Model Output Discussion 12z 23/05/13

[Gibby]

Hi everyone from a sunny West Country. Here is the report on the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Sunday May 26th 2013.

All models show a ridge of High pressure over the UK currently. This will be replaced tomorrow by Low pressure feeding down from the NW and sending an occluded trough East across the UK over Bank Holiday Monday and overnight into Tuesday with rain and freshening breezes in association with it for all areas. Thereafter a period of sunshine and showers looks likely as Low pressure is shown to sink SE over the UK through Tuesday and Wednesday before exiting away from SE England on Thursday leaving a less unstable NW flow for most parts with the showers restricted to the SE by Thursday.

GFS then shows a weak ridge crossing the UK from the NW on Friday with a dry and bright period but a bit on the cool side before a showery trough moves South over Saturday. Pressure then builds strongly over the UK with High pressure over Ireland and Wales ensuring dry and warmer conditions with sunny spells next weekend. The trend through FI this morning is for High pressure to remain in control of the UK weather with various positions occupied by slack and open centres maintaining largely dry and quiet conditions with temperatures on the warm side of average and just the risk of the occasional shower later.

The GFS Ensembles show that unfortunately the operational run described above was on the top of the tree with regard to temperatures in the second half of the run. Nevertheless, the trend is an upward one still with most areas achieving temperatures close to average or a smidgen above by a week's time. Rainfall spikes while scattered about throughout the output are never exempt indicating some involvement with showery Low pressure remains possible.

The Jet Stream shows a continuation of the pattern of late with a separate arm way South over Europe while the Northern arm moves across the Atlantic towards the UK before turning South to the West of the UK. The Northern flow become disorganized and broken later this week with some support for the flow to rise further North away from mainland Britain between Scotland and Iceland next weekend.

UKMO today shows a slightly showery NW flow to end the week and start of the weekend. With pressure relatively High quite close to the SW the showers would be concentrated towards Northern areas whereas parts of the South could see drier conditions with some sunshine. With winds in the NW it will never be overly warm at this point.

GEM today shows improvements as we move through next weekend as a ridge of high pressure builds down from the High over Northern Scandinavia. Away from North Sea coasts conditions would become mostly dry with some sunny spells with average temperatures. On North Sea English coasts low cloud and sea haar could give rise to rather cool and dull conditions here.

NAVGEM too shows slow improvements next weekend with a strong ridge trying desperately hard to get into Western Britain. However, even by the end of day 7 a small Low near East Anglia is sufficiently close to promote showers and cool conditions under a Northerly wind for many Central and Eastern parts.

ECM continues it's trend of building High pressure to the North of the UK later next weekend but on it's transit NE this morning it takes it way NE of the UK to Northern Scandinavia with the UK in no mans land under a shallow cool pool in association with shallow Low pressure over much of Europe. The net result of this weather-wise is to see slow improvements next weekend never reaching the SE with scattered showers here. The risk of showers then spreads to many areas later as the cool pool aloft expands to affect other areas too. Temperatures would be unlikely to be better than average by day and night's would most certainly stay cool.

In Summary the High out West is having to work hard on displacing the cool and showery feed of air over the UK this coming week. It is shown to succeed in varying degrees of success with GFS leading the field in this evolution today. Most of the others show half-hearted improvements especially in the West and north with some decent dry and fine weather to be enjoyed. Further South and East we are made to wait rather longer and in some cases shown improvements don't reach these areas at all with a chilly Northerly aspect to the airflow maintained resulting in continuing bright weather but with a risk of showers, average only temperatures and very chilly nights still for June. As in previous runs the lines are very fine lines and it wouldn't take much of a shift in the pattern to show vast improvements for all or conversely more unsettled conditions for all. The one constant it looks like there is unlikely to be high temperatures in the next two weeks over the UK though that's not to say that there won't be any pleasant weather to be enjoyed either. It really is down to a case of one's perception as to what constitutes decent weather in June.

[Frosty.]

Great news from the Ecm 00z ensemble mean, it takes the middle ground approach compared to the gfs and ecm 00z op runs with the azores anticyclone building strongly northeastwards through the uk and bringing a long spell of warm and sunny weather to all parts of the uk, northern & eastern coastal areas would be cooler with onshore breezes but the ecm 00z ens mean is just about perfect, the Gefs 00z and Ecm 00z ens mean bring a very summery spell to the uk as we head into June.

Edited May 26, 2013 by Frosty039

[Tamara]

the ecm ens and spread from the 12z were more encouraging wrt the repeating troughing. however, the 00z op is not. the ens are out soon so we'll get a better idea of how supported it is. btw, the 12z naefs from yesterday didnt fill me with excitement from a settled perspective.

 

EDIT: the 00z ecm ens mean is better than the op re the jet in fi. spreads look ok on ecmwf.int but i find it easier to see the nuances on meteociel which hasnt updated as yet.

