In depth (chilled out!) model discussion

[stodge]

Morning all

A reasonable Bank Holiday weekend here in London so far and certainly less rain than some had forecast. As is often the case at this time of year, the warmth of the sun is offset by the chill of the breeze so it's possible to be warm one second and cold the next and trying to gauge suitable outdoor attire hasn't been easy. Unfortunately, for those wanting prolonged warmth, there's been plenty of cold and the evenings especially have yet to achieve that late spring balm we all enjoy.

The model outputs have brought the MoD back to,life and the usual suspects who seem to want dry, warm sunny weather all the time from May to September and those who simply want to cook and eat dinner outdoors have been venting their spleen at the thing of beauty that was yesterday morning's GFS 00Z OP which kept a NE'ly flow right through to mid May and beyond.

Anyway, what they want and what I want is completely immaterial so let's see where the models are this morning with the output taking us to Thursday May 11th:

Let's start with GEM 00Z:

A beautiful run for those of us who like unusual synoptics. The strong build of HP near Scandinavia from tomorrow dominates the weather as the HP moves westwards across or just to the north of Scotland duding this week so a reasonable week with an ESE or E'ly wind flow but as the HP migrates to Greenland, the wind turns NE next weekend and starts drawing in cooler air from Scandinavia and an LP forms in that flow which swings towards the British Isles before retreating back to the Baltic.

The original core of HP traverses the Atlantic (which is a wonder in and of itself) east to west but there are enough residual heights to maintain a ridge SE over the British isles so a dry, cloudy and cool prospect but you'd think a return of the Atlantic from the west or south west looks the next move in the dance.

ECM 00Z at the same time:

ECM follows the GEM evolution initially but the end of the evolution is one of those "not quite sure what's going on" ECM charts which suggests no strong signal. The whole of NW Europe ends up under weak LP with rain or showers likely and a pool of cool, if not cold air over the British Isles. This is an evolution we often see in May and that means sunshine and heavy showers by day and cool clear nights. The Atlantic is dormant but there are weak LP areas to the NW and SW while heights have also fallen to the north. I'm not sure about this evolution but the idea of a shallow trough over the UK I can understand.

GFS 00Z OP at the same time:

Some similarities with the other models. The evolution up to this time next week is pretty much the same. GFS develops two new and significant LP areas - one over the Gulf of Bothnia which rolls around deepening all the time while the other deepens and is forced south by the strong heights over Greenland. To compensate, heights are building over the Low Countries so for the south and east not too bad with some warmer weather while rain threatens the far north west of Scotland.

Further into FI and it's great news for those who hate NE'ly winds as the Icelandic LP deepens further and draws a SW'ly flow back over the British isles but it's an unsettled flow with small LP bringing periods of rain before heights build from both the Azores and the east at the very end of the run signalling a transition to much warmer and drier conditions.

The Control breaks down the NE'ly by moving the LP over the Azores NE up and over the British isles reintroducing a more W'ly flow.

The 00Z GEFS at T+240 shows much less certainty than was the case on Thursday last week. The OP is an unsatisfactory blend of a number of different evolutions. There are undoubtedly some warmer evolutions out there which occur where the Greenland heights are blocked out by mid Atlantic LP. Some members bring the Baltic LP into play but they are a minority and most concentrate on developing either the LP over the Azores or by creating a new LP over Iceland. The tendency around mid month is to see the northern heights erode and a warmer but more unsettlled regime take over with LP close by to the west drawing up south or south westerly winds.

To conclude, a fascinating week of E'ly and then NE'ly winds in prospect and the west and north west of the British Isles will do very well. From the middle of next week onward, there's plenty of uncertainty but a clear trend to lower heights which will shut off the NE'ly and introduce much warmer air but also a more unsettled evolution with rain or heavy showers quite possible. Details are far from clear though these will likely firm up over the next few days. It's quite possible we'll have a shallow trough over NW Europe for a while before HP builds back in again towards the end of the month. 

[stodge]

Morning all

A chilly start in London this morning but it's warming up nicely and some decent days ahead in all likelihood.

A mixed and uncertain picture from the models in the medium term yesterday but let's see where we are this morning with the view for the early fours of Friday May 12th.

Starting with GEM 00Z:

An anticyclonic outlook dominated by heights to the NW. The HP duly moves west this week allowing the trough and the colder air to follow SW towards the British Isles. A small area of LP develops between Iceland and Greenland early next week but this sinks south on the GEM to be over southern Britain by the end of the week pulling in an ESE'ly flow and bringing rain or showers for many with the east coast affected by sea fog and haar.

Similarities to the GEM evolution but a tad slower as the LP develops more slowly over Iceland before moving SE toward the British Isles. The T+264 from this might well see the LP close to the GEM evolution though note the trough extension to the east. This would also be unsettled for many with the worst of the weather to the NW and the SE not too bad.

GFS 00Z OP at T+240:

A recognisable blend of the GEM and ECM solutions. The key is the trough remains out to the west and further west than either GEM or ECM. This keeps a warm but unstable ESE'ly flow over the British isles and the trough would keep rain or showers for many.

Further into FI, the LP continues south then fills in situ before edging back NE leaving much of the British Isles under a weak trough at the end of the run.

GFS 06Z OP at T+234:

Not a huge amount of difference from the 00Z but the trough is a little closer but the wind flow over the British Isles is much lighter. Further into FI, the trough remains a dominant feature for several days providing a spell of unsettled and often wet weather before pulling back to the north as heights slowly begin to rise.

The 00Z Control fills the trough to the west but keeps slack areas of LP close to the British Isles.

The 00Z GEFS at T+240 shows broad agreement on the overall evolution but the interplay between the Icelandic LP and the residual LP near the Azores was very variable and this had a huge impact on the weather over the British Isles.

To conclude, after a fine week for many, the weather next week looks more uncertain with LP developing between Iceland and Greenland and swinging south or south-east. It's possible the LP may end up over or close to the British Isles or it could be further west but it seems likely next week will become progressively more unsettled with rain or showers developing widely. The onward evolution is less certain but it seems possible the trough will remain close to the British Isles through mid month before a hint of pressure rises from the south west but it's only a hint at this stage. 

[stodge]

Morning all

Retrogression week is in all swing and parts of London had their first notable rain for some weeks in the form of some quite sharp showers driven in on a NE'ly flow yesterday afternoon. This morning is all about the overcast but signs of brightening perhaps.

Interesting to read comments from Tamara and others indicating the evolution to a more traditional mobile pattern with lower anomalies in the Atlantic and Pacific leading to a positive NAO. Details of course still to be worked out but the MetO signal for warmth later this month might derive from the possibility of an amplified pattern with heights building to the east.

