stodge

Evening all High Pressure (HP) very much the theme of the models last evening. The current heights over central and south eastern Europe look set to be re-enforced by the Azores HP ridging NE and that leads to a new core of heights developing just to the east or south east of the British Isles. The possibilities from there were numerous last night but in the short term (and it will be early March, remember) settled days will be pleasant but clear skies at night can still lead to extensive ground frosts and some quite low numbers in favoured hollows with a wide diurnal range. Let's see if we have any clues tonight. T+144 and T+240 charts from GEM, ECM, GFS OP and GFS Parallel to start: T+144 (March 2nd): T+240 (March 6th): At T+144 the anticyclonic trend is very much in evidence. ECM pushes the ridge cleanly to Iceland and links to heights over eastern Greenland. GFS OP, on the other hand, is more progressive breaking down the heights from the west with a stronger Atlantic dominance. GEM and GFS Parallel have the core of heights just to the east of the British Isles. From there to T+240, GEM and Parallel stay close with both building new heights into mid-Atlantic but with significant energy to the north preventing the heights getting any further north. GFS OP is the most progressive breaking down the heights with a shallow trough moving in from the west, Conversely, ECM builds a wedge of heights to the north west with a moribund Atlantic and a light NE'ly across southern areas of England and uppers of -4 or lower. Quite a cold evolution from ECM which starts with the heights building north at T+144. Moving on and the T+312 (March 9th) and T+384 (March 12th) charts from GFS OP, Parallel, Control and CFS: T+312: T+384: For the first time in a while, definite signals for a change in the pattern emerging in far FI. While Parallel keeps the anticyclonic pattern in place, both GFS OP and Control show a breakdown to a much more unsettled and colder evolution with a dominant trough over or to the north of the British isles and some powerful LP bringing stormy conditions with strong winds. CFS not quite as dramatic. Plenty to consider in the evening output which, after a period of relative stability and conformity, is starting to show signs of divergence. The current benign spell runs for at least another 7 days but GFS OP is looking to break that down while ECM re-positions the HP to a much more advantageous position for cold by T+240. Further into FI, GFS OP and Control offer a considerable change in the pattern to a much more cyclonic synoptic with powerful LP coming quite far south. It's not the only game in town by any means with Parallel keeping the anticyclonic and relatively benign pattern for another 7 days so we await to see evidence of a new pattern change in the first week of March or whether the current pattern will be around for a while yet. For snow fans, particularly those in the north and on higher ground, the GFS OP and Control are not without interest in far FI.

Evening all Thee doesn't seem a lot to say currently - a pleasant if breezy day in lowland East London. I'll put up the usual T+144 and T+240 charts from GEM, ECM, GFS OP and GFS Parallel: T+144 (March 1st): T+240 (March 5th): The T+144 charts all very consistent and following the theme, now established over several days, of HP building over or just to the east of the British Isles and pulling in a SE'ly flow but with positive uppers it should mean mild days but of course it's early March so under clear skies frost is likely in rural areas. From there, GEM and ECM keep heights over the British isles but between a ridge pushing up from the Azores and residual heights to the east. GFS Parallel can't have two HPs so introduces a weak LP close to south west Ireland. OP makes rather more of this lowering heights across Europe with a more pronounced LP over Holland and heights to the north so a light NE'ly over southern Britain by T+240 and much colder air with 850s of -4 or lower. From there, T+312 and T+384 chars from GFS OP, Parallel, Control and this morning's CFS offering: T+312 (March 9th): T+384 (March 12th): Not a raging zonal SW'ly to be seen in all fairness. OP has a decent E'ly in early FI but that's breaking down by T+384 while Parallel finally retrogresses the HP and looks set to being in some really cold air (-20 850s over Iceland). Control has a messy evolution while CFS keeps heights to the north and west into FI so no dramatic cold but certainly not mild either. A slightly better picture for coldies tonight with clear signs of some interesting amplification beyond T+240. Both OP and Parallel more than hint at something colder and to be fair GFS OP puts us into a much colder evolution as early as T+240. After some dispiriting days there's a new signal of interest and while we're a long way from a widespread countrywide snowfall hints and possibilities anew tonight.

Evening all It's hard to think just two weeks ago the evening output was promising an extended cold spell for the British Isles. 14 days later and the mildies have won the day and the rest of the month and, to be frank, on the basis of last night's output, there wasn't much hope for early March either with the current fairly settled and benign spell set to continue and extending to those areas which have been drenched in recent days. Let's see what tonight's tea leaves tell us: T+144 is February 27th, T+240 is March 3rd, T+312 is March 6th and T+384 is March 9th. T+144: (GEM, ECM, GFS OP and GFS Parallel respectively: T+240 (GEM, ECM and GFS OP only): GEM goes it alone tonight and that may or may not be significant. It's a model I've always rated and it has at times picked up trends before some of the other models. The key to the evolution is at T+180 when the heights over north western Europe phase with heights further east and that enables the Scandinavian block to form. The other models keep too energy in the northern arm for that to happen and any attempt is quickly flattened with the HP sinking back towards the British Isles. Other than that, a very settled and benign outlook for most well into March. Some warm days but cold nights with frosts and perhaps fog especially if the core of the heights ends up over the British Isles. Moving on, the T+312 and T+384 charts from GFS OP, Control and CFS this evening as Parallel seems to be on a go-slow: T+312: T+384: Not without interest in the deepest realms of FO albeit very contrasting evolutions from GFS OP and Control. I actually found Control's evolution the more convincing while CFS keeps it all very anticyclonic though a prelude to quite a sharp colder snap around mid March.

Evening all Looks like another quiet day on the thread so I suspect tonight's output is unexciting but we'll give it a go as always. The star last night was Parallel which offered an extended cold spell into early March but looked on its own though ECM was also able to project heights into Scandinavia. The overall medium to longer term message was anticyclonic to start the new month. T+144 tonight takes us to Friday 26th, T+240 to March 2nd, T+312 to March 5th and T+384 to March 8th. Starting with the shorter range charts for GEM, ECM, GFS OP and GFS Parallel respectively: T+144: T+240: A difference tonight between the American models and the rest this evening after T+144. Parallel is the most bullish about building the anticyclone over the British Isles but all extend a ridge NE from the Azores to combine with existing heights over central Europe so it looks as though there could be some welcome relief from the incessant rain in the west. From there, GFS OP and Parallel both build heights to the north east while GEM ridges from north of the Azores to Scandinavia but ECM keeps the heights to the south and west and brings a strong trough through Scandinavia and a brief push of colder PM air especially for northern and eastern Britain by T+240. Moving on and it's GFS OP, Parallel and CFS for T+312 and T+384: T+312: T+384: Not much for cold fans to get excited about to be honest, The signal for a high-latitude block to the north east advecting a new push of colder air from the east seems to have gone for now. Indeed. the GFS models seem more interested in re-establishing the PV in its usual place (GEM does this a bit earlier). CFS holds the PV back for now and there are signs in far FI on both OP and Parallel of a new attempt at warming but the PV still looks large albeit not as cold as in mid winter (again, as you'd expect).

