stodge

Morning all I've done the detail elsewhere but the clear trend is to more unsettled and LP dominated into next week. The question of the position and orientation is yet to be clear. The ECM 00Z looks out on its own in all honesty.

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.

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.

I do agree we are seeing the probable end of the NE flow early next week but I'm far from clear as to the evolution from there. I quite like the GFS Control option of drawing the trough up from the SW and I think that more plausible than the OP at this time. The other possible is the ECM where a pool of stagnant cold air gets trapped over the UK - this has happened many times in May and brings showery days and cool nights with little or no wind. Indeed, it might be the outcome if the col becomes established. Either way, I think a more unsettled evolution is the way ahead into the middle of next week.

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.

GEM 12Z is much colder at the end with a N'ly wind for us all. The battle between the colder and warmer air flows looks set to be joined in the middle of the second week of the new month. Looking at the 12Z GEFS and admittedly right out at T+312, the OP looks on its own and the colder option of having LP close to or over Scandinavia looks the majority option. Obviously very early days and plenty of runs needed. Strong cross-model agreement out to T+168 however - roll on the easterly !!

I think the orientation and position of the Atlantic trough is of equal significance. GFS 06Z has continued the theme of lowering heights in far FI but it's by no means certain and it may be we will have a prolonged if weak NE'ly flow with rain or showers for the south and drier conditions further north.

Morning all Didn't expect to have to scrape ice off the car this morning but this final hurrah of winter is now at hand and on its own way out to be replaced by, well, a confused weekend. Perhaps best in the north and east but the details still to be worked out. Yesterday, the models were strongly in favour of a build of pressure to the NE gradually transferring to the NW over time but there were many permutations and much to resolve. This morning's output takes us to the early hours of Sunday May 7th: Starting with the GEM 00Z at T+240: Quite a simple story this morning. After a brief unsettled hiatus through the early part of the coming weekend, pressure builds strongly from north and south on Tuesday and the northern HP becomes the dominant feature first to the NE of the British Isles and then retrogressing to be centred over Greenland but with a ridge SE back to the British Isles. The air flow over the British isles is sourced from a long way north so this would be a cooler NE'ly but the weather would be fine for most and the further west the better in terms of sunshine. ECM 00Z at the same time: Some subtle differences to GEM - note the orientiation of the Atlantic trough - but the net effect is much the same. The HP starts in the northern North Sea but retrogresses to Greenland with the ridge more ESWE and that means a more defined NE'ly for much of the British Isles sourced from some cold air over Scandinavia and NW Russia. Dry weather dominates the British Isles with the best of the weather in the west and north west. GFS 00Z OP at T+240: Subtle differences again starting with the Atlantic trough which is further south and with a different orientation to the GEM and ECM. The HP evolution is broadly similar though GFS creates a small LP to the far north which runs east into northern Scandinavia before sinking south. This cuts off the relatively warm E'ly and introduces a weak NE'ly flow but pressure falls across the south of Britain as LP moves NE from Biscay so by T+240 the south would be unsettled with rain or showers at times while the far north and north west holds on to drier conditions. Little changes further into FI with pressure always high to the north and low to the south and the wind flow oscillating between a warm SE'ly and a cooler NE'ly. The south would be vulnerbakle to showers or longer spells of rain while Scotland stays largely dry. The Control brings the trough up into the British Isles in furthest FI. The 00Z GEFS at T+240 show strong agreement for the overall evolution and for strong HLB to the north and north west. The position and orientation of the trough has a number of variants but the majority produce a NE'ly flow of some degree. In summary, while the details of the weekend may still need finalising, the trend to build strong heights to the NE early next week is confirmed this morning. All models take these heights toward Greenland though with varying orientation of the ridge. Some bring the ridge back SE over the British Isles keeping us broadly dry and fine while others keep the ridge further north allowing pressure to fall to the south and less settled conditions to encroach from the south and south west. The net effect is, after a brief warmer E'ly interlude to swing winds to a cooler NE'ly direction.

