A few recent GFS runs have been hinting at this in the last few days. Whether or not it develops into a meaningful trend, we don't know yet, but it's something to be looking out for in the coming days I reckon.

Do you get to see the ECM32 dayer?

No, I don't only the 50 member ensembles out to T+360

What is the ECM 32 day forecast going for at the moment? Apologies if this has already been mentioned in here.

 Thanks.

Looking mild across the UK (apart from far N isles) and much of mainland Europe also, at the end of the reliable range:

Here is the 12z GFS t2m chart for the last time point of the high res section http://www.wetterzentrale.de/pics/Rtavn19217.html

It just looks like more of the same westerly typical early winter/December weather picture we have been having for a few days. Averagish or sometimes a little milder in the south, coolish in the north with the chance of some wintriness in parts of the NW especially. In other words the status quo.

Agreed, it is a case of mild interlocking with cool or (even cold in Scotland) as each system moves through. very mobile, very westerly, very typical.

Just a little more amplification in the 12z GFS op run days 6-8 and hints of that again toward the end of the run.

Going by what I'm about to quote from the very well-informed Tamara Reid, the latter 'hint' really ought to evolve into something far more pronounced (I've underlines all the less technical parts for those who like to avoid the jargon):

"

....+AAM is now finally signalling an increasingly negative tendency and this should inevitably impact, with time, on the Pacific pattern - shifting the EPO ridge further westwards and northwards. The downstream response of this in the atlantic sector will be to retract the Azores High correspondingly westwards and weaken it. We should not therefore worry about any of the hints from some modelling of High pressure setting up shop to any extent over Europe to introduce a sustainably mild pattern.....

These developments also favour a reduction of the fast Pacific Jetstream strength over mid latitudes (again with time). It furthermore indicates the demise of the Ferrel cell signal, as discussed recently, with the NH atmospheric signal ending its aloof stance with the oceanic El Nino signal - which in turn teleconnects nicely to strengthening further still the Siberian High, Aleutian Low - and associated -AO feedbacks. More so, a path to those -AO feedbacks bearing productive fruits to mid latitudes towards our parish.

As posted previously, we already have in place a southward tendency/displaced Pacific Jetstream. With a retracted Pacific pattern evolving over the medium to longer term, we have the mechanism for weakened and split flow downstream in the Atlantic over the medium and longer term. So, a very important part of the jigsaw to also breaking the stubborn +NAO stranglehold and turning it through neutral (as the Altantic sector amplifies) and negative thereafter as the negative forcings over the pole turns the pattern much colder courtesy of a very likely SSW.

In the first instance (probably post xmas), cautious, but still good enough reasons for those long range G5 and ECM ensemble signals for greater northerly element to our weather to maybe verify (and just perhaps associated wider snow potential?) to end the year. The amplification in the atlantic will also provide us with the Greenland wave activity ammunition we need to help progress to the next stage and back the pattern even further west.

So, in summary:

Stage one is the retrograding Pacific pattern ( now indicated through second half of December) and leading thereafter to the proper amplification of the Atlantic (late December reasonable estimate) that gives us a reasonable chance of a decent arctic maritime shot.

Stage two is the wave mechanism into the pole, courtesy of amplification. to hurt the vortex further and complete breaking up the stubborn lobe of vorticity to the NW (turn of the year and more especially early Jan)

Stage 3 is the in-tandem pincer effects both sides of the pole - as the Siberian High, primed by autumn SIA feedbacks, reacts to the ocean vs  atmospheric Nino coupling and in turn enables the pattern to back even further west

Stage 4 is very likely SSW territory.... with the Beast heading west towards NW Europe and UK in January as the NAO flips completely, undercutting the deep cold and marching it towards and hopefully right across the North Sea...

Simple innit "

Yet another truly brilliant post on her part, level-headed and fully explained - what I would give to see her posting directly on TWO

Obviously the caveats must be taken seriously - more decent northerlies seem likely towards the end of this month but for all we know we could be unlucky yet again - some recent GFS runs have been showing a notable plunge of cold just to the east of the UK.

It's also clear how the timing of events in January is open to variation, though the breaking down of the low heights to our NW is earmarked for the 2014/15 transition and shortly beyond that, which should lead to some chaotic model output by the final week of December - good chance of an entertaining final week of output, especially with the data shortfalls that occur on the special days.

After that comes the SSW, and while it looks very likely to occur, those final 6 words tell the old 'close, but no cigar' story that is the stuff of nightmares for many TWO members. I say this just to keep expectations for mid-January from climbing too high at this stage.

Very interesting SC  Thanks for relaying the analysis and summarizing. It makes the weather seem like as a game of chess.

