stodge

On and on, the story goes Where the pressure systems stop Nobody knows... Well, the models do at least hazard a guess each day - the last day of the current fine spell draws to its conclusion so how and where (and above all when) will new stability occur? Tonight's 12Z output at T+240: That's the usual suspects - ECM, GEM, GFS OP and GFS Control The immediate view is they are all very different suggesting the only clear thing is a lack of clarity. ECM is the most positive for the British Isles overall with much of the north and west under the influence of a ridge but the south and east remain close to the European trough and that's fairly pronounced on both GFS OP and Control though the former isn't bad for the Hebrides. GEM looks on its own tonight with the Azores HP in completely the wrong place and orientation ad a deepening LP to the NW set to enhance unsettled conditions for most with wind and rain spreading from the NW. Further into GI, GFS OP keeps a very slack pattern in place which isn;t unusual in summer. A broad but shallow trough to the east and south against weak heights trying to build in from the SW. Not, as it has to be said, exciting warm with the heat to the SE generally at bay. Control's evolution is rather different but hints at something more summery. After drenching the British Isles, the Iberian LP withdraws slowly west and allows a weak ridge to develop to our east which suggests a possible plume around midsummer or just after. All a very long way off but a possible escape route back to heat for those who want that.

Evening all One final fine day tomorrow, it would seem, before the descent into proper summer weather begins but will it be a "blip" or is the pattern resetting but not necessarily to our advantage? Looking at the 12Z output tonight, I'll take the line at T+216 so that's Wednesday June 10th: While there are a couple of straws for fans of settled weather to clutch - GFS Control ridges the Azores HP encouragingly toward the south west of the British Isles. the problem is more prosaic. Between heights to the NE and heights to the SW, the negatively-aligned trough is in charge with shallow areas of LP moving ESE through northern Britain and then down to the North Sea. Pressure remains low on the Continent as well so the outcome is traditional British summer fare - on the cool side, cloudy with rain or showers. Some brighter spells of course and we're hardly talking about ark-building quantities of rain but it will be disappointing after the anomalously sunny spring we have all enjoyed. The Azores HP isn't in the wrong place but it's not oriented well for us at this time. Further into FI, GFS OP keeps the weather very unsettled with more Atlantic LP sweeping in while Control is a little more optimistic but we see the prevailing pressure pattern and problem - the core of HP moves across the British Isles to Scandinavia but the European trough remains the dominant force and keeps the south in particular at risk of rain or showers - warm and humid though to compensate a little. The CFS anomalies continue to suggest higher pressure to the north and lower to the south into July so I suspect the changed pattern may prove harder to shift then some think. We'll see.

Not sure I'm as convinced. There seems a strong signal for lower heights over NW Europe which would suggest more unsettled conditions with thundery showers or rain moving up from the south. I agree for Scotland and the north it looks much better and I'm certainly seeing nothing cold or cool - warm, perhaps very warm and often humid in the south perhaps. We'll see - the CFS anomaly for January next year may interest a few: With our luck we'll get heights over Greenland and a west-based negative NAO through December and January !!

Evening all Is a pattern change coming or simply a blip, a mere interlude, in the general progression of summer 2020? Will those of us with allergic rhinitis be sniffing and sneezing for the next few weeks or will the weather provide some much-needed relief? Looking into the medium term this evening and away with us to T+240 on the 12Z output suite - ECM GEM GFS OP and GFS Control: Encouraging for those looking for a rapid return to more settled conditions but it all looks very half-hearted to this observer. ECM has moved away from its "nightmare" scenario of three nights ago to something which many will find more acceptable but this ins't a long fetch S'ly but a WNW'ly so probably quite cloudy and while warm never hot. GFS OP has the HP in the wrong place to we end up with a NW'ly. GEM keeps a slack NE'ly over most of the British Isles with fantastic weather for the Hebrides and a risk of showers elsewhere. Oddly enough, Control ends up much better in far FI than the OP so the journey to the middle of June may well have a number of twists and turns yet.