Morning all As I've said in my In Depth analysis (shameless plug), there's a good deal of agreement across models this morning. As I said yesterday, the source of the air flow would be crucial and the idea of an E'ly or SE'ly sourced from warmer regions has been diluted somewhat in favour of a more ENE'ly flow from west Russia which will obviously be cooler. There are more differences in the orientation and position of the trough than the heights which look remarkably similar into next week.

Morning all Very much like the bleak midwinter here in London with a cold N or NE'ly wind and doubtless close to a ground frost outside the capital. I saw a shower of rain and soft hail yesterday afternoon in SW London and I suspect those with altitude have seen something more wintry. This is a snap, however, not a spell and the trend to build HLB to the NE was very strong yesterday leaving the British Isles in a warm or potentially very warm SE'ly flow. Let's see where we are now with the model outlook to the early hours of Saturday May 6th: Starting with the 00Z GEM: The evolution through the Bank Holiday weekend and early next week is pretty well set with the trough splitting next Tuesday as heights rise strongly to the NE. Part of the trough recedes back into the Atlantic while a smaller element remains around the Low Countries helping to prop up the northern HP. That passes close to or just north of the British Isles by this time next week before receding into Greenland. Battle is then joined between the colder NE flow and the returning Atlantic trough and the latter prevails bringing more unsettled conditions back in from the SW. It's worth noting the very strong Greenland heights which may keep the jet running well to the south (the Azores HP is out of the picture) through the British Isles so once set in, it could be quite a prolonged unsettled spell. ECM 00Z at the same time: A number of similarities with GEM but some key differences. The position and orientation of the Atlantic trough is different - it is weaker and further south. This maintains a broad NE or E flow across the British Isles at T+240 though the risk of showers in the far SW in the strengthening E'ly breeze can't be ignored. There's little sign of a coherent Scandinavian trough but the possibility of disturbances in the flow to the NE is another factor. The jet is very weak and held a long way south. It would however be a fine and dry outlook especially for NW Scotland. GFS 00Z OP at the same time: As is often the case, GFS goes a different route. Initially it's much the same as you might expect but GFS has hinted for the past few days at low heights penetrating further into Europe next week so while the HP builds strongly to the NE before retrogressing NW in tune with the other models, the development of the trough is very different. Rather than holding the trough in the Atlantic, GFS OP brings it into western Europe and specifically over France with a change to a cooler and more unstable ENE flow across southern Britain with a heightened risk of rain or showers especially in the south, SW and the Channel Islands. Scotland would stay mainly dry, warm in the west, cooler with haar to the east coast. Further into FI and the pattern remains broadly unchanged with strong HLB and the jet sent a long way south. A chance of the jet moving back at the very end of the run with LP approaching the south of Britain from both east and west accentuating the chance of rain or showers. Looking at the 00Z GEFS at T+240 and it's hard not to be surprised by the lack of disagreement. The OP is strongly representative of the suite and the location and orientation of the HP around Iceland now seems to be the favourite option. Needless to say, there are more options further into FI but while the Control goes for a more Atlantic-based breakdown, a number of the members develop a strong Scandinavian trough or LP and a return of cold N'ly winds around or just before the middle of May. To conclude, more agreement than I've seen for a while. The ending of the cold spell presages a more unsettled weekend with the trough attempting to move in as heights build strongly to the NE. This brings in a warm but brisk SE'ly wind and the likelihood of rain or showers for southern and south western areas. The heights win out into next week but the trough moves across the south on Bank Holiday Monday bringing a potentially disappointing day before conditions improve from the north and the whole of the British Isles enjoys a few days of dry and warm weather albeit with sea fog or haar a threat for eastern coastal areas. Further into next week and with LP close to the south on some evolutions, rain or showers for southern counties are quite possible while the best weather will always be to the far NW - that trip to the Western Isles you've always promised yourself, a good time to take it !!

Indeed and so does GEM though the exact placing and orientation of the HLB isn't clear as yet. The key difference is sourced airflow - IF the HP sets up over Scandinavia the air is sourced from Eurasia and will probably be warm at this time of the year but if the HP ends up more to the north the air could be sourced from the Arctic - a kind of indirect Polar Maritime airflow and would be much cooler. The key to this evolution is what happens at the weekend - IF the trough fails to break across the country, the HP sets up over Scandinavia but as GFS shows if the LP clears to the east and sets up over Denmark, the HP builds further to the west and the air comes from the Arctic.

