stodge

Yes, the next pattern change to a westerly-based regime was and has been well signalled and those hoping for some continuation of the cold were really clutching at the flimmiest of straws. As to the week beginning 22nd, mild or very mild conditions but much windier and probably dry for much of the south of Britain. Further north, a likelihood of rain though not in large quantities but again probably strong winds the main feature. At the end of the month, who knows? It's far too early to come up with ludicrous assertion that the chances of lowland snow have gone - there's the small matters of February and March both of which (oddly enough more the latter than the former) can deliver snow for many. On a personal note, we are overdue a traditional cold February - will 2024 be one?

Evening all The clear story remains a slackening of the colder conditions by this time next week. Beyond that a potentially stormy week across the north of the British Isles with rapid cyclogenesis spawning some vigorous and intense LP running in the powerful jet stream just to the north of Scotland. Just a hint perhaps in the far distant of FI of a slackening flow in the jet aloowing heights to build from the south - whether this will translate into an attempt to build a new block through Scandinavia remains to be seen but it seems to reflect the next attempt to push the PV to Siberia and weaken the core over Canada/Greenland sending it more over the Pole. Very early days and may come to nothing but something to keep an eye on but we have to enjoy or endure 7-10 days of mild or very mild Atlantic-dominated weather.

If you want a laugh, go and look at the CFS 12Z for the month. Lots of cold starting as early as January 31st. Mild spell? More like blink and you'll miss it.

Evening all Plenty of depsondency on here this evening though to be honest the notion of the cold being maintained past next weekend was always marginal at best. I love NAVGEM 12Z as it at least keeps us cold to Saturday. My view is the prolonged Wave 1 warming has sent the remnants of the PV over to Canada/Greenland dispersing the warmer uppers from Greenland and encouraging explosive cyclogenesis off Newfoundland as warmer and colder airmasses collide. We could very well have a 14 day milder spell or interlude but the PV remains distressed at best and the chance of a cold outbreak in February remains very much on the table. As for snow this week, don't know - certainly in northern Scotland and on higher ground - as for prolonged disruptive snow to lower ground it doesn't look like that type of breakdown. More of a whimper than a bang as the cold flow dies away, we have a col and a short lived final ridge (could be very frosty next Friday and Saturday for example) before the Atlantic systems arrive and we return to more typical winter conditions with rain and wind and it could be quitre stormy to end January.

The GFS 12Z OP fully illustrates how battered the vortex could get: The predominantely Siberian warming ongoing is going to lead to a relaxation of the cold in our part of the world early in the week of the 22nd but the renewed assaults in that week will I hope (and it is only that, nothing is guaranteed) offer some possibilities in early February. The question then becomes what recovery we will see through February - last year the PV recovered strongly from the warmings in January.

Evening all Some disappointment and the ritual throwing of the toys out of the pram it would seem. As I said last night, the evolution in the south was always going to be one of risk and reward - it looks as though the colder 850s will reach the south on Monday and then perhaps get pushed slightly back north before a second dig south and even by the end of next week (an eternity away in model terms), some still hold the cold air in place (NAVGEM, UKMO possibly even ECM). The nature of any snow events is best left to nowcasting - whether I see any in lowland East London is largely immaterial. My expectation is a transient covering but no more. Those further north and with altitude can expect something better but again the devil, as always, is in the detail. Maintaining the cold through the 20th and beyond was always problematic and a relaxation was well touted by the experts for the week beginning the 22nd and fans of winter may just have to accept this will be a 10-14 day cold spell at best. As to the extent and longevity of any relaxation, the weakened PV at 10 HPA is there for all to see on the GFS 12Z OP as are the weakening zonal winds and those suggesting early February might have something good to offer for fans of winter weather still have plenty of cards left in their hand. It seems "clean" retrogression remains a chimera - this time we've been afflicted not so much by a shortwave as by a lobe of heights moving SE into northern France which interrupts the northerly feed especially across the south. It's more a pause than a break and as the LP approaches from the south west it elongates and disrupts through Wednesday and into Thursday and that's when the fun may or may not begin,

Evening all Another day and I remain none the wiser for next week. If I had to put my hard earned on a forecast, I'd say cold all in the north and midlands. For the south, starting cold, a brief milder spell midweek and the cold returning south by next weekend. GEM 12Z OP is my evolution of the day - GFS continues to be on its own and let's be fair, it could be right. I think Friday's 12Z runs will be key to detemrine the path through midweek next week. Some interesting hints of new height rises over Scandinavia and I remain convinced if we get a moderation in the cold in the last third of the month we'll see another cold outbreak in early February. Huge amounts of detail to be resolved at this time.