This morning's models take us to Saturday May 13th in the early hours:

Starting with the GEM 00Z output:

A more complex evolution than yesterday. The trough approaches the SW at the end of the week bringing rain or showers to southern parts but quickly fills and dissipates as a brief renewed ridge moves in from the NW. This in turn declines south as a new LP forms to the far north and a secondary feature approaches from the NW. Heights are rising again over Greenland in response to the deep LP over Svalbard and points north. Probably reasonable for the south and east but more unsettled conditions approaching from the north and west. Not an evolution where the next step is clear.

ECM 00Z at the same time:

Very different and much simpler. The heights pull away and the trough over the Baltic extends west and south west to dominate NW Europe so cool conditions with rain or showers for many and certainly no sign of warmth. That being said, signs in the Atlantic of a reset to more "normal" conditions as the LP around the Azores fills up and heights lower to the NW so it may be a few days of pain for longer term gain might be the prognosis.

GFS 00Z OP at the same time:

Different again but akin to yesterday morning's GFS evolution. The winds stay in the east right through next week but the HP declines away to the west and an area of LP which forms around Iceland in the middle of next week sinks south and joins with the LP near the Azores and the two combine to form an LP to the west of Ireland with a small secondary feature over the southern North Sea. This will mean unsettled conditions with rain or showers for many and strong winds over the far north of Scotland.

Further into FI and it turns more unsettled with the jet a long way south. LP systems cross the southern part of the country with spells of rain and showers while new heights build to the NW so welcome rain for southern counties.

Looking at the 00Z GEFS at T+240 the Control is pretty close to the OP and the members all have some form of LP influence though positioning and orientation vary as you would expect. Many keep the trough to the SW and an E'ly or SE'ly flow while others bring the trough closer to the British Isles. A smaller number keep the core of the LP further NW. None of the members keep the HP in charge and none have an ECM type solution.

To conclude, there's a lot of uncertainty as you might expect into next week. In broad terms, the current HP dominated picture breaks down briefly over the south at the weekend with a threat of rain or showers before the ridge builds back in from the NW briefly. However, by the middle of next week onwards, LP is very much in charge bringing increasingly unsettled conditions especially further south and west with rain or showers. Details are far from certain.

[stodge]

Morning all

Certainly a chilly day in London yesterday with cloudy skies and a chill NE'ly wind.

The models were unanimous in expecting a more unsettled spell next week until UKMO 12Z came out which seemed to suggest a renewed rise in pressure to the east. We'll see if this is a new signal or whether the UKMO were leading us up the proverbial garden path.

Today's output takes us to the early hours of Sunday May 14th:

Starting with GEM 00Z:

GEM have dropped yesterday's Baltic-led evolution and come more into line with GFS. We see the twin-centred trough develop towards the end of next week as the LP over the Azores drifts NE while a new LP develops near Iceland swings south. The two combine briefly over the British Isles at the start of the weekend after next but then pull back westwards (this alluded to by Tamara and others) as we get hints of a pressure rise from the east.

After an unsettled and potentially quite wet spell, the weather has settled and the south and east might  be quite reasonable. It's fair to say the west would still be close enough to the LP to be affected by rain or showers.

ECM 00Z at the same time:

Not a million miles from GEM but with some subtle differences. The developing Icelandic LP becomes the dominant feature absorbing the Azores LP but unlike GEM the centre of the LP remains out to the west and there's a more defined rise of heights over Scandinavia. The trough extends from the core LP over the southern part of the British Isles which would accentuate any areas of rain or showers while the north and north east would face issues of sea fog and haar. It seems probable the Scandinavian HP will develop further and introduce a warm SE'ly flow over the British Isles which again ties in with the thoughts of some longer-term forecasts.

GFS 00Z OP at the same time:

A very different evolution to the ECM and GEM. The modelling is quite different around the Azores and indeed over the Baltic and Scandinavia.

The Azores LP extends NE across northern France midweek of next week which would increase the likelihood of rain or showers for southern parts. The trough expands via new centres of LP over southern Norway and south west Iceland to cover most of NW Europe bringing an unsettled spell for the whole of the British Isles. The French and Baltic LP centres combine and swing rapidly east while the Iceland LP moves south and then east to be close to the British Isles maintaining the unsettled theme of rain or showers.

Further into FI and weak troughs cross the British Isles while the Azores HP develops but with a south-north angle to the ridge (rather than the traditional SW-NE alignment with the ridge across southern Britain) suggesting heights more mid-Atlantic focus.

This was the counter-scenario to the one supported by the ECM and indicative of a different upstream evolution across the Pacific. The resolution of this will dictate European weather moving into June.

The GFS 06Z OP at T+234:

Not a huge difference - note the slightly more defined heights to the north. The Icelandic LP is holding back more in the Atlantic. though it does move across further into FI. Again, there's a hint of mid-Atlantic heights after that.

Looking a the 00Z GEFS and the Control has gone where I think the 06Z OP may be going in terms of building mid Atlantic heights, taking the trough into Europe and leaving the British Isles in a cool and unsettled NE'ly.

Moving on to the Panel at T+240 there's broad agreement on the dominant influence of the LP system and most have it to the west or south west. The OP is slightly out on its own and the more favoured solution seems nearer to the ECM which keeps the LP out to the west or south west with heights building to the NE and a SE'ly flow over the British Isles.

To conclude and with some valuable input from one of this forum's top forecasters, there seems a battle (if you like) developing between two evolutions as we move toward and beyonf the middle of the month and we are seeing the first signs of it in the medium term low-res modelling.

Scenario A, supported by the ECM, some of the GFS members and some long-range forecasters, develops, in response to upstream developments in the Pacific and elsewhere, a mid-Atlantic trough which encourages a build of heights to the east or north east and a flow of warmer air over NW Europe and the British Isles.

Scenario B, favoured by the GFS OP and some other forecasters, develops not a trough but a mid-Atlantic ridge or heights while taking the trough over Europe. This would keep the British Isles in an often cool and generally unsettled and wet regime,.

It does seem likely we will have to go through a more unsettled spell from next midweek onward - if scenario A turns out to be correct, the more unsettled weather will withdraw west as warmer, drier conditions build from the south and east. If, however, Scenario B turns out to be valid, we could be facing a prolonged spell of cool, unsettled conditions with the worst of the rain to the south and east.

Let's see where we go...

[stodge]

Morning all

I've a busy day so not perhaps time for as much discussion as I would like.

The model output this morning takes us to the early hours of Monday May 15th:

Starting with the GEM 00Z at T+240:

GEM moving in a different direction this morning and something more hopeful for those wanting better weather around mid month. The LP which develops over Iceland flirts with the British Isles but is rebuffed and heads away north west allowing both secondary LP and more significantly the Azores HP to move in from the SW. Note the heights to the NE and it seems likely from the evolution we will move to a classic NW-SE split with SW'ly winds over much of the British Isles. Driest and warmest to the east and south while the north and west likely to be under a more Atlantic influence with occasional rain and strong winds.