Morning all Quite a shock to the system this morning to leave the house at 6.45am and realise the winter hat was required. A sparkling morning here in London Town but the much anticipated colder snap has duly arrived and we'll see if convection builds enough later on for us to see a hail shower down this way. Moving on toward and into May and plenty of evidence of northern blocking in the outputs yesterday with perhaps a warmer interlude from an ESE next week trending colder as the wind shifted round more to the NE into the second week of May. Today's model output takes us to the early hours of Friday May 5th: Starting with GEM 00Z: This morning's GEM evolution matches some of the GFS/ECM evolutions present on the 12z outputs yesterday. The current cold spell is followed by a brief ridge before the trough to the NW digs SE which in turn throws up heights to the NE and the British Isles is the battle ground with a flow of warm SE'ly winds. The weather would be fine to the north and east but the south and especially the SW would be at risk of rain and showers. From there, the HP pushes west to the north of the British Isles and the SE becomes more of an E'ly as warmer air pushes into Greenland and the dreaded Greenland HP sets up. The T+240 chart has a strong ridge coming SE so for many it's a dry and warm prospect. ECM 00Z at the same time: The actual evolution isn't dissimilar to GEM and while the final synoptic set up is also similar it's worth noting the source of the air over the British Isles is from the north not the Continent so this would be a much cooler E'ly for most. On then to the GFS 00Z OP: Superficially, only slight differences but the GFS takes a different evolution to get there. The weekend battleground ends with an LP moving across the south on Bank Holiday Monday which would be a washout for many but heights rise behind that LP from the south and the north and its the northern arm of the heights which becomes the dominant feature as the trough stalls well out to the west. The HP strengthens just NE of the Faeroes into a major HP cell by T+240. Further into FI the heights move west then south west and this brings a cooler ENE'ly flow across the British Isles with colder air from Scandinavia generating a small LP which goes down the east coast bringing a spell of rain or showers for eastern counties. GFS 06Z OP at T+234: A cleaner evolution to the E'ly but not much different to the 00Z in all honesty. Further into FI and while the heights retreat to the NW, we get something akin to a negative west-based NAO setting up as the trough comes back in from the SW and the winds over much of the British Isles fall light before backing WSW in the south. Looking at the 06Z GEFS at T+240, there's a lot of northern blocking and the OP is a fair guide as to the rest of the suite though as said yesterday the position and orientation of the HP are varying from run to run and will continue to do so. In conclusion, more certainty this morning. The brief cold spell will be followed by an equally brief drier interlude before the trough approaches from the NW just in time for the Bank Holiday. GEM and ECM limit the effect of the trough to the south and west under a brisk SE'ly but GFS takes and LP through the south of the country on Monday which would be a poor day for many. Pressure builds from next Tuesday from the north with a strong HP setting up by the end of the week though exact position and orientation aren't settled - it could be a warm E'ly or something much cooler depending on air source. From there, broad agreement on some form of retrogression into the second week of May but as kid month approaches, there's huge scatter and uncertainty and nothing reliable in the way of a forecast.

The Exeter update read well if you want warmth but it's mentioning it did also allude to more unsettled conditions in southern and south-western parts which you'd expect from an E'ly flow with HP to the north and LP to the south. The 06Z OP isn't a million miles away from the 00Z OP with the HP starting over continental Europe before north then North west ending up behind absorbed in a new strong Greenland HP and more than a hint of a return to colder N'ly conditions into the middle of the month.

That's an incredibly short-sighted and narrow viewpoint. As someone having to care for an elderly relative, I know full well many older people do not like extremely hot conditions - say 30c or above - especially if that is twinned with high humidity. Apart from exacerbating existing bronchial conditions, older people don't always drink enough or eat the right things to manage extreme heat. We don't have, as many hot climates do, the luxury of air conditioning in most homes and, as you do rightly say, the economics is a big problem but I would repeat extreme heat is as much if not more of a risk to older people than extreme cold.