Tonight's GFS 12Z shows the vortex under further assault but this time from a European warming in FI. I would assume that would clear the way for Scandinavian height rises in early February. The Siberian wave 1 warmings will send the PV back to Canada and lead to a relaxation of the cold probably from the 22nd-25th onwards for maybe ten days before we see new height rises over Scandinavia in early Feb. Just my thoughts...

Evening all Have to say 24 hours on and I'm not really any the wiser about the coming weekend and into next weekend. Will we even get a cold spell? (GFS says no, the rest are still on board). How long will it last (till the end of next week or perhaps beyond?). Will we see snow? (prospects for the midlands and north currently look reasonable, further south, as I said yesterday, huge risk and reward).

That's the point, though. Most snow events in southern Britain are very marginal - we talk with awe about December 2010 but that was incredibly rare. The snowfall of February 1st 2009 was just as plentiful in my part of London but very marginal - on that occasion we were on the right side but you know the great big snow flakes tell you it's marginal. The evolutions being put forward by the models currently emphasise that risk and reward. That can even extend to rain at sea level and snow at 100m (November 2009). As to whether (so to speak) we will be on the right or the wrong side of the snowline I honestly don't know but for me the most favourable synoptic for southern snow remains the elongating and disrupting Channel LP bumping up against entrenched cold air - that could happen, the line might equally be over the Midlands or even northern France.

Evening all A mixed bag of 12Z output as you might expect with an eternity until next week. Hopes of a clean retrogression of the UK HP to Greenland have been dashed ans we have to "wait" for a final LP to pass between Greenland and Iceland before we can get som traction and that runs the risk of pushing heights south east rather than north west. That said, on most of the models (JMA looks the exception) we sort of get there in the end and the fun and games begins as the trough drops from Scandinavia towards the British Isles as Atlantic LP approach from the south west. As I've said here before, the key is for the N'ly to be sufficiently robust to force Atlantic LP to elongate and disrupt along the Channel. It's frighteningly fine margins as others have said. For the south, it's enormous risk and reward - the risk is the cold airflow hangs too much to the north but the reward is if it's doesn't... For the north of the British Isles, the certainty of cold is much greater - that may be counted by a paucity of snow (again for some). This is all detail which probably won't be firmed up until Thursday. As for longevity and severity, we often see an almost default "bring back the Atlantic" and the currently moribund jet seems to be fired up presumably by colder air over the north east of North America (this is evident on the GFS 12Z OP but ECM 12Z OP keeps the storms spinning back north west over Canada). It's upstream to which I think we have to look. The crucial difference is GFS spins a low out of Newfoundland into the Atlantic at T+240 and brings the whole PV (or rather what's left of it) over to Canada/Greenland (response to a Siberian Wave 1 warming?). ECM at T+240 keeps the North American lobe of the PV well over Canada keeping heights over Greenland and maintaining the N'ly over North-West Europe. Lots of uncertainty into next week but it wouldn't be fun if every chart was identical at T+288, would it?

Afternoon all Nice to see some sleety snow here in East London though nothing has settled in the urban heat island.

Evening all Certainly very chilly in East London this evening. A positive end to the day it seems - to state the obvious, we aren't there yet. If we are still in this position on Thursday I will certainly be on board. As to longevity and severity of the cold spell ftom 14th-15th onwards, that remains to be seen. Tonight's chart of beauty was GEM 12Z but a lot of the models playing with favourable trough development. It bears repeating but the key will be to have enough strength to the northerly or north-easterly flow to encourage Atlantic LP systems from the south west to elongate and disrupt along the Channel. That's the snow nirvana for southern and south western Britain.

Evening all Here in East London, I wouldn't be surprised to see snow falling tomorrow but I'd be more surprised to see any lying for any length of time.

Just noting on the GFS 12Z another strong warming at the end of FI but centred on Europe and western Russia rather on Siberia. I don't like Siberian warmings as they can knock the PV back towards Canada/Greenland but a European warming is very different. Any thoughts?

Evening all Worth re-iterating the rather tired comment - we aren't there yet. A mixed bag from the 12Z output - GFS OP is a thing of beauty especially for snow fans in the south. The key to a successful retrogression is not just getting in the N'ly (or NE'ly) but that being robust enough to force the Atlantic LP systems from the south west to disrupt and elongate along the Channel giving the south a real opportunity for snow. ECM doesn't looks as friendly (though I've seen worse) and ends on a knife edge at T+240. The problem is of course the dreaded shortwaves which may or may not be well forecast. ICON showed what can happen if they aren't there but GFS has had them regularly for the past few runs albeit on the 12Z OP it's very much a case of getting there in the end. JMA looks very good this evening as well and let's be fair - we are desperate to nail down T+168 but we know evolutions change and can change radically until we get to T+72 to T+96 which means Tuesday or Wednesday before we start seeing something we can start to rely on. That means an anxious 96 hours for model watchers and especially those watching every twist and turn. There are always outliers and "poor" runs which challenge the concensus (or should it be hopesensus?) - it's encouraging to see so many of the other background signals remaining solid. It's easy to put a lot of faith in an OP - it wasn't that long ago some OP runs were even doubting a southern Scandinavian HP or putting it over the Faeroes - the models suddenly firmed up en masse (or en bloc if you prefer) at T+96 so the Wednesday and Thursday 12Zs (which are the only runs I look at each day) will be critical as to whether we a) get a notable retrogression, b) it's a glancing blow or c) we miss out completely.