Evening all 12Z GFS OP last night was a bit of an outlier it seems - ho hum. It might yet indicate a direction of travel - it might not. Well into the mild and benign spell down here in lowland East London but will we move seamlessly into spring or has winter one last surprise for us? Let's see if tonight's output has any clues in the medium and longer term. Charts for T+144 (Thursday 25th) and T+240 (March 1st) from GEM, ECM, GFS OP and GFS Parallel: T+144 : T+240: The T+144 charts look remarkably similar - heights over central and south eastern Europe with a new HP building NE from the Azores. A shallow LP to the north of Scotland and a deeper mid-Atlantic trough well to the west but heights building across the British Isles and notably in the south. From there to the start of March (T+240) and the build of heights continues - GEM and GFS OP keep the core of heights to the south or south west - OP keeps a bit more energy in the northern arm of the jet but GEM offers a hint of heights to the north east. ECM has a strong build of heights up over Scandinavia supported by a shallow trough over the Ukraine and new heights building from the west but it's Parallel which is best for cold fans with a substantial core of heights over or just to the west of Scandinavia and an E'ly moving across southern Britain. Why does this work? Well, between the pre-existing heights over Europe and the new heights building over the Azores a shallow LP develops and as the HP from the Azores tries to push north this extends east into Iberia and across the Mediterranean basin supporting heights further north over the British Isles and Scandinavia. It's an example of how what is little more than a shortwave pays dividends. Moving further into the new month, charts at T+312 (March 4th) and T+384 (March 7th) from GFS OP, Parallel, Control and of course CFS: T+312: T+384: OP doesn't really get there though like the CFS it has a large HP right over the top of the British Isles by T+312. Control is a bit messy though not without hope but Parallel is tonight's gem. It's a belter for cold fans with uppers below -12 over southern and central England in a chill ENE'ly and the retrogression pattern holds with the HP holding firm south east of Greenland keeping the air flow between north and east. We keep seeing these colder evolutions so the signal is there id not well defined at this time. Beyond next week, the signal is strongly for heights to build toward and over the British Isles but whether these will migrate to Scandinavia remains to be seen. It's by no means certain but it's no lost cause at this time and it could be, as has happened many times before, we get a final spell of winter in early March before the true arrival of spring. Let's hope.

Evening all Last night's models emphasised how far we have travelled from the cold of last week - we are now four days into what looks an extended period of milder and generally benign weather probably taking us through the end of the month and into March. To be fair, most winters are a protracted mild spell with occasional colder interludes. There were a few hints of a possible change in the early days of next month with Atlantic amplification allowing heights to rise sufficiently to the north east to create a block to the east. Let's see if there is any evidence for it tonight. The new pattern is first the T+144 and T+240 charts from GEM, ECM, GFS OP and GFS Parallel. T+144 (Feb 24th): T+240 (Feb 28th): Not without a bit of interest this evening. The T+144 charts are variations on the theme of LP to the North West and heights to the South East. From there, a new HP cell builds near the Azores and ridges north east and the question is whether it can phase with the existing heights over the Alps and build further north and east or not. GFS OP is the least successful and GEM keeps the core of heights to the south west but both Parallel and in particular ECM successfully build heights into Scandinavia against what looks a much weaker Atlantic by the end of the month. Let's see if this promise translates into something more interesting as we go into March: T+312 is March 3rd and T+384 is March 6th. Charts from GFS OP, Parallel, Control and CFS: T+312: T+384: From an unpromising start, OP produces a wonderful FI for cold fans and yes, those are -12 uppers covering most of the British Isles. From a promising start, Parallel fails completely but it has a much stronger PV over Greenland and NE Canada. Control is a near miss while CFS delivers northern blocking yet without the dramatic uppers of GFS OP. The models continue to sniff out a colder evolution early next month and events around T+216 are significant. Getting that extra push of heights across north west Europe and building those into Scandinavia looks the catalyst to the formation of a strong Arctic HP which, with heights near the Azores, sets up a very cold trough but a lot has to go right for that scenario to happen. High latitude blocking exists on other models as does mid-latitude blocking so it's all to play for later in the month and in the early days of March.

Evening all Once again, hardly any posts in the thread so I think we can assume tonight's models are just, well, boring and yes I know all weather is interesting and all the rest of it but the number of comments tells it's own story. I'll head to T+144 (23rd), T+240 (27th) for GEM, ECM, GFS OP and Parallel respectively to kick off the evening's fun and games: T+144: T+240: At T+144, Parallel has the LP further south and OP has the trough closer albeit positively aligned to the north west. GEM and ECM not too different and both try to raise heights nearer to the British Isles by T+240 - ECM has the core of HP just to the south-east. GFS OP ends up close to GEM leaving Parallel the most interesting with a clear attempt at upstream amplification and the LP finally getting across the meridian with a flow of returning PM air so a little less mild. Moving on and we'll have the T+312 (March 2nd) and T+384 (March 5th) charts from GFS OP, Parallel, Control and the 06Z CFS offering for fun value. T+312: T+384: A bit of interest from GFS OP and Parallel going into March and it's caused by a nice bit of upstream amplification right at the end of the month which pushes the HP north and allows ridging first from Greenland and then from Russia. Some decent uppers on both charts, -8 and even below -12. To be fair, Control not interested and CFS keeps the HP closer to the British Isles. Tonight then only glimmers of hope in the distance for cold fans. I do think we need to get the cold air out of North America which is fuelling strong cyclogenesis and creating powerful Atlantic storms but as that lifts back north we'll see an opportunity to slow the Atlantic and get that upstream amplification we need to get a colder pattern.

Evening all You don't need me to tell you what the models are showing - 3 pages of discussion in 24 hours compared with 20-30 in the run up to the cold spell tells you all you need to know. It's almost not worth me wasting my valuable putting up the charts because we know it's going to be unremittingly mild and benign for the rest of the month so I'm not going to bother. I'll go off the deep end and start with the T+192 and T+240 charts for GEM, ECM, GFS OP and GFS Parallel. T+192: T+240: Well, pretty much as I expected. Heights never too far from the south and LP to the west and north so the wind flow is generally between south and west. ECM gets the HP cell over the British Isles by T+240 and GFS Parallel offers a brief N'ly at T+240 but that's about it until the end of the month. Looking further on and changing the pack a little, the T+312 and T+384 charts from GFS OP, Parallel, Control and the latest offering from CFS: T=312 takes us to March 1st, and T+384 to March 4th: T+384: Well, it's nice to find a couple of not so mild charts and CFS has been playing this theme consistently for days of a sharp change to a colder evolution in early March. Time will tell but that's all cold fans have tonight. It's arguably the mildest set of charts for several weeks and with GFS wanting to bring back a strong PV it may be those hoping for an early spring cold spell are going to be out of luck. Obviously, even the PV runs out of time but for now it's looking like a prolonged period of unremarkable weather - even some of the signals for a plume type event have faded tonight so mild or very mild - not too much rain in the south and east, a bit more further north and west looks a pretty safe call for the next 14-21 days.