Evening all A real sense yesterday of enjoying the next few glorious days with a clear decline later next week to something much less pleasant. Where are we this evening? Let;s roll forward just one week so T+168 on the 12Z: That's GEM, GFS Control and GFS OP. Not much to get excited about if you want heat - GEM is just plain awful and while the GFS runs are slightly better that's only by degree. To be fair, the GFS OP is better in FI finally buiding the ridge across northern Britain to Scandinavia though as that declines the shallow European trough is wating to spread warm thundery conditions across the south. Control goes in a different direction ending with the HP to the south west though not well oriented. As for ECM, the morning's chart showed a vicious but brief N'ly and illustrated the passage of the LP is vital. IF it misses the UK and then heads ESE toward Denmark and the North Sea the net effect is still far from pleasant.

Evening all Awaiting the 12Z from ECM but GEM shifted even further to GFS this evening and looking at the main models at T+168 for a change: That's GEM, GFS OP and GFS Control with ECM to come. IF (and it's still a big IF) this verifies, GFS has done really well. The OP has consistently over the past few days modelled the HP cell to the NW or West in mid Atlantic and the other models have at this stage come toward it. It's not a done deal of course and not only could the signal flip completely but it may be the HP will extend enough of a ridge eastward to keep most of the British Isles dry if cool. We await the ECM 12Z - I'd be surprised if it was a as dramatic as this morning's output which developed quite a vigorous little LP and ran it south across the British Isles.,

Evening all Growing signs for an easing of the current settled conditions as we move further into June. Looking at four main model output at T+240: So that's 12Z ECM, GEM, GFS OP and GFS Control All keep the main cell of HP too far west and not well oriented to throw a meaningful ridge across the British Isles so the trough squeezes in from the north and east and introduces a much cooler air flow from the North or North West. The ECM is slowest of these to make the change and looks 24-36 hours "behind" GEM in its evolution but the net effect is the same. The extent of the new Scandinavian trough varies across the models. Further into FI, GFS OP continues its theme of many days of moving the HP up toward Greenland and Iceland and even Control keeps heights to the north. I know many think we will have a fine and warm June but I'm far from convinced - the first half of the month looks a typical "flaming June" with plenty of rain and perhaps some quite cool conditions in marked contrast to what we are experiencing now and have done for several weeks.

Afternoon all The journey from the end of next week onward remains, as it often is, replete with many paths. GEM this morning showed what can happen if the second HP from the Azores doesn't get over the British Isles quickly enough or ridges too far north. The European trough moves up from the south and threatens showery if not stormy conditions for southern Britain while further north the fine weather is maintained. ECM this morning looked quite similar here - the question then becomes as to whether the core of the Azores HP will shift north rather then NE (this was the outcome on the much-derided GFS 12Z yesterday afternoon). The 06Z GFS OP is actually very good Further into FI, however, it doesn't really build the ridge east but shifts it north and that alloes the more active trough to the north to come down over Scandinavia and introduce a much cooler airflow. Control shows the growing influence of the European trough: Indeed the rest of FI in Control isn't that inspiring as the scenario ends up not far removed from Control. The Mean at T+198 also suggests the influence of lower heights to the south and an E'ly picking up for southern areas.

Surprised to see ECM moving toward GFS - well, up to a point. Nowhere near as extreme a solution as the 12Z OP but a clear indication of what I said earlier. As the first HP retreats further east and the British Isles falls out of its influence we need the Azores HP to be ridging in as quickly as possible to maintain a settled picture. If not, as we see on the ECM 12Z at T+192, the trough fills the gap from the south and we get a breakdown to a more unsettled weather type. The HP tries to build in again by T+240 but is further NW with the trough's influence closer to the SE. This is how wet Junes can occur - the "European Monsoon" as someone called it and there's a hint of the Indian Sub-Continent about how the heat builds up and then pressure drops and the rains come. As we saw in 2007 and 2012, if you get warm water over the North Atlantic that can encourage blocking scenarios to the north and allow trough formation and development over western Europe with large amounts of rain. I'm not saying June 2020 will go the same way at all this time but I'd be looking at the European trough and hoping the Azores HP doesn't ridge too far north and north west.