Evening all I see as soon as a hint of a shortwave appears some go into full panic mode. Overall, it remains very solid and secure from this weekend's all too brief Scandinavian HP to mid month retrogression. It's worth re-iterating - retrogression is risk vs reward in extemis. IF it occurs cleanly it can deliver snow and cold to the majority of the country but getting there let alone keeping it in place for any length of time is fraught with risk. We may get a very cold and snowy week and that will be all though in truth that wouldn't be a bad outcome. The risk is BOTH from the Greenland HP AND the Scandinavian trough. Keeping both in place to allow and extended period of north of north east winds is going to be difficult - the tendency is for LP to form over the British Isles and pull a W'ly flow back in to the south while the HP pushes towards Canada and we lapse into a west-based negative NAO. I have to say the weakness of the Atlantic looks to be a big plus - the notion of deep LP coming up from the south west seems not to be a runner and that helps the ridge coming SE from Greenland which pushes Atlantic systems to the SE and keeps us on the cold side of the street. In any case, January 15th is still T+240 and that's an eternity away. We will likely get the Scandinavian HP in place and some form of retrogression attmept looks on the cards but I wouldn't want to be dogmatic about the extent and longevity until Wednesday or Thursday next week and there's no need to get agitated every time an OP run shows a problem. It might well take two attempts (and possibly be better for it). MY favourite charts of the evening from the much maligned South Korean model: To be fair, there are plenty of other excellent charts as well.

Worth re-iterating the Greenland HP option is fraught with risk. The notion of a west-based negative NAO has to be there in calculations - it's happened plenty of times before. Keeping the synoptics in perfect alignment for an extended period isn't going to be easy. The UK HP could sink back SE and there may be no retrogression at all - another risk but not being well supported currently.

Evening all We aren't there yet though we are getting closer and the cross-model consistency through to T+144 is unusual and impressive. The big question remains what kind of retrogression (if any) will we get? The ideal is not to have the trough get too close to eastern Britain as that invites LP formation over the British Isles and pulls the winds back round to the west or south west across the south. Keeping the trough to the east and maintaining heights to the west and north west (and especially the ridge SE out of the Greenland/Iceland HP) is the key to maintaining the cold N or NE air flow. It can be on a knife edge - both GFS and ECM OP show that this evening. If the LP to the south west can come north, it will break the ridge and effectively we'll in a west-based -NAO but if heights and the N'ly airflow persist the LP elongates across the Channel and the prospects of snow across the south and Midlands are significantly enhanced. As we saw in 2018, it can come down to a stark choice - cold without snow or snow followed by a quick thaw. However, with perhaps a slight relaxation, we are looking at a 7-10 day spell of below average (and perhaps significantly below average) temperatures which would be notable at the least - whether it becomes memorable is far from certain. However, GFS Control prolongs the cold and it does offer at the very end of FI height rises over Scandinavia which would be the nirvana for the cold fans. Oddly enough, I'd almost argue we don't want retrogression to happen too quickly as we need all the pieces on the board to be where they need to be.

Evening all Without wishing to belabour the point, we aren't there yet. The T+120 charts show a strong uniformity across the models but what I find interesting (and I only look at or follow the 12Z output) is the option of centering the HP on southern Scandinavia has suddenly sprung on to the table like a leopard at Sunday lunch. Previously, we had some models with the HP over the Faeroes while others went straight for a UK-centred block - now suddenly it's southern Scandinavia. That brings colder air over more of the UK at once and it will be a chilly if fine weekend especially across the south where for all the wind and rain it has been anomalously mild this week with daytime maxima around 13-14c. To bring that down to 4-5c (with windchill) will be a shock for many and we even see some frost. Easterlies may start fine but often pick up cloud for a spell before drier air follows. The $64,000 question then is retrogression. Whether, when and to what extent? GFS 12Z OP gets there but it's a brief spell as the HP detaches and comes back south pretty quickly. It's brief on Control as well as the vortex core shifts back west from Siberia to the Pole and we get stormy Atlantic conditions returning. Glancing at the ensembles, some don't even make retrogression while P29 (as someone has already said) would bring a week of unremitting winter and few would miss snow. The weekend is looking pretty well set as you'd expect at T+120 but after that it's still very much up for grabs. For those wanting cold and especially cold and dry, the weekend is going to deliver for, if not a record breaker, -8 850s in January are going to be chilly enough. For those wanting snow, retrogression remains the best hope but that's a dangerous game. The N'ly or NE'ly may well set up and could well deliver for many (especially but not exclusively on high ground) but it's tenuous and the breakdown may well not deliver either. More runs needed (and somebody once said).