Evening all So the February 2021 cold spell moves into history and more "usual" late winter fare has taken over. Last night, the models seemed broadly agreed on an initial Atlantic bias this week but increasing heights over Europe bringing an even milder spell next week but from there possibilities of the HP shifting north back towards or even north of the British Isles with hints (no more) of a possible return of colder air but all very speculative at this stage. T+120 takes us to Saturday 20th, T+192 to Tuesday 23rd, T+240 to the 25th, T+312 to the 28th and T+384 to March 3rd. Charts as usual from GEM, GFS OP, GFS Parallel and ECM T+120: T+192: T+240: A bit more divergence in the modelling this evening. GEM keeps more of an Atlantic influence throughout and it gets quite unsettled over northern and western Britain. GFS OP builds ressure to both the south east and south west and ends with a core of heights just to the north of the British Isles propped up by a small cut off LP to the NE of the Azores. That feature is much further south on both Parallel and ECM with the latter building a ridge north west toward Iceland and Greenland at T+240. By then, the Atlantic has slowed across all the models and the PV not obviously a huge influence. Nothing for cold fans with winds between south and west over the next 10 days though GFS OP throws a light E'ly in at T+240. Moving further ahead, are there signs of a possible pattern change into March? Over to GFS OP, Parallel and Control: T+312: T+384: Two different directions - OP and Control seem keen on building heights to the east and you could imagine some retrogression from that OP scenario. Parallel isn't that interested to be fair. Conclusion: it's all looking very uneventful for the moment. GEM keeps things a bit less settled but generally, with heights to the south and east, it's mild and benign for most over the next 10 days. From there, hints of new heights to the east around the start of next month will doubtless tease and tantalise in the coming days but it's a regular signal in recent days and tonight GFS OP has the build of HP close to the British Isles as early as T+240. A "cold March surprise" ? You wouldn't rule it out.

As an example of how models can flip - last Sunday evening's GFS 12Z for tomorrow compared with where we are tonight.

Evening all As the cold spell eases away we seem to be facing a prolonged period of milder temperatures. Any initial Atlantic incursion is pushed back as heights rise over Europe and we enter a new period of mild, benign and settled conditions and indeed it could get warm or very warm for the time of the year in the last week of the month. Now, anyone with a functioning brain cell can call winter to be "over" if they want but we often see renewed cold incursions in late winter or early spring (if you count March as spring) before the warmer airmass prevails and we move fully into spring. These can mean some quite marked changes in temperature (as we are seeing now) as the cold winter airmass find sits way back in either from the north or the east. I'd also mention last Sunday evening most of the models had the cold continuing well into this week but within 24 hours all that had collapsed. The models can and do change abruptly if a new signal emerges so there's no reason for coldies to throw in any kind of towel just yet. Anyway, let's look at tonight's offerings from the 12Z suites of GEM, GFS (OP and Parallel) and ECM: T+120 takes us to February 19th, T+192 to February 22nd and T+240 to February 24th leaving T+384 to March 1st or 2nd. T+120: T+192: T+240: Significant agreement through the coming week with a deep Atlantic trough positively aligned to the south west of Iceland and heights to the south and east of the British Isles over Europe. A mild or very mild SW'ly airflow which brings predominantly dry weather to southern and eastern Britain but spells of rain and strong winds to the north and west - a pretty typical winter pattern to be honest. From there to T+192, little changes with GEM but the other models start to build stronger heights over Europe with these pushing north or north west and GFS OP has an HP cell over southern and eastern England by T+192. Settled and benign conditions extend further as, with the exception of GEM, the Atlantic trough withdraws north and west. Moving on and even GEM builds heights by T+240 but there's plenty of energy in the northern arm of the jet and Parallel is similar but a cut off LP to the NE of the Azores allows GFS OP to extend the core of heights and a new Atlantic ridge north (also on Parallel) looks set to intensify the ridge. ECM goes it sown way sending the HP north to Scandinavia and setting up a mid-latitude block over the Baltic by T+240. Looking further ahead toward the end of the month and the very start of March with the far FI from GFS OP, Parallel, Control and this morning's CFS for some amusement: T+312 (Saturday February 27th): T+384 (March 2nd): You'd normally expect quite large variations that far out but there aren't. All four have an anticyclonic evolution - GFS OP puts the core of heights to the north of the British Isles - the other models have heights sitting almost directly over the British Isles - but there's no sign of anything Atlantic -based. Conclusion: it's unusual to see such broad anonymity in the evening output. The key word is anticyclonic - from Europe they build back north or north west by month end to be over the British Isles. GFS OP has some -8 uppers crossing - the other models would be less obviously cold but with frost or fog an issue and the question would then be whether retrogression would be possible - it seems unlikely with Parallel and CFS but possible with OP ad Control. The signal for a strongly anticyclonic end to February has been there for a while - some of the earlier output modelled last week's Scandinavian HP as the catalyst for that but the Atlantic has proved too strong in the short term. That seems not to be the case later in the month.

Unless of course you look at the 06Z CFS run which, after a mild interlude of less than a week, puts us back in the freezer for three weeks with two spells of retrogression. Bring it on

Evening all The cold spell which I think has been remarkable in terms of the longevity of cold here in lowland East London is ending and it certainly looked as though we would be embarking on a prolonged spell of quiet rather benign weather with mild air and little rain. There didn't seem much if any prospect of a further cold encroachment from the east with heights in Europe rather than further north and too much energy going into the northern arm of the jet. Let's see how it looks tonight: T+120 (Thursday 18th), T+192 (Sunday 21st) and T+240 (Tuesday 23rd) charts from GEM, GFS OP, Parallel and ECM respectively: T+120: T+192: T+240: Nothing for cold fans in the next 10 days at all on tonight's evidence. The general pattern reflected across all the models is to have the HP sink into Europe with a brief unsettled spell at the end of the coming week but the heights to the south and south east become more dominant and push the Atlantic systems further to the north and west. From there, GEM and GFS OP build heights over the British Isles but both Parallel and ECM keep the core of heights more to the south east. It may get a little colder if the HP settled over the British Isles but otherwise it's mild or very mild all the way. I suspect it won't be as mild/warm as it was late February 2019 but it will begin to feel more spring like. Looking further ahead, GFS OP, Parallel and Control at T+312 and T+384 respectively: A glimmer of interest at the very end of the OP at the turn of the month but both Control and Parallel remain mild and benign to month end. Conclusion: fans of an early spring will be salivating at tonight's charts as there look plenty of prospects for some very mild and settled conditions in the second half of February and within a few days the recent cold spell will be a distant memory. It's possible we'll see the anticyclone sit over or very close to the British Isles and if we can keep the PV away (as OP does) there's an opportunity for renewed amplification but that's still a fortnight away.