The OP does look curious but Control is not atypical and it keeps the HP to the north west so a prolonged NE'ly flow for southern Britain with any real heat kept a very long way to the south. The mid-Atlantic HP option (though perhaps without the full ridging to Greenland) not quite as much of an outlier as some seem to be suggesting.

Afternoon all The key question into the medium term is whether the various HP cells can maintain continuity of settled weather. The GEM from this morning shows how it can go wrong - the current HP builds and moves NE into Scandinavia but as it gets further away and the ridge orientates away from the UK we need the next build of HP from the Azores to be ready in the wings otherwise the troughs from north and south can extend into the gap and much more unsettled weather will result. This morning's ECM get sit right for the north with the Azores HP ridging strongly NE but the south comes under the influence of the Iberian trough so showers or perhaps storms. The hint of the next HP cell moving further north and west was present last evening on the GFS Control. The current 12Z OP gets it right for fans of settled weather: Note the Azores HP has already split with the core still well to the west of the Azores but a new HP cell developing to the NE and ridging toward us. Unfortunately, as was the 06Z OP, the 12Z OP looks to be developing the core of HP into the mid Atlantic which may not end well for the British Isles as a push of warm upper air into Greenland will drag the trough down over us and leave early June potentially cool and unsettled. A more likely scenario, I think. is the HP sits moe to the NW keeping the hot air well to the south but settled conditions for the British Isles.

Evening all After a brief pause at the weekend, the settled theme returns next week but beyond that where does the summer pattern take us? ECM this morning showed the risk of the HP over-extending and allowing the trough to move up from the south and GFS Control picks up a similar theme. The OP isn't done with northern blocking and ends up shifting the Azores HP north and opening the door for a much cooler N'ly - shades of 1975? Well, not quite thought that summer was excellent. GEM OP is about as good as it gets with the ridge solid from NW of the Azores through the British Isles to Scandinavia and NW Russia though by T+240 pressure is falling and the European trough is encroaching and this is a pattern we often see in June with more unsettled conditions over Europe encroaching into southern Britain.

A really sudden and abrupt change this afternoon - up to nearly 18c but back down now to 12c. It's the change you would expect if a strong cold front had passed through but instead cloud has spread from the NE and the wind has noticeably strengthened from the ENE.

The area of rain and storms over Normandy is only very slowly edging north into the Channel - a second storm is moving toward Cotentin while Guernsey has seen some heavy showers this evening.

Perhaps - what I love is the LP which develops over Southern Sweden, moves NE to northern Finland and then deepens explosively to be sub 970MB at T+72: That would be a decent storm in mid winter - it then moves west across the top of Scandinavia toward NE Greenland. A second LP which formed over eastern Europe deepens over NW Russia by T+96: It also heads west but the HP coming down from the Pole through Iceland to the NW of the British Isles stops that and it steers SW down the coast of Norway: The LP fills up as it approaches Shetland. I love odd synoptics and I've never seen that - I've added the jet stream chart because it picks up a noticeable jet streak over Scandinavia and then west toward the Pole. The jet then turns SW before decaying.