Evening all More decent output though obviously still plenty to moan about for those who like a good moan. The pattern of UK HP followed by retrogression is becoming more noted in the medium to longer term. The initial positioning of the UK HP still yet to be absolutely confirmed - here in downtown East London chances of a light E'ly or NE'ly remain. In any case, classic retrogression can happen whether the HP is over the UK or slightly to the north and some of the later output is of course dramatic. GFS has a push of -8 850s over southern and eastern England this weekend before slightly less cold air early next but the stage is then set for the retrogression. Worth saying of course we aren't there yet - retrogression doesn't happen that often and the risk is it can become a west-based NAO so we need to keep the ridge SE out of Greenland. The 10HPA shows the weakened vortex under further attack as we move through mid month.

Evening all Here in downtown East London, the wind strengthened notably from lunchtime. THis morning has oddly enough been almost calm with steady moderate rain, that soaking rain water companies love. From late morning, the wind gradually increased and the afternoon has been blustery to stormy with occasional showers. Shower activity and winds have eased down in the past couple of hours - not an exceptional storm and certainly nothing like Eunice in February 2022. The unsettled theme looks set to continue for another couple of days before a dramatic pattern change at the weekend.

Evening all Some more eye candy this evening though not as yet within reliable. The New Year weekend looks unsettled with shallow LP in charge so presumably back to watching the rainfall totals mount up. Breezy in the south tomorrow but the succession of LP could cause some flooding issues through to the middle of next week. It seems then we may get the next LP coming up from more southern latitides with heights building to the north though that's far from confirmed. The form horse could be a UK-centred mid-latitude block with occasional attempts at retrogression. That's one option - as others have said, even in the most memorable of winters there have been occasional relaxations which have allowed less cold air to return. The other side to this is beauty being in the eye of beholder - many on here want only snow for others cold is the desired outcome. It may well be we'll get both - certainly it's good to see the zonal winds well down and a possible split later next month (I'm not a big fan of Siberian Wave 1 warmings unless they can push the vortex far enough over Canada to propagate heights over Scandinavia). I'd also add recent experience with Greenland HP don't fill me with glee - reversion to a west-based NAO seems to occur all too quickly (as happened in December 2010 and 2018). The Scandinavian HP/Genoa LP is where I'd like us to end up but if wishes were horses, I'd own half the Grand National field by now

Evening all Given the absence (for most) of a White Christmas, it's little surprise the 12Z output isn't getting more attention. I'm not usually a fan of Siberian warmings as they tend to knock the vortex back over to the Canada/Greenland side but this seems a very powerful warming so may have more impact. Somebody last week was remarking on the increasingly southward movement of the jet and the Atlantic LP systems and after a relatively quiet Christmas, a series of LP start to cross the British Isles from next weekend. Presumably these features, as they cross through the British Isles, will offer snow to northern hills and perhaps lower ground but it's all transient at this time.

Afternoon all Winter on Netweather, don't you just love it? The truth is, we often do well to get any cold weather - cold and snowy is rare and cold and snowy in southern Britain is up there with a big lottery win or hen's teeth. In a 90 or 91-day winter (December, January, February), to get a 7-10 day cold spell isn't that bad, to get two noteworthy and to have a whole month of cold goes straight into folklore. Everyone remembers December 2010 but who remembers January and February 2011? And yet - in my part of lowland East London, where I've lived 25 years, I've had snow lying most years. Yes, it's often transient and melts quickly in the urban heat island but nonetheless I've known snow fall well into March (famously, one Easter Sunday). The default for the British Isles, given its location and geography, is mild and wet - the opposite to us is Japan, islands off a large continental land mass but sea currents and the like offer something wholly different and I believe one of the snowiest places on Earth is on Hokkaido (Sapporo?). The weather I miss is cold and foggy under an inversion - the disappearance of fog is the one weather characteristic I would note and I presume that relates to a more turbulent and warmer atmosphere. We just don't have a week under a cold anticyclone (cold at the surface, much higher 850s) any more. I prefer cold to snow in all honesty - you can keep ice and freezing rain but a cold, crisp, sunny winter's day will do nicely. We are, however, where we are and perhaps January or February 2024 will deliver that cold spell we'll be talking about in 20 or 30 years time - I doubt it. The last memorable cold spell for me was March 2013 with an ice day in mid month.