stodge

At least I'm in good company being 24 hours and 17 pages on and still far from clear how the second half of the week is going to develop. In lowland East London, I never expect snow - whether I'll get any time I've no idea. It was much colder today (5c and with a notable windchill) but that's still a step off lying snow. However, many on this forum live further north and some have the additional advantage of altitude and I can completely appreciate the excitement. The exact passage of Wednesday and indeed Friday's LP are still far from clear and all points north of the midlands look to have a chance of seeing lying snow while Scotland and especially the higher ground look pretty much set for snow. Between the residual cold bloc and the Iberian heights, the trough, as others have said, elongates through the British Isles - as both sets of heights relax at the end of the week, the LP can push through with a further brief but potent NNW'ly air flow. Beyond that, it's mid to late March and the PV is in shreds - I think we all knows if you're going to get northern blocking this is the time and conditions for it and with the PV so weak, heights rises over Scandinavia can't be ruled out - still plenty of interest.

Evening all 24 hours later, 16 pages later and one sense of deja vu later - I'm still none the wiser. Wednesday-Friday looking very complex and messy across the models - some bring back milder air quickly especially for the south while others keep colder conditions going or return colder air after a brief milder incursion. The fact is these type of cold outbreaks don't usually last - the energy which creates them rapidly dissipates and we are relying on a strong Greenland ridge to keep the jet stream and Atlantic systems crossing over or just to the south of southern Britain. A strong build of Iberian heights tilts the trough further positive and pushes the milder boundary north. Beyond the immediate snap/spell, GFS quickly dissipates the Iberian heights allowing the Atlantic LP to move in and the trough sets up across southern Britain keeping plenty of cold air over northern Britain - indeed, I'd argue the GFS 12Z OP is a stellar run for Scotland especially the higher ground. Just seen the ECM 240 - a very quiet Atlantic and heights to north and south - a very different evolution certainly compared to GEM and JMA at the same time. It's probably fair to argue the models are still to converge on a clear resolution and even at T+96 we have some considerable divergence.

Evening all 24 hours and 16 pages on and to be blunt, I'm none the wiser. ECM offers a rapid return to milder SW'lies after the briefest of cold incursions yet against that you have both GFS OP and JMA where the cold never really moves off. To hold on to the cold, you need either an LP in the north Sea to keep the N'ly flow or the jet stream angled to push LP through the Channel. The key probably is to see a much more timid push of heights from the Canaries to Iberia - ECM pushes a serious HP into Iberia (I can see why @Tamara likes it given her location) and that's it for cold for NW Europe but a more muted response keeps the cold over northern Britain and makes the south a possible battleground (with all that might or might not result). The strength of the ridging from Greenland also helps to steer the LP onto a more E'ly rather than NE'ly track so there's lot to look at. I have to say in far FI the GFS OP offers some very interesting synoptics for a "reload" with the PV over north west Siberia and the possibility of some Atlantic ridging - one to watch as the models continue to take into account the impact of the recent SSW and the sustained drop in zonal wind speeds which will again serve to promote amplification. Will I be any wiser this time tomorrow evening? Possibly - I will be older though.

Evening all I said a few days back there was a lot of risk and reward about the synoptic evolution. Despite some ready to throw in the towel last weekend, the colder evolution from the north east has prevailed - this is a pattern we do see but often further into spring. The problem is making it last beyond 3-4 days - as the Atlantic tries to move back, the HP ridges in to Iberia and turns the tilt positive bringing the mild SW'lies back in. It's not a west-based negative NAO in the strictest sense - the best we can hope for (and it's shown on some of the output tonight) is the north remains cold with the core of LP crossing through the Midlands or further south with milder air on the southern flank. That creates a large temperature divergence through the British Isles - below freezing in the far north to double figures on the south coast. GFS 12Z OP quickly brings back a new Scandinavian HP - an interesting evolution and what you'd expect in a post-SSW situation. The zonal winds are suppressed and the PV remains fragmented. Plenty of fascinating model watching in the days ahead.

Mrs Stodge's mother got her power back after six days last Monday. The disaster has left a deluge of silt covering the land including the valuable agricultural soil. Unfortunately, eleven people are confirmed dead with eight still missing. Roads remain closed and bridges remain down cutting off access to many areas but it's improving slowly. Looking at the latest GFS it seems the next cyclones forming off New Caledonia and Vanuatu will stay to the north of the North Island but that doesn't mean no impact from wind and rain.

I think UKM is interesting tonight - unlike both GFS and ECM with the core of HP much nearer Greenland and offering a quicker route to a glancing Northerly.