I would simply point out a prolonged hot spell is far more dangerous for the elderly than prolonged cold. Look up records of the French heat wave from 2003 - I know the one thing the authorities here worry about is a 1976-style event with temperatures in London approaching 40c for 10-14 days at a time. The "cull" as you put it of the elderly would be far greater than the coldest of winters.

Morning all I've done my daily analysis over on the "In Depth" forum (shameless plug). The first thing to say is there is a lot of uncertainty starting from T+96. GEM offers a very different evolution in to the weekend from GFS and ECM and these two diverge sharply early next week. I do think some form of HLB is the form horse especially given the time of year and points NE rather than NW look more favoured for now (though retrogression isn't a complete outlier on the GEFS). The crucial points will be the location and the orientation of any HP cell - an ECM style solution will bring warmer weather than the GFS but there are plenty of other options on the table.

Morning all A dry morning to start the new week in London but I suspect tomorrow and Wednesday are going to be a real shock to the system with a plunge of very cold Arctic air taking us well below the seasonal temperature numbers. That doesn't last but the coming Bank Holiday was far from clear and the extended forecasts suggested a big change in early May to extensive northern blocking which might or might not bring some warm air across from the SE or keep things cooler from the NE. Let's see where we are this morning with the outlook out to the early hours of Thursday May 4th. Starting as always with the GEM 00Z output: A fascinating evolution from GEM this morning. The short-lived N'ly is snuffed out by HP collapsing SE in the face of a new trough over Eastern Greenland digging south. However, as that happens, pressure builds over Scandinavia and the Atlantic is repulsed by a cool E or ENE'ly flow bringing disappointing conditions for the Bank Holiday (especially for the south). LP remains near the south early in the new week bringing rain or showers but that fills and we are left at T+240 with weak but extensive northern blocking with the core heights just to the east of Iceland and a large mid-Atlantic LP which you would think would start to shift NE toward the British Isles. ECM 00Z at the same time: A very different evolution. The trough coming SE from Greenland fills and disrupts to the west of the British Isles so the Bank Holiday weekend isn't too cold but has rain or showers for most especially on Monday. After the Bank Holiday pressure builds strongly first from the south and then more robustly from the NE and at T+240 we have a classic Scandinavian HP centred over Southern Sweden with a ridge SW over the British Isles. This will mean dry conditions for most but it's hard to be certain about the temperatures. The problem is with central Europe quite cool it may be the air is not as warm as we think so we're left with a cool HP but that's far from clear. GFS 00Z OP at the same time: Another model, another evolution and it seems FI could be early as T+96 as there's no clarity for the immediate aftermath to the midweek cold snap. GFS holds the trough to the NW as HP builds in toward the end of the week but over the weekend the HP declines and the trough takes over and the Bank Holiday Monday chart from the GFS OP isn't that far removed from the ECM chart at the same time. The flow is a more defined SW'ly so temperatures reasonable but a risk of rain or showers for all. After the Bank Holiday GFS builds pressure from the south but that switches to the NE but not Scandinavia and more over the Northern North Sea and we get this curiously oriented HP and a flow which may look superficially favourable from the SE but in fact the air is sourced back over NW Russia (note the small LP over Finland) so may not be that warm. It's a curious evolution and some of the modelling of pressure systems to the east over Scandinavia is a little off-putting (one LP moves north for seemingly no reason). FI is a nightmare for those wanting warm spring sunshine as retrogression moves the core of the HP to the NW and the trough starts to encroach from the east keeping the winds N or NE throughout so little or no warmth and by the end of the run a very real threat of rain with snow to altitude coming from the east and NE. Looking at the 00Z GEFS at T+240 and I can only see a couple of members keeping LP near Iceland and the rest have blocking and the majority have HLB albeit of many and varied positions and orientations so the signal for northern blocking of some flavour is very strong. Resolving the position and orientation of the HP is of course critical to determining our weather and that's far from clear at present. In summary, a morning of model confusion and uncertainty past this week's brief colder interlude. GEM is slightly on its own wanting to build the Scandinavian HP more quickly than ECM or GFS which have a milder but more unsettled flow for the Bank Holiday. However, both these models agree on the return of strong HLB next week with an attendant E or ESE flow which GEM keeps as a weaker feature. The possibility of HLB dominating the further outlook is very high and while if the 00Z GFS Control is a guide could bring us some fine and warm conditions, the OP would provide a dry but much cooler if not colder scenario with winds from the N or NE and a risk of the trough encroaching back as we move further into May.