ECM 00Z at the same time:

A very different evolution from GEM. The Icelandic LP rotates around to the west but with a new ridge building south from persistent heights over Greenland the LP moves east toward the British Isles. Note also the very different modelling of heights over Scandinavia. This chart would bring unsettled conditions for most with rain or showers heaviest in the NW and suppressed temperatures with quite a pool of cold air setting up. The secondary feature to the west of the Azores is interesting - will that deepen and move NE ? The Azores HP is kept well to the south and deflects the African warmth further east over Italy and Greece.

GFS 00Z OP at the same time:

A recognisable blend of the GEM and ECM solutions. Essentially the Icelandic LP rotates around the Atlantic but starts at this point to edge toward the British Isles. The ECM modelling of the Azores HP and LP to the west of the islands is not too dissimilar while Scandinavian heights are kept further NE and more over the Russian Arctic.

Further into FI and it's a poor evolution for those wanting heat - the LP crosses to the north and strong heights rise in the mid Atlantic and over Greenland and a new LP forming off Eastern Greenland threatens to sink south toward the British Isles. A cool NW'ly flow threatens to swing more N'ly.

The 00Z Control sinks the trough over the British Isles but leaves us in a col after mid month.

A two-second look at the 00Z GEFS at T+240 suggests the OP is slightly out of line in its positioning of the LP. Many of the members keep the LP further south and thus draw in a more SE'ly flow (Perturbations 5,10,11 and 15 being good examples). The odd one has the LP over the British Isles but that's a real minority outcome. Resolving the location and orientation of the LP will be critical as we approach mid month.

Have a good weekend.

[stodge]

Morning all

Hope everyone had a good weekend.

The fascinating tussle between cold and warmth has continued in London - with the Sun out and the winds light, you'd be forgiven for thinking summer was at hand but when the clouds build and the wind blows, it seems we're still close to winter. Quite remarkable changes in the weather on a daily and even intra-day basis.

There was a strong move toward warmer but more unsettled conditions in the models last week so let's see if that has continued.

Today's output takes us to the early hours of Thursday May 18th.

Starting with GEM:

The evolution here isn't too complicated. The trough which develops from midweek this week controls the weather over the British Isles into the weekend bringing a more pronounced chance of rain or showers especially to western parts. Into the weekend and the LP pulls away sharply west, bringing in a warmer SW'ly flow but as the new week starts pressure builds strongly over Scandinavia and a warm E'ly sets up but the core of HP transfers across the British isles to sit just west of Ireland. Fine conditions for all and warm inland but the south is plagued by an onshore NE'ly which will likely keep things a notch cooler. Will the HP decline SW (more likely) or NW (less likely) ?

ECM 00Z OP at the same time:

Plenty of HP about on the ECM this morning. The LP keeps further west before filling and moving further west as the Azores HP builds more north than north east. Pressure is high over Eastern Europe leaving the British Isles in a bit of a col and, you'd think, vulnerable to a slack area of LP setting up. I'm not sure where the ECM goes from this chart and it's another of those ECM "doesn't look quite right to me" charts.

GFS 00Z OP at the same time:

Not a million miles from the ECM though the modelling to the north is more defined. The LP shifts west but doesn't disappear and starts moving back east. Pressure builds initially to the south and to the north east of the British isles but the two HP centres combine only briefly before splitting as a weak trough develops in the North Sea and the main pressure build is to the SW. This leaves the British Isles in a light and fairly benign W'ly so dry for many if not excitingly warm but less ettled in the far north with rain not too far away.

Further into FI and we get a brief but fairly unpleasant N'ly before the LP fills up and we are left again in a bit of a col.

The 00Z Control is much warmer further into FI and has a nice plume for those who like that sort of thing.

Looking at the 00Z GEFS at T+240 and the first thing that struck me was how many of the members, contrary to the OP, continue with strong Greenland heights. I mentioned the battle between opposing scenarios last week and there seems a significant minority cluster continuing to build mid Atlantic heights through the middle of the month leaving the British isles on the cold side of the trough. The Mean hints at the line with LP to the north or NE of the British Isles and a cooler NW'ly flow.

The path to a drier and warmer end to May doesn't look clear yet - the evolution into next week is far from certain. Pressure may well build in mid Atlantic as the Iceland LP retreats west but we also see heights building to the east. A number of options are still on the table and more runs are needed for clarity (or to enhance the confusion further).

 

 

[stodge]

Morning all

Another dull and chilly morning in London but the signals for next week were still far from clear yesterday morning, Let's see if that meteorological and metaphorical fog has lifted to any extent.

The models take us to Friday May 19th:

Starting as always with the GEM 00Z OP:

Yesterday's evolution has been pretty much continued. As pressure tries to build from both SW and NE in the middle of next week, a new LP fills the gap and brings another brief unsettled spell to the British Isles before a renewed push of HP from the SW settles things for southern parts. The jet is still running close to the north of the British Isles and it's much less settled here with rain or showers from shallow Atlantic LP systems.

ECM 00Z at the same time:

There's the briefest of flirtations with some very warm air next Tuesday and Wednesday but the problem is the gap between the Azores HP ridging north, rather than north east and the heights over Eastern Europe invites a trough to develop and we see a vigorous little LP develop over western Scotland and Ulster at the end of the week so any warmth quickly replaced by more unsettled and windy conditions with rain or showers especially for the north west. It's entirely possible the LP could sink south or south east as the ridge builds to the north behind it.

GFS 00Z OP at the same time:

Something a little different. GFS develops a strong build of HP from the Azores across the Low Countries to southern Scandinavia dragging up a pool of very warm air. However, the trough to the NW cuts that off and while pressure builds again to the west and southwest, the airflow is cooler and the flow a light WNW'ly. The weather would be benign if not excitingly warm with any showers restricted to the far NE.

Further into FI and the HP oscillates around to the west so again nothing exciting in terms of temperatures. Quiet weather for many but just an occasional Atlantic influence affecting northern and north eastern areas.

Glancing at the 00Z GEFS and it's fair to say the ECM solution is well represented with LP very close to or over the British Isles with its exact location unresolved. There's a minority cluster keeping HP closer to the British Isles ridging from either the SW or the NW (those Greenland heights are still evident on a few of the members).

To conclude, the pattern for this week is well set and as the LP recedes further west and pressure builds from the SW it's quite likely we'll get a warm snap early next week especially for the south. However, the likelihood of a return to more unsettled conditions remains high and with heights setting up in mid-Atlantic, the possibility of the British Isles being under the trough can't be ignored. It may be that, as with GFS, the HP remains close enough to keep us settled if not overly warm but the possibility of a more thundery outcome depending on where the LP ends up can't be discounted either.

The two things I don't see on the morning output are prolonged cool/cold conditions or prolonged warm/hot conditions. 

