stodge

I don't think a "major" SSW was ever on the cards. What we are likely to see is another hint of a split but this time a less dramatic recovery - the zonal wind speeds forecast (15 m/s) are still on the low side of average - and this seems confirmed by the briefest of breaks in the Atlantic dominance in the last week of the month. March continues to show a prolonged further weakening back towards zero so you'd expect the Atlantic train to slow again with more opportunities for heights to build and amplification to occur. We could end up with a warm early spring or we might not. As we see, the response to a strong Wave 1 is to re-strengthen the vortex so the signs are March will see a gradual weakening which might be more conducive to blocking on our side of the globe.

Met4Cast Yes, I am firmly of the view Wave 1 warmings from Siberia (far more common than Canadian warmings) have regularly affected British winters for decades if not centuries. The PV is sent back to Canada/Greenland and we all know what happens then. This process of PV development, displacement via Wave 1 and eventual split either via an SSW or final warming has, I suspect, been the pattern for hundreds of years. As to why there are nuances - some winters see much less Wave 1 activity than others, I don't know. I don't know if there has been any study into how the polar vortex behaved 100, 500 or 1000 years ago. As to how it will behave in a warming world, I don't know either. A warmer atmosphere suggests more energy and more volatility so you'd expect more warmings but would it be weaker longer term?

Evening all A lot of negativity on here tonight and it's not hard to see why. However, we do have, based on GFS OP and Control, an "interesting" storm set to move over us at the end of next week which would doubtless be named whatever the next name is. Other models not so keen on the storm coming as far to the south but the Atlantic train rolls on into the last week of the month with yet more rain and wind as the jet edges back south. The vortex does continue to look weak with another strong warming later in the month so far too early to be negative about March and the seasons take little notice of the arbitrary definitions of when season should begin and end. There's also the not unjustifiable thought we might get our most favourable winter synoptics in spring - cold Easter anyone?

Evening all Still outside the reliable so only eye candy at this point but a much more unsettled theme especially later next week with a vigorous LP close to or over the British isles in ten days which in turn, as it clears, offers the possibility of a 3-4 day N'ly to close off February. The 10 HPA stratospheric charts continue to show a very much weakened vortex by month end and while I'm still very much of the view March will provide fascinating synoptics (as it often does) how this will play out for the UK in terms of cold vs mild (and it's that which defines March and the transition to spring most years) is far from clear.

Indeed, a very poor 12Z suite for cold weather fans. After what will likely be another exceptionally mild spell this week a hint of something more unsettled later in the month and indeed perhaps a stormy end to the month with hints (no more) of negative alignment and the jet inching south. March, we are told, goes "in like a lion and out like a lamb". Perhaps, perhaps not. The ongoing stratospheric developments do offer possibilities of a pattern change of sorts and as the PV will ultimately weaken in the month the likelihood of amplification remains. I always thought early March had possibilities and I've not given up on that because of one poor suite three weeks or more in advance.

Evening all Still seeing a distressed 10 HPA vortex in the last week of the month and fans of cold will be hoping for a rapid downwelling but I still think early March is the favourite for a pattern change. To be fair, plenty of the 12Z output teases at height rises to the NE (KMA tries the Greenland HP approach which looks too much too soon) but none of this is yet within the reliable so another portion of eye candy for the cold weather fans and another week of mild weather for the rest of us.

Evening all I yield to the greater knowledge of many on here. Early musings - I’m not a fan of Wave 1 warmings from Siberia as they serve only to knock the PV over to NE Canada/Greenland. Once the stratosphere and troposphere couple we have to wait for there to be enough strength to completely disrupt the PV and hope the tropospheric response is both quick and favourable. I suspect the recent tendency toward early and later cold spells while the traditional midwinter is Atlantic dominated is part of this. Could it be the Hadley Cell expanding north? I don’t rule it out but that would mitigate against hotter summers if we are looking in July for the trough to dip to the Azores and pull up a Plume? On a complete tangent, the long term evolution of the European climate, in my view, is toward something like the present day Indian Sub Continent. Back to this winter, we have also once again learned the lesson eye candy is nice to look at but too much of it makes you sick. How often in truth have the nirvana winter charts got to T+96 or T+120 which is where “reliable” kicks in. I suspect if we only had charts, models and forecasts which went, pace UKM, to T+144 we’d have been less emotionally invested in cold spells which proved to be a chimera. I also want to mention the demise of fog - how many foggy days have there been this winter? A warmer atmosphere would suggest more energy, more movement and more volatility and in time more cloud. The synoptic evolutions toward cold require the atmosphere to slow down and lose energy - even if we can get the right synoptics they don’t last. What we call “cold zonality” where PM air dominates is a more sustainable winter pattern nowadays than getting an anticyclone to sit over us for days creating inversion.