Afternoon all I suspect I'm going to be in a minority but I think this week's cold spell has been quite impressive. I can understand the frustration if snow is all that matters to you - I live in lowland East London and we got probably 3 cm of lying snow so nothing remarkable. We've had a lot more snow in the not-too-distant past - 15cm in February 2009 and January 2013. Many people quote December 2010 and we got 10cm out of that. This week has been the largest amount of snow since March 2018 but in itself nothing remarkable. What has been much more remarkable has been the longevity and severity of the cold. We've had seven days of freezing or near-freezing temperatures. I'm not sure how many of these have been ice days but I would guess five at a minimum. That's highly impressive for London - ice days are uncommon. I think we had one in the BFTE three years ago, certainly March 2013 (and that was incredible as that was a month later in mid March) and December 19th 2010. The problem is large quantities of snow usually come from marginal events and it doesn't make much for that snow to melt once the margins go the other way. In December 2010, we lost 50% of the snow cover by the Monday. Those living in more rural areas or with altitude see the snow surviving longer. This week we had two main snowfalls - Sunday/Monday and Wednesday/Thursday. Neither was large in accumulation but the snow cover was largely maintained - obviously we lose cover to evaporation or sublimation but it's not melted. It's not melted because we've had this week of below freezing temperatures which is the longest sustained spell of cold I've experienced since moving to this part of the world in 2005. I was living in Cornwall in late 1995 and I have a vague recollection of it being extremely cold but no snow. I also see from the records horse racing was stopped for the whole of the week from Boxing Day apart from Limerick suggesting it was a shade milder in my part of the world. This has however been impressive - for an urban area to have not only seven days at or below freezing but also the severe nigh time minima which has meant standing water has frozen solid in situ. Temperatures to -5 or -6 aren't unusual in rural locations but they are in urban areas and the severity of the frost has been accentuated by the wind chill. Overall, for snow amounts 3/10 - for longevity of snow 6/10 and for cold 9/10.

Evening all A bitterly cold day here in lowland East London and the sixth successive day of very cold temperatures but it looks like tomorrow will be the final very cold day and after a transition on Sunday it will be a significant change to much milder conditions on Monday with temperatures moving above average to 10-12c for much of the south east next week. I changed the format last night and I'll try it again tonight so GEM, GFS OP, GFS Parallel and ECM at T+120, T+180 and T+240 respectively. T+120 (Wednesday 17th): T+180 (T+192 on the ECM T+240 (Monday 22nd): There's very little for cold fans on tonight's models in the short to medium term. The heights end up sinking into Europe but GEM brings the HP back up over the British isles and the general themes are mild for all, settled for most and benign for the majority with temperatures above average , little rain or wind and no frost or snow. Oddly enough, the UKMO seems the most unsettled at T+144. Let's take in some longer range charts covering T+312 (Thursday 25th) and T+384 (Sunday 28th) from GFS OP, Parallel and Control: They say if you wait long enough, you'll get what you deserve. The message to the end of the month is strongly anticyclonic and just a hint we might get the HP in the right place oriented the right way for a late winter surprise. Control has -8 uppers to end the month which would be decent. That's a very long way off and in the short to medium term there's not going to be much weather to talk about unless you like it mild and quiet.

Evening all No time for the usual blah tonight so just a quick look at the main charts at T+120, T+180 and T+240 from (respectively) GEM, GFS OP, GFS Parallel and ECM T+120 - Tuesday 15th: T+180 (T+192 for ECM): T+240: Saturday 20th: Brief thoughts; the cold spell ends on Sunday/Monday and it turns much milder from the south and west. The anticyclonic signal from last evening is a shade more muted and while GFS keep the HP to the south or south east, GEM and ECM build heights back into Scandinavia - both are some way from anything really cold but it's also some way from Atlantic dominance and a zonal jet.

