Model Output Discussion 12z 23/05/13

[ANYWEATHER]

Ecm is a little better by the far reaches of t+168, but im not convinced by any model output at the moment, that far out.  

[Frosty.]

The Ecm 00z eventually turns out fine with high pressure building strongly across central and southern parts of the uk with a warmer and more settled outlook.

Looking at the bigger picture, the 00z models have delayed the arrival of the azores/atlantic ridge next weekend, it slowly pushes into the west so west would be best, the Gem 00z builds the high to the west and then a strong anticyclone develops to the north of the uk in FI, the Gfs 00z is the glaring exception to the improving story but it will probably have little or no support with it's cool unsettled spell next week, the Gefs 00z mean looks rather better than the op with a narrow ridge of high pressure to the west and northwest of the uk but with a trough (weakness) to the southeast, eventually the gefs mean settles down with the azores anticyclone ridging across the uk, the gfs 00z op run also settles down and warms up further into June.

In summary, it's not looking like a straightforward transition to a warm and settled outlook by any means, the west is likely to become settled first but beyond that, it could be the west and north which have the warmest and sunniest weather with the south and east affected by slow moving shallow troughs as per the gem 00z op and gefs 00z mean or the ecm 00z which shows high pressure building across most of the uk with only the far north being cooler and showery.

Edited May 27, 2013 by Frosty039

[Gibby]

Good morning folks. Here is my interpretation of the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Bank Holiday Monday May 27th 2013.

All models show an unsettled week to come. All areas will be influenced by the transit of Low pressure from the far NW today to a position off SE England later in the week. After all areas experience a period of rain today and tonight a mix of sunshine and showers with some longer spells of rain here and there predominate from Tuesday to Friday with a return to rather cool conditions generally as winds turn towards the North later in the week.

GFS then shows next weekend as a showery one with a Northerly flow generating showers and sunny intervals with the heaviest showers towards the East. A ridge of high pressure is then squeezed out of existence as it crosses East early next week ahead of fronts moving in from off the Atlantic with more cloud and rain in tow for most. This breezy and unsettled weather remains until the second weekend when High pressure develops from the South slowly extending it's influence North to all areas eventually with a centre just to the West of the UK with a strong ridge across Britain ensuring fine, warm and sunny conditions.

The GFS Ensembles still look fairly healthy this morning with the vast majority of members supporting a rise of uppers to above average levels in a weeks time, maintained thereafter. The operational was a warm outlier at the end and precipitation is still shown scattered about throughout the warmer stages indicating that the weather will not be totally High pressure based.

The Jet Stream shows the flow still blowing SE to the west of the UK for a few more days before it breaks up and becomes very weak, certainly around the UK and NW Europe. A thin jet streak then is indicated way South over Europe and way North near the Arctic Circle.

UKMO today shows a cool and showery weekend likely under a Northerly flow. A ridge of High pressure is just to the West of the UK but to me it looks under pressure from further Atlantic developments off Southern Greenland to threaten the UK later next week.

GEM today shows High pressure having built way up to the North of the UK with the net result of keeping things at risk of being or remaining showery over Southern Britain while the North sees the driest and brightest weather. At the close of it's run it looks as if a North/South split will develop over the following days with an unsettled South and dry North.

NAVGEM shows a NW flow at the weekend maintaining cool and breezy weather with scattered showers. A weak ridge then crosses from the West ahead of an Atlantic depression bringing rain in from the West by midweek.

ECM shows a showery weekend under a Northerly flow. A weakening ridge then looks like being squeezed across the UK, weakening somewhat as equally weak upper air disturbances allow rather cloudier weather to accompany it with the odd shower, chiefly in the North. In the South though the middle section of next week would not be too bad with some decent warmth to any sunny spells and light winds.

