stodge

Morning all Happy Maundy Thursday to all Another fine and chilly start in London - a notable part of the current evolution has been the cold nights and clear starts - but the cloud has been building steadily. Easter down here looks dry but uninspiring with a chill wind and temperatures barely at average values in a weak NW'ly flow. Moving on toward the following weekend, the only certainty was uncertainty yesterday but has to day brought any change ? The morning's output takes us to Sunday April 23rd: Starting with GEM 00Z OP: A very anticyclonic run this morning. After the weekend, the anticyclone develops strongly over the British Isles but never gets into a position or orientation to favour the advection of warm air. Instead, it flirts with retrogression to the NW so the wind direction is either N or E - yes, it would be fine for many especially in the NW but cool with night frosts likely. The mid-Atlantic LP starts to edge north hinting at a return of a more mobile pattern toward month end but we'll see. ECM 00Z OP at the same time: Another anticyclonic run but again a frustrating one for those wanting spring warmth. The HP sets up to the west and is orientated to ridge across the south of the British Isles but the wind is from a N or NW direction and by T+240 retrogression is well under way and LP areas to the east of Iceland look set to advance SE toward the British Isles with the trough set to drop into Scandinavia. Still mainly dry for most at this time but rain or showers threatening from the NW. Cool and once again rural ground frost under clear skies. GFS 00Z OP at the same time: Again, very anticyclonic and in many ways similar to GEM and ECM at his time but there are some subtle differences which are worth discussion. The mid-Atlantic LP is interesting - GEM has modelled it very differently to both ECM and GFS - ECM has kept it as a minor feature but GFS has done something different and I'll put up the T+228 chart to illustrate: The mid-Atlantic LP extends the trough north just as the GEM model suggests and that triggers the creation of shortwave LP on the east coast of Greenland which has two key impacts on the evolution - one, the heights build back into the Atlantic returning the mid-Atlantic to a cut off feature - two, the new LP cuts off the retrogression of the HP nearer the British Isles (or rather delays it) as it passes east, to the north of Iceland, around the top of the HP cell. Further into FI and the LP heads to Scandinavia while the HP rotates to the SW of Iceland with the ridge orientated south into the Atlantic before migrating NW to Greenland by which time the trough has extended SW from Scandinavia and the British Isles is in a cool if not cold N or NE'ly flow so spring very much put on hold with some cold air from Scandinavia heading down the east coast. Looking at the 00Z GEFS at T+240 and as you'd expect there are plenty of options on the table though I don't see much promising warmth. The key is, as it has been for several days, where the HP ends up. A significant cluster have the HP more or less over the British Isles but the majority follow the OP with a centre to the west or north west. Another group go for Greenland based heights and these have the trough much closer (p10 and the extraordinary p15). To conclude, an uninspiring but useable Easter outbreak looks to be followed by a return to anticyclonic domination for much of next week but with the HP centred to the west or north west, the accent will be on dry rather than warm conditions for most. There is a growing signal for retrogression from the end of next week and the likelihood of an even cooler regime with N or NE winds dominating and these bringing more unsettled conditions especially to the east and the south while the far north and west (as often happens in late April and early May) doing pretty well,

Morning all The change to something more seasonal duly occurred and indeed temperatures are now pretty much where they should be moving into mid April at around 13-15c in London. It did look on Monday as though Easter would be okay for most - nothing terribly warm and certainly far removed from last weekend's values but no washout either. Quiet generally and especially the further south and west, but with LP closer to the NE, more risk of rain or showers and a cool or indeed cold NW wind. The possibility of a pattern change was still present - it's often the case with these changes that there is an initial teaser before the change actually happens as though the atmosphere tries to move to a new solution, fails, resets and then tries again. That's a poor choice of words admittedly. The evolution of LP digging SE, lowering heights over Europe and raising them to the NW as warmer air moves North into Greenland is one the models have frequently shown in low-res but which has yet to come into high-res. It looked as though it would take three "tries" to make the change happen (if it happened at all). The first LP was due today, the second on Saturday and the third on Tuesday and it was the last one that would initiate the change or so the models suggested on Monday but where are we now ? Today's output takes us to Saturday April 22nd. Starting then with GEM 00Z OP at that time: GEM keeps a slack cool NW'ly over the British isles through the Easter weekend until the post-Easter LP drops through the country introducing a brief N or NE'ly flow before pressure builds in again at the end of next week. This would be a decent outlook with pklenty of fine and dry weather and a slow warming with the Jet kept well to the north. ECM 00Z at the same time: A very different evolution. The Easter NW'ly becomes a SW'ly by Easter Day as pressure builds from the SW but LP systems are never far away and brush NE Scotland on both Monday and Wednesday eventually sinking south to allow a brief E'ly across southern parts. The remnant of the LP is over Iberia with pressure higher to the west. Generally decent weather on offer with perhaps a residual shower in the south but again not very warm. GFS 00Z at the same time: As we can see, another evolution and it's all about the orientation of the HP which is different on all three models and that has huge impacts on the weather over the British Isles. GFS keeps winds in the N'ly quarter so while there would be a lot of dry weather, it wouldn't be warm with a risk of ground frost under clear skies. 00Z remains cool through much of FI with strong height development over Greenland (yes, I know) and the trough digging into Scandinavia keeping the N or NW'ly theme going. 06Z OP at T+234: Once again something different - the HP is weak and declining and a new area of LP is forming just north of Iceland and you'd think it would move East then SE into Europe with heights rising to the NW behind it. Well, not quite - more E than I expected into Scandinavia and in fact the trough swings south and a new LP forms just to the north of Scotland and moves down the east coast so a bleak few days of eastern Britain with rain, showers and a cold wind but not too bad further west. In furthest FI, it all goes a bit slack as the N'ly flow subsides. Looking at the 06Z GEFS at T+240 I find the OP atypical of the suite. A majority of members have significant blocking to the NW either via ridging from Greenland or from an HP cell centred to the NW of the British Isles and nearer Iceland. Further into FI and there's a clear distinction between those keeping the theme of Greenland heights going and those collapsing the heights and re-introducing LP systems passing well to the north of the British Isles and building ridging over the British Isles. To conclude, Easter looks uninspiring with cool winds to start and possibly continuing though there is a chance the winds will shift SW on Easter Day as the core of HP moves across the country. Into next week and there's general agreement a new LP will form north of Iceland and move E or ESE dragging down a N'ly as heights rise behind it. By the end of next week, the core of HP is to the west but the orientation is far from clear - it seems unlikely to be warm (certainly compared to last weekend) but it should be largely dry. There's little sign of an Easter heat wave or an Easter wash out at this time but into next week the more unsettled them looks set to dominate with the possibility of a longer or shorter spell of N or NE'ly winds.