Evening all A sparkling winter's morning in lowland East London - my favourite kind of winter weather. You can keep your snowdrifts and blizzards - a hard frost and a sparkling sunny morning . Cloudier this afternoon and I suspect we moved above freezing but under clear skies tonight it's going to be very cold. Sublimation and evaporation are seeing off the snow but some of it has held for three days which is unusual in my part of the world. Last night called the last rites on the current cold spell which should be gone by Sunday or Monday and from there not much for cold fans and instead a more benign spell of mild and dry weather seemed the most likely outcome. Anyway, let's see what tonight's procrastination has to offer. T+120 takes us to Monday 15th, T+240 to the 20th, T+312 to the 23rd and T+384 to the 26th February. 12Z GEM: by T+120 heights remain strong to the east but the HP has split with one centre over southern Scandinavia and the other over Germany. A S'ly air flow covers the British Isles by this time with the Atlantic trough throwing energy ESE from the main LP centre near SE Greenland. The HP is ridging North west but it doesn't look sufficient. However, the colder air is hanging on in eastern and northern Britain with 850s still below zero but milder air has arrived further south and west with positive uppers. From there, the heights gradually decline south into Europe and by T+180 the HP is over Slovakia and Romania with a weak ridge north west across southern and eastern Britain. This keeps calm conditions over much of southern and eastern Britain. Further north and west there's more of an Atlantic influence but the main trough has actually withdrawn west and a new vigorous LP has moved into mid ocean and thrown a ridge downstream. 850s remain just below negative. Moving on and the vigorous LP swings north but all this does is causes the ridge to intensify across Europe and to migrate north as a new wedge of HP emerges out of Russia and by T+240 we have a new Scandinavian HP at 1045MB and an ESE'ly air flow back over the British Isles. 850s are positive at this time but colder air is approaching from the east. No sign of an Atlantic onslaught from GEM - indeed, heights to the NE return with a vengeance and you'd not bet against a colder evolution from there. 12Z GFS OP - at T+120 the HP is over southern Scandinavia with the main ridges south west towards Iberia. A vigorous LP is to the south west of the British isles with the main trough further northwest and positively aligned to feed energy over Iceland. 850s either side of zero across the British Isles with the coldest air to the north and east and positive uppers to the south and west. Moving on, the vigorous storm swings north past Ireland and triggers new height rises across the British isles and Europe and, having started to decline south, heights return north and by T+180 a broad HP covers Scandinavia and North East Europe with a SE'ly air flow over the British Isles. Meanwhile, a ridge is extending toward Iceland as the Atlantic trough disrupts south east toward Iberia. 850s are broadly negative across the British Isles by T+180 but no lower than -4 and milder air is approaching from the south west. From there, heights persist to the north and east while a new LP develops and deepens to the north of the Azores ad stalls to the south west of the British Isles throwing up a mild S'ly airflow. Uppers are generally either side of zero but coldest in the north and milder air moving up from the south. GFS nearly gets there with a thought of retrogression and it's an option we may see taken further in some of the Ensembles. 12Z Parallel - nice to see the Parallel back. at T+120 the HP is still holding on over Scandinavia with the air flow SE'ly over southern and eastern Britain and SW'ly further west ad the Atlantic trough aligns negatively but with a deepening secondary LP to the south west of the British Isles. Negative uppers remain most of the British isles and indeed below -4 over Scotland with the milder uppers pushed slightly back by T+120. From there, the Scandinavian heights persist but re-orient to form a ridge north west to the east of Iceland. The HP is supported by shallow areas of LP forming over France and Iberia and tis sends an ESE'ly air flow over the British Isles by T+180. The Atlantic LP has withdrawn further west against the block and its energy is projecting south east against the block. A new push of colder air has uppers from -8 to -12 back over the British Isles. From there, heights continue to the north and east but we don't get full retrogression as a new LP develops near the Azores and moves north in mid=Atlantic. In response, the HP slips south east to be just to the east of the British Isles by T+240. The SSE'ly flow has brought back milder air with positive uppers for almost all parts. Another fascinating evolution with a brief but intense return of cold and very anticyclonic with the Atlantic held well at bay. 12Z ECM - at T+120 ECM is quite different. The HP has declined to the Baltic and oriented south west- north east ridging to Iberia. Much more energy is moving further north on ECM than on the other models with the Atlantic trough to the north of Iceland and a SW'ly air flow over the British isles by this time. Positive uppers over all parts with 850s of +4 over southern parts. Indeed, whereas the other models keep us cold on Sunday, ECM has pushed positive uppers across most parts by T+96. From there, the HP declines further south but new heights build first over Iberia but these extend back north and by T+192 a new HP is just to the east of the British isles with a new vigorous Atlantic LP moving back west and a secondary LP forming in its circulation to the south. Calm conditions over southern and eastern Britain with a S'ly airflow further west. Uppers remain positive over the British Isles at T+192 with the mildest air to the west and coldest to the east. From there, the HP intensifies in situ and by T+240 is over or just to the east of the British Isles with troughs held at bay to the north, west and south west. 850s are generally +4 but this might not reflect any inversion at the surface. ECM goes mildest quickest but ends anticyclonic and benign. Moving on, the T+312 and T+384 from OP and Parallel respectively: The key theme is anticyclonic which is through all the models tonight. Control joins the anticyclonic crowd as well. Even JMA is rebuilding Scandinavian heights at T+192. Conclusion: anticyclonic is the mot du jour tonight. All the models are toying with rebuilding Scandinavian heights and it works best on Parallel with a brief but intense push of cold. GEM has a strong Scandinavian HP while you sense GFS OP is looking for that solution. ECM goes its own way as usual but gets heights close to the British Isles. Getting the heights oriented in such a way as to advect the colder air still over eastern Europe (it is the second half of February) is going to be the challenge but we've come a huge step from the mild horror stories of Monday night and to an extent last night. It may well be a brief milder interlude could be followed by a new burst of anticyclonic cold from the east if everything drops right. Let's hope.

Evening all Another bitter day here in lowland East London but I'm not sure if it was an ice day - certainly if we made it to zero we weren't there for long. Occasional mainly light snow but the increasing wind and evaporation has already got to work on the lying snow though with some frigid air due in the next 48 hours I suspect it will be an icy mass that takes us into the weekend. Plenty of signs last evening, after a stellar set of charts on Sunday evening, of the writing on the wall for the current cold spell by next Sunday but that will be 7-8 days of significant cold so nothing to sniff at in any sense. Are there any signs of a flip back to cold this evening? I suspect not given the number of pages on this thread but we'll see. T+120 takes us to Sunday 14th , T+240 to the 19th, T+312 to the 22nd and T+384 to the 25th February. 12Z GEM: by T=120 pressure remains high to the east but is now oriented north-south with a ridge into Scandinavia allowing a SW'ly air flow to edge across the British Isles though the main Atlantic LP is centred far to the west and north west near to south west Iceland. Milder air with positive uppers has reached much of the British Isles but colder air with 850s negative to -4 persists over northern Scotland. From there, the Scandinavian HP declines south to eastern Europe but the first trough fills to the north of the British isles and a new pulse of PV energy comes out of North America and is passing the south of Greenland by T+180. Weak heights to the south lead to a broad WSW'ly air flow. Behind the cold front, PM air has brought some lower 850s which are just negative over the whole of the British Isles by T+180. Moving on and the new Atlantic LP slows and re-orients in mid-ocean trying to dip south and encouraging heights to rise over mainland Europe with a large HP centred over Romania and the Black Sea by T+240. With a secondary LP zipping close to north west Scotland by this time there's a mild or very mild SW'ly air flow over the British Isles. 850s either aide of zero but with +4 uppers over southern England. GEM quickly goes mild and stays mild - it's been the least enthusiastic of the models over this cold spell but to be fair it was the first to call the end so some kudos. 12Z GFS OP - by T+120, the milder air is still battling to get across the British Isles with a large HP still to the east and the Atlantic LP oriented negatively on GFS OP rather than positively on GEM. Winds over the British Isles are still SE in the east and have turned south west in the west. 850s remain negative over all but the far west - generally below -4 over eastern areas so one more cold day it would seem. From there, the HP to the east is stubbornly persistent and by T+180 is still in situ having edged only fractionally east and it is the original Atlantic trough which has disrupted to the west but a new storm is moving off North America at T+180 as a ridge develops to the west of the British Isles. Positive uppers cover most of the British Isles by this time. From there, the Scandinavian HP declines south but maintains a ridge back into Scandinavia and the Atlantic remains held well to the west at T+240. 850s remain positive over most parts by T+240. No sign of an Atlantic onslaught on the GFS OP - indeed, the HP remains close by and it's actually quite a benign evolution to something more settled. 12Z Control: T+120 is similar to OP though I note the more defined heights over Iberia. There's not a huge amount of difference at T+180 either with the Atlantic trough trying to send energy North east through Iceland as the HP starts to decline south. One main difference is the shallow LP in the south western approaches which is more defined than on OP. By T+240 the HP is centred over the central Mediterranean but the Atlantic remains sluggish. Mild with positive uppers over the whole of the British Isles by this time. 12Z ECM: the most interesting of the evolutions on offer last night but let's see if it's a trendsetter or back following the herd. By T+120 it looks more progressive than GFS OP and Control in breaking down the block and positive uppers have reached all parts except north-east Scotland. From there, a major storm is spawned in the circulation of the trough and that runs NNE in mid ocean deepening considerably. Downstream, heights are rising over Iberia and the HP is over Belarus rather than sinking south as on other models. Slightly surprisingly, the 850s over the British isles are just negative with another push of milder air approaching from the south west. From there, the HP is over Belarus and the Ukraine by T+240 with a ridge into Scandinavia and the Atlantic LP systems remain held well to the west . Positive uppers over most of the British Isles by this time with any colder air well to the east and south east. All a bit meh from ECM - it's a different evolution but the net effect is much the same - HP somewhere over Europe and LP out in the Atlantic which equals SW'ly winds for the British Isles and mild air. Looking further ahead, GFS OP and Control from T+312 and T+384 respectively: Control is Atlantic-driven and boring but OP teases with a new push of heights from the NE down into Scandinavia - the cold air gets close to the British Isles but not close enough this time but it's one to watch for the next amplification. Conclusion: it's clearly game over for the current cold spell despite the promise of just 48 hours ago. If GFS is right, we might squeeze out one more cold day on Sunday but otherwise the milder air marches in and that's that. No sign of an immediate return to cold on any of the models and the more likely evolution looks to be mild and benign with HP not too far by but in the wrong position to send over any colder air. The Atlantic isn't exactly raging either so it may be another waiting game until the next opportunity for amplification. The PV is looking formidable now and unlikely to be of any help so it's a 10-14 day milder spell starting on Sunday at the moment. As always, the models can pick up new signals so it's not a certainty but tonight the prospects for further cold this month after this week don't look bright.