In Summary the better spell I've indicated in recent runs looks far from nailed this morning as all models to some degree or another have watered down the full on High pressure expanse shown on previous output. There will still be a ridge of sorts to cheer things up but it's unlikely to have much affect on the weather until early next week with plenty of changeable conditions with outbreaks of showers or rain until then for most. Upon arrival it then becomes under pressure from developments off Southern Greenland either as a charge of SW winds and fronts moving East over Britain or as a cut off feature such as GEM shows bringing a North/South split in the weather later next week with the North seeing the best share of dry and bright weather while the South lies under the threat of Low pressure and showers. The one constant though is behind the current upcoming spell of chilly weather from next week on it does look like being somewhat warmer as the direct Northerly feed loses it's impetus.

[johnholmes]

There is still little in the predicted upper air pattern to indicate anything more than a day maybe two here and there with temperatures to make it feel summery. The upper flow remains stubbornly set from either westerly or north of west. Equally the trough is never too far from the country. So any expectation in the 6-15 day or so outlook of dry warm and settled weather is very far from what I see?

The best of the weather could well end up in the NW into the start of June, it being furthest from any upper trough effect. Mind you this morning the GFS version has scuppered this idea but currently I would favour the NOAA and ECMWF upper air patterns as being closer to the mark.

Edited May 27, 2013 by johnholmes

[Purga]

The 06 ENS showing up the wet period to come pretty well

 

 

The continued FI promise of warmer drier weather later on is there as well, with the majority of the runs supporting this, although the Op is on the extreme warm side of the main grouping.

The upper level anomaly charts appear to back the METO longer term view.

 

 

Edited May 27, 2013 by Purga

[Frosty.]

There is still little in the predicted upper air pattern to indicate anything more than a day maybe two here and there with temperatures to make it feel summery. The upper flow remains stubbornly set from either westerly or north of west. Equally the trough is never too far from the country. So any expectation in the 6-15 day or so outlook of dry warm and settled weather is very far from what I see?

The best of the weather could well end up in the NW into the start of June, it being furthest from any upper trough effect. Mind you this morning the GFS version has scuppered this idea but currently I would favour the NOAA and ECMWF upper air patterns as being closer to the mark.

I tried to put a more positive spin on the outlook because there are some nice looking charts on offer this morning, as well as some crud from the gfs in particular.

[Summer Sun]

If you want rain you best make the most of tomorrow according to the ECM Birmingham ensemble as we have a downward trend after this lasting for the first week of June at least

 

 

[Evening thunder]

I don't understand some of the negative/downbeat posts in here this morning? even the GFS is showing a more average June affair not the cold northerly winds we've seen recently.

 

I also must admit I don't really understand what John says about the upper flow always being suggested from the W/NW with only one or two summary days at best, especially with ensemble means like the ECM from last night (conveniently today's are just showing as blank yet and can't view yesterdays now on Wetterzentrale) which would clearly give more than 1 or 2 summary feeling days even if the upper flow was still somehow W/NW'erly, with high pressure stretching near or across us and decent and warming 850hpa temps?

[Tamara]

I don't understand some of the negative/downbeat posts in here this morning? even the GFS is showing a more average June affair not the cold northerly winds we've seen recently.

 

I also must admit I don't really understand what John says about the upper flow always being suggested from the W/NW with only one or two summary days at best, especially with ensemble means like the ECM from last night (conveniently today's are just showing as blank yet and can't view yesterdays now on Wetterzentrale) which would clearly give more than 1 or 2 summary feeling days even if the upper flow was still somehow W/NW'erly, with high pressure stretching near or across us and decent and warming 850hpa temps?

I don't think there is negativity - just attempts to read between the lines and be realistic. I'm sure that if the overall background picture was better, then some of the more cautious and less enthusiastic posts about the arrival of summery weather would adjust accordingly.