Evening all It looks like a classic Mexican stand-off tonight - the GFS kid versus the ECM gang. UKM sits on the sidelines playing its own hand. The differences re enormous - arguably they start with the atlantic profile - GFS has a much weaker atlantic and this enables the HP to relax west and opens the door for the Northerly. With ECM and GEM the LP sweeps in as the HP declines through the British Isles. Which way will this go? I have no clue. For now, we have the HP just to the north of the British Isles and there's a cold flow over Europe - heavy snow in Germany currently and -8 850s over southern Britain tomorrow. UKM at T+144 looks different to both GFS and ECM to add to the confusion.

The evolution from the sinking HP is what's of interest as the ECM Control run suggests. With nothing in the Atlantic to fill the gap, it's eyes to the north as the colder air follows in after the HP. The nose of HP out of Greenland prevents the Atlantic systems making inroads and we have a short-lived col before the northerlies arrive.

Evening all More interesting output this evening - if we accept for the moment FI starts at T+120 we have the HP centred just to the north of the British Isles and a chilly E'ly flow across the south. Needless to say, tonight's GFS 12Z OP has drawn plenty of interest and deservedly so - it's very much and example of everything coming to those who wait. It's also said patience is a virtue but it's been fraught for those looking for a quick trop response to the SSW. In truth, you don't really want a quick response - IF you get the trough to drop from the north over the country it rarely lasts as it pulls in a W'ly flow. Indeed, those wanting snow might prefer a prolonged period of chillier conditions to get everything in place. That's the thing - the risk is high and the reward is brief (you can say that about so much else in this life). The key is to hold the northern blocking in place or at least to the north west to bring the LP systems south.

The problems will presumably be where the two airmasses meet - over there, it's the most violent of storms, the tornado, which is the consequence of that conflict. It's clear from that chart the usual suspects in "tornado alley" will be in the firing line,

Thanks for the response and as someone else has commented, we do actually agree. The one thing I would say is in such a dynamically fluid situation to imagine you would get agreement beyond T+144 is ridiculous. We know that options begin to diverge after that point so anything after that is just speculation so all we can do is argue about someone else's computer-generated scenarios. Being dogmatically certain, one way or another, whatever your preference, about a chart for March 4th on February 22nd is ridiculous - we know that. If we only saw charts to T+144 (UKMO) and no further the discussions on here would be pretty sterile. Yes, it could all go "wrong" (as the majority wanting cold or snow on here would say) and as we've seen in the past, even at T+6 there will be those unconvinced but if we see the synoptics at T+96 I begin to get interested. At the moment, all I see for sure are heights rising to the north of the British Isles - a few days ago that led to a build into Scandinavia but now it doesn't as the signals have changed and the data has improved closer to T 0. For me in the far south that means an E'ly wind and a likelihood of chillier conditions into the weekend - ground and air frost if we get clear skies perhaps. Hopefully some sparkling late winter sunshine otherwise it'll be dull and overcast (you never quite know with easterlies)

I really don't understand this comment. How do you define "consistent & strong" and how do you define "proper cold weather" ? There is a strong and consistent signal for a build of heights to the north of the British Isles and that's about as far as I would go tonight. There are plenty of models offering full retrogression but not all (GEM). If retrogression is achieved, what then? ECM, GFS Control and JMA certainly offer the prospect of a cold incursion from the north and north east but GFS OP for example moves us to a west-based NAO, at least for a period with a potentially much milder but very wet spell for England and Wales while Scotland remains in a colder regime with snow especially to higher ground. Given I have experienced lying snow in East London at the end of March, I don't rule out the possibility of a repeat - the more sensible option would be to suggest any incursion of a colder regime is likely to favour snow in the north and especially over higher ground so the Highlands, Pennines etc would be favoured (as you would expect). How long such a severe spell would last I don't know - to get even a week of severe cold is difficult and I suspect we'd soon see the really cold uppers mixed out in the south. The after effects of the SSW (in terms of northern blocking and a weak Atlantic) may be with us for several weeks but as we know such patterns aren't uncommon in April and May.

Evening All Justifiable interest now as a pattern change seems to be coming into view. After a brief NW'ly midweek heights will build through the British Isles into Scandinavia through the end of next week into the weekend. From there? Who knows? Some have suggested a benign SE'ly or even S'ly air flow - maybe - it seems more likely heights will extend west and north west toward Greenland. GFS OP does this but it's all too quick and we end up with a West-based negative NAO and that's always a possibility. GFS Control is much better for cold fans with the trough setting up nearer the British Isles and very potent N'ly for the first week of March. The continuing fragmentation of the PV suggests no quick return to the usual pattern and we'll just have to see if we can sustain the colder conditions for more than a fortnight - even if we don't initially, the likelihood of northern heights will continue to keep colder synoptics in play.