Evening all Well, a real rarity - an ice day in lowland East London with maximum temperature of -1c. After the overnight snow, not much has been added but apart from some evaporation, very little has gone. A brief foray to sort out the bins confirmed a biting E'ly wind and a significant windchill. Last evening the models seemed keen to prolong the cold spell past the weekend with GFS OP in particular offering a prolonged colder episode thanks to a retrogressing Scandinavian HP. I'm vaguely aware of some toys being thrown out the pram and some wailing and gnashing of teeth so we can assume that's now off the table (or can we, options get picked up, put down and retrieved all the time?). T+120 is Saturday 13th, T+240 the 18th, T=312 the 21st and T+384 the 24th February. Let's see how down the downgrades really are: 12Z GEM: - the least certain of all the models about prolonging the cold spell yesterday in all honesty, At T+120, pressure is high to the east and north east with twin HP cells of 1040 MB over southern Scandinavia and the North Sea. The Atlantic trough has two centres - the main centre sits well to the west having swung up from the south west and another LP has also swung north well to the west of Ireland. A SSE'ly covers the British Isles at this time - positive uppers have returned to Ireland and the far south west of England but remain below -4 over most northern and eastern areas. From there, the HP over Scandinavia quickly collapses south into Europe and by T+180 the Atlantic trough has elongated east to the north of Scotland a WSW'ly airflow covers the British Isles. The colder air has been pushed well to the north and east and 850s are generally either side of zero with the mildest air over the south by this time. From there, one secondary LP develops to the south of the main trough and runs north east close to the British Isles and by T=240 another secondary LP is crossing into the North Sea with a very windy spell over the Pennines. Heights persist to the south and far to the north with the trough elongating into Scandinavia by this time. 850s generally around zero by this time. A disappointing start from GEM with the Scandinavian block offering very little resistance early next week to the Atlantic. 12Z GFS OP - the T+120 looks different to the GEM with a stronger HP over Scandinavia ridging to the east of Iceland and a SE'ly airflow over the British Isles. Milder air has reached Cornwall and the far south west of Ireland but elsewhere it remains cold with uppers below -8 over most of eastern and northern Britain. From there, the Atlantic trough launches a sustained assault on the block which begins to weaken in situ or drift slightly north west. The trough aligns negatively and by T+180 one LP is pushing south east as it pushes against the block from the south west. After an initial pushback against the trough, milder air tries to come in again from the southwest but by T+180 has only reached south western areas but it has turned a little less cold elsewhere with the coldest air confined to northern and north eastern Scotland and the northern isles by this time. From there. another vigorous Atlantic LP forms to the south west and this finally breaks down the block with the residual HP declining east and a SSW'ly air flow setting up over the British Isles. Much milder air has now moved across all of western Europe with 850s of +4 over the British Isles. What a difference a day makes!! A significant change from GFS OP with a powerful Atlantic trough breaking down the block - I'm struggling to see what signal has caused the change in the evolution and I suppose the obvious question is it's T+240, it's changed before and it can change again. 12Z Control: at T+120 it's very close to the OP but from there the Scandinavian HP puts up more of a fight than on the OP and while it starts to drift north west, the Atlantic LP is forced south east towards Iberia with a SE'ly air flow over the British Isles. Uppers remain negative everywhere with the coldest air (850s still below -8) over northern and eastern areas. The attempt at retrogression, however, fails and the trough declines back east allowing the Atlantic trough to re-orient in mid ocean and send a new lobe of energy east by T+240 leaving the British Isles in a SSE'ly air flow. Positive uppers by now over southern and western parts and it's less cold albeit with 850s still negative further north. 12Z ECM: I strongly suspect this model will follow the herd towards a milder evolution but let's see. The T+120 chart is more like GEM with a north-south wedge of heights over Germany, the North Sea and south west Scandinavia. The LP centre remains far to the west and a SE'ly air flow over eastern parts of Britain is a SSW'ly air flow further west. As you might expect, positive uppers have reached the west and south west but it remains cold with uppers below -8 over extreme eastern areas. From there and slightly surprisingly, ECM goes down a different route with the HP persisting to the north east and the Atlantic trough first elongating and then disrupting to the south west of the British Isles. This maintains a broad SE'ly air flow over all parts at T+192 with 850s still negative over almost all areas and below -4 generally over northern and eastern regions. From there, heights remain strong to the north through to T+240 with the next Atlantic trough held well back and a light E'ly over the British Isles. Uppers are either side of zero so nothing very exciting. Oddly enough, it's not unlike last evening's evolution but it's very different to the other models. Looking ahead, GFS OP and Control at T+312 and T+384 respectively: Both end with Atlantic domination and with Control showing signs of the PV returning the OP - not so the OP. Conclusion: there's no point denying the obvious - cold fans have taken several steps back this evening. Indeed. we're back to last Tuesday which had the cold spell ending by Thursday or Friday. We've gained a couple more days but by the end of next weekend it looks as though the Atlantic will break through in one form or another. I'm left then with the question - what has changed? The signal for a strong Scandinavian block grew during the week and on last night's output was formidable but tonight it's back to a quick collapse against a powerful Atlantic trough. I don't get it - seriously I don't. Let's see where we are tomorrow to see if this is a clear new trend or one of those instances of a signal picked up, discarded and then picked up again. We've seen it before - we'll see it again.

Morning all A reasonable covering in lowland East London but no more than a couple of cm in depth. It's that light snow that takes time to accumulate rather than the heavy wet flakes in more marginal situations. The other aspect is the air temperature remains below freezing even here only 6 miles from the City. Currently -2c. Will it be an ice day? I suspect we'll get to zero for a short while in early afternoon but I imagine it'll be an ice day for a lot of people in our area. I expect snow on and off for most of the day but accumulations still struggling but it's going to stick rather than rapidly melt as often happens.