 

[stodge]

Morning all

A glorious morning in London snapping our two day overcast spell. An early chill it has to be said though nowhere near as cold as some parts of the rural north west which saw minima well below freezing. Frost in May isn't uncommon of course but to see -5c certainly is.

The models take us to Saturday May 20th this morning.

GEM 00Z OP:

GEM ends on a familiar summer pattern with a NW/SE split and a strong Azores ridge. Perhaps not a heat wave but pleasantly warm and settled especially for the south. The evolution is fairly simple - the trough attempts to come in over the British Isles but fills and dissipates while heights to the NE sink SE and weaken. Mercifully, the real heat is kept far to the south but it's far from unpleasant.

ECM 00Z OP:

A very different and less settled outcome from ECM. The LP oscillates around Iceland but never disrupts west. Instead, it comes back east and extends the trough over the British Isles keeping many in an unsettled scenario of rain and showers. The Azores HP is weaker and not really influencing the weather. Heights are also much stronger to the NW and there's a hint of a new mid-Atlantic ridge building in with the trough coming SE and stalling over the British Isles.

GFS 00Z OP at the same time:

Not a million miles away from yesterday's evolution in truth. Akin to the GEM but with a very different orientation on the HP leaving the British isles in a weak WNW'ly flow. Benign conditions and quite pleasant in the south west but not excitingly warm elsewhere.

As yesterday, FI isn't very kind to those wanting heat - the mid-Atlantic ridge sets up and LP systems moving from the NW keep the British Isles cool and often unsettled with rain or showers and some quite windy conditions for the north and east in particular.

Worryingly, the Control goes down a similar route with pressure high to the north west.

Even more worrying, the 06Z OP retains stronger northern heights into far FI.

To conclude, the chance of some much warmer weather next week has eased somewhat and by the end of the week LP isn't too far away. It's possible the alignment could be quite favourable (SW/NE) like the GEM or it would be a lot closer and less favourable. Both ECM and GFS tease with the return of northern heights later in the month which could mean quite an unsettled end to the month and start to June but we're a long way from that at the moment.

[Methuselah]

5 minutes ago, stodge said:

Morning all

A glorious morning in London snapping our two day overcast spell. An early chill it has to be said though nowhere near as cold as some parts of the rural north west which saw minima well below freezing. Frost in May isn't uncommon of course but to see -5c certainly is.

The models take us to Saturday May 20th this morning.

GEM 00Z OP:

GEM ends on a familiar summer pattern with a NW/SE split and a strong Azores ridge. Perhaps not a heat wave but pleasantly warm and settled especially for the south. The evolution is fairly simple - the trough attempts to come in over the British Isles but fills and dissipates while heights to the NE sink SE and weaken. Mercifully, the real heat is kept far to the south but it's far from unpleasant.

ECM 00Z OP:

A very different and less settled outcome from ECM. The LP oscillates around Iceland but never disrupts west. Instead, it comes back east and extends the trough over the British Isles keeping many in an unsettled scenario of rain and showers. The Azores HP is weaker and not really influencing the weather. Heights are also much stronger to the NW and there's a hint of a new mid-Atlantic ridge building in with the trough coming SE and stalling over the British Isles.

GFS 00Z OP at the same time:

Not a million miles away from yesterday's evolution in truth. Akin to the GEM but with a very different orientation on the HP leaving the British isles in a weak WNW'ly flow. Benign conditions and quite pleasant in the south west but not excitingly warm elsewhere.

As yesterday, FI isn't very kind to those wanting heat - the mid-Atlantic ridge sets up and LP systems moving from the NW keep the British Isles cool and often unsettled with rain or showers and some quite windy conditions for the north and east in particular.

Worryingly, the Control goes down a similar route with pressure high to the north west.

Even more worrying, the 06Z OP retains stronger northern heights into far FI.

To conclude, the chance of some much warmer weather next week has eased somewhat and by the end of the week LP isn't too far away. It's possible the alignment could be quite favourable (SW/NE) like the GEM or it would be a lot closer and less favourable. Both ECM and GFS tease with the return of northern heights later in the month which could mean quite an unsettled end to the month and start to June but we're a long way from that at the moment.

Are you sure it's still morning, Mr Stodge?

[stodge]

2 minutes ago, Ed Stone said:

Are you sure it's still morning, Mr Stodge?

Had to go a meeting and forgot I hadn't sent the update.

Never mind - time is relative, lunchtime doubly so.

[knocker]

48 minutes ago, stodge said:

. Both ECM and GFS tease with the return of northern heights later in the month which could mean quite an unsettled end to the month and start to June but we're a long

 

I'm sorry I'm not quite following that. Which ecm output are you using for the end of the month and what do you mean by the 'return of northern heights? Thanks

Edited May 10, 2017 by knocker

[stodge]

On ‎10‎/‎05‎/‎2017 at 17:07, knocker said:

I'm sorry I'm not quite following that. Which ecm output are you using for the end of the month and what do you mean by the 'return of northern heights? Thanks

Both the ECM 00Z OP at T+240 and the GFS 00Z OP at the far end of FI on Wednesday morning had strong northern blocking with heights returning to Greenland.

[knocker]

37 minutes ago, stodge said:

Both the ECM 00Z OP at T+240 and the GFS 00Z OP at the far end of FI on Wednesday morning had strong northern blocking with heights returning to Greenland.

But as it's a bit of a leap from a day ten chart on the 20th May to, "which could mean quite an unsettled end to the month and start to June" I was merely wondering whether you were referring to charts from later that would support that.

[stodge]

Morning all

Some very welcome rain at last for most though with the Daily Express ("if it's in the Express it must be true") claiming we need weeks of rain, yesterday's was the proverbial drop in the metaphorical ocean. That said, it seems likely more will see more serious rain especially in the south west so a damp woodshed for some perhaps.

This morning's output takes us to the early hours of Monday May 22nd:

Starting as always with GEM 00Z OP:

A period of more mobile weather in the coming week with Atlantic systems moving NE just to the west of Scotland and HP never too far away from southern counties. Heights build from the far north into Greenland with a hint of the jet returning back south as a ridge builds SE toward the British Isles so while there's a N'ly drift it should be generally settled with sunshine especially for western parts albeit with temperatures not where some would like them to be.

ECM 00Z at the same time

Heights to the north or north west much in evidence though with a slightly different evolution to GEM. The mobility ends at the end of next week as heights build strongly to the west and later north west. The British Isles moves from a cool NE'ly to a warmer E'ly wind and the weather looks set fair for many especially to the north and west.

GFS 00Z OP at the same time:

Something different again from GFS. It's less keen to build heights over Greenland at the end of next week but instead sends the Azores HP ridging north rather than NE. LP remains over southern Scandinavia (following GEM) and the British Isles is left in a cool N'ly flow with rain or showers for eastern parts and fine conditions to the west though again temperatures not where many would like them to be.

