stodge

I know it's going to turn very or even exceptionally mild at the end of the week. Wasn't the December temperature record broken as long ago as 2019? Just below 19c recorded in Foehn conditions in Scotland? Nothing about which to be too excited. As far as the morning output is concerned, we're still looking for hints and teases in the darker recesses of FI. GEM tantalises but we can't take it too seriously yet. I'm still looking for the jet to be pushed back south so a period of stormy and very unsettled conditions in early January before we see the next hint of amplification.

Evening all While I appreciate all the caution etc, if we never discussed any charts beyond T+72 on the grounds they won't verify, there wouldn't be much point. The point of this thread is to look at the wider trends and signals and see if we can see the cake from all the ingredients. I mentioned on the SE thread this morning I was watching the jet being squeezed back south as we move into January - this would be a consequence of the build of polar heights referenced by @Singularity above. This in turn suppresses the Iberian HP back to the Canaries - the consequence for us is a period of potentially stormy and very unsettled conditions as a series of LP systems track through the middle of the British Isles. Whether the jet will be forced far enough south to push the LP south of the Channel remains to be seen.

Merry Christmas to all. Just been out for my pre-lunch constitutional. A keen SE'ly wind has certainly taken the mildness of the past couple of ways. The ARPEGE 06Z chart for now would suggest calmer conditions but there's a noticeable breeze out there. I think we're still in negative 850s though not for much longer. The dew point tells the other part of the story. If the trough had elongated and disrupted ESE through the Channel the negative 850s and dew points would have ended up further south - still marginal for London and the SE but perhaps those on higher ground would have fared better. I don't normally look at the 06Z output but as it's Christmas Day - after the push of the jet north this week signs the jet starts coming back south through New Year to run through or just to the south of the British Isles. That suggests, after the exceptionally mild push this week, it's back to a more traditional state to start 2022 with quite a stormy outlook with plenty of LP running west to east often across the middle of the British Isles with plenty of rain and wind.

Evening all Thought as a change from the usual, I'd have a look at how tomorrow's chart has evolved through the ECM 12Z suite of runs in the past 10 days: So that's the chart for Christmas Day at 1pm starting from T+240 on the 15th to T+216 on the 16th, T+192 on the 17th and T+168 on the 18th Then: T+144 on the 19th, T+120 on the 20th, T+96 on the 21st and T+72 on the 22nd, T+48 on the 23rd and T+24 tonight The more I look at this, the more convinced I am the prospects for lowland snow in the south were never that great, the T+168 chart was the best but the others all suggested a milder flow. A small bump of heights far to the south over the Canaries has helped keep the LP further north but the elongation and disruption ESE through the Channel and into Europe just hasn't happened. The modelling of the Atlantic profile has only been resolved at T+72 and separating the Atlantic and Scandinavian troughs hasn't helped. I think the T+144 chart was the real nail in the coffin - that was a substantial move from the previous day's chart. We talk about "FI" and when it starts and it's clearly a variable concept - I also think there are levels of "FI" - it's almost a three stage process - stage 1 is T+240-T+144 and that's pretty much not to be taken too seriously apart from establishing broad trends. Then, from T+72 - T+144 we start firming up the details but there's still scope for a lot of variation at the local level before from T+72 we're pretty much in the final stage with only very minor variations likely. Going forward, it may well be best to adapt similar rules to the chase - charts from T+144 onward are just about the general broad direction - if what you want gets past T+144 it's time to get more interested but it's not a done deal until T+72 (and many will say not even then). Happy Christmas to all and I'm sure there will be other chases this winter.

That's an interesting point - my recollection of the BTFE from 2018 was how quick the HP moved west across the northern hemisphere. We just seem unable to hold on to an east-based negative NAO currently - it quickly heads west. Looking at the 12Z GFS from December 14th and seeing the T+216 is enlightening - the HP was even then not retrogressing but moving into Scandinavia after flirting with Greenland. As you say, plenty to chew over in the days ahead.

Do you think our possible cold spell was scuppered by Wave 1 activity which displaced too much energy back to the Canadian side?

Evening all Not much in this evening's charts to inspire fans of cold it would seem but as others have said, it's early days. The question has to be as it often is - will event sin the stratosphere give us some options? Clearly, the PV is under plenty of pressure it would seem right into the New Year at 10HPA and I do idly wonder whether one of the reasons we've been scuppered has been a classic Wave 1 displacement which has kicked too much energy back over to the Canadian side. Anyway, whatever and however, have a wonderful Christmas.

Musing on the post-Christmas scenario, I'm interested in the 12Z GFS OP as it is moving away from the "form horse" of a deep mid-Atlantic LP and mild/very mild TM air drawn up from the Canaries or similar. This occurs because the LP is more rounded and slightly negatively aligned on the GFS OP while other models go for a more elongated and positively aligned feature. There was quite a lot of talk about a continued favouring for Scandinavian heights (MJO Phase 7?) and I just wonder if the GFS OP is teasing out a new alternative. I also see a continuing signal for a further Eurasian warming into the New Year - I'm never keen on those unless they can lead to a full vortex split.