Evening all A sudden change from spring warmth to winter chill on offer over the weekend but this often happens at this time of year as the winter and summer air masses clash and the end of the PV allows colder air to flood southward. The T+240 charts this evening from ECM, GEM, GFS OP and Control taking us into mid month and beyond: A few items of interest - after the cold blast, the HP remains overor just to the north before slipping away SE and this allows the European trough to move north and take control of the weather for southern districts so an unsettled spell with rain or showers likely later next week. From there, ECM, GEM and Control send the trough east and a more traditional pattern re-establishes with an Atlantic feed and the Azores HP ridging NE in response to the Atlantic LP moving in. GEM keeps the jet to the south with strong heights over Greenland but ECM and Control go for a more northerly jet pattern. GFS OP is the outlier here because instead of sending the European trough east allowing heights to rise as the Azores HP ridges in it sends part of the trough energy west with a new area of heights developing over the Faeroes and extending to Norway. This keeps an E'ly flow over southern Britain but further into FI the joining of the Azores and Scandinavian HP cells creates a strong ridge over the British Isles with the trough held to the south - the problem with that for heat fans is the orientation of the HP doesn't allow for the hot African air to advect north.

Evening all A final taste of winter next week for some? We'll see but beyond that where are we this evening? T+240 from ECM,GEM, GFS OP and GFS Control Some cold air about early next week - especially so for the time of year over Scotland. Further ahead and the trough to the south looks an interesting player. This is basically coming out of North Africa and is the main response to northern blocking. It's quite a pronounced feature over Spain on the GFS OP but both ECM and Control have it though it's weaker on GEM. We often see this in May and June and it can bring early warmth and storms and a lot of rain across Europe and fringing the British Isles. The positioning of the HP varies from just to the north east to over the British Isles - it's not really the Azores HP but the former Greenland HP drifting south to the west of us. ECM and GEM are more progressive with the Atlantic profile with GEM (as it often does) modelling quite a deep feature. GFS OP never really gets that warm and there's no sign of any significant early heat - with the trough due south rather than to the west, the air flow is more SE or ESE but this isn't an Atlantic trough digging south and advecting warm air on its eastern flank but the North African trough extending north into Europe so it doesn't work so well for fans of heat.

Evening all Another day of April showers in lowland East London - not quite as sharp as yesterday but we're a long way from summer yet. So, what of this evening's offerings from the models as we head further into the new month? The T+240 charts tonight from ECM, GEM, GFS OP and GFS Control The first thing to say is the GFS OP looks out on its own tonight but even that has some heights over Greenland whereas both ECM and GFS Control have very strong blocking over Greenland so it becomes a question of modelling the trough. ECM has the kind of chart which, if it was at T+6 in early January, would have many salivating uncontrollably. It's a uniformly cold and bleak chart for the British Isles with a strong NE'ly flow bringing plenty of rain or showers. GFS Control has the trough rather further north over Scandinavia so the NE'ly becomes a N'ly or NNW'ly with pockets of -8 850s over Scotland which suggests snow for the mountains. GEM plays a different game with more extensive blocking from Greenland to the north of the British Isles so the flow is more E or ESE over most parts so dry and fine conditions with decent temperatures by day but a risk of frost at night (for both ECM and GFS Control there would also be a strong likelihood of rural ground frost under any clear skies). As for the GFS OP, the key difference is the core of heights never becomes established over Greenland but sinks SE back toward the British Isles and by T+240 there are weak heights over us keeping the weather fine and dry. Again reasonable day time values but chilly evenings. As I've stated before, none of this is unusual for May - as Michael Ventrice points out, the collapse of the PV often allows for a negative NAO/AO regime in May. In some years, the block is over Scandinavia as we saw last week and the British Isles benefits from clear skies and warm sunshine but if the block retrogresses to the NW, the air flow shifts to the north-east or north and that just draws in the cold air from north Scandinavia or the Arctic. In addition, we see lower pressure over Europe in response and that either leaves us in the ECM situation (at the sweet spot between the pressure systems) or under the influence of the trough to the east. Either way, it's cool if not cold and unsettled but this is the Buchan cold spell which we often see in early May. It lasts 7-10 days and what often happens is the Atlantic moves back in before the summer pattern asserts.