 

There is persistent evidence of an upper trough close to the UK. The Azores High keeps flattering to deceive, and it

seems to always be a week away from moving east towards/over the UK. That seems to have been a repeated mantra for quite some time

 

There are quite a few of the EPS members which depict this at day 7 time with that upper trough close by over the continent and eastern/south eastern parts of the UK

 

I think it is true to say that in relative terms, temperatures are going be something of an improvement on what we have seen, but that still means they are likely to be rather cooler than normal in any cloudier wetter areas with the best prospects for sun and pleasant feeling temperatures the further North West one goes

 

 

The NAEFS anomalies suggest pressure lower to the south and that rather underpins the NW/SE split in the weather conditions

 

Edited May 27, 2013 by Tamara Road

[johnholmes]

I also must admit I don't really understand what John says about the upper flow always being suggested from the W/NW with only one or two summary days at best, especially with ensemble means like the ECM from last night (conveniently today's are just showing as blank yet and can't view yesterdays now on Wetterzentrale) which would clearly give more than 1 or 2 summary feeling days even if the upper flow was still somehow W/NW'erly, with high pressure stretching near or across us and decent and warming 850hpa temps?

I will try and explain what I think these charts are showing

[Frosty.]

I will try and explain what I think these charts are showing

I thought you had, seems clear to me.

[J10]

Some downbeat posts in here, after today's rain, gradually improve into western areas especially towards next weekend. The Azores High never to far away from SW areas, making any NW incursions ala the the GFS op run, less likely.

 

At this moment, runs seem a world away from last June.

 

One difference for me though is HP ridging from the SW giving NW winds as per next weekends current forecast tends to give decent weather for here, so we would do comparatively well of such conditions.

[J10]

 

I think it is true to say that in relative terms, temperatures are going be something of an improvement on what we have seen, but that still means they are likely to be rather cooler than normal in any cloudier wetter areas with the best prospects for sun and pleasant feeling temperatures the further North West one goes

 

The NAEFS anomalies suggest pressure lower to the south and that rather underpins the NW/SE split in the weather conditions

 

 

Sorry to partly quote.

 

I think that those near the east and South East are less keen on current outputs than those in the west.

 

John mentioned that the flow of winds forecast is more North of West, than for South of West, for us that is good, while meaning slightly cooler, NW winds will generally give better weather her than SW winds.

[Frosty.]

Some downbeat posts in here, after today's rain, gradually improve into western areas especially towards next weekend. The Azores High never to far away from SW areas, making any NW incursions ala the the GFS op run, less likely.

 

At this moment, runs seem a world away from last June.

 

One difference for me though is HP ridging from the SW giving NW winds as per next weekends current forecast tends to give decent weather for here, so we would do comparatively well of such conditions.

Agreed, the models look a lot better than they have done throughout the spring so far, but most of the uk haven't really had a spring as such, we can only hope the early summer will bring some cheer, most of the models are showing a spell of warmer and more settled in early/mid June.

Edited May 27, 2013 by Frosty039

[johnholmes]

The NAEFS anomalies suggest pressure lower to the south and that rather underpins the NW/SE split in the weather conditions

 

It does although I have not so far either done any nor seen any checks on how NAEFS rates compared to the other 3 anomaly height charts. Anyone willing to do this please? That way we have fact not gut feelings on another model?

Sorry to partly quote.

 

I think that those near the east and South East are less keen on current outputs than those in the west.

 

John mentioned that the flow of winds forecast is more North of West, than for South of West, for us that is good, while meaning slightly cooler, NW winds will generally give better weather her than SW winds.

Julian- remember the flow I am talking about is at 500mb not the surface although with that upper pattern the surface flow is not going to often from south of west?

[johnholmes]

my reply for Stormad26-hope it helps?

stormad26 reply 27 may 13.pdf

[Milhouse]

That troublesome low looks like it may spoil things at the weekend, but on the plus side Thursday and Friday look good for the majority of the UK with just a few showers around. GFS 6z shows a max of 22c in the south on Friday which is not to be sniffed at.