Evening all I must confess once again I was expecting to see a strong flip to milder on the 12Z suite and again I'm left none the wiser. I've never had much hope for snow here in lowland East London and it looks like I won't be disappointed but further north and with altitude, who knows? It's certainly encouraging to see the colder air trying to return south after Boxing Day. From there, a lot of the models seem to be offering a mild/very mild scenario with a static deep Atlantic LP and a pull of SSW'ly winds up from the aforementioned Canaries - unless you look at GFS OP which has gone in a whole new direction into FI. GFS OP, ECM and GEM at T+216 on the 12Z suite. Keeping the Atlantic LP to the west and negatively aligned allow for the re-build of heights further east. What we don't want is an elongated feature aligned positively (GEM). Good luck to those in line for some snow and for those who aren't - we've barely started winter and there's so much more "fun" to come (it'll be a meaning of the word most of you won't recognise).

Evening all On we go along the edge for another 24 hours - I really did think after yesterday's step back we could see a big flip to milder charts this evening but that hasn't happened as yet. My original take of a brief milder incursion into southern areas followed by a return to something colder on Boxing Day or this time next week still seems to be in the frame but so do many other options at this time. As we've often said, micro variations on a regional level can make a huge difference in our small corner of the globe. Looking further on and I now see GFS Control offering an alternative to the mild/very mild options previously on offer for the New Year. By having the mid-Atlantic LP stalling further west, it allows a general rise of pressure across NW Europe so we get another shot at a Scandinavian HP. The problem is if the Atlantic LP is too close, we get the classic west-based NAO set up with the Greenland HP no help and the Azores HP moving to Iberia and pulling up a very mild SW'ly flow.

Evening all I must confess I half expected to come on here and be witness to much wailing and gnashing of dentures as the model suites flipped unambiguously to mild. No, sir. I wasn't any the wiser two nights ago and I'm still struggling if truth to be told. My initial take on the output was a brief milder incursion into southern areas before colder air returns south for a time and then perhaps another onslaught of mild but that forecas tis flakier than a Flake factory which is on double production. To help me (and I need all the help I can get), I'm going on pick on a few charts and offer a few thoughts. GFS OP at T+168 and I'm dreaming of a green and mild Christmas in my part of the world but 48 hours later and while it's not an epic freeze, it's a deal colder and for those wanting wintry precipitation, go north and get high (not necessarily in that order). GEM has been the coldies' friend for much of the week - the 850s on the T+168 make good reading for northern and eastern Britain (below -4 which should do certainly for higher ground). As for ECM, I know it's the one we all wait for and with a chart like this you can see why: None of this alters what seems to be becoming the path - an increasingly unsettled spell following the quiet conditions of recent days. Rain and milder air moving up from the south west but getting pushed back south and west through Christmas as colder air re-establishes from the north and east. We've seen this pattern before - a succession of rain-bearing frontal systems moving up from the south west and grinding to a halt against the cold bloc before, as the parent system disrupts ESE through the Channel, the colder air comes back south. As they don't say in my part of the world "I'm dreaming of a White Twixtmas, just the ones I've never known".

To quote the oft-used cliche on here: Evening all To quote another well-quoted term: It's all on the knifiest of edges. Strangely, the prospects of snow have increased dramatically in the past 48 hours as the original notion of an anticyclonic cold spell has eased away. The Atlantic attack (there's always one, isn't there) may just pass to the south for many people but the worrying signs of a West-based NAO remain. We're frantically looking for some kid of medium term cross model consistency - and yet, here are some of the T+192 chart on offer this evening GEM, JMA, GFS OP and ECM respectively: Plenty of variation, plenty of options, plenty of scope for happiness, plenty of scope for the toys to be turfed out of the pram. To quote yet another maxim: More runs are needed,

CFS 12Z for Boxing Day: Puts us back in SW'lies on the 20th.....of January !!

Evening all Well, I've looked at the 12Z output and I'm still none the wiser for next week. GEM, once again, is the model on which we can pin our hopes - GFS is, as ever, progressive in extremis. It now seems in lieu of either a Greenland or a Scandinavian HP, we are looking at LP sliding SE past SW England and a cold SE'ly with residual cold uppers providing the precipitation opportunities. I'm sure this one has been put up ad infinitum already but to get us all in the Christmas spirit: Just glanced at the CFS 06Z for January - I imagine most on here would take that.

Afternoon all I have to say the GEM 00z OP is the run I would take home to introduce to my parents Apart from that, as always the case, plenty of caution required.

Colder air crossing a warmer sea raises the possibility of convection and a "lake effect" of snow or rain showers over eastern and south eastern Britain. The higher atmospheric pressure might mitigate against that so we'd be left with the cloud leading to a less varied diurnal range of temperatures. We really need an ESE'ly with minimum fetch over water to bring colder, clearer and drier air across southern and eastern Britain - an anticyclonic NE'ly flow will disappoint.