That's a fair point, Knocker. I certainly don't think the Easter weather is in any way "settled" as yet and intra-run variation adds to the confusion. I do think the key is the extent to which the trough digs SE over the North Sea on Saturday. Some earlier modelling suggested quite a plunge into the southern North Sea which encouraged a height rise to the west oriented more North-South and maintaining a N or NE flow - something like P10 on the 06Z GEFS. What we are now seeing is a more ESE'ly drift into southern Scandinavia which restricts the N'ly plunge and keeps heights to the SW and these build back across keeping the Easter weekend fairly benign before a second attempt at what I shall call "the plunge" after Easter. At T+168 (Easter Monday), there's broad agreement in the GEFS for a new LP to develop south of Iceland and it's what happens to this that drives the FI evolution. Move out to T+240 and you can see the OP and the majority lowering heights to the E and SE over Europe and introducing a cool N or NE'ly but the big spread is Eastern Greenland - this is between those Members which develop Greenland heights and a ridge S or SE and those which build heights from the mid-Atlantic NE but lower heights over Greenland. The latter option leads to the jet sinking the HP while the former locks in the colder airflow. At T+324, this divergence becomes enormous - look at P12 and compare with the OP for example. The modelling has consistently shown the possibility of Greenland heights in low-res but they've rarely come into high-res so caution is very much the watchword. The repeated plunge of Arctic air with associated Greenland heights has been consistently and persistently modelled in high-res but has not so far come into low-res. This may be because of the continued persistence of PV energy over NE Canada and NW Greenland - this has, throughout spring, encouraged MLB rather than HLB but as it dissipates (final SSW anyone ?), there is the potential to import that warmer air into Greenland and encourage blocking and I wonder if the record snowfall recorded might strengthen that blocking as we move further into spring but that's an observation for another place. Yet, it hasn't happened - the PV energy has persisted and held back the development of HLB - once again, until we see it strongly in low-res I would be cautious. For now, it looks as though Easter will be unremarkable - neither warm nor cool, probably near average with perhaps a warmer day or two in the south but also a little rain for all at some point and perhaps something a bit more defined for NE Scotland and NE England.

Morning all As expected, a glorious weekend. My part of London reached 23c yesterday afternoon and it's no exaggeration it was more like July than April. However, that's on the way out for now and although it's a fine morning again the maximum here today is likely to be 13-14c which is pretty close to where it should be and would still be pleasant under sunny skies (currently). Easter beckons and it's fair to say there was plenty of uncertainty over the coming long weekend and points thereafter with more than a hint of something more akin to late winter on some of the output so where are we this morning ? This morning's look takes us to Thursday April 20th: Starting with GEM: GEM was perhaps the most bullish for an Arctic outbreak but has watered down the evolution somewhat this morning. During this week, HP remains close to the SW but that doesn't prevent a couple of brief NW'ly incursions before the HP declines on Good Friday and we get a more notable N'ly on Easter Saturday. Pressure tries to build back to the north and there's a brief E or ESE'ly flow before the HP migrates back SW and we finish with the above. The Atlantic looks set to roar back with a lobe of PV energy dropping south. I'm not convinced but we'll see. ECM 00Z at the same time: A very different evolution. A messy Easter weekend but not too bad though LP never too far away and from Easter Monday a strong build of heights to the NW though signs of the PV setting up again over NE Canada and the heights looking to collapse but a few days of cool NE'ly winds especially for the SE corner with rain or showers but not too bad for the far NW. GFS 00Z OP at the same time: Not a million miles from the ECM evolution this morning. As with ECM, we just about get away with Easter but it'll be nothing like as warm as yesterday but useable for most though likely to be some rain for all at some time that will be outweighed by dry weather especially in the south. It then turns very cool and unsettled immediately after Easter. Into FI and the HP sinks rapidly south but the evolution remains messy with heights rebuilding strongly in Greenland while the trough is shunted south. Looking at the 00Z GEFS and the Control isn't too far from the OP though the N'ly is more intense. The Panel shows a lot of uncertainty into next week - a number of members follow the OP and keep heights over Greenland or to the NW but a significant minority are breaking away from that and there is a mix of solutions on offer. As we've seen repeatedly since mid February, the modelling of Greenland height rises is wonderful in low-res but falls apart in high-res. The problem remains the continuing reluctance of the PV to move or die away from NE Canada even in the throes of final warming. A pool of very cold air remains preventing the push of warmer air north (those Members which successfully build Greenland heights either dissipate the cold pool or send it further west into Canada). In summary, yesterday's summer-like warmth isn't likely to be repeated until, presumably, summer. We're not looking at a chilly or cold washout for Easter at the moment and most will, I think, have dry and useable weather. A spell of cooler, more unsettled conditions at some point (Saturday seems the most likely) in the long weekend is probable but heights rebuild and most will get away with it but after Easter it's more uncertain with a strong likelihood of a few fays of cool wet conditions for the SE from a NE'ly or N'ly set up though GEM offers the possibility of a return to HP conditions. In truth, it's still very uncertain and FI is really T+120 or even sooner at present.