Evening all After a typical day of April showers here in lowland East London what will May provide. Looking out to T+240 tonight and the charts from the usual suspects: ECM, GEM, GFS OP and GFS Control respectively from the 12Z output. ECM, not for the first time recently, looks the "odd man out" with heights much lower over Greenland and an Atlantic LP heading towards the British Isles (hinted at on the GFS Control). The tilt of the trough looks more positive too. The other models all show strong heights to the NW which keeps the jet running well to the south. Control has a pronounced mid Atlantic ridge leaving the British Isles in a very cool NE'ly flow with LP close to the south-east coast while GEM and GFS OP have a broadly N'ly flow with a pronounced trough over Scandinavia showing on the GFS OP. None of this unusual for early May which often has an E'ly or N'ly flow as the winter flow ebbs.

A proper day of April Showers - just had a heavy shower pass over East London, our fourth downpour of the day. What a difference a week makes - just 168 little hours - (as someone never said).

Evening all As often happens as we transit from the winter to the summer pattern, warm days are interrupted by much colder days. Today has been more like late February than late April but it's transient (the cold not the rain). Moving into May where are we tonight ? Tonight's 12Z T+240 output from GEM, ECM, GFS OP and GFS Control respectively. A decent signal for a push of HP from the Azores (GEM a shade more reluctant) but more to the north and west of the British Isles (and indeed retrogression according to GFS FI) which is something we occasionally see in the mid spring pattern. The signal for northern blocking remains powerful and with pressure low over Continental Europe we see a residual NE'ly across the south and south east and the best of the dry and warm weather to the NW Highlands and Islands which can enjoy some of their best weather of the year at this time with the Atlantic quiet.

Evening all It certainly looks a much more unsettled week next week for most of the British Isles with rain and cooler temperatures for most. Looking beyond that the 12Z ECM, GEM, GFS OP and GFS Control at T+240: Actually, less varied than you might suppose with only ECM not having LP firmly in charge. Signs of a mid Atlantic ridge but strong northern blocking on GEM in particular and both conspire to keep the trough close to or over the British isles so while not cold very unsettled with rain or showers heaviest in western and southwestern parts. ECM is also alone in keeping heights low over Scandinavia and while there are hints of a northward push of heat on all the models from North Africa it's not coming our way but heading either east or staying in the Mediterranean basin. This is a pattern we sometimes see earlier in the summer season as the pulses of heat occur to the east and west of the British Isles and we are caught under the trough - further west and we'd get a S'ly draw and some decent warmth - further east and we'd be getting a chilly N'ly but the LP is over Ireland so not cold - just wet.

Evening All Looking at the output, the one word that comes to mind is unsettled. It will be a marked contrast to the glorious weather of the past few days with largely cloudless skies and low humidity. ECM, GEM, GFS OP and GFS Control respectively at T+240. I'm struck by how GFS seems keen to maintain blocking over Greenland and a weak mid-Atlantic ridge. Pressure is trying to rise over SE Europe leaving the British Isles dangerously close to the trough which threatens to align into Scandinavia. ECM and GEM offer a different evolution and it's interesting to see ECM trying to bring the Azores HP closer via a small LP over the islands sending the HP nearer us. We've yet to see the Azores HP play its hand but there's more than a hint from GFS, GEM and some earlier comments on this thread that we might see the trough dig well south between the Azores and Iberia which would be good news for summer fans as that would allow for a S'ly flow and of course potential instability. We aren't thee yet - the LP is too close and we end up with an unsettled SW'ly flow which will be damp for many though warm for the SE. ECM's evolution is very different and is more traditionally mobile though the strong LP coming out of Newfoundland at T+240 might encourage the mid-Atlantic ridge to push up in front - we'll see.

Evening All MY usual suspects at T+240 off the 12z output: That's GEM, ECM, GFS OP and GFS Control respectively. Not much agreement there it would seem so the journey from the breakdown of the current regime to the end of the month far from resolved.

Evening all Three days without a cloud in the sky here in lowland East London but as others have mentioned a noticeably chilly ENE wind. To be fair, it's my favourite type of weather - fine with sunshine and low humidity.