Afternoon all Just a brief thought or two from me. The 06Z GEFS is all about northern blocking in FI, whether that's to the NW (OP) or NE (Control). The main scenarios seem to be either: 1) Heights to the NW or NE are close enough to influence the UK and keep us in a mainly dry pattern with winds from the north or east. 2) If the heights develop too far to the north, the gap exists for the trough to take over which is in effect a combination of the Atlantic trough and the cut off Baltic trough migrating back SW. In that scenario, we turn much more unsettled with rain and showers. Both options are on the table and it's a toss up for me which one wins out. The next Bank Holiday could either be dry, cool and fine or a warmer washout and all places in between.

Morning all A less inspiring day in London Town but all eyes are turning toward next week's "Arctic blast" and where we go from there. There was a clear shift away from Greenland heights in the medium term on yesterday's models though plenty of HLB still in evidence as we moved into May. This morning's output takes us to the early hours of Bank Holiday Monday, May 1st: Starting as always with the GEM 00Z output: Significant changes from yesterday morning's output. The brief but quite sharp midweek N'ly next week is replaced by falling heights to the west and rising heights to the NE sending the jet back south. The British Isles becomes warmer, true, but much more unsettled with periods of rain or showers for all and with quite light winds any showers could be heavy and prolonged for the south and west. Pressure remains high to the east of Europe and it will be interesting to see if following LP systems take a more southerly track into France and Iberia. ECM 00Z at the same time: A variation on yesterday's theme of the British Isles in a col between pressure systems. After the midweek N'ly pressure rises from the west as the Azores HP ridges in but it doesn't hold and the trough moves in instead with frontal systems nearing the west of Ireland by T+240. Further east, there's a more interesting scenario with a large HP cell over northern Scandinavia but pressure still low over Denmark, Germany and central Europe. It's not hard to imagine from the alignment of the trough a NW-SE move of the trough into Europe going right through the British Isles so potentially the far north of Scotland could have ESE'ly winds and the south a more W'ly flow. None of it screams settled and the likelihood is an increasingly unsettled pattern with rain or showers developing as pressure falls. On then to GFS and while 06Z OP is rolling out, I'll look at 00Z OP at T+240: A different evolution again. GFS develops a stronger ridge than ECM and holds the Atlantic trough well out to the west allowing pressure to build through the British Isles to link to heights to the far north. The cut off LP is over western Poland helping to build the heights to the north and west. In terms of weather, this would leave the British Isles generally fine and dry and warming up nicely as we draw in warmer air from the south. Into FI and heights build strongly to the north and the British Isles moves into first a cool NE'ly with the cut off trough advancing back SW and then a warmer air flow from the East. The 06Z OP has rolled out in the interim and here is T+234: Very different again - a much shallower and weaker Atlantic feature and no northern blocking at all with a pulse of cold air moving down from Labrador and Newfoundland into the Northern Atlantic. For the British Isles, HP is in charge with fair if not fine conditions and pleasantly warm. FI looks to keep a strongly anticyclonic theme but with the HP drifting to the West or North West cooler temperatures and an onshore breeze for the south and east. Back to the 00Z GEFS and it's interesting to note the Control follows the OP in broad terms which is always worth noting. The suite though contains a myriad of options and very broadly three options - one and possibly the majority cluster has heights to the east as the dominant feature while another significant cluster brings in the Atlantic quite strongly. The OP looks a little out of line as only three or four members build the core of the HP over the British Isles. To conclude, a brief N'ly blast next midweek is followed by extreme uncertainty. The form horse looks to be a build of HP back across the country from the east and/or south but a more unsettled Atlantic-dominated pattern can't be ruled out if the HP builds too far north and the trough is able to extend either from west or east across the British Isles. We'll know more after the weekend but the next Bank Holiday could either be glorious or a washout and both options are currently modelled.