Afternoon all A rare foray into the weekend models for me and it's been a wonderful day in southern Britain with 21c recorded in my part of London and something similar tomorrow before a sharp return to more average values early next week. Easter seemed very much open to question yesterday so let's see where we are now. The 12Z output takes us to the middle of Tuesday, April 18th: Starting with GEM 12Z OP: The GEM evolution hasn't changed too much in the short term. The weekend's heat is rapidly displaced by two thrusts of colder polar maritime air but both are brief and more as glancing blows with HP never far from the SW and building back over the British Isles to start Easter weekend but by Monday it's a weak and declining feature to the SW with a new build of heights to the NW and cooler air from a very light NE'ly flow with pressure falling to the south and east suggesting rain or showers a growing threat for SE areas but fine and dry to the NW. ECM 00Z 12 hours earlier - so that's the early hours of the 18th: A much less settled evolution with Good Friday the best of the days as the HP recedes west and the trough develops and moves down over the British Isles. The south might get a half-reasonable Easter Day but otherwise the accent is on rain or showers and fairly cool conditions with Easter Monday looking a right washout. Heights to the NW suggest no early break and if the trough pulls further east, we'll pull in a very chilly NNE airflow for the post-Easter period. GFS 12Z OP at the same time: The most progressive of the evolutions (which is no real surprise) but the most disappointing for Easter especially for the east and south with plenty of rain opr showers and a cool if not cold N'ly airflow as heights build down from the NW but by the afternoon of the 18th the heights have split from Greenland and the HP is sinking south cutting off the N'ly airflow and introducing warmer air back in from the west. The SE remains coolest for longest with a lingering NE flow. The rest of FI is dominated by the new anticyclone but it remains to the west of the British isles so while there will be plenty of dry weather, there will also be plenty of cloud and it's not going to be a heatwave. Benign and pleasant enough but unremarkable. Looking at the T+240 GEFS it's fair to say there are a lot (a majority) of cool and cold options among the Members and many have the winds coming from a N or E position. The question seems to be the positioning of the HP - the OP keeps it close to the British Isles but a number of options keep the HP over Greenland with a ridge extending south allowing the trough to come south and leaving the British isles in an unsettled N or E airflow. The HP alignment and orientation remains as difficult to pin down as it did a couple of days ago. To conclude, after this weekend's exceptional weather, it's back to something more akin to April next week as pulses of colder PM air alternate with briefer HP periods but nothing too warm. Easter remains very unclear - GFS would provide a pretty poor outcome but other models delay the decline and retrogression of the HP until the latter part of the Easter break.

Morning all Another glorious day here in lowland East London and a wonderful weekend to come but more than a hint on the midweek models of a significant change into next week and perhaps an evolution into something more synoptically interesting. So, with Easter approaching at the same speed as every other time, what can be expect ? The models this morning take us to the early hours of Easter Monday, April 17th: Starting with GEM: Quite a complex evolution to get to this point, Early next week, a brief N or NW'ly gives away to a new build of HP from the SW and that gives quite a benign run-in and start to Easter though with the winds from the NW or W, not as warm as it will be this weekend. The Holiday weekend sees a deterioration as the HP collapses and the new build of HP is further north and west opening the door to pressure falling over the British Isles and NW Europe. It's more an offshoot of the Scandinavian trough which is over Finland but nonetheless an evolution to a cooler, more unsettled phase. ECM 00Z at the same time: A very different evolution. After this weekend's HP, a longer lasting NW flow until midweek would keep it cooler and more showery but pressure builds again on Good Friday and the Easter weekend is fairly benign with a lot of dry weather - not as warm as the coming weekend perhaps - and no sign of a GEM-type evolution of heights to the NW. GFS 00Z OP at the same time: Something different again. Similar to ECM in predicting two brief plunges of Arctic air, one on Monday and one midweek before HP builds back in for Easter and GFS offers a decent Easter for most but with the HP drifting NE with time and introducing a light E'ly flow to southern areas by Easter Monday. Note the Azores HP is well out of position indicating a weak Atlantic and quite an amplified flow. The rest of FI on the 00Z OP is strongly anticyclonic so another long dry spell with the HP initially over Scotland before declining slowly SW. The 06Z OP at T+234: Quite similar to the 00Z but the HP is further east and this allows a warmer SE'ly flow over the British Isles so perhaps some showers for Eire and the far west but otherwise very pleasant. Further into FI and the LP in the Atlantic fills and disrupts south allowing pressure to build over and to the north of the British Isles with the centre over Scandinavia and a very long ridge. Looking at the 00Z GEFS at T+240 it's an anticyclonic dominated picture but the positioning of the HP is critical and it's far from clear how this will resolve. 7-8 members keep blocking to the N or NW which would enable a colder airflow but others keep the HP just to the west or right over the British Isles. The 00Z OP looks a little out of line. To conclude, a glorious weekend to come but a sharp reversion to a more typical (for early April) weather pattern next week with much cooler conditions and the chance of some rain or showers. It looks certain HP will try to build in again just before Easter and it may be we get away with a largely benign holiday albeit not probably too warm. The risk of a breakdown to something colder and unsettled remains high and not to be discounted but the odds have shifted in favour of a more anticyclonic outlook albeit with much uncertainty over the position ing and orientation of the HP.