Indeed, I see very little this month but I think March is looking more "interesting" and while some on here don't consider it a "winter" month, 2013 and 2018 would disagree. The chips will fall where they may as a wise man once said and we may get an early spring out of the SSW but the likelihood of northern blocking in March and April is there and could work even at this late stage to the advantage of those looking for a final hurrah from a winter which has disappointed many. Again, I'm watching the synoptic pattern consistently trying to build heights to the north east and disrupting LP in the vicinity of the British Isles.

Surprising not to see more comment on the stratospheric situation. GFS 12Z OP has a clear 10 HPA split in far FI as has Control. Many questions follow, none of which I'm able to answer with my limited knowledge of these things but I would suspect our old friend Mr N. Blocking and party will be paying us an extended visit from March to perhaps May (who knows?). Nothing terribly unusual in that and of course for every 2018 there's a 2020 so a late winter could just as easily be an early spring. An early final warming? Again, too early to tell but looking at CFS monthly this evening, I'm drawn to the synoptic pattern which keeps trying to build heights to the north east and north with LP disrupting over or close to the British Isles. Snow for low ground? You'd bet against it. Snow for northern hills and mountains? You wouldn't bet against it.

LRD I'm afraid both you and @cheeky_monkey are wrong. Whether you like it or not, March is basically a winter month - remember the infamous BTFE was in March, March 2013 was an absolute cold and snow lovers classic. The back end of winter is probably now until Cheltenham - you know what they say, spring comes in behind the last horse in the Gold Cup !!

LRD In all fairness, most expected a back-loaded winter which really means from mid-Feb onwards. The early December cold spell was a bonus and the current 3-week mild spell (based on a mild January) was also well touted in early winter forecasts. I'd also argue there's a lot to be resolved and a lot happening so as ever more runs are needed.

Evening all Well, colour me none the wiser after this evening's output. GFS 12Z OP has certainly thrown a proverbial in the works with having the LP move away to the north - ECM is just a mess. GEM and some of the others keep the idea of the LP moving away east and heights building behind and moving into Scandinavia and I suspect that is still widely shown in the ensembles. GEM 12Z OP takes the energy south east into Europe and to be fair GFS 12Z OP starts down that road but the ridge quickly builds in from the Iberian HP and cuts the energy too leaving the main LP to the north of the British Isles and a small cut off LP in Europe and the mild airflow quickly re-establishes. There's a huge amount still to resolve especially for the weekend but certainly a much wetter spell for southern counties than we've seen in the past 3 weeks.

Just thought I'd pick up on this old chestnut. The saying "as the days get longer, the cold gets stronger" isn't entirely false. As winter goes on, the sources of cold air (north and east) get progressively colder and for the far north and north east, it's still dark most of the time so not much to warm the air. Thus, an early December easterly often has modest 850s while by late February we can still see -20 850s and as you rightly say, the sea can be at its coldest. MY cold nirvana is a SE'ly from a frigid and snowbound continent with the minimum fetch across the Channel - tonight's 12Z JMA at T+264 is nearly there but note the initial cold is often mixed out before the real cold arrives so it's often a waiting game to get the synoptics right before the real cold arrives. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5029878

Just thought I'd pick up on this old chestnut. The saying "as the days get longer, the cold gets stronger" isn't entirely false. As winter goes on, the sources of cold air (north and east) get progressively colder and for the far north and north east, it's still dark most of the time so not much to warm the air. Thus, an early December easterly often has modest 850s while by late February we can still see -20 850s and as you rightly say, the sea can be at its coldest. MY cold nirvana is a SE'ly from a frigid and snowbound continent with the minimum fetch across the Channel - tonight's 12Z JMA at T+264 is nearly there but note the initial cold is often mixed out before the real cold arrives so it's often a waiting game to get the synoptics right before the real cold arrives.

Once again the vortex at 10 HPA this evening looks like a boxer up against the ropes but by T+384 it's got a new opponent raining in punches with a European warming building strongly. By then, on the 500 HPA chart, the core of the vortex is at the Bering Strait which does nothing to hinder Greenland height rises.