Nearly afternoon all Well, another chilly start in London Town and this cool but dry weather looks set to continue for a while before a colder spell next week. Another Bank Holiday looms so where will be we be on April 30th ? Let's have a look at the models: Starting with GEM 00Z: A very different evolution to yesterday. The Greenland heights rapidly collapse in the middle of next week as the Atlantic fires up to the north but heights remain low over Europe so the British isles is in a col with a nagging NE'ly across the far SE which will keep it cool and possibly showery but fine for many. ECM 00Z at the same time: A not dissimilar evolution. The Greenland heights collapse as the Atlantic fires up but perhaps orientated differently to GEM. Again, there's a col but the British Isles are more to the east so a more defined E'ly and cooler conditions with a Scandinavian HP in charge. GFS 00Z OP at the same time: Thus has mobility triumphed (it seems). Again, Greenland heights swiftly collapse as new LP develops over NE Canada and heads east. Residual weak northern blocking remains but under a transient ridge, the British isles would be mainly fair but with Atlantic weather systems approaching. Further into FI, the LP continues SE and disrupts as heights build over Scandinavia and the British isles gets an E'ly which, as the HP transfers west, becomes a NW'ly at the very end of the run. GFS 06Z OP at T+234: Not a huge difference from the 00Z and clear the long trough extends right into Scandinavia keeping the UK in a mild SW'ly but with plenty of rain or showers. Further into FI, a large Scandinavian HP develops and Britain enjoys a warm SE'ly but this is brief as pressure falls (aided by the Azores HP returning) and Britain ends up under LP with rain or perhaps thundery showers with the best of the warmth and heat shunted to the east. Looking at the 06Z GEFS and the OP is a fair blend of the various solutions in the suite. There's still a lot of blocking in the suite but the emphasis has shifted more to the NE than the NW though the OP solution of a more Atlantic-dominated evolution in the medium term is obviously well represented. In summary, we've seen a major shift overnight in the models away from a prolonged spell of Greenland heights and blocking to a (at least temporary) more mobile solution. It appears the encroachment of warmer air over Greenland to pump up the heights isn't sufficient to maintain the block in the absence of any cross-polar ridging and therefore colder air re-establishes to the north of Greenland and that inspires cyclogenesis which sends active LP systems across from the west and collapses the heights. From there, the evolution is much more uncertain though a number of options keep low heights over Europe and build an HP over Scandinavia leaving the British Isles in a col by the end of the month with the possibility of northern blocking resuming into May so it looks as though this could be a temporary phase rather than a significant pattern change.

Morning all Another glorious morning here in London but a decidedly chilly night with only 3c at 7am suggesting rural areas will have had quite a sharp ground and indeed air frost around dawn which isn't good if you have (or indeed are) a tender sapling. Yesterday morning's models suggested considerable uncertainty towards the end of the month with the strength and duration of any N'ly spell far from decided, This morning's output is for the start of Saturday April 29th: Starting with GEM 00Z at this time: A thoroughly cold evolution from GEM this morning and were this December or January, there would be salivation all round (except from Sidney). HLB very much in evidence with a strong ridge from an HP cell developing over SE Greenland augmenting the N flow and as the trough backs SW, a very cool and changeable spell midweek next week before the HP builds into Scandinavia and the British Isles ends on an E'ly with a cold pool covering much of NW Europe so a far from exciting end to the month if you are after warmth. ECM 00Z at the same time: About as different an evolution as you can get. LP is in charge with no real sign of HLB. Yes, there's a N'ly early next week but the trough lingers further north keeping a weak cool NW'ly over the British Isles with small secondary LP forming augmenting any rain or showers. Perhaps a sign of a return to a more Atlantic-based pattern in the further outlook. Nothing warm here either and likely to be showery if not wet at times. GFS 00Z OP at the same time: Different again. Next week's N'ly is fairly brief but sharp. However, the HP cell is never far from the SW and builds back across the country before transferring NE into Scandinavia albeit with the ridge persisting over the British Isles so a fine and dry outlook. Again, not sure how warm this would be with a weak flow from the NE and perhaps sea fog would be an issue to coasts but not too bad overall. Further into FI, the Scandinavian HP holds off the Atlantic LP systems until at the very end of FI, more general HLB builds to the north leaving the British Isles in a warmish E'ly flow. The 00Z GEFS at T+240 tell a different story again and are supportive of the Control which wants to resume a more traditional Atlantic-based mobility with deep LP to the NW and any ridging further south. It's a strong signal but runs contrary to the OP and other model output. We often see GFS, almost as a default, attempt to restore mobility from the west into FI and this often occurs when there is no clear signal and we may be at that point where the evolution for the end of the month is far from clear. The Mean illustrates this by keeping LP to the west of Iceland over SE Greenland but that's nowhere near either the GEM or ECM evolutions. In summary, uncertainty rules (probably). After a benign few days, there's general agreement on the HP moving west or north west and allowing a plunge of N'ly air early and into the middle of next week. After that, it's fair to say it's confusion. Both GEM and GFS build an HP into Scandinavia and both offer it as the main way forward with HLB in charge. ECM is nowhere near that and its T+240 chart looks an unlikely evolution to this observer. The GEFS strongly hint at a return to a more mobile and less amplified pattern but again is that a default response in lieu of no strong signal or a hint the effects of the final warming are ending and the default summer pattern is re-emerging ? As ever, more runs are needed.