 Edit: A few more interesting solutions do seem to be turning up in the far reaches of the GEFS postage stamps - not just differences in phasing of the ridge/trough over the UK.

im loving stormchasers post FANTASTIC post always excited to read stormchasers posts, that azores high has been very strong for a VERY long time and always makes its self known, A mild xmas, either way im happy, just hope london see some decent cold and some snow this winter, all i know is ill be saving on the heating bill over xmas meaning if it does turn out to be mld , and spending my money  more wisely like down the PUB,   im looking forward to the new year thats where i think we might see some decent cold and some snow, if we lucky, [ sorry for off topic ] 

ECM looks a little more amplified as well

Yes, but we had the same hints a month ago?

Classic pizza slice pattern by the end of its run. Chillier early on. No real change. IMO there's a tendency to read too much into the minutiae of successive runs. 

True, but we were further back along the sequence at that time (the initial stages of strat. vortex disruption took place 2nd half of November), and that was looking at conditions some 40 days ahead, whereas this time we're talking about 20-30 days range.

Sure, that still leaves room for it to go wrong, hence all the usual caveats being present - it does rely on that weakening Pacific jet in the next fortnight or so proving an accurate foresight.

For what it's worth, past experience suggests to me that this sort of thing is not going to be well handled by GFS in lower-res - it seems to have a positive jet stream strength bias of some sort, particularly with the subtropical jet (favours stronger storms tracking NE).
If anyone knows of some statistical product that can verify or disprove this I would be most grateful - I'm relying on 6 years of watching the GFS model try to handle all manner of situations.

GFSP seems more willing to explore other options, which is good.

Turning back to today's model runs, and ECM has completed the set as far as more amplified runs go. My local forecast on South Today mentioned high pressure for next weekend which is a rather unusual longer-range suggestion, so perhaps some of the professionals are anticipating something close to the ECM 12z op run. It is the most logical outcome from applying a bit more amplification to a pattern that would otherwise bring a Euro-High - but is this amplification a red herring? only time can tell!

So really all we can take from today's runs is some suggestion that it may turn more settled in the run up to the Big Day as a ridge of high pressure gets more involved in our weather, but with low confidence in the positioning or extent of influence.

No

  Perhaps you need to take a trip here:?

On second thoughts there's not a lot on offer there either

12 days in and you write off half the Winter ????

The trend toward a UK high continues with the GFSP 18z op run. Top left is the GFSP 12z op run jet stream chart for day 7, top right is the 18z equivalent. Notice how the jet is considerably weaker and features a far more prominent 'hump'. This brings the output in line with ECM's solution out to day 8, the major change setting in around day 6.

That leads to a more prominent mid-Atlantic ridge which then drifts across the UK.
This results in temperatures close to average overall on the GFSP 18z run - perhaps a touch above by day and below by night.

Taken as gospel, it's not inspiring I know, with any cold relying on clear skies followed by daytime fog. 

Taken as a trend, it could turn out chillier if less in the way of low pressure rides over the top.

Now, this is the strongest trend I've seen for a while in the model output, as it's cross-model and has persisted across 4 GFSP runs and 3 ECM runs. Despite this, given the huge shift between the GFSP 12z and 18z op runs, and the rather half-hearted (but still definitely present) shift between the GFS 12z and 18z op runs, we certainly need to wait for tomorrow's output before allowing expectations to start to adjust.

Just to be clear, I'm only talking about the potential for a UK high positioned far north enough to allow a home-grown chill or perhaps a continental drift of some description.

In other news, I was looking at the 'bias corrected' GEFS on meteociel earlier (http://www.meteociel.fr/modeles/gefs_cartes.php?ech=0&code=0&mode=0&carte=0&bc=1) and noticed that many of them developed a very strong west-Pacific ridge later in their runs (some of them truly extreme), far more so than from the GEFS that had no correction.

It just so happens that both the 18z GFSP and 18z GFS op runs have since developed this feature, and in both cases we see the Atlantic jet start to ease off and meander about thanks to the downstream effects of that powerful ridge. A strange coincidence I suppose... or an extraordinary feat of anticipation by who/whatever does the bias correction.

I've only bothered pointing it out because it fits with the weakening Pacific and Atlantic jets theme discussed in Tamara's post that I quoted earlier - at this stage it's just an interesting feature to keep an eye out for, because we might as well really 

With respect, that is jumping the gun somewhat IMO. The furthest ahead that any of the model output goes at the moment is a couple of weeks ahead (GFS) whick takes us to just after Christmas and, according to when the meterorogical winter starts and ends, the mid-way point for winter isn't until the middle of January of thereabouts. At the moment we have no real idea what set-up we are likely to have in the early part of January, let alone after that.

The one thing I learned very quickly about the model runs when I first began following them back in early 2005 is that sometimes, the models can be almost as unpredictable as the weather itself often is in this country. Andy Woodcock knows this only too well from his own experience around that time.

Still remaining cold and mobile for the forseeable future. 192hr

Still marginally cold enough for snow (blue is virtually certain, red is virtually impossible)

BTW does TWO support GIF images?