Evening all The mood has lightened here somewhat after the 12z output. ECM reminds us cold air can find its way even without a storm force E'ly and a 960MB LP in the Channel. Many of the other model outputs suggest a period of cold conditions around the Christmas period - not surprisingly, longevity and severity still very much to be resolved. This morning's 6Z GFS showed how inversion makes nonsense of the 850s and promotes ice days. We aren't there on the GFS 12Z OP but still seasonably brisk in the run up to the big day - note the warmth in the Southern North Sea:

Unfortunately, a Eurasian warming is the last thing we need or want right now. All it will do is knock the core of the PV over to Canada/Greenland and put us back to square one. The real rarity is that hallowed of all beasts, the Canadian Warming, which would send the PV over to Siberia but they seem so rare now (wonder why?).

Afternoon all A rare day visit on my day off (supposedly Christmas pre-shopping but don't tell Mrs Stodge). The GFS 06Z OP is about as anticyclonic as it gets and it's a real treat and a rarity to see a strong mid-winter anticyclone right over us with most of the country "enjoying" pressure above 1040 MB for nearly a week. Can we hope for some decent inversion under that HP? Ice days are entirely possible in central England and in favourable frost and fog hollows and it's an ideal time with the minimum level of solar activity to allow for that cooling but we need clear skies so let's hope. Control also goes cold in FI but from a different route and it's no inversion or faux cold (as some call it) but the real thing with 850s of -4 to -8. A milder few days coming - possibly very mild - but as pressure rises from the south and south east, we'll see the south and east cool down first while the north wets in particular maintains the mildest conditions for the longest period.

Evening all Three takes from the 12Z model output: First, we've got another week of disrupting LP with heights over Scandinavia promoting negative alignment and sending LP into Europe - we may get some snow from that we may not. Two, by next weekend, it looks as though another big Atlantic storm will eventually push the heights away and encourage positive alignment as the Azores HP can start to exert its influence back into Europe. Third, as @Knocker ventured last evening, the rise of pressure from the south starts but that extends north east into Scandinavia as we see linkage with the positive heights over the Urals and they lead, as GFS OP and Control suggests in far FI, to a powerful block. Two observations from that evolution - first, the movement of heights from south west to north east has been an integral element of many winter set ups - that's the source of my comment the route to very cold often starts from very mild as you need a Sceuro-type evolution (with accompanying mild or very mild TM air) to begin the amplification process. Second, the orientation of the block is vital - what we don't want is a block aligned north-south through Scandinavia as that will draw in mild S'ly winds. We need to see the block orienting more west-east to allow the colder air to advect from the south east or east. Hints of that in far FI this evening and while disappointing for fans of snow, fans of cold may yet get a Christmas treat.

Evening all The world moves on apace it seems. Two nights ago, the deep LP for early next week was either to lift away NE (GFS) or sink South (ECM and others). It seems the appetite for disruption SE into Europe remains unabated and the return of positive alignment of the Atlantic LP systems and Azores HP continues to be put back possibly due to the persistence of heights through Scandinavia. Looks like plenty of cold rain for most at low levels but those with altitude in the north may well get some snow at times.

All I can offer is:

Evening all Well, I'm none the wiser. The questions seems to be whether the rapidly deepening Atlantic LP at T+120 either does the traditional and swings NE aligning everything positively, sweeping away and heights and sending us off down the zonal highway or slows and sinks SE as heights rise to the NE. I don't know - really, I don't.

Sometimes it's a "tails I win, heads you lose" situation. If the Strat and Trop vortices remain uncoupled, the Strat could behave and the Trop doesn't. I don't like warmings much as they tend to come from the Eurasian side and the first thing that happens is it bounces the vortex core back over to Canada/Greenland. Warmings from Canada are rarer than me backing a winner at Ascot so we're left with the lottery that is an SSW - sometimes they work and spectacularly, sometimes they don't and we're left on the mild side of the street. I suppose the best analogy is that popular party game "pass the hand grenade" - you don't want to be the one holding it with the pin out when the music stops.

Late evening all By this time it's generally all been said and micro-analysed. My take from this evening is the switch of roles. GEM was repeatedly on the "mild" side of the street last week - not so tonight. On the other hand, GFS OP and Control toyed with some cold options last week - not so tonight. The GFS OP FI looks depressingly plausible with a succession of deepening Atlantic LP on a strengthening jet forcing the Azores HP to decline and tilt positively leaving us in a balmy (or barmy if you prefer) WSW flow. The option of seeing heights rise in Scandinavia relies on continued amplification in the Atlantic and a slow jet with a PV nearer central northern Canada. At this time of winter, for that to happen, we'd have to have all the cards dropping right - it doesn't happen too often and that's why.