Evening all To be fair, a lot of the good forecasters have called this well in terms of us having to endure a period of uninspiring charts before the more eye candy looms on the horizon. GFS very much leading the way on the 2 suite and it seems a midweek cold or cooler snap may be the precursor to something more interesting at the turn of the month. The many and varied signals do need to align perfectly (s we know) for the possibility of something memorable for March but with experience showing lying snow perfectly possible even in London at the end of the month and ice days possible in the middle of the month the old adage of the cold growing stronger as the days get longer may yet be apposite. We'll see - heights over Scandinavia look the favourite in the medium term - I understand the talk of a Greenland HP nd it may be the traditional path of retrogression will be what's needed.

Mrs Stodge's mother is in Greenmeadows, near Napier and Hastings, in the Hawkes Bay region. First thing, she is fine - she is in a retirement village which didn't get flooded and she didn't have to evacuate. The village has no power apart from a generator at the main building which is powering the kitchen where they are working overtime to make meals and hot drinks for the residents and they have Wi-Fi. Hopefully @Karyo is okay but the power went off across the whole of Hawkes Bay on early Tuesday morning (local). The main sub station serving Napier and Hastings is submerged and it may be several days before power is restored. This morning, authorities are saying up to a week. Gabrielle has been an extraordinary weather event with the LP centre moving SE from just east of Cape Reinga down the coast through the Hauraki Gulf and passing to the north of the East Cape. To the south of it (remember we are in the Southern Hemisphere) very strong E'ly winds battered the east coast of the North Island and very heavy rain accompanied the gale across the east and north of North Island with the heaviest falls in Coromandel, around Gisborne and in Hawkes Bay. There are severe thunderstorms forecast today for the Bay of Plenty as an upper level residual trough passes west to east. Winds gusted to 130 km per hour in the far north and around 90 km per hour at Napier. I've not seen accumulated rainfall numbers but would expect 200-300mm to have fallen quite widely and perhaps up to 400mm in the Ruahine Ranges and the Esk Valley. So far, five people are confirmed dead and there are serious concerns this figure will rise as the authorities reach areas which are currently inaccessible.

GFS has the centre over the Bay of Plenty for 36 hours - Cyclone Gabrielle could bring more very heavy rain to the Coromandel with up to 300mm (basically a foot) of rain. The storm is then due to impact Hawkes Bay, Cyclone Gabrielle set to reach 'severe' category 3 status | Stuff.co.nz WWW.STUFF.CO.NZ The cyclone is forecast to hit Northland before rolling into Auckland and "dropping down" to Hawke's Bay - with bad weather set to begin from Sunday.

The line of sub-tropical N'lies bringing active troughs and moisture has shifted slightly west and is now impacting the west coast of the South Island with very large rainfall figures for Westland and Fjordland over the weekend (which is a long weekend in NZ with Waitangi Day early next week). However, a secondary LP passing close to the tip of South Island to introduce a complete change to cooler SW'lies during next week. GFS predicts a new tropical storm will form just to the south of New Caledonia and head SE but it looks currently as though it will pass to the north of New Zealand but there may be some impacts in terms of rain or showers.

Evening all More fascinating model watching tonight. Even the emerging anticyclonic profile is still subject to change and perhaps there may be a stronger incursion of continental air into southern and south eastern Britain in the coming week. It looks dry but that's a no-brainer with a 1040 MB regime in evidence. Further on and we continue to see the longer range model (GFS) tease and tantalise with weakening 10 HPA profiles and the zonal wind clearly weakening. None of this guarantees anything and as we've seen before even an SSW is no guarantee of cold but anything which promotes amplification upstream is going to put us in the game if it turns out right and while I did hope mid-February would be the pattern change I think we are again looking at early March which as we know can certainly deliver in terms of cold and snow. I don't know what's going to happen - as others have said, there are positive signs and we can but hope the elements to promote a cold spell fall into place at the right time in the right way.