Afternoon all I think it's fair to say the signal for heights over Greenland and a N or NE'ly flow has ebbed and flowed since early last month. It has yet in truth to come within the reliable timeframe. Heights have continued to build NE from the Azores HP into the British Isles and that has kept much of the country in a benign and often pleasant situation. The 06Z OP isn't atypical of the suite of GEFS Members - a number have heights to the NW and variations on a cool or cold flow from NW to NE. Yet until this comes into high-res it's wise to be very cautious - it's been the story of the past couple of months as the displacement of the PV has either not occurred or not occurred cleanly leaving behind a lobe of energy. OTOH, this is the time of the year when the likelihood of a N or E sourced airflow is at its greatest - it would not be unusual (though it might be a shock to some) to have a much colder end to April and beginning to May than we are currently enjoying. Yet relatively small differences (on a hemispheric scale) mean so much - it's possible we could get a continuation of warmth with HP close by - the GEFS points to a more N or NW centred block and that doesn't mean warmth for us but that's a very long way off.

Afternoon all Another very pleasant day in the south and the start of a 4-5 day of fine conditions with some potentially very warm weather over the weekend as the HP migrates from west to east. Into next week and the run in to Easter wasn't looking so clever. Where are we now with the output for the early hours of Easter Saturday, April 15th: Starting with the GEM 00Z OP for this time: After the first HP weakens, a new HP cell builds in from the west and crosses the country through Good Friday setting up just to the E and NE the following day. Warm conditions with a SE'ly flow but perhaps increasingly unsettled from the west. No sign of Greenland heights but the Azores HP has been displaced so the evolution from here could be to a more E'ly flow. ECM 00Z at the same time: Not a million miles away from GEM overall with HP in charge and centred to the East with a North-South orientation and the Atlantic trough digging S or SE down to the Azores. Decent conditions for the British Isles especially to the east and south. GFS 00Z OP at the same time: A more conventional west-east pattern, flatter and less amplified than GEM and ECM - fair to the south, more unsettled to the north, temperatures unremarkable. The 06Z OP at T+234: The flow is more amplified with the trough to the west more defined and while that throws warmer air over the British Isles, the threat of showers to the west is present. 06Z, further into FI, keeps a lobe of PV energy over Greenland and develops strong LP features which pass well to the north of the British Isles but quite an active flow for the time of year. It's not too far removed from the 00Z FI and it seems the signal to re-locate the PV over Siberia which was present earlier in the week has gone. The GEFS, however, hasn't completely closed the door on northern blocking even at T+240 on the 06Z. I count at least five members with significant northern blocking so this isn't dead yet. I'd go further and say the scenario at the end of the run in FI on the OP is atypical of much of the suite many of which build heights over Greenland through the week after Easter. So, it's a fine spell for now and nothing too unpleasant in the run up to Easter. The OP runs suggest a benign Easter break for now but far from a done deal and more runs are and certainly will be needed.

To put a contrary viewpoint, GEM 00Z and to an extent GFS 00Z and, it seems, the 06Z OP (rolling out now) all have the HP lasting to the weekend but declining from there so three or four decent days but the evolution into next week far from certain. One or two have grasped at the straw of the ECM 00Z and it's a reasonable evolution but both GEM and much of GEFS go down a progressively more unsettled route so by this time next week: The LP is heading SE to the west of the British Isles and that suggests an E'ly or NE'ly set up as Easter approaches - note the heights building over Greenland as well. What I don't see is an Easter heatwave - we might get away with a dry holiday weekend but I think it's odds against and whether we get the cold and unsettled set up from GEM or with heights to the north and the more unsettled weather affecting the south, which would be warmer but still far from settled especially for the south, remains to be seen.

Morning all Apologies again for a few days break - busy time of the year for me I'm afraid. The week coming looks very reasonable apart from a small hiccup tomorrow as HP builds strongly from the SW and sets up shop over southern Britain. The models did indicate however this would slip away at the weekend and the evolution into next week looked far from clear. Has a new week brought new clarity ? Today's output takes us to the cusp of Easter - Maundy Thursday, April 13th: Starting with GEM 00Z OP: About as far away from spring as you can get but the story of the evolution is clear. The HP doesn't fade east but first west, inviting the trough to the NW to move down and eventually we see a full retrogression as heights build over Greenland. Cool if not cold and unsettled with rain and showers for most and perhaps even snow to higher ground in the north. ECM 00Z at the same time: About as different as you can imagine. For ECM the HP declines east and pressure falls to the west and disrupts to the south - a ridge fills the gap as Easter approaches so a benign if not terribly warm outlook but certainly no Easter washout. GFS 00Z OP at the same time: Something different again - for GFS the HP declines SW and the trough moves in over the British Isles. It's not so much the Arctic trough as a re-alignment of the jet to a more NW-SE axis bringing the Atlantic :LP systems down across us. Yes, it would be unsettled with showers or longer outbreaks of rain but not as cold as GEM. Further into FI, the trough disrupts to the west and the south leaving the south of Britain in a cool E or NE'ly flow while further north it looks settled and warming up. As others have said, the PV is becoming less of a player as we move further into April and this might be a factor in the very different evolutions on offer. The GEFS at T+240 has a number of cold solutions but the message is a lack of consistency with a number of evolutions on offer and nothing decided. There is a minority cluster which builds the Greenland heights but others which keep heights more to the SW. Oddly enough I see more overall agreement right at the end of FI with the OP solution of northern blocking well supported. To conclude, a fine few days from midweek onward but as the HP declines at the end of the weekend the evolution is far from clear. Easter could be cold and wet or less cold and wet or possibly dryish but I don't see an Easter heatwave at all at the moment. Beyond the middle of the month and northern blocking becomes a stronger theme with the likelihood of winds from the north or east quite high after Easter.