Then it gets complicated with low pressure, having affected the UK at the start of the week, coming back again to affect the eastern half of the UK for the weekend. How close it gets to the UK is still undecided but the eastern half of the UK always fairs worse in this situation. The best of the dry and sunny weather across southwestern England.

The 6z so far is making much less of the weekends low pressure so things are no set in stone just yet.

By Sunday its a little closer but notice all the warm air just to the east of the UK.

By Monday the low has all but vanished and high pressure takes over.

Edited May 27, 2013 by Jackone

[bluearmy]

naefs and ecm ens have been consistent with this low euro anomoly, together with the high anomoly to our north (moreso scandi). tbh, given the door remains ajar, somewhat, to our nw to energy off the atlantic, i dont think the fortnight folllowing this w/end is going to be easy to call on a countrywide basis. could go in any direction with very little adjustment.

[J10]

It does although I have not so far either done any nor seen any checks on how NAEFS rates compared to the other 3 anomaly height charts. Anyone willing to do this please? That way we have fact not gut feelings on another model?

Julian- remember the flow I am talking about is at 500mb not the surface although with that upper pattern the surface flow is not going to often from south of west?

Same applies though with the upper flow with regards to our weather, at least locally.

[Tamara]

It does although I have not so far either done any nor seen any checks on how NAEFS rates compared to the other 3 anomaly height charts. Anyone willing to do this please? That way we have fact not gut feelings on another model?

Julian- remember the flow I am talking about is at 500mb not the surface although with that upper pattern the surface flow is not going to often from south of west?

Hello John. I'm not sure it is based solely on a blend of intuitive feelings, as even I wouldn't be able to get away with that *she self deprecates* All opinions obviously have to be based on some reality  I think it has been clear enough for several days that there was no straightforward evolution to a wider settled spell and the METO have not at any time been as bullish as stated often in this thread.

 

The pattern may not be like this time last year ( other than a little harmless weekend teasing) but as far as i see it, it is still some way from the sort of traditional pattern where the jet stream is much more predictable and takes low pressure systems reasonably well to the north of the UK and allows the Azores High to strtch NE 'wards, much as quite a few have kept predicting for quite some days and some face value model output has also suggested 7 to 10 days away.

 

The traditional June westerlies often arrive after meridional patterns during the Spring, and this is often the gateway to some of those classic summer spells. I just don't see us in that position at this time and we are stuck in upper trough pattern and, as this week shows again, a pattern that is very eager to disrupt energy southwards. In terms of what happens from the weekend - as bluearmy said recently, atlantic energy has to go somewhere, and the current anomalies suggest that it might not be far from parts of the UK. This is not a SE centric based opinion as some might believe - it is based on realistic likelihood that the SE is most likely to come under the influence of upper troughing very close by on the continent. On that basis the opinion I agree with closest is the one as last recently posted wrt to this euro low anomaly. The balance of split in the weather is indeed quite finely balanced at this time - albeit the NW continuing imo to look most favoured.

 

Whatever the weather does in the foreseeable future, today sun is shining and it is glorious  so an outdoor afternoon is there to be enjoyed

Edited May 27, 2013 by Tamara Road

[Summer Sun]

The met office continue to point to a north west south east split this coming weekend with the warmest and sunniest weather in many northern and western parts whilst the south east will remain more unsettled with occasional spells of rain or showers some of which maybe prolonged and heavy

[Evening thunder]

I don't think there is negativity - just attempts to read between the lines and be realistic. I'm sure that if the overall background picture was better, then some of the more cautious and less enthusiastic posts about the arrival of summery weather would adjust accordingly.