Evening all It would sometimes be nice, if boring, if all the charts said the same at T+168 and could all verify. That may happen one day but not yet. Quite apart from Thursday and Friday's drama (on which I'll leave others to muse though the UKM chart did cause even Mr Stodge, here in lowland East London, to raise an eyebrow), what we need I suspect is for the heights building to the north west behind the LP to move through cleanly and quickly into Scandinavia and not linger round the British Isles. If that happens, we'll get the nice Scandinavian HP we se eon GEM and JMA but both GFS OP and ECM are messier to say the least. Plenty of angst and anguish to get through in the next 48-72 hours I suspect.

Evening all A lot of eye candy on offer tonight - the 12Z GFS Control takes the cold potato award with classic retrogression which of course never happens. The key seems to me the build of heights in mid Atlantic after the LP has gone through the British Isles - doubtless rain for lowland East London but I'd like to think someone somewhere to the north and especially with some altitude is going to get some snow. Huge amounts to be resolved and GEM OP shows what a non event would look like. The 10 HPA charts suggest a stratosphere in some distress and the expulsion of the vortex shown on the 12Z GFS Control is a thing of beauty.

BIGDOG2 Well, a little caution is never a bad thing but I've even heard people say it's a downgrade at T+6. I don't have a clue looking at tonight's output - it's confusing even at the 7-10 day stage let alone beyond. There's a strong warming in the mix but what strikes me is the rise of heights to the east causing the trough to sit over the British Isles so if I had to put money on the forecast (and very nice money it is too) I'd be in the cold and unsettled camp. Probably rain to lower ground in the south but with altitude further north, snow looks a possible option. Beyond that, all I'll say is GFS 12Z Control is a thing of beauty in far FI - it's the sort of evolution you want to take home and introduce to your parents. T+372 has -12 850s over the British Isles - time to book the Abbey?

Evening all Recognising it's been frustrating to see a significant part of winter pass under benign mild nothingness but clear indications this evening of "doings a-transpiring". The jet, slowly but remorselessly, is to be pushed south next week and that will turn our weather increasingly unsettled once again. Into FI and I see another powerful warming forecast at 10 HPA but the trop response seems as yet to be finalised. It may well be messy - when isn't it - but the thrust of colder but settled conditions from the north suggesting the core of heights becoming centred more to the north than over Iberia. That's far from a done deal but we are, to this observer, very much still in the game.

All I can offer is the 12Z GFS OP seems to be building another strong warming, first from Europe then migrating to Siberia. I don't like these unless they can knock the PV far enough over to central and western Canada to enable heights to build over Scandinavia - one or two little hints at that in the middle of next month.

Evening all Oddly enough for all the excitement about the GFS 12Z OP, I much prefer Control as it fully flushes the vortex out of Greenland and leaves a moribund Atlantic which offers the possibility of an extended colder spell. At this stage it's all speculation and hopecasting.

Evening all As I often say, the route to very cold usually starts from very mild with the displaced Azores HP serving to put pressure on the vortex enabling other events and factors to come into play. Given the focus of LRFs was on a back-loaded winter, I fully expect a cold early March which will annoy many but the weather does what it does.

Far be it from me to say you're wrong but you could be wrong. So much depends on the orientation of any block. An elongated block does allow colder, drier continental air to be advected from the south east over especially southern Britain (I'm in East London so shameless local plug). There's also as always the possibility of fog and frost (what is termed on here faux cold) under an inversion so while I appreciate for snow fans this is all horrible for cold fans it offers some possibilities. Oddly enough, I wouldn't want to see the HP move too far NE as the shorter the sea distance for the airflow the less likely it is to be diluted by a passage across a relatively warm (even then) stretch of water.

Evening all So ECM, GEM, GFS OP and GFS Control in the 12Z suite all derail the Atlantic train next weekend. Far too early to be anything more than eye candy but perhaps a well-signalled sign of how we break out of the pattern coming in over the weekend. The big question as always is or will be the strength of the northern arm of the jet - it may well be it'll take two or three attempts before a Scandinavian block can fully assert but it's encouraging for fans of dry in particular and cold to an extent to see the trend. I'm not keen on another Siberian warming emerging in early February as it rarely ends well unless it can do something significant. Baby steps for now - many will welcome the dry trend to the weather especially in the south and east after the December deluges.

Inasmuch as recent perturbations have weakened the stratospheric vortex, yes, I entirely agree. I'm hoping the tropospheric mechanisms will be more relevant going forward (as they often can be in early winter) and the hints tonight offered by FI on the GFS 12Z suggest a possible path which demonstrates having a strong PV isn't the be-all and end-all (it wasn't in 62-63 after a much stronger Canadian warming).