Confirmed we've smashed 70F in lowland East London. 21c at 3pm. Extraordinarily pleasant day - by no means the earliest hit for 70F but not bad at all.

Morning all A pleasant week in southern England for the most part and another very good day looks in prospect as our spell of anticyclonic dominated weather continues. Will it continue well into April or are signs of a change on the horizon. A glance at the extended output yesterday suggested a continuation of anticyclonic weather next week but where could we be after that ? The output this morning takes us to Sunday April 9th: Starting with GEM 00Z OP: The anticyclone continues to dominate having moved east and developing a ridge NE into Scandinavia with the trough further east still. Could the Atlantic trough head SE into Iberia - it's possible but for the British Isles, benign conditions with light winds and perhaps the best conditions to the NW. ECM 00Z at the same time: The weather would be much the same for the British Isles as on the GEM but the synoptics are quite different. A strong northern jet persists but cut off features around the Azores and Iberia complicate matters slightly with the Azores HP significantly displaced and ridging NE. Perhaps more of a risk of a shower or two in the south but overall not bad. Another one of those ECM charts where it's hard to see the evolution. GFS 00Z OP: Nearer GEM than ECM I would argue but a messy set up. Note the Azores LP displacing the normal HP feature but the British Isles ends up under a weak HP cell and in fairly calm benign conditions. From there and further into FI, it goes badly pear-shaped: The HP is held far out to the west and the door is opened for the trough to sink SE and introduce a much more unsettled and colder regime from the N or NW. This has been posited for a few days in FI on a few runs and I do wonder if GFS is picking up on a signal for a breakdown to more unsettled conditions in the second week of April. Looking at the GEFS, the T+240 OP solution isn't without support but the exact position of the HP is crucial. Some members keep it to the west allowing a N;ly flow while others have the HP a notch further east introducing a warmer SE'ly so nothing decided as yet. Picking up on a point from my previous, IF one of the factors supporting the ongoing pattern is the prevailing weak warming that looks set to disappear in 10-14 days as the overall temperature of the stratosphere rises. This might explain pattern changes and more blocked scenarios in April as the PV weakens, the winds fade and the overall temperature profile and contrasts flatten as well. One to watch.

The evolution shown isn't that unusual for late April/early May and leads to the classic Buchan cold spell around the first week of May. Occasionally, we can luck out and get a prolonged spell of anticyclonic weather albeit with an E'ly hint (rather like now in fact) but no one should be surprised if we get colder interludes late in April.

Morning all First, apologies for a lack of report over the past few days. I've had some health problems relating to my shoulder which has made typing at a keyboard quite unpleasant. I'm on the mend and the weather has been of considerable interest. Some have called the weekend "glorious" in the south and if by that is meant sunshine and fairly clear skies, it's a fair observation. The appearance has often been deceiving with a strong, cool if not cold NE or E'ly breeze which has meant that if you can be out of the wind in the sun it's been wonderful but in the shade and in the wind more like winter. Daytime maxima have improved from last midweek to reach 15c in lowland East London on Saturday but the nights have been much cooler and I wouldn't be surprised if there had been a nip of frost in more rural areas. As a man from Sheffield once said "that was then but this is now" and with April fast approaching how do the models look this morning. Taking my medium term look out to early on Thursday April 6th and starting with the GEM 00Z OP chart: It's a benign and largely anticyclonic work from the Canadian model this morning. Two deep Atlantic LPs (one in existence now and another forming later in the week) have two significant and (for many) beneficial effects - one is to pull the Jet well to the north and the other is to allow HP to ridge up from the Azores. It's more typical of July than April and while the T+240 chart hints at more Atlantic influence and keeps some heights over Greenland it all looks pretty fair especially the further south and east you are. ECM 00Z at the same time: This run also ends anticyclonic and while the positioning of the HP might not be the optimum for spring warmth, there's little to complain about. The PV looks to be just east of Greenland with a strong jet moving far to the north. GFS 00Z OP at the same time: If you're looking for something different, you've come to the wrong place. The evolution is slightly different to both GEM and ECM but it gets to a similar place. Perhaps the jet isn't as far north but HP is very much in charge of our weather and while the far NW may face Atlantic drizzle at times, for the bulk of us it looks set fair. The NH overview of the same chart: The weakening PV remains poorly placed to help the UK achieve any kind of northern blocking with a new lobe setting up to the north of Greenland after a further displacement back from Siberia. However, more interesting developments into furthest FI: The PV displaces again back to Siberia but cleanly and that allows a block to develop between the Eurasian HP, weak heights over Greenland and strong cross-Polar heights. This forces a re-alignment of the jet and sends the trough SE over the British Isles and down into Europe. For us, this would mean a change to much colder and more unsettled conditions with rain or showers becoming more prevalent. It's a very long way off but it's not unusual for mid-April to have a colder spell after a fine start to the month. Looking at the GEFS and at T+240 there's fairly broad agreement though it has to be said some members are interested in raising heights to the NE as well so we pick up a warmer SE'ly flow but that is a minority while at the end of FI there are, as you would expect, a wide range of options. In summary, while GFS offers a more unsettled interlude over the coming weekend, it's a generally fairly unremarkable and benign spell of weather in the offing especially for the south. Hard to say it will be warm or very warm but certainly average or just above at times. Hints in the outlook of a change to a fairly different regime towards the middle of April but far too early to be confident. As a final observation, looking at the 10 HPA charts and again we see this relentless low-level wave 1 activity which I think has been so crucial this winter. Any attempt to displace the PV to Siberia is countered by this wave 1 warming which pushes it back over to NE Canada/Greenland. Occasionally, for brief periods, the displacement is successful and we get blocked conditions near the UK but the warming sends the PV energy back. In the absence of wave 2, we don't get the full split of the PV just an on going displacement cycle. FI charts which show complete PV displacement never come to fruition because the low-level warming prevents a clean displacement and maintains PV energy back over Greenland/NE Canada.

