may not - we don't know; my opinion however is still that we might see more influence from the Azores anticyclone than currently indicated by the ECM.

That's all, nothing more nothing less, a freely expressed view in the course of model discussion.

[SP1986]

In my experience I tend not to argue with the GFS when it forecasts high pressure ridging in from the Atlantic, not of course because it's what I want to see necessarily, but simply because it's usually the defining pattern that the GFS picks up on better than most other models in my experience. So I wouldn't write off the GFS operational because it's an outlier. However things are almost certainly going to change, as it has done many times over the last few weeks.

The ECM does look a little caught in the cog so to speak but it has an even chance of breaking out.

Whatever occurs though in the next 4 days we have a summery outlook.

[Thundery wintry showers]

oh i fully agree, which is what i was refering to in my reply to conor, sorry if i gave the impression that it could be a dirty high.

the ecm is having non of the siberian/scandinavian block the gfs is still championing into fi... the ecm still paints a disappointing picture with low pressure being locked in over us for some time. the gfs however would produce some splendid summer weather IF fi became reality. atm it look like very pleasant weather from now until the middle of next week with temps slowly rising. the 'uppers' from sat - thurs are decent and should translate into at least average temps but above average for most.

Don't worry Mushy- I was thinking more of the TV forecasts suggesting a dirty high (there were a couple over on the BBC earlier), I can't remember any of your posts giving the same impression.

The models are now postponing the next Atlantic system's arrival until Tuesday, perhaps even Wednesday in some eastern areas- it certainly appears that the models were being far too progressive in bringing the Atlantic system (which, perhaps, might be why they placed low pressure over Scandinavia in FI when most teleconnections favour low pressure centred to the NW).

The models seem agreed on a cyclonic west/south-westerly regime past Wednesday but there is divergence on the likely weather- UKMO and ECM suggest minimal disturbances, implying a showery thundery type regime, while GFS models numerous disturbances. Usually in these situations the reality turns out somewhere in between, but I won't be surprised if this low pressure ends up further west for longer than is currently suggested, as that has been the recent trend.