The latest NAEFS has done away with the suggestion of heights just to our north retrogressing towards southern Greenland and from a general pov that will be welcomed as more supportive of the latest ECM ensembles and constitute warmer temperatures. However, it looks like pressure will be much shallower to the south, so the kind of north/south split I mentioned yesterday does seem an increasing possibility. But from the Midlands and especially further north into Scotland the prospects look potentially very pleasant indeed for a time at least - assuming this is the way forward

 

 

 

The EPS members are reasonably supportive of the operational at day 7, Bit of a mixture with a few still showing the trough close by and the High held out west. But at this range enough of a majority support the operational output

 

Edited May 26, 2013 by Tamara Road

[Milhouse]

A pleasing GFS 6z it has to be said. Towards the end of the week we will see winds switch round to a more northerly direction but not for the first time this month it will be bringing down warm humid conditions rather than cool ones. Then on into the weekend high pressure builds with Sunday looking the day likely to see more in the way of widespread warm and potentially sunny weather. Then a gradual breakdown into the following week but presssure remaining fairly high.

[Frosty.]

This unsettled spell next week is becoming shorter and shorter, for most of the uk it only lasts a couple of days according to the Gfs 06z op run before high pressure begins to build from the west, so a few unsettled days with heavy rain for some southern & central parts of the uk on tuesday & wednesday but beginning to settle down from the west by thursday, the 6z then shows an increasingly anticyclonic and warmer spell with long sunny spells and light winds for all parts of the uk which lasts into the start of the following week, an atlantic low close to ireland then brings another brief unsettled blip before pressure becomes high once again. So, the general theme of the 6z is for the current settled spell to be eroded during tomorrow with western britain becoming unsettled, breezy and cooler with outbreaks of rain but most central and eastern areas having another fine and pleasantly warm day with sunny periods but clouding over from the west during the afternoon and evening. FI shows a generally summery outlook but still a few mini cool troughs floating around within the generally slack anticyclonic benign pattern.

Edited May 26, 2013 by Frosty039

[Cloud 10]

 It really is down to a case of one's perception as to what constitutes decent weather in June.

 

 

At least it looks fairly certain we will be starting summer in a far better position than last year...

 

last year..  this year..

[Milhouse]

That chart from last year brings back memories. It was just after the lovely spell of late May and the models were hinting at another settled spell to take us into Summer proper. However as the days passed the troublesome low over Scandinavia remained stuck with the Azores high ridging too far west to be of any use. It only served to reinforce heights over Greenland. Thats how it stayed for the next 7 weeks.

[Frosty.]

The met office must be using their own model (ukmo 00z) for the unsettled start to next weekend in their latest 6-15 day update, they most certainly are not using the gfs 6z because that shows a robust looking ridge building across the uk next weekend but then the model they appear to go with is the Ecm 00z op run which builds the azores anticyclone northeastwards past nw scotland and we then get the northwest-southeast split they are mentioning, it's very good news for the usually cool, wet and windy northwest corner of the BI but ho hum for the majority of the uk if this is how things evolve, however, the ecm ens mean is much better and we could still end up with a middle ground scenario which would be very good news for everyone in the uk who likes warm and sunny weather.

[Tamara]

Before anyone gets there hopes up, the latest met office forecast is terrible, they must know something we don't. Wish Ian Ferguson was still posting so he could clear it up for us.

As posted earlier basically, and yesterday, I think the reasons lie there. Although I am no expert by any means, I think it isn't difficult to see why, taking all the evidence available and not the daily output at face value. Its not quite terrible though - definitely better the further north west one heads, and often the fortunes are reversed so some welcome warm sunshine there for a change - but a widespread UK settled spell this does not look being and in my honest humble opinion, so far, it has never seemed likely to be at any time either

Edited May 26, 2013 by Tamara Road

[phil nw.]

If you find your posts have disappeared then you know they were off topic or worse juvenile.

Let's keep this thread informative and sensible for all visitors please folks.

Remember the thread is only as good as the members make it.

 

Thanks-back to the models then.

[bluearmy]

The london ecm ens show an fi split 75/25 approx in favour of warm and settledish. The op at the bottom end of the ens temp wise days 8 thru 10.

[Frosty.]

After yet another disappointing met office update (apart from northwest scotland), the latest GEFS 06z mean keeps us on track for a more anticyclonic blocked and warmer outlook with pressure generally rising to 1020mb or higher, temperatures trending warmer after the unsettled blip during the week ahead.

Edited May 26, 2013 by Frosty039

[bluearmy]

Karl, there is troughing of some description close to the the uk despite a generally decent mean. The atlantic energy, needs to go somewhere. If we have blocking to our northeast, then it will probably be funnelled over the uk. If the blocking is to the n or nw, it will probably be funnelled to our south into europe but at a latitiude which will still affect the uk to a greater or lesser degree. ( too early to be specific). unless we lose the northern blocking, we will really struggle to break away from shallow troughing and associated rainfall.