Afternoon all After the pre-spring warmth of last week, a reminder here in London today it is still only March with a cold strong wind and a hint of rain in the air. Those thinking spring had sprung (so to speak) have thankfully got a sharp reminder of winter and the week ahead looks set to be in complete contrast to last with colder upper air feeding down from the NW leading to rain, showers, strong winds and yes, perhaps some of the white stuff over hills. Anyway, is this going to be a profound pattern change leading to a cold, wet spring or a mere blip soon forgotten ? Today's analysis of output takes us to March 30th. Starting with the GEM 00Z: The HP has drifted NE and the opportunity for heights to the north of the British Isles looks quite strong with the Atlantic messy and going nowhere slowly. The PV has headed cleanly to Siberia with a strong N'ly over western Russia. All that said, conditions over the British Isles would be pretty benign under a light ESE'ly. ECM 00Z at the same time: Very different and much less amplified. Pleasant conditions for much of the British Isles it has to be said but a stronger northern arm to the jet keeping LP systems passing well to the north and no sign of Greenland heights. Now a tale of two (very different) runs - GFS 00Z at T+240: Closer to GEM than ECM. 06Z OP at T+234: Very different and much closer to the morning ECM so significant inter-run variation at this stage as you might expect. Looking at the Ensembles for the 06Z and at T+240, there are plenty still arguing for Greenland blocking (I count 7 of 20) and a smaller cluster arguing for blocking close to the east of the British Isles. I would argue the OP is atypical of the bunch but we'll see: The divergence remains the same through the end of the run. In conclusion, the evolution from the end of the week remains far from clear - one option (and probably the form horse) would be the return of the Atlantic in one form or another but a significant minority of GFS members and the GEM OP suggest a chance for a more northern-based and therefore colder blocked regime to end the month. The evolutions vary, I think, on the development of the PV. Most models take the core of the PV to Siberia by this time next week allowing heights to rise across Greenland but the 06Z GFS and 00Z ECM soon begin a process of transferring energy back across the Pole (a pattern which dominated the winter it has to be said) and re-generating the PV back over Canada/Greenland shutting off the Greenland heights and firing up the Atlantic. Those models which prolong the blocking either have no or a much reduced energy transfer back over the Pole. As ever, more runs are needed.

This morning's GFS 00Z OP has a stronger warming at the turn of the month which is presumably our "final warming" working through.

Morning all Back to normal after yesterday's late show. A much cooler morning here in London and a sense of the weather not having quite decided whether it's spring or winter. Perhaps the models will help - unlikely but you never know. This morning's output takes us to Monday March 27th: Starting with GEM 00Z: The evolution is similar to yesterday with a strong ridge of HP (the Azores HP cell itself in fact) moving across the middle of the British Isles in the wake of the coming trough disruption and the cut off LP to the south. The HP is a tad further south this morning so less of a continental flow over the south and generally fine and cool conditions. As the T+240 chart shows, however, some sign of the HP receding and perhaps splitting with more than a hint of heights building into Scandinavia even as the core slips SE. With the Atlantic moribund we could see quite a warm SE'ly flow develop. ECM 00Z at the same time: Dominated by HP albeit a weak and flabby cell and note the new HP developing in mid Atlantic. This is one of those ECM charts that's neither fish nor fowl though settled and quite warm conditions over the British Isles albeit with issues of morning fog perhaps. GFS 00Z OP at the same time: Quite a cold evolution for southern parts in particular, the migrating Azores HP cell moves from the south west around and over northern parts of Britain before heading into the North Sea. At times there's a noticeably chill NE'ly flow over southern areas and even by T+240, there's a stiff E'ly breeze. The rest of FI remains broadly anticyclonic but a hint of something chillier from the NW as we go into April. Looking at the NH perspective, the T+240 as follows: The PV is over the Pole and the OP FI take sit over to Siberia but that goes in the "I'll believe it when I see it" file for now. Back to T+240 and the GEFS has a majority of members building heights to the north - most over Scandinavia but a couple building Greenland blocks as well. Plenty of cool not to say cold air on offer so definitely a swing away from the spring-like conditions of earlier this week back to something near if not below normal as the month closes. In conclusion, the evolution to something cooler if not colder has strengthened this morning with GFS in particular and GEM to some extent. ECM remains stubbornly anticyclonic and that can't be ignored but the likelihood of our air coming from the north or east rather than the south or west from the middle of next week onward remains strong.