Morning all A glorious morning here in London and after a benign 00Z OP yesterday, 06Z OP picked up the retrogression scenario and offered a strong full on N'ly for next week. The possibility and intensity of retrogression and a N'ly outbreak dominated the output yesterday but let's see where we are now. Today's output takes us to Friday April 28th: Starting as always with the GEM 00Z OP: Subtle changes from yesterday's output. The LP which develops to the west of Iceland next weekend dives more south then south east through the British Isles and heights rise strongly to the north behind the LP which fills but maintains a shallow trough to the SW linking back to a mid Atlantic LP. An E'ly flow for most and quite unsettled in the south with rain or showers while the north turns fine. Not terribly warm either. ECM 00Z at the same time: ECM continues to play the retrogression card quite strongly and now has it clearly to T+168 which is the cusp of low-res so more likely to verify (perhaps). A ridge from Greenland to Iceland linking back to heights over Svalbard and the Pole and the trough is essentially a cut off feature over the northern North Sea. Cool and unsettled for much of the British Isles away from the far west with rain or showers. GFS 00Z OP at the same time: Very different evolution backing away from retrogression on the OP to a large extent. Next week's LP heads not south but SE to Denmark so there is a brief N'ly before pressure builds back in from the west. Thereafter, a new and far more vigorous LP forms to the east of Greenland and pushes the HP back south while maintaining the ridge over much of the British Isles so a benign spell after the transient N'ly - warming up by day but with still chilly nights. It all gets a bit messy further into FI with the HP moving east across the British Isles into Scandinavia but then heights fall and a weak trough moves down over the British Isles so we end on a cool and unsettled note. GFS 06Z OP at T+234: Not too dissimilar and very different from yesterday with a pulse of very cold air (not quite the PV but not far removed) over NE Canada firing up the jet and encouraging cyclogenesis off the east Greenland coast. The main trough heads east but a secondary feature heads south lowering heights and with the Azores HP displaced far to the west the trough is in charge so very different weather for early May with rain or showers. The 06Z GEFS at T+240 shows less spread then yesterday's 00Z and most of the Members develop the LP around Iceland but some send the trough further SE more quickly with the HP retrogressing further with time. I do think there's more uncertainty at the end of this month/early May but the move, while it's been away from the coldest of Northerlies, has been to a wetter, more unsettled evolution with the trough dropping more or less over the British Isles. In summary, a pleasant week ahead for many and the first attempt at a N'ly will hardly be felt but the course of the second LP set for early next week remains far from settled. It could drop right through the British Isles (GEM) or set up a N'ly (ECM) or a more transient spell as the LP heads SE (GFS). Thereafter, the trend looks ominous for the next Bank Holiday with the trough threatening to set up near or over the British Isles bringing a significant change to a more unsettled scenario with rain or showers though rain would no doubt be welcome for many.