Here in lowland East London we've had a dusting on most surfaces but it is very cold - now below freezing - and any snow has become that icy mass which sticks to bin lids, car doors and the like. Some slight breaks in the overcast so it will be a penetrating frost with the notable wind chill. Day 1 of the cold spell over and while it would have been nice to see more snow settle it was just the wrong side of marginal for most of the day for me. We've never had the big wet snowflakes of a real marginal event - it's been the lighter more persistent snow but the ground has needed more time to cool and dry after yesterday's rain but we have lying snow, albeit a dusting, for the first time in winter for some while.

Evening all A memorable snow day for a few, a disappointment for some. Here in lowland East London, a bleak overcast day with occasional rain, sleet and snow and temperatures falling back close to freezing. I don't know if we'll get more snow overnight or tomorrow - that's a discussion for a regional thread. Looking further ahead, some excellent model output yesterday evening hinted at an extension of the cold spell into next weekend and perhaps beyond but a variety of evolutions - so much depended on the Scandinavian HP "behaving itself", remaining in situ and heading WNW rather than sinking south or retreating east. T+120 takes us to Friday 12th, T+240 to the 17th, T+312 to the 20th and T+384 to the 23rd February. 12Z GEM: at T+120 and intense HP (1045MB) sits over central southern Norway with a ridge north west toward Iceland. A large LP sits positively aligned in mid Atlantic but well to the west and north west of Ireland. Another LP sits over the Ukraine. A SSE'ly air flow covers the British Isles at this time. Milder air with positive uppers has reached Cornwall and south-west Ireland but uppers remain -4 to --8 over most of the British Isles with pockets below -8 over northern England. From there, the Atlantic trough tries to move in to the British Isles but is held at bay and by T+180 has withdrawn north-west towards southern Greenland. The anticyclone persists over Scandinavia with further heights re-enforcing from the south. Winds remain from the south or south east over most of the British Isles and this has drawn in less cold air with uppers generally either ide of zero by T+180. From there, the anticyclone gradually sinks into Europe and by T+240 is centred over the Czech Republic but a ridge extends back over the south of Britain as the Atlantic LP starts to try to move NE round the top of the HP towards the north of Scandinavia. Uppers remain either side of zero generally with the mildest air in the south and the coldest in the north. A disappointing start to the evening from GEM which largely follows the ECM evolution from last evening and suggests the HP won't retrogress but will eventually collapse south allowing the trough to in time move round to the north. 12Z GFS OP - by T+120 a large HP (1040 MB) is centred over south western Norway and Denmark and a strong SE'ly air flow covers most of the British Isles with any Atlantic influence confined to the far west of Ireland with an intense Atlantic trough to the south west of Iceland. Uppers remain below -8 over most northern and eastern parts with less cold air just getting into the far south west of Britain and Ireland by this time. From there, the Scandinavian HP intensifies further and re-orients to a classic SW-NE pattern over north-central Scandinavia. The Atlantic LP starts to align negatively as it tries to approach the British Isles and the SE'ly air flow persists over most parts. The brief push of milder air is halted and reversed so that by T+180 much colder air is back over most parts with uppers generally -4 to -8 and below that in eastern areas. From there, the fun and games really starts - the Scandinavian HP pushes an increasingly cold air mass over the British Isles but then itself starts to move NW to be just to the east of Iceland by T+240. The Atlantic trough has been forced south east by the block and one part of that energy has passed to the south of the British Isles and is centred over the Gulf of Genoa. Meanwhile, another storm system from lower latitudes has phased with the colder trough and formed an intense storm system which at T+240 is far to the south west of the British Isles. A brief flirtation with -16 uppers notwithstanding, it remains cold over much of the British Isles though slightly less cold in the far south and uppers below -8 confined to northern Britain. Decent - very decent - in fact bloody brilliant if you are a cold fan and a snow fan for parts of the south with a Beast Reload for the early part of the week after mid month and a brief taste of -16 uppers which we've not seen for a fair while. 12Z Control - as might be expected, at T+120, Control follows the OP closely. On to T+180 and while the Scandinavian profile remains the same, the Atlantic profile is different with a intense LP in mid ocean after one storm passes from south to north well to the west of Ireland. The colder air is marching back in from the east with uppers below -8 over eastern and south eastern England and 850s just negative further west. Unlike the OP, the more intense storm does push the block back a little and the block starts to move NNW out of Scandinavia which in turn blocks the cold flow from the east and allows another push of milder SW'ly air into western areas. Uppers are largely below negative but the coldest air is now over northern and north eastern parts with milder air approaching from the south west. Control is let down by this monster mid-Atlantic storm which is strong enough to dislodge the block and break the cold flow from the east. 12Z ECM - this was the disappointment of last evening sinking the Scandinavian HP early and allowing the mild air back rather quickly. Let's see if it can do better this evening. I suspect not. By T+120, the stand off is in place with the HP over south west Norway and the positively aligned Atlantic trough far to the west. Uppers remain below -8 over eastern Britain but milder air has already arrive din the far west of Ireland with positive uppers returning. From there, the evolution looks a whole lost better than last evening with the Scandinavian HP growing in intensity and the Atlantic trough disrupting completely with a small residue of energy to the far south west as a new storm emerges at T+192 from the eastern seaboard. The HP extends across to the north east of the British Isles with a chill ESE'ly flow, strongest over southern and western Britain by this time. Uppers are negative elsewhere with the coldest air (850s below -8) over eastern and south-eastern England. Moving on and the HP remains firmly in charge and by T+240 it is centred over the Faeroes looking lie it will retrogress to Greenland. A cold ESE'ly continues across the south with a weak LP over Iberia and a negatively aligned Atlantic feature far to the west. A final push of cold has been mitigated somewhat by T+240 as the air is now being sourced from south east Europe rather than points further east. ECM actually ends less cold (surprisingly) vet hardly mild, It's not quite as good an evolution as GFS OP but still decent. Looking further ahead, T+312 and T+384 from OP and Control to end proceedings for the evening: Both interesting and neither what you'd expect for mid to late February in a "normal" winter. Conclusion: the Scandinavian HP is going to play a big part in the evolution from the end of the coming week onward. GEM and to an extent GFS Control are a little disappointing but both ECM and especially GFS OP use it to maintain a cold pattern for several more days especially for eastern areas. Indeed, we could get a second "bite" of the cold cherry in a few days but this will be more about cold and less about snow I suspect. GEM and Control hint at a more traditional breakdown but it could be something less common such as a "different" E'ly or indeed no breakdown at all. I don't rule out a brief milder incursion into western areas at the end of the coming week but as the HP takes over the cold might well return from the east albeit not as we are seeing now but a drier cold. We've come a long way since Tuesday with ever ynight showing incremental extensions to the cold spell. It's been quite a ride.

