ECM 12z remains unsettled but the trend towards more cold incursions continues.

Next Saturday looks pretty unpleasant 

December 1962 was dominated by high pressure to the south and the jetstream to the north until a week before Xmas when the Scandi high started to form.  Even then it was just cold and foggy until a huge Greenland block developed suddenly on 25th.

If that verifies as shown, I wouldn't rule out the possbility of some wintry precipitation in places, especially over higher ground in northern areas.

Someone mentioned December 2015 earlier. I think the main difference between the synoptic set-up we had during that month and what we are seeing from much of the current model output is that while the atlantic is active now as it was then, pressure to the SE of the UK was consistently high during December '15 whereas at the moment the Azores High is centred just to the west of Iberia according to many runs. For sure, what the cold loving fraternity here will not want to see is a major pressure rise over central & southern Europe; the so-called "Euroslug" position.

I actually think there's much to be interested in in terms of how the output is developing at the moment, if it's cold you're after. Might come to nought, but I don't see the zonal or Bartlett express getting going for an extended period anytime soon. Look at the tendency over all model runs for lows to track more south of their usual habitation at this time of year.

Someone described a pattern in one of the model runs that sounded like what I call a "zonal Bartlett". I wasn't suggesting it was or wasn't a likely outcome and I can't even remember which run was being discussed! Nonetheless, I'll reiterate  - for me the zonal Bartlett is the most terrifying winter weather pattern in the UK! It should be made illegal.

It was the 00z GFS output today🤔 orrible it was....

Agreed. We both remember those awful winters where the discussion revolved around the pressure at Berne and the highlight was a 24-hour cold snap passing through.

Pizza slice for the UK again Brian? 

That beautifully illustrates the pointlessness of posting t850hPa charts in isolation, particularly at this time of the year. Here are the t2m values for the same time  http://www.wetterzentrale.de/maps/GFSOPUK18_252_48.png 

The 18z GFS follows the same basic pattern as the 12z, inflating a significant blocking high in the Scandi area later in the run.

Finishes up with this:

Too far out to worry about the detail but an interesting evolution again. I wonder where it will sit in the ensemble.

From what I have seen, there have been a few GFS op runs in recent days which have shown something along these lines developing in deepest FI. I know that given it is a long, long way off in forecasting terms, it is really nothing more than entertainment value. However, I have seen some people day in the past that one strength that GFS has is that sometimes it can be among the first to spot the emergence of a new pattern.

While I know we are not looking at a repeat of December 2010 at the moment, neither am I convinced that we will see a repeat of the same month five years later. The jet is very active at the moment as it was in 2015, but I am fairly sure that pressure over central Europe was consistently somewhat higher three years ago than is being indicated by the models just now.

Looking at the charts over the last few weeks, my assessment is that something is brewing out to our NE mid December.

Too far out to be confident of course, but the trend has been there late in many recent GFS runs. ECM is beginning to pick up on the trend also.

Interesting times.

ECM 12z ensemble for London

The trend towards cooler conditions beyond Day 10 is more marked on this run: the main cluster is for several days of quite cold weather but obviously with the usual scatter.

Not bad late on hopefully start of a trend. Also nice end to the gfs para goes all March 18.

The GFS is often the first of the models to spot a new trend: it's apparent default to zonal weather often serves to test blocking options and you get a lot of flip flopping between potential outcomes. They either verify or not, but I look for the numbers of  similarly block. Related cold runs. If the numbers of block driven cold runs increases, the chances are greater that this cold spell will verify. We have been led down blind alleyways before by the models, hopes of cold dashed at quite short time frames, so you never know. It is reasonable to conclude that the indisputable warmer world and Uk, we now live in compared to the longer, colder winters I experienced in the 60s and 70s, that the hotter world has led to a stronger jet, less prone to blocking. Cold is cumulative too, and blocks are needed to build cold pools of air, and allow this to advect westwards to the UK under a blocking feature. This does not mean that blocks are impossible, just less likely, and certainly can occur in response to a SSW event, as last year, but are still possible, but they do seem to be shorter in duration thank the  decades of my youth, it's all just more mobile. The Jet does seem to be. Prone to buckling and bifurcating right now, so more short term blocks and the potential for cold spells is possible. The GFS is hinting this still could happen in time for the big day.

ECM ends rather interesting this morning. A toppler scenario is possible towards mid month.
Ensembles for De bilt show a change out east too:
http://www.weersite.net/?actueel&ensemble&ecmwfpluim

Gfs 00z is a revolting zonal dominated mess as the Atlantic empties it’s bowels onto us for the entire run.

Both the GFS and ECM throw up a large ridge heading into week 2, but the core of heights remain over Iberia and with the MJO likely to moving into an unfavourable cycle by then, then I would expect a toppling towards Europe and the lower heights from the NW winning out.

ECM op was out of range at the end.

Like this (00z GFS op run)?

Good potential, well spotted.

yes a likely scenario, the heights to the south remain stubborn and not favourable, however it should add some brief interest. GFS notably wet for a period too, could be some flooding about if it were to verify 

I think we are likely to see colder air to the North with snow becoming a player in Scotland and N England with time .