Further into FI and Scenario B as I termed it the other day starts to evolve. The initial heights fade south west and the Atlantic trough takes over from the NW - the Bank Holiday looks distinctly underwhelming but the possibility of a renewed mid-Atlantic ridge as the month leaves the long Atlantic trough over the British Isles.

The 00Z Control has the HP closer and, although not warm, isn't a bad outlook.

As for the 00Z GEFS at T+240, there's broad agreement the HP to the south west is the dominant feature. However, the orientation of the HP is far from resolved. Some members have a more pronounced NE tilt to the ridge bringing it over the British Isles while a couple keep it more NW'ly linking to heights over Greenland. There's no sign of any prolonged wet weather at this point nor does any member bring in a warmer S'ly feed.

To conclude, a more mobile pattern of weather for much of next week seems likely though HP remains close to southern areas. Later in the week there are signs of HP building back in but the direction and orientation of that development is far from clear. The form horse seems to be heights building to the north west so a cooler spell of weather looks likely but fine for the north and west of the British Isles.

[stodge]

Morning all

One of those rarities - a damp morning in London Town. The first indications of a significant change away from the predominantly dry conditions of the last few weeks toward something more typical for late spring/early summer. With the rain has gone the chill (almost poetic).

The models this morning take us to the cusp of the next Bank Holiday, Thursday May 25th:

Starting as always with the overnight 00Z output from the Canadian GEM model:

GEM is fascinating this morning for those who like interesting synoptics irrespective of the weather they produce. This week's brief warmer spell is short-lived as the Azores HP builds north into the mid-Atlantic rather than NE across the British Isles and by the weekend the trough is in charge albeit not a very pronounced feature.

What does become significant is or are the build of heights to the west of Norway later in the weekend and in a repeat of the first week of this month the HP intensifies and moves west to the north of the British Isles ending up centred over southern Greenland with a ridge SE toward the British Isles which are in a weak NE'ly flow leaving many areas fine with the best of the sunshine to the north and west.

ECM 00Z at the same time:

The discussion about the two Scenarios, A and B, on this and the MoD thread might have suggested that IF we got LP in the Atlantic there was a chance of drier, warmer conditions with ridging to the east. Not so it seems if the trough extends east over the British Isles as a kind of "trough sandwich" between the bready heights to the north and the south.

The crucial difference between the GEM and the ECM is or are the heights to the south. The LP is kept further north but that's not good news for the British Isles as it keeps us unsettled with rain or showers at times. The alignment of the trough at T+240 suggests the far south could be on the warm side of the line going into the Bank Holiday with another area of fine weather tantalisingly close to the far north.

GFS 00Z OP at the same time:

The morning's OP run is very unsettled.. Once the ridge builds north and the trough covers the British Isles at the end of the week, LP is then never far away initially centred to the NE keeping us in a cool and showery NW'ly before the winds shift to a warmer SW'ly direction and the next LP swings in from the Atlantic. With heights to the SE and NW, the alignment of the trough keeps temperatures reasonable to perhaps sporadically warm in the far SE but rain or showers will be the dominant features.

Further into FI, LP remains in charge with another small feature set to be a real spoiler for the Bank Holiday for many. At the very end of FI, heights build to the NW with LP over Iberia and a strengthening E'ly across southern areas.

Unfortunately, the Control isn't too dissimilar - in fact, it's a little worse for southern areas with the LP centres passing more or less across southern England.

It's by no means all doom and gloom on the 00Z GEFS, however, and the OP seems progressive enough in bringing the LP into the British Isles. A number of the other members hold the LP further west and offer warm or very warm S'ly winds. Some even keep HP in charge whether as a ridge from the NE (as the GEM solution) or from a ridging building up from the south.

In conclusion, the midweek warm snap will be followed by a steady progression to more unsettled conditions over the weekend with LP setting up close to or over the British Isles. Into next week and while there's a call for a re-build of northern heights from all the models, the degree of influence that has on the weather over the British Isles is far from clear. GFS keeps the trough very much in charge while ECM develops its own "trough sandwich" leaving GEM to re-run the first week of the month with a strong HP retrogressing to Greenland.

All options from a spell of dry warm/hot conditions to a complete washout are on the table this morning for the next Bank Holidays so placez votre bets as the French croupiers would say and let the dice fall where they may (papa needs a new pair of everything !!)

[stodge]

Morning all

A warm morning in London Town but one suspects rain is close at hand.

The next Bank Holiday is coming into the range of the models and today's output takes us to the early hours of Friday May 26th:

Starting as always with GEM at T+240 this morning:

After yesterday's retrogression which did look a bit of an outlier, a much better chart for those wanting warmth and very much a "Scenario A" biased evolution. The LP and trough move over the British Isles through the coming weekend which looks disappointing on the whole but the LP backs away west in the early part of next week and the large LP is lift spinning round in mid Atlantic leaving the British Isles in a wash of warm SW'ly winds with a hint of height rises to the NE. A decent chart weather wise with the south and east best placed for warmth and sunshine while further north and west the Atlantic influence would mean occasional rain or drizzle with hill and coastal fog.

ECM 00Z at the same time:

Very different evolution and nearer to Scenario B. Heights are stronger over Greenland than on GEM so we don't get the dominant LP system in mid-Atlantic. The weekend's trough has deepened and crossed the British Isles and lies over southern Scandinavia leaving us all in a cool WNW'ly flow. You'd think the next shallow LP might swing SE with heights building into the mid-Atlantic locking us into a cool and unsettled spell for the Bank Holiday.

The T+240 chart would mean rain or showers for many especially to the north and east but above all disappointingly cool weather.

On then to the GFS 00Z OP at the same time:

Another fascinating evolution and not too far from where the equivalent run was yesterday. The trough (and LP) are never too far from the British Isles and with strong heights over Greenland and a more major trough over Finland a cold NE'ly flow from the Arctic sweeps down into the NE Atlantic and over Scandinavia. The jet heads south and with it the LP systems so the Atlantic LP, instead of oscillating quietly in the Atlantic which it can do with weaker HLB on GEM, is sent SE by the powerful HLB over Greenland.

This leaves the British Isles under two very different airflows - a warm SE'ly for many but a much cooler NE'ly for the far north of Scotland and the Northern Isles. I'd also suspect an unsettled scenario with plenty of rain and showers (or possibly thunderstorms) for many though perhaps the east coast faring best.

Further into FI and it looks like a grim Bank Holiday with LP systems crossing southern counties but, naturally, as we all go back to work, HP builds again and settles everything down in time for June as the last of the northern heights fade.

The Control isn't dissimilar though there is more of a build from the Azores HP though the ridge is more over France than the British Isles.