Afternoon all Apologies for the late running of Thursday - another pleasant day but it seems the warmth of Tuesday is already a memory. I note the coldest place in France at the moment is Cap Gris Nez at just 8c followed by Cherbourg and Le Havre at 9c whereas around Paris it's 20c so the line between late winter and early summer isn't far away. Moving on and it's that time of the day when the 12Z output rolls out so this may be a bit of mix and match but it takes us to Sunday March 26th or thereabouts: Starting with GEM 00Z at T+240: GEM builds a ridge of HP through the British Isles early next week and basically it's a protracted period of settled conditions but with a temperature inversion from the norm given cool NE'ly winds across the south and SW'ly over Scotland. The Atlantic looks set to trundle in before too long. ECM 00Z at the same time: A similar evolution in some respects. The trough disruption leads to the formation of a cut-off LP over Iberia which supports the migration of the Azores HP to the NE over and to the north of the British Isles. The Atlantic is moribund so a settled spell but again a chilly E'ly flow across the south so spring slightly on hold. GFS 00Z OP at T+240: Much less support for lower European heights and while the Azores HP is ridging NE, the jet remains strong to the north so consecutive LP systems are passing east toward Scandinavia. The last hints of a NE'ly to the south but basically a benign W'ly flow setting in. The 06Z OP at T+234 is very different: Recognisably similar to both GEM and ECM. More unsettled to the south with a chill E'ly flow bringing rain and showers especially to the SW but fine in the far north. I'll have more time for a better update tomorrow but spring not quite fully on the horizon.

Thank you for the kind word, my friend I can't hope to compete with the expertise of Matt Hugo so I won't. If you want some real weather knowledge, read his blog. If you want the ravings of an enthusiastic amateur, read on. A gorgeous morning here in London and a promise of another fine, spring day with temperatures likely well into the mid to high teens. Does it continue or do we cast a glance back toward winter - let's see ? Looking to the early hours of Saturday March 25th on this morning's output and starting with GEM: We've been here before - a brief N'ly or NW'ly immediately precedes this but there are no heights to the north to sustain the ridge and there is enough energy for a gentle toppling of the ridge which is starting - a cool NE'ly to southern and eastern parts of England and Scotland but the wind is backing SW'ly over Northern Ireland. The problem is this chart and evolution has been shown before by GEM this winter and hasn't verified so we'll see... ECM 00Z at the same time: You'd be forgiven for thinking this was GEM at T+264 - it's certainly a more than plausible continued evolution and apart from timing (ECM is more progressive), the two models are very similar in synoptic evolution this morning. GFS 00Z OP at the same time: Recognisably similar though the evolution to this point is very different. GFS models a much stronger northern arm with the jet displaced a long way north which has allowed LP in the classic Gulf of Genoa area. Looking at the NH overview of the same timeframe: The PV very much at home in its usual home so no chance of heights over Greenland but a chance (given the orientation of the PV back across the Pole) of Scandinavian heights and further into FI, a brief Scandinavian HP develops before the PV is displaced toward Siberia at the very end of the month: Again, we've been here before. Vortex displacements are frequently modelled but rarely come off as new micro-warmings send the vortex back to Canada/Greenland. Could heights build into Greenland in early April ? Wouldn't be unusual but it's a very long way off. Looking at the 00Z GEFS at T+240 and it's a very anticyclonic story with most members having HP near the British Isles and, it has to be said, quite a few having that blocking to the north (including NE and NW) - I count seven members having the core of blocking to the north of the British Isles so not to be discounted and others have a strong anticyclonic bias with the HP centred just to the west or right over the British Isles. To conclude, plenty of dry HP weather looks the call after the trough disruption at the weekend coming and early next week though the centre and orientation of the HP is far from clear and, as ever, more runs are needed.

Morning all Five weeks since the end of the last cold spell as the HP block retreated rapidly SSE into Europe. I had thought we would be seeing clear signs of the next change in the patter away from the milder Atlantic set up but I suspect the movements in the stratosphere indicated by Singularity above have a lot to do with the fact the PV is reluctant to fully displace and offer the possibility of heights rising to the NW (or indeed NE). Looking first at GEM 00Z for the early hours of March 24th: Earlier charts showing quite a southward plunge of the jet and attendant LP systems appear to have been overdone and this morning shows a more northerly aligned jet and a fairly uneventful synoptic evolution with a not terribly active Atlantic keeping small systems going W-E to the north of the British Isles. Decent conditions for the south for the most part. ECM 00Z at the same time: No Greenland heights at all and although the model makes more of the brief trough disruption at the weekend by the end of next week it's business as usual with a broadly SW'ly flow and the jet well back to the north. GFS 00Z OP at the same time: Something rather different - HP centred more or less over the British Isles with more than a hint of possible retrogression to heights over Greenland. This was hinted at in the GEFS yesterday. It comes to nothing as a new Atlantic LP smashes through to the south of Greenland and the jet quickly takes over. The 06Z OP: HP in charge but a much more mobile and flatter scenario with a strong northern jet sending LP well to the north of the British Isles. The 06Z GEFS show plenty of spread: The Greenland HP option isn't dead and it would also be fair to say there's a solid minority with colder air over the UK. That being said, there's been a clear step away from some of the colder options being shown yesterday (the 00Z OP being an exception). The PV continues to weaken as the month progresses but doesn't displace favourably so it may well be that this year March will come in like a lamb and go out like one as well. None of this means there can't or won't be a late cold spell in early April but the odds have lengthened somewhat this morning and it may be we'll have a long spring before a move in to summer.

Afternoon all The equivalent 10HPA for the 06Z OP for next Tuesday (tomorrow week): Signs of the emerging final warming at the end of the month.