[Barry12]

From Liam Dutton on twitter

'Early days, but there are hints that high pressure may pay us a proper visit at the beginning of June, with sunshine and warmth. Stay tuned!'

[Frosty.]

Karl, there is troughing of some description close to the the uk despite a generally decent mean. The atlantic energy, needs to go somewhere. If we have blocking to our northeast, then it will probably be funnelled over the uk. If the blocking is to the n or nw, it will probably be funnelled to our south into europe but at a latitiude which will still affect the uk to a greater or lesser degree. ( too early to be specific). unless we lose the northern blocking, we will really struggle to break away from shallow troughing and associated rainfall.

It's generally ok though with high pressure close to the uk and no atlantic lows in FI, that was my point, the mean lacks some of the finer details but the main reason I posted those charts was to point out it looks significantly better than the latest met office update has just described with the cool and rainy weather generally affecting the south and east of the uk....... apart from the sunnier and warmer northwest corner of the uk.

Edited May 26, 2013 by Frosty039

[Scorcher]

In my experience the Met Office and BBC are often quite slow in predicting settled weather and often err on the side of caution. They also often make quite conservative temperature predictions several days out before revising them upwards closer to the event. For tomorrow for example they were predicting rain for many western and central areas from the word go right up to this morning but have now changed that after clearly realising the eastward progress of the rain will be slower than first thought.

[Milhouse]

Thursday looking good on the GFS 12z with 20c quite widespread. I guess this will be dependant on lengthy spells of sunshine. If it remains cloudy then i see the mid to high teens more likely.

 

Friday looking warm for most but cooler air slipping into western Scotland as the Azores high approaches.

 

[Milhouse]

Dry nationwide by Sunday with average temperatures.

 

[Milhouse]

UKMO in agreement too for next weekend with a decent ridge of high pressure building north. Ideally we need low pressure to slip away east across Europe to allow the high to descend over the UK cutting off the coolish upper temperatures.

 

[Summer Sun]

Now UKMO is on board in the semi reliable we should begin to see the met office move from the cautious side to the more positive side (providing it lasts more than one run of course!)

 

A BBQ weekend in store for many if UKMO is right this afternoon

 

Edited May 26, 2013 by Gavin.

[Methuselah]

Maybe an extra balance of females is what is needed ?  We don't seek to argue - we just take the science, make it user friendly and less scary to the average Joe/Joanna in the street, use intuition, logic and our own brand of common sense plus some gentle persuasion to suggest the possible model outlook  And we look to speak in simple tongue and seek to break down long technical words - decoding the techno babble that guys give us So it should be a no brainer 

You are absolutely right, in what you say, Tamara... Women (Margaret Thatcher excepted) do tend to look for constructive, as opposed to destructive, arguments...Patriarchal meteorology is doomed to failure, IMO...

 

And I promise not to say mmmm... 

[Evening thunder]

According to the GFS Finland and that area is going to start summer with 30C heat lol:

 

 

They do seem to be able to sustain long periods of well above average temperatures in summer in recent years, far better than us of course. Even recently they seem to have been getting into the 20's for several days and are forecast to for the next several days, and reached and at least 26C in parts several days to a week ago I think. At least 22-24C often higher somewhere in Finland for the entire GFS run

 

Anyway hopefully the signs of a better start to summer for us continue to build with a bit of luck.

Edited May 26, 2013 by Stormmad26

[Scorcher]

Very annoying how we seem to be left with the cooler uppers while areas much further north enjoy the warmth!

[Frosty.]

The Gfs 12z op run sticks close to the 6z with a strong ridge of high pressure building north through the uk next weekend with lots of pleasantly warm sunshine which lasts into the following week, there is then a brief unsettled interval as low pressure spreads in off the atlantic but this is only the prelude to a major anticyclonic spell through most of FI with some nice eye candy charts to enjoy with temperatures into the low to mid 70's F, next weekend may also creep into the 70's. This upcoming unsettled spell is not much more than a 48 hours blip for most of the uk with most of the rain across central and southern areas on tuesday and wednesday but then we are on a slow upward curve with increasingly settled and warmer weather, especially by sunday and the following monday. This run is much better than the latest met office update today but falls well short of the stunning Ecm 00z ensemble mean this morning, on balance, it looks to me like settled weather is going to be in control more often than not during the next couple of weeks after this week's unsettled blip either side of midweek.

Edited May 26, 2013 by Frosty039

[Milhouse]

Very annoying how we seem to be left with the cooler uppers while areas much further north enjoy the warmth!

 At least they are generous to send some of it our way for the second half of the week. Might be enough to give 20c on Thursday and Friday.