The 00Z GEFS at T+240 has, as you might expect, a mixed picture with the biggest divergence to the west and south west of the British Isles and that's between those models which keep the core of the LP in that area and those which don't.

To conclude, after a brief warm phase it's a steady descent into something more unsettled into and through the coming weekend with rain or showers likely for many and suppressed temperatures. Into next week and it seems probable the unsettled phase will continue with LP never too far away. IF the LP becomes effectively cut off in mid Atlantic, it is likely pressure will rise nearer to the British Isles with increasingly dry and warm conditions but the form horse today looks to me for further cool and disappointing weather approaching the Bank Holiday with GFS OP particularly set for rain. Such rain would be very welcome in southern areas after the prolonged dry spell but with strong heights continuing to be shown over Greenland through to the end of the month a washout now seems more likely than a heat wave.

We'll see what tomorrow brings.

[stodge]

Afternoon all

For various reasons, this morning's update has become this afternoon's update and the way things are going it will crash into the 12Z output before long.

A spell of overdue heavy rain in my part of London last night but still very humid and sultry and perhaps a second deluge incoming - we'll see.

Thoughts turn to the coming Bank Holiday and let's see where we might be on Saturday May 27th as the long weekend starts:

Starting with the GEM 00Z at T+240:

An interesting evolution. After the weekend a new Atlantic LP stalls far out to the west and pressure rises next midweek over the British Isles though that links to heights to the far north. These are in turn swiftly eroded from the west as the LP and trough move in. At T+240 the LP is over Scotland and points NE with much of the British Isles in an unstable WSW'ly flow promising rain or showers for many . A secondary LP looks set to  move in from the SW.

ECM 00Z at the same time:

A lot happens on the ECM evolution from a warm S'ly next Monday to a cool N'ly by next Friday. Weak heights to the NW and a cut off LP over the Azores leave the British Isles in a col. Probably reasonable weather though not excitingly warm.

GFS 00Z OP at the same time:

GFS 06Z OP at T+234:

I'd say these were variations on a theme. The big picture items are the same - strong heights over Greenland and the trough over Scandinavia (albeit with different position and orientation). The 00Z offers a twinge of hope with a small HP centre but the jet is to the south and the 06Z keeps LP rolling in towards southern parts of England so an uninspiring long weekend on the cards with perhaps only the far NW of Scotland seeing something brighter.

The 06Z FI is a horror show for those wanting fine and warm weather as the British Isles is assailed by a series of LP from north and south west with the only certainty being rain and plenty of it.

The 06Z Control isn't much better though a glimmer of hope for southern parts with the faintest hint of rising heights. The 00Z GEFS plays the theme of northern heights strongly and many of the members have them as the key influence either pushing a ridge SE over the British Isles or keeping the trough on a more southerly path. A few members try to make the heights less influential by driving LP to the north but we'll see.

To conclude as the 12Z is on the horizon, we are moving into a much more unsettled spell which could well last the rest of the month. GFS is particularly strong on holding the heights in place to the NW and keeping the trough closer to the British isles but ECM and GEM offer alternatives which is as unsettled in the case of the latter but perhaps a glimmer from the former if heights can drop down from the NW.

[stodge]

Afternoon all

Once again, the day is running late it seems. Yesterday's overnight rain in London was followed by a fine morning but the clouds have built significantly and I think we'll do well to avoid a shower later.

On then to the models and today's output takes us to the early hours of Sunday May 28th:

Starting as always with GEM at T+240:

A very different evolution to yesterday. Greenland heights are gone in favour of pressure rises from the south - the first as early as Sunday promising a much improved day for southern and eastern parts. The second height rise occurs on Tuesday and is more focused on western parts but soon moves countrywide. It's a weakfish ridge in MSLP terms and the core is to the NW so not perhaps as warm as some would like but certainly a return to something drier and more settled for many and while the threat of a shower in the far south remaisn the T+240 chart looks reasonable for many.

ECM 00Z at the same time:

It's not a million miles away from the GEM but the journey is somewhat different and the key is ECM continues to play northern heights. A tentative build of heights to the east is soon eroded while the second quickly links to the north and north west and with the jet heading back south, the Atlantic LP sinks SE toward Iberia keeping the British Isles reasonable under a ridge. Scandinavia remains cold and unsettled but it's warmer if not excitingly so for the British Isles.

GFS 00Z OP at the same time:

 

The GFS 00Z told a different tale of strong northern heights and a southerly tracking jet sending successive LP systems across southern parts of Britain during next week. A sign perhaps of a change from this chart but not set fair - more likely sun and showers. The rest of 00Z FI going into June was far from pleasant with plenty of unsettled conditions and rain sometimes with strong winds. A hint at the very end of the jet trying to move back north.

The 06Z OP at T+234:

Not too different essentially with a southerly jet and heights to the north and north west. The next area of LP is poised to dive SE into France and under a transient ridge it's probably not a bad day for many especially in the north. The south and especially the south west more at risk from rain.

I thought the further FI from the 00Z OP was bad but the 06Z beats it hands down with a cool NE'ly for many and periods of rain and showers for most.

To pour petrol onto a good fire, the 06Z Control is also very unsettled with the jet close to the British Isles and plenty of rain or showers.

The 06Z GEFS at T+240 sings a very similar tune with strong blocking over Greenland keeping the LP on a southerly track and combining with LP over Scandinavia to send a cool N or NE'ly airflow into the northern Atlantic and over NW Europe. To be fair, a number of the members keep heights closer to the British Isles either to the NE or NW which would keep many dry but a significant cluster keep LP very close suggesting a more unsettled evolution.

To conclude, the path into next week looks reasonably set but there's a divergence as the weekend approaches between GEM/ECM who offer a glimmer of hope for something drier and more settled and GFS which once again plays a strong unsettled card which looks locked in through month end and into the start of June based on the OP and Control.

One thing I don't see any sign of currently is heat or a southerly flow of any kind. Those wanting heat at this stage will have to be patient but the rain, although unwelcome for those wanting a decent half term break, is much needed. 

 

 

[Darren Bown]

Morning all! It's my wedding day next Saturday and am chuffed to pieces that it looks set to settle down next week. What are the current chances of the possible 'breakdown' at the back of next week? It can do what it likes on the Sunday haha!

[stodge]

Afternoon all

A glorious day in London Town and it seems the more pessimistic of the model forecasts for this week and the weekend have been cast aside. The key factor seems to be the relaxation of heights to the north and a strong build of pressure to the south.

June approaches however and today's update takes us to the early hours of Thursday June 1st:

Starting as always with GEM:

A fine and settled GEM evolution for many this morning with a strong build of HP from the south west through this week keeping most parts dry, sunny and increasingly warm. A breakdown of sorts next Sunday cuts off the wamr/hot SE'ly and reintroduces something more W'ly but another build of heights early next week brings another briefer settled spell. By Thursday however this has fallen apart and while heights are strong to the NE and SW, the British Isles is in a col with lower heights to the NW and SE so perhaps an increasing risk of showers and maybe turning cooler as a more Atlantic component is introduced.