Evening all Certainly looks an extended period of anticyclonic weather in the next 7-10 days with little if no rain for many. As for how we break out of that I presume we will have another longer or shorter period of W'lies before the next pattern change. For those who argue March can't deliver, 2008, 2013 and 2018 would disagree at least in my part of London - I certainly remember March 2013 as being an exceptional month with an ice day on March 11th and heavy snow in the Channel Islands and far south east of Kent. Are we building a little sequence here of cold March spells? To be fair, there are some interesting developments in the stratosphere and perhaps aligning with a favourable MJO to offer some "possibilities" but it's no more than that.

Evening all Again, one or two flickers of interest (GEM and to an extent ECM). To this observer, it's simply a question of whether those wanting colder conditions can catch a break in terms of the jet slowing enough to allow heights to build over Scandinavia and then not flattening them with the next push. Seeing more Wave 1 activity toward mid month on the GFS makes me think we won't get lucky and it's all still outside the reliable (look at the T+216 charts from ECM, GEM, GFS, CFS and JMA if you want to see the variation in evolutions or rather five ways to skin a cat). I'm also far from convinced we'll get from now to the middle of March without some form of colder outbreak though the severity and longevity is of course quite uncertain. We may have to wait a while and thos heading for Cheltenham might need to pack something warm:

Evening all As I feared, last night's "signal" for height rises into Scandinavia is more muted and any such rises are quickly flattened by the strong northern arm of the jet. As others have also mused, some of the other pieces of the jigsaw are just not there for the next fortnight. That's a huge way from calling time on winter as a whole and while many on here aren't enthused about a cold mid to late February, we often see a colder interlude or interludes between the increasing warmer trend that marks the transition from winter to spring.

It actually called the breakdown consistently from T+384 down on the 12Z OP when other models were looking to prolong the very cold spell well into January 2011.

Evening all I thought tonight's output might provoke some interest though it seems a less than stellar ec46 (I mean, really) and it's all doom and gloom once again. I can accept for snow fans it's a long journey to nirvana but for fans of cold the build of heights into Scandinavia (whether we may it to full HLB or end up as an Upper MLB) is an encouraging development. Let's not get too excited or ahead of ourselves - signals come and signals go and one or two rubbished last night's GFS 12Z OP in far FI for even postulating a Scandinavian HP but of course GFS goes out to T+384 and perhaps there's a lesson here about an OP seeing a scenario before the Ensembles and we shouldn't be too quick to disparage an outlier OP specially if it repeats the signal over the next series of output. The fact is we are seeing more hints of a build of heights into NW Europe and possibly into southern Scandinavia across a number of models at the T+240 timeframe so still a long way off - if it's there and across all models (especially UKM) at T+120 we can start taking it seriously (cynics might say even T+24 is taking a chance). Yet it may be gone this time tomorrow only to return in a few days - that's the nature of it. IF we get the synoptics right there's plenty of cold air to tap into and I'm sceptical because the continuing Wave 1 attacks on the PV should be keeping it strong and in the NE Canada/Greenland area but if this is a trop response to other developments we could well be in with a shout.

Evening all Forgive my ignorance on this but I've always thought the continued Wave 1 attacks on the PV at 10 hpa don't do us any favours because all they do is send the PV back to Canada/Greenland. At the far end of FI, we are seeing the end of that and the much diminished PV is left staggering round. I'm therefore thinking 7-10 days after that is when I would be expecting us to get to some favourable conditions for cold weather fans. I don't know if the strat is coupled to the trop currently (or really what that means) but the Wave 1 push from Siberia keeps the PV in NE Canada and maintains a strong jet through the North Atlantic - I think we're in this position for the next 2-3 weeks. I've thought mid-Feb was when we would see a decisive pattern change to some late winter cold for the British Isles - the softening up of the PV and the consequent relaxation in zonal wind speeds are part of this but we do need other pieces of the puzzle (MJO) to fall favourably.

Evening all Here in East London no fog as yet - it's the one thing I've observed in the last 20-30 years, we have fewer instances of fog than was the case. I assume that's down to a warmer, more turbulent, more energetic atmosphere. The days of midwinter anticyclonic "quiet" weather have largely gone and I regret it - there's a lot more to winter than just snow. Another hard frost beckons tonight - this will be the sixth in succession. Last night's was very sharp and as others have remarked, the frost never cleared in shaded areas. Last Monday night's frost was the most severe of the week and didn't even clear in the sunshine on Tuesday and Wednesday with any residual water readily turning to ice. That was accentuated by the cold NNW'ly wind through midweek - today has been calm and in the sun hasn't felt too bad but chilly in the shade. Two very different winter cold spells so far - the snowy mid-December (four inches in East London) and now the frosty mid-January. Plenty will complain it's been a bad winter for them in terms of snow and frost - not me.