 

There is persistent evidence of an upper trough close to the UK. The Azores High keeps flattering to deceive, and it

seems to always be a week away from moving east towards/over the UK. That seems to have been a repeated mantra for quite some time

 

There are quite a few of the EPS members which depict this at day 7 time with that upper trough close by over the continent and eastern/south eastern parts of the UK

 

I think it is true to say that in relative terms, temperatures are going be something of an improvement on what we have seen, but that still means they are likely to be rather cooler than normal in any cloudier wetter areas with the best prospects for sun and pleasant feeling temperatures the further North West one goes

 

 

The NAEFS anomalies suggest pressure lower to the south and that rather underpins the NW/SE split in the weather conditions

 

 

You may be right about that and it just being some more realistic posts, just the charts like the GFS and ECM ensembles I have seen recently suggested high pressure building nicely near the UK settling things down, and the runs I had seen this morning didn't seem too bad, but then I will be happy with more average conditions for the time of year and am not necessarily looking for heatwave conditions.

I fully agree with people that advise caution to a settled outlook especially at the timeframe shown, and the models could swing back to a cool unsettled low pattern like recently, I just don't think they have done that overnight and personally think the mid range outlook isn't too bad right now bad using the charts I easily have access to.

This may also be because I am in Devon at the moment and it has shelter from E/NE surface flows like suggested if high pressure is to out north, or at least weaker than usual westerlies if pressure is lower than normal to the south and higher than normal to the north. Locally my warmest weather usually comes with an easterly surface flow.

 

Also thanks for posting those ECM ensemble charts, hasn't managed to find any that had updated this morning.

 

my reply for Stormad26-hope it helps?

stormad26 reply 27 may 13.pdf

 

Many thanks John , I think was was confusing me was I presumed with a W/NW flow West Scotland would be more unsettled with low pressure presumably to the north rather than being the most settled/warmest location like on the Met Office longer range forecasts, which I presumed to imply high pressure to the north and low pressure over the continent a more NE/E flow making west Scotland more sheltered and closer to the high. I think this is similer to GFS and ECM ensembles recently but obviously they show surface flow and there are other forecasting tools that perhaps give a better idea.

 

I was expecting my confusion to be due to me more having the wrong idea/interpretation and was not questioning your interpretation but my own one, because you have more experience and understanding of these charts, thanks again for explaining that I understand what you were meaning now.

[Tamara]

 

 

Also thanks for posting those ECM ensemble charts, hasn't managed to find any that had updated this morning.

 

 

You are welcome . I personally find these most useful in being able to actually see the pressure patterns that the individual ensemble members are suggesting. This can be much more revealing and put an extra complexion on an ensemble mean which doesn't always tell the whole story. Also going out to 7 days is plenty far enough if there is going to be any really worthwhile reliability in them. It can then be useful to match these to the NAEFS anomalies and make interpretations from there

Edited May 27, 2013 by Tamara Road

[Frosty.]

A very interesting Gfs 06z op run which shows a warm and increasingly humid outlook with sunshine and thundery showers across the uk as the uk falls within a very slack pressure field with warm/very warm and muggy continental type conditions. The next few days look unsettled and cooler, especially further south but later in the week it looks like becoming warmer but still with a risk of showers, a ridge builds in from the west at the weekend but it becomes fresher although still pleasantly warm in the sunshine but even with a ridge over the uk, there is still a risk of some showers, then next week becomes much warmer and sticky with sunny periods but with thundery rain and showers, if we can't have a warm and settled outlook, this would be the next best thing since it would at least be warm.

[legritter]

I can only do a quick post ,looking at todays data so far i think it could be a hard one to call from next weekend onwards .IF a NW /se situation IS going to set up and the possibility is certainly there, it would only need slight adjustments over our island to bring the more populated areas under a mixed bag of rain sun rain .this time last year i spent 5 wks in canada ,holiday and bereavement .the weather channel over there was constantly showing the UKS interesting weather .todays met office update should be interesting when it comes out soon ,i think at the moment those looking for solid dry and warm need to be looking to the NW for developements and pressure predictions for central europe .As always alot to watch out for ,but of course thats why we have modell runs ,and a great Forum to discuss any possible outcome ,sorry gang i told a lie saying i would keep it short ,tend to get carried away .