Morning all Well, the cold arrived in lowland East London quickly overnight - this morning it's overcast - the rain has turned to sleet but isn't settling anywhere just yet. Having been out for the morning paper, a biting E'ly wind has now developed. Temperature still just above freezing - currently 1c here. I would imagine those with altitude or those outside London are doing very well and I suspect our time will come later - for now, it's just the wrong side of marginal.

Evening all It seems we are on the threshold of a significant spell of winter weather with snow (hopefully) for many and perhaps even here in lowland East London I'll see some of the white stuff. Today started pleasantly mild but rain has arrived this evening which I suspect id the harbinger of the significant change tomorrow. I squeezed five days out of this cold spell on last night's models but by Thursday/Friday the game was up as the Atlantic LP aligned positive and the Scandinavian heights mostly collapsed south. A growing minority of options, however, kept a cold flow going by holding the Atlantic at bay and let's see if tonight offers any hope for prolonging the immediate to perhaps this time next week or beyond . T+120 is the 11th, T+240 the 16th, T+312 the 19th and T+384 the 22nd 12Z GEM: The T+120 chart shows an HP over south western Scandinavia with a ridge to Shetland. To the south east, the residual trough from this weekend is over Romania and a new Atlantic LP sits in mid ocean. Calm conditions over northern and eastern Britain with a strengthening SE'ly over southern and western areas. 850s remain below -8 over most areas with only the far south west of England and Ireland coming into slightly milder air. From there, heights continue to strengthen over Scandinavia and by T+180 the main core of heights is over northern Scandinavia with a ridge south west just to the east of the British Isles and a further ridge extending to Greenland. The Atlantic LP has withdrawn west north west but a light S'ly covers much of the British Isles. In terms of uppers, not much has changed - eastern areas remain cold with uppers below -8 while positive uppers have reached Cornwall and south west Ireland. From there, the stand off continues with a large Scandinavian HP in situ and Atlantic systems swinging north east then north to the west of Ireland. By T+240 a SSE'ly air flow covers all parts. In terms of 850s, the stalemate continues - positive uppers are confined to the far south west and if anything the colder air has made more inroads into central Britain. A real battleground and a significant extension of colder conditions especially for northern and eastern areas into the week after next making it a 10 day cold spell for many parts. Further west, milder air returns next weekend and you'd wonder if, between the two, there were opportunities for snow. 12Z GFS OP - GFS is generally the most progressive of the models and I'd be surprised if it wasn't more bullish about the Atlantic breaking through. At T+120, the battleground is defined with an HP over Scandinavia holding up progress of an Atlantic airmass oriented positively. A SE'ly covers all the British Isles at this time - positive uppers have already returned to Cornwall but much colder air remains in situ elsewhere with 850s below -12 in the north and generally below -8 over most northern and eastern areas. From there, the Scandinavian HP strengthens considerably and stays over southern Norway holding the Atlantic trough well to the west but with a SE'ly airflow over much of the British Isles tending more SSE further west. The push of milder air has been reversed with uppers of -4 to -8 back over southern and eastern areas and positive uppers confined to far western areas by T+180. From there, the Atlantic trough splits with a new system trying to approach from the south west but getting nowhere while by T+240 the HP has started to retrogress west and is over or just to the north of Scotland and drawing in an ESE'ly airflow to most parts. By then, the coldest air is over southern Britain with uppers of -8 close to the Channel coast while uppers of -4 to -8 cover southern and western parts. Conversely, 850s are only slightly negative further north. A brief attempt at a milder incursion is driven back and in the end, while not the brutal cold some might expect from the synoptics on offer, it's a very satisfactory evolution for a continuation of cold especially for southern and eastern parts which look in the "sweet spot" tonight. 12Z Control - again, no Parallel. T+120 follows OP and from there the basic evolution is very similar so that by T+180 an intense anticyclone sits over Scandinavia and the Atlantic trough has bene pushed back WNW leaving an ESE'ly flow over much of the British Isles. Uppers of -4 to -8 cover most of eastern Britain with positive uppers confined to Cornwall and the west of Ireland. As with OP, there seems a little mixing out of the coldest air as we move into next weekend but it's still pretty cold for many parts. As with the OP, Control starts the retrogression process after T+180 and by T=240 the HP is moving west out of Scandinavia and continues as an intense feature dragging in an increasingly bitter E'ly flow for southern and south western parts leaving much lighter winds over Scotland and especially the north. Yes, those are -12 uppers over southern England by T+240 with -16 uppers close by so very cold for southern counties into the week after next. It's rare I gasp at a synoptic evolution but this is very close to nirvana for cold fans - any brief less cold respite is swept aside by the Scandinavian HP and it turns even colder though not snowier into the week after next. That chart is almost perfection for cold for me - if we have a snow covered continent and snow lying over southern England, that synoptic regime is perfect for advecting the coldest conditions. 12Z ECM - why do I think this will be the fly in the ointment? I don't know but I have a sinking feeling (as might the Scandinavian HP). However, the T+120 looks all right - little concerned about a couple of shortwaves but hopefully they'll not get in the way. Uppers remain very low - generally -8 but with some pockets of -12 uppers over southern England. Here goes...from there, the HP over Scandinavia continues to strengthen and by T+192 core heights extend south west from Scandinavia to south east England. The Atlantic trough has been driven well back to the west and a light SE'ly air flow covers eastern and southern Britain with a stronger S'ly based flow further west and north. Milder air with positive uppers has reached northern and western Britain with colder air restricted to south east England. From there, the HP moves to sit over the British Isles with 850s either side of zero over all parts. As I feared, ECM is the fly in the ointment with the Scandinavian HP sinking rather than retrogressing. In truth, we have three different evolutions at T=240 and while we'd all love the GFS notion of retrogression to come to fruition, it's far form confirmed. That said, the colder spell looks set to continue through this week and into next weekend for many especially in the south east oddly enough. Looking further ahead, the T+312 and T+384 charts from OP and Control respectively: OP is cold throughout but Control lifts out the coldest air from the south further into FI. The two things on neither evolution are a raging PV and a zonal Atlantic and indeed heights persist to the north and east throughout. Conclusion: I was wrong - well, to a point. Those who argued the cold spell would last longer than seemed evident from the Tuesday 12Z runs were right. After an uncertain start, the evolution of intense heights over Scandinavia now looks assured and while the Americans offer nirvana, there's still caution from the Europeans and Canadians over whether retrogression can and will happen. The cold spell now looks set for a week and while the snow prospects may well diminish with time, the cold won't. The upgrades for cold fans since Tuesday have been significant and it doesn't need much more to extend this into a 14 day cold spell or more. The intensity of the anticyclone looks to mitigate against snow further on but very low night time minima across any snowfields under clear skies look entirely possible. I hope everyone gets the snow they want and some of the Regional threads will be wonderful in the next few days (hopefully).

Afternoon all I'm cautiously optimistic about seeing some snow in lowland East London tomorrow or Monday but it never stays for long with the urban heat island effect.