Thank you for the kind word, my friend. Yes, that's an interesting parallel. Onwards and sideways on this Bank Holiday morning and the Easter weather has played out much as expected so far. There have been some warmer interludes with sun shine but the persistent cool breeze hasn't helped and while it's been dry here in lowland East London there has been a little rain elsewhere as weak weather fronts have slipped SE in the flow. The models have been suggesting a fine anticyclonic spell before a renewed push of Northerlies but let's see where we are this morning with the picture out to Thursday April 27th: Starting then with the GEM 00Z OP output: A very anticyclonic run from GEM this morning. This week the HP tries to set up to the North but pressure from the jet shifts the core HP south to lie across southern Britain by Thursday before a half-hearted retrogression into the weekend after which the HP sets up close to the SW early next week before moving back across the south of the country during midweek. Little or no rain is the obvious conclusion so the incredibly dry spell continues. LP systems move round the HP to the North and SW and then slide SE down into Scandinavia where it stays quite cold and wintry. Perhaps a little rain to the NE on occasions bu little else. On the other hand, nothing desperately warm wither and overnight ground frosts under clear skies remain a hazard to farmers and growers. ECM 00Z at the same time: Perhaps a sign of a more defined change at the end of the ECM output. This run has made a little more of the N'ly incursions and brought a couple of fairly weak and transitory Arctic outbreaks in the next week or so but ends with the HP being moved east as the Atlantic trough gathers but that draws in warmer S'ly winds so a lift in temperatures before the possibility of something more unsettled. GFS 00Z OP at the same time: Something a little different from GFS which has chopped and changed quite a bit in recent times. The immediate evolution is a recognisable blend of GEM and ECM but with a more pronounced N'ly early next week as the LP comes closer to NE Scotland then other models suggest but after that GFS creates a large LP to the far north just as ECM and this runs due east on a more N'ly track across to northern Scandinavia bringing warmer SW'ly winds across all of NW Europe. However, that LP marks quite a change in the pattern as heights rise again over Greenland and the jet shifts back south in furthest FI with heights lowering across the British Isles and a more unsettled but warmer outlook greets the start of May with the next Bank Holiday likely to be warmer and wetter,.The coldest of the northern hemisphere air shifts over to Siberia by this time. The 00Z GEFS are fascinating this morning - the OP has some support but the spread is fascinating: There's a huge difference between those like the OP which develop LP around SE Greenland and those which maintain heights to the NW and there are to my eye at least 9 members keeping significant heights to the NW up over Iceland and Greenland so the OP is by no means a done deal. As an example, this is P9 at T+240: This is typical of the significant cluster maintaining heights to the NW via retrogression and that would see much colder and more unsettled condition than the OP with a sharp N'ly flow. To conclude, a quiet week up;coming with HP moving round the British Isles before ending up across the south. Nothing terribly warm and indeed chilly nights possible under clear skies with rural frost. From there, a significant divergence - some models keep HP very close with LP systems and the attendant cold N'ly plunge far to the east while others offer the occasional glancing blow of a transitory N'ly. There is however a significant group among GEFS suggesting more emphatic retrogression and a build of heights to the NW with the trough sinking south over Scandinavia and N'ly winds impacting the British Isles. So nothing warm in the immediate future but probably nothing wet though the possibility of a colder evolution to a more unsettled spell especially for the East of the British Isles can't be ruled out.

Morning all I'll do a more detailed analysis later but a huge difference between GEM/ECM and GFS this morning. Both the former go foe retrogression and a strong N or Ne'ly flow to end next week while GFS keeps the weather quiet and anticyclonic. ECM at T-240: GFS 00Z OP at the same time:

For all the cherry picking of "warm" charts, the 06Z OP evolution follows a similar line to the 00Z with disturbances forming to the N of Iceland or off the Greenland coast heading E and then SE into Scandinavia. A wind direction from the NW and occasionally N doesn't suggest and immediate return to spring like conditions and as others have said, the continuing very dry spell is starting to cause some concern. The position and orientation of the HP post-Easter is still far from determined, however, and until that's resolved we won't have a clearer picture. The GEFS offers many solutions and subtle differences to the HP will have more significant impacts over the British Isles.