ECM 00Z at the same time:

Not a million miles away from ECM. A succession of LP exiting North America slow in the Atlantic and allow ridges of HP to build in front of them but by the middle of next week the LP is approaching from the west while pressure is falling over Iberia with a slack and potentially unstable E'ly setting up over southern parts. Warm but fans of thunder and lightning might have something to which they can look forward.

GFS 00Z at the same time:

A superb evolution for fans of heat. With the jet far to the north, successive HP cells build in from the SW across the British Isles and into Europe drawing up a warm or very warm SE'ly airflow. Further into FI there's a brief thundery breakdown before the long ridge of Azores HP builds across the British Isles once again and keeps most places dry and settled though perhaps a notch cooler.

GFS 06Z OP at T+234:

Superficially not too different and not too different for the British Isles though LP is more defined in the Atlantic and FI goes on to re-strengthen heights to the north.

06Z Control brings LP in from the west and turns the weather more unsettled but still warm.

So a fine few days ahead for many before the briefest of interruptions over the weekend and a return to decent conditions for much of next week though into June and uncertainty intrudes with the possibility of more unsettled conditions returning but that's far from decided at this time.

 

[Glacier Point]

As summer proper comes into view, I know the model output comes in for greater attention given the trend of the last few summers (starting with 2007) for the weather at the start of June to be a precursor to the remainder of the season.

How are we looking at the moment ?

My seasonal assessments to clients have been very critical of the chances of an El Nino event evolving, and it looks like that will be the case. Upper ocean heat content just hasn't been supportive of a warm ENSO event developing. 

So that's a non-factor. What then of what has been much more significant as a sub-seasonal and inter-seasonal driver since last autumn, what we might term Indian Maritime Tropical Forcing (or a persistence of coupled ocean-atmospheric windlfow patterns denoted by thunderstorm activity around Indonesia and New Guinea) ?

Of late the sea temperature anomalies leading this have weakened and rainfall patterns shifted in the spring. This was more to do with the lagged effect of a sharp breakdown of the stratospheric polar vortex. Although sea temperatures across the Tropical Indian and Pacific Oceans remain only weakly conducive, this driver looks to get a bit of a boost from the passage of a MJO wave in the next two weeks. Strangely, the MJO was suppressed in this region during the winter, and its renewed strength might indicate that this lo level tropical forcing is no longer as sustained. Either way, MJO phases 4, 5 and 6 and tropical forcing in this region during tend to support ridge development over northern and western Europe in response to troughing in the Atlantic.

My eyes are really drawn to two factors which I think will be key players (or more indicative of other forcing and the atmospheric responses).

The sea temperature anomaly profile of the North Atlantic is near perfectly aligned for troughing and downstream ridge development over Europe.

Anomalously warm pools off the Eastern US coast and to the west of Africa and Iberia have developed over the last few months whilst cold pools all the way through the central part of the North Atlantic have developed and been reinforced by weather patterns in the last month (again related to stratospheric breakdown).

That is a warm signal for much of Europe. Repeating cut off lows off the Eastern US, and possible enhancement later in the season by tropical systems should persist that cold pool and lock down the warm-cold-warm spatial arrangement of sea temperatures.

The other key development has been in the polar atmosphere.

This isn't necessarily a driver per se (although it was in terms of the breakdown of the polar stratospheric vortex in April), but it serves as a useful tool in understanding how the atmosphere is responding to global drivers.

The breakdown in the polar vortex in April serves as useful starting point. Sharp downwelling of negative zonal winds (positive height anomalies) were observed, and this basically imprinted the atmosphere with a blocking (-AO) signal, which manifested itself throughout the circulation, even over the Tropics). The anomalous warmth over the Arctic will have served to constructively interfere with this signal, culminating in those destructive night frosts recorded during May.

However, since the breakdown of the stratospheric vortex, the upper part of the polar atmosphere has cooled and heights have fallen quite substantially in the upper part of the atmosphere.

There are two years which illustrate why the coming few weeks will be keenly monitored.

During 1995 and 2007, two completely different summers (dry and warm versus blocked and wet), the evolution leading up to and during the breakdown of the polar vortex was very similar. However, what followed in the stratosphere and upper part of the troposphere were completely different. During 1995, a cooler stratosphere and lower heights extended their influence much lower into the atmosphere and the resultant weak polar easterly flow was characterised by much less blocking. Contrast that with 2007. The extension of low heights was much less, with blocking (positive height anomalies or red shading) much more robust in the lower part of the atmosphere.

Looking at the profile to date, the extension of low heights is impressive and suggests something more akin to 1995 is the case (although there is still some time for similarities with 2007 to rear their head). It is the speed of the atmospheric response to the breakdown of the stratospheric polar vortex that is most telling for me.

So we have a weak polar easterly (less risk of influential blocking over the Arctic) signal allied to a trough signal in the North Atlantic. Those two suggest a higher pressure tendency for Western Europe and summer where the continental ridge is allowed to develop as the season progresses. So in essence, the June through August signal is more weighted towards above average temperatures and below average rainfall for much of Western Europe.

Edited May 23, 2017 by Glacier Point

[stodge]

Morning all

First, thanks to GP for his valuable insight. and an encouraging contribution for those wanting warmth and settled conditions into June. It's always interesting to look at the deeper picture and GP seems to offer the same reasoning that Tamara has done on the main discussion thread and elsewhere for what I've called Scenario A - the mid-Atlantic trough encouraging height rises into north-west Europe.

We've enjoyed or endured (delete as appropriate) a Bank Holiday weekend of contrasts. I was with Mrs Stodge on Friday in Ely and the weather was sublime with the interior of the Cathedral providing useful shade and refuge from the heat. The other three days were more mixed with rain (though the heaviest at night) and plenty of cloud but not without sunny and warm moments.

Fresher today - more typical early summer fare.

Where are we going as June approaches ? Today's output takes us to the early hours of June 9th:

Starting with the GEM at T+240:

The GEM evolution this morning is typical summer mobility. Heights persisting over Greenland but not pushing south keep the jet running close to or just to the north of the British Isles. It's hard work for LP systems to cross the British Isles and that allows ridges to build from the SW (Scenario A as explained above) so the south doesn't fare too badly with only right and sporadic rain. Not so cheerful further north with more persistent and heavier rain especially for north western areas. Temperatures average but perhaps slightly warmer in the south. The trough aligns SW-NE into Scandinavia with plenty of heat for eastern Europe but it's a typical summer pattern.