Morning all Back to the 00Z outputs this morning and a quick run through the medium term as we look to next week's developments after what looks like being, as it so often is for Cheltenham week, a generally fine and dry week especially in the south. Looking at the output for early on Thursday March 23rd and starting with this morning's GEM 00Z output: Picking up from last night's 12Z, the brief disruption caused by the LP diving through the British Isles at the end of next weekend and early next week leads to pressure rising strongly from the SW but with a cut off LP over Iberia there's a light NE flow over southern parts but the Atlantic is gathering to the NW and you'd expect the heights to sink south as the wind backs SW. ECM 00Z at the same time: ECM has probably just about got there. The jet is displaced well to the north and it's a benign outlook for much of the British Isles under a long ridge of HP. GFS at the same time: The 00Z OP makes much less of the previous weekend's disruption and maintains a more mobile environment but with the jet displaced a long way north, it's not as much spring but more a summer-like evolution as pressure gently builds from the SW. It's no surprise with an NH profile as such: The PV remains limpet-like around Greenland and NE Canada but in further FI this starts to finally dissipate a little: At the very end of FI, we see heights over the Kara Sea and the trough heading SE into Europe but we've been here before many times: Looking at the 00Z GEFS, only four of the 20 members have some kind of blocking over Greenland or Iceland but that influences the spread over the UK: The Control goes for a large HP to the north of the British Isles in FI with an attendant E'ly over much of the UK. Out at furthest FI, there's a huge range of solutions as you'd expect but it's fair to say the OP and Control represent the two main clusters so the likelihood of some interesting synoptics toward the end of the month remains this morning.

Evening all A busy life this past week so apologies for the paucity of reports but now it seems I have a little free time so a rare foray for me into the 12Z outputs. After a glorious Saturday in London, a more seasonal albeit still above average Sunday - 14c in London against a normal early March value of 10-11c. The coming week seems set to continue the early spring theme but for a while the outputs have trended colder and more unsettled into the last third of the month and I still think we will have a colder spell before we get properly back into spring. Tonight's 12Z output takes us to lunchtime on Wednesday March 22nd which will be six weeks after the end of the previous cold blocked spell. GEM first of all: A more interesting evolution for fans of colder unsettled conditions. Basically, the LP breaks through into Europe over next weekend and while pressure is building quickly behind it, there remains a cool NE'ly flow. ECM 12Z Op at eh same time: Something quite different or just a matter of timing ? An intense LP moving into the SW Approaches with pressure rising to the NW behind it. Hard not to think a GEM-type evolution might follow at T+264. GFS 12Z OP at the same time: While the rising of pressure to the west is similar, the northern profile is very different with a strong PV and plenty of energy firing LP systems on a quite northerly focussed jet. Beyond that, HP builds strongly across the country before far off FI shows a different pattern emerging. The NH profiles tell the story - at T+240: Note the main core of the PV is over the Pole but there remains energy close to Canada/Greenland but that energy seems to be dissipating. By T+384: A very weak PV almost gone with heights building over the Pole and Greenland and the Azores HP suppressed. Looking at the GEFS and the picture at T+240 is far from certain: I count six members building heights either in Greenland and ridging SE or around Iceland from the south while the majority of the members keep pressure much lower around Iceland. Clearly, IF we were to see heights around Iceland or to the south, the likelihood of a cool NE'ly flow over the British Isles would increase. Further into FI and it's worth noting a majority of members are raising heights to the NE - some quite substantially. All of this suggests amplification, a slowing Atlantic and the possibility of interesting synoptics in the last third of the month. To conclude, a benign and indeed pleasant week ahead - for many, more like May than March but winter or at least colder conditions aren't done with us yet and tonight's output convinces me further there will be a reversion to something much colder and more unsettled in the final third of March.

Evening all I'm sure fans of warmth are going to be enjoying tomorrow and indeed much of next week but the question for me is whether there will be another colder spell before the end of the month or even into April. It's not unusual for mild early springs to be interrupted by the return of something more wintry and it's quite possible to see snow even at low levels at the end of March under the right synoptics. Early signs of a mid-month cold spell came to nothing and while FI continues to tease, we've yet to see anything reliable come into view. I don't like spring - it's my least favourite time of year and I realise that probably makes me a minority of one but for me it means just a few weeks until hay fever purgatory begins. My thought (and indeed hope) is for a notably colder spell of weather around month end and into April with a northerly or ne'ly outbreak as the PV eases away and heights rise to the NW.

Morning all A couple of busy days out and about so no time for the detailed report and analysis. A very pleasant morning here in London after a couple of quite unsettled and wet days which has brought the rainfall totals up though it was a very dry winter certainly compared to recent years. Spring has sprung but where is the weather taking us ? Today's analysis takes us to Sunday March 19th and beyond: Starting with GEM 00Z OP: GEM starts with the jet moving north but it returns south as there is some disruption early next week and to be honest next week looks pretty unsettled and perhaps on the cool side with plenty of rain or showers under quite a cold air mass. The Azores HP is suppressed to the south and secondary features moving across southern counties seem set to bring more prolonged wet weather at times. ECM 00Z at the same time: A milder WSW'ly flow for the British Isles with the Azores HP extending a ridge just to the south so drier conditions here but more unsettled and breezy further north. Note the absence of lower European heights compared to the GEM. GFS 00Z OP at the same time: Possibly closer to GEM than ECM at this time but nothing terribly different, A traditional W'ly or WSW'ly flow though sourced from the colder North Atlantic. That said, always drier and warmer to the south while the north stays breezier, cooler and more at risk from rain and showers. In furthest FI, the OP builds HP across the British Isles as the PV is partially displaced toward Siberia: There's not much happening in the stratospheric profile at this time as we await the final warming. Looking at the 00Z GEFS, there's more spread than I was expecting and quite a few colder and stormier options than the OP which suggests the end of next week isn't yet set in stone. A couple of members build strong heights to the NE and while there's no appetite for the Greenland HP option, a lot of members have LP much closer to or over the British Isles. In conclusion, a couple of warmer, brighter days especially for the south but next week sees a return to something more seasonal with a not terribly mobile WSW'ly flow. It's possible Cheltenham week could be fairly benign but it could also be quite cold and unsettled and that issue hasn't been resolved.