ECM 00Z at the same time:

Somewhat less inspiring would be my immediate comment. The trough dominates the Atlantic and NW Europe and quite a vigorous feature swinging through the British Isles offers rain and showers for all with cool temperatures. This is a secondary feature with the main LP sitting further north. The Azores HP is held well to the south though there are perhaps signs of a more settled spell  with pressure rising in mid-Atlantic.

GFS 00Z OP at the same time:

Cat, meet pigeons. Not quite - after one or two adverse comments yesterday GFS has pleased those looking for warmth with a very satisfactory mid term chart. The Atlantic trough heads further NE to sit near Iceland so the Azores HP ridges up over and through the British Isles and links to heights over southern Scandinavia. It's also worth noting the Iberian LP and low heights over the Mediterranean. It's not a plume scenario yet but it could be if the LP shifts north.

Further into FI it's not quite a plume but it does become more unsettled with LP coming in from the west and trying to drop SE into Europe.

The 06Z run hasn't finished but a more vigorous LP develops to the west and swings into the British Isles around T+240 but ominously heights are building to the north and clear signs of the jet heading back south into mid month but that's just one OP run.

Going back to the 00Z and its ensembles and the Control is very unsettled in FI to be honest with a southerly jet. The 00Z GEFS are as you would expect a mixed picture. Only a couple of members offer serious heat and conversely a couple of others have LP right over or to the east of the British Isles. The OP is fairly representative of a broad SW'ly airflow between LP to the north west and HP to the south west. The OP is more biased toward the dominance of HP but make of that what you will.

In conclusion, a slightly messy pattern for the start of June. GFS OP and GEM to an extent offer the Scenario A pattern of a mid-Atlantic LP allowing ridging from the SW providing fair conditions but ECM goes for a more unsettled prognosis with LP shifting more to the north and secondary features swinging in on a more W'ly breeze. It's not without some support from GEFS but probably less likely. Northern heights continue to tantalise and frustrate in equal measure and continued hints (though if GP and Tamara are right that's all they will be) of a more southerly jet into mid month.

As is often the case and as the song has it, there are more questions than answers...

[stodge]

Morning all

June is nearly upon us so will it flame or fizzle ? A fairly non-descript start in London Town today.

Looking to the early hours of Saturday June 10th and where might we be ?

Starting with the GEM 00Z at T+240:

A fascinating evolution from GEM this morning and a move away from what we've seen of late. The trough slowly extends across the British Isles over the weekend and into early next week but the next LP out of North America slows down allowing heights to build but mainly from the north rather than the SW. The LP than fills and swings SE toward Iberia and we end with a strong HP ridge to the north from centres over Greenland and just north of the Faeroes and the British Isles in a warm ESE'ly flow. Probably plenty of sea fog to eastern and southern coasts but inland areas and particularly those in the north and west would be enjoying fine and warm weather.

ECM 00Z at T+240:

A very different evolution but one which hinges on the movement of next week's LP from North America. While the GEM model slows the LP down and eventually disrupts it, ECM is more progressive and incorporates the second LP into the remnants of the first keeping the British Isles unsettled and cool with rain or showers for most.

GFS 00Z OP at T+240:

It's a recognisable blend of GEM and ECM in that the second LP comes in and stalls close to the British Isles. The ridge is thrown slightly to the east and while the south east fares well it may be too far away for western areas and as the trough fills and moves in the unsettled conditions become more widespread.

Further into FI and strong HP builds first to the SW and then to the NE leaving the British Isles in a warm but increasingly unstable ESE'ly flow.

The Control gets very strange disrupting the LP to the south then sending it back north or north west. HP builds briefly over Scandinavia but loses out to the thundery trough from France leaving the British Isles in a warm or very warm unstable thundery set up by mid month.

Looking at the 00Z GEFS at T+240 and it's a mixed bag of options. It's perhaps symptomatic of a lack of a clear signal.

To conclude, some residual warmth into the coming weekend but the LP which has sat out to the west and allowed the ridging and the warmth will finally move east across the British Is;les through the weekend and into the early part of next week.

From there, it all depends on what happens to the next LP coming out of North Atlantic and GEM, ECM and GFS all offer different solutions with consequences down the line which either leave us very unsettled or potentially in a very warm and unstable thundery "plume". It's hard to call at this time and as ever more runs are needed.

[stodge]

Apologies, that's the GFS 06Z OP chart at T+240 - I had some problems with the 00Z chart which was:

[stodge]

Afternoon all

Another late running day it would seem. It seems my take on yesterday morning's output wasn't shared by some who are so expert as to declare the first half of June "screwed".

Never mind - where are we today which takes us to the morning of Sunday June 11th:

Starting as always with the GEM 00Z:

Not a bad run from GEM if you're after warmth. It's classic Scenario A with successive LP systems slowing in the Atlantic and allowing ridges to be thrown up from the AW across the British Isles. I don't see a lot for eastern and southern areas to be worried about from this evolution. There will be some light rain as the cold front moves through but HP swiftly re-asserts from the south and south-west. Further north and north west it is probably less settled and it is to be noted the LP is closer to the British Isles than its predecessors so the range of unsettled conditions would be closer.

ECM 00Z at the same time:

ECM was poor yesterday and a notch better today but it keeps the LP systems moving and passing close to or through the British Isles. To be fair, this chart would offer some warmth and sunshine for the far south and east but less clever further west with rain or showers and quite a stiff breeze. I also note the attempt to build a mid-Atlantic ridge behind which wouldn't augur well for mid month if the LP shifted east and sat over the British Isles.

GFS 00Z OP at the same time:

This is a fine chart for those wishing to call the first part of June "screwed" and the GFS OP output, as remarked elsewhere, is disappointing for those wanting warmth with plenty of cloud and rain or showers as the trough sets up over NW Europe and Scandinavia. Cool too for the time of year. Into FI and it's full own Scenario B with the ridge dropping south out of Greenland and Iceland and trapping the British Isles in a cool N or NW flow before at the very end the ridge moves to the NW and we pick up a cool NE'ly flow.

Here's the 06Z OP at T+234:

Is it any better ? Possibly even a notch worse and certainly a long way from any notion of a "flaming" June. The following FI evolution isn't too far removed from the 00Z OP which suggests a worryingly strong signal.

The 06Z Control offers a brief period of hope from the Azores HP ridging NE but rising heights in mid-Atlantic quickly end that and the trough ends up over the British Isles.

The 06Z GEFS at T+240 show the largest divergences over Scandinavia and to the south west of the British Isles. Some members show Scandinavia bathed in HP, others have the trough over Sweden. It suggests plenty still to be worked out.

In conclusion, the end of the warmer spell over the weekend doesn't necessarily mean the end of decent weather - if GEM has it right, the warmth will return as successive LP systems stall in mid-Atlantic but both ECM and especially GFS paint a much more mobile picture with LP systems sweeping in from the Atlantic on a southerly jet bringing rain or showers for many and while ECM keeps things fairly warm, GFS does not.