To be fair though, I think we can be extremely confident it will be both drier and colder than average (unusually confident in fact). But really we can't be confident in the one thing that people on this forum care about, the S word!

Yes, worst run I've seen in the last few days, 2 or 3 day cold snap then the Atlantic rolls back in. 

Are we not blaming lack of data or does this only apply to colder ENS!?

Would appear to be the case from ecm ens as well.   A typical modern winter cold spell.  What would have been prolonged cold spell in the 80s is reduced to a brief fart 

Seems to apply to whatever folk want, which makes it ever more fanciful. Apparently Russia/ Ukraine war affects the charts too now (unsubstantiated) so lack of data could apply at any given moment. 

00z keeps the new trend of flattening everything with HP firmly parked to our south west. 

Yes it is but potential is still there since pattern change and hopefully will continue through metreological winter .......

I won't deign my personal troll with the satisfaction of a quote, but suffice to say at midnight here it's still Christmas Day in America. There's still data loss until later today (as Boxing Day isn't a thing in the States and it's internal flights that generate the majority of the data). Let's see what the op runs do this evening - by the 18z runs data should be back to normal, and I'd expect to see the op runs gradually becoming more blocked through the day as the data returns. 

The GEFS this morning is excellent, FWIW, the coldest set so far this winter. The op run stands out as being the mildest of all the runs for London in terms of minimum 850s reached. 

Hope you right as due to lack of data most models just programmed to default set up.  It crucial to get genuine deep cold this time of the year at solar minimum.

FAX - current HP linking with new cell on the Atlantic and wandering around between Iceland and Scotland, so the E-lies continue. By Tue 30th the HP is 1041mb near Greenland which means that the E-lies are being supplied with Arctic air arriving via the N Sea.

GFS Op - keeps the idea of a N-ly from FAX but weak and only affecting the E Coast; eventually (Sun 4th) sinking S and setting up a W-ly or NW-ly with LP near Scotland. A major development for Fri 9th as a further Greenland LP moves tto the N Sea 960mb with storm force N-lies for all of Britain and some very cold air in its wake as it moves off to the Netherlands Sun 11th.

ECM - like GFS to Sun 4th when it keeps the blocking HP in place and continues with weak N-lies down the E coast, finally moving the HP to N France where it's still in place Sat 10th with mild SW-lies - couldn't be more different from GFS.

GEM - brings the HP south to Ireland as early as Thu 1st with W-lies from that date, finally  E of the Azores Mon 5th, with W-lies strengthening

AIFS - London, cold at first then maxima about 5C, milder after Wed 7th, some rain Mon 4th. Edinburgh, maxima cooling to 2C Wed 30th, then warming intermittently reaching 12C by Fri 9th.

GEFS - in the S from 5 C above norm sliding  to 5C below by Thu 1st, mean then stays below norm but with some wild outliers (op and control respectively 10C above and below norm on Mon 5th, chances of a little rain in the first week of January maybe snow in East Anglia. in the N, similar but less extreme, snow quite likely in the first few days of January for NE Scotland and the Highlands though not great amounts.

You have to hope that the GFS output for noon on Fri 9th doesn't verify but given the GFS record on N-ly plunges it probably won't.

In terms of the GEFS, as has been mentioned, despite the op's mid/longer term mild and unsettled flirtation they're a generally cold set with decent clustering on the cold side. ECM suite is less encouraging, with a coin flip approach in the longer term although conversely the op is in the cooler cluster for a lot of the time. There is decent cool/cold clustering for the period 30/12 to around 03/01, where the scatter increases albeit there's (imo) a reasonable cluster that keep colder uppers going. 

UKMO and Mogreps probably should be mentioned too - the op is borderline terrible if you're after cold as you head further into the run although the spread on the Mogreps set suggests little certainty past 30/12, which is an unusually short timeframe for scatter to increase. 

Given all the above I'm on hold re the mid to long term pattern although even if you assume no issues with data and it's a pattern change of sorts the fact the GFS still goes on to build a textbook greenie HP at the end is encouraging albeit it's one chart in deep FI that statistically is probably only marginally more likely to verify than something I sketch out on paper using crayons after several pints.

You could I guess make a not unreasonable argument that a more zonal interlude is gaining traction and use the GFS op, UKMO op and ECM ens to justify it but my usual cold bias notwithstanding I think it's premature to do so at the moment and there's too much uncertainty to call things and still a strong enough cold signal to suggest that's still a decent possibility. More runs needed and all that.  

I would like to see some frosts soon though as they are becoming as hard to come by as snow in recent years. It could be to our benefit that my friend in central Canada has said it hasn't snowed yet this winter!

Yes there has despite some great charts there has barely been a frost let alone a flake and this must be taken into account this winter so far

And despite what CField says above we have already had some very heavy snow falling (and briefly settling) and several frosts in this part of Hampshire. 

I’m not sure the likelihood is any more or less than it has been shown over the last few days, certainly not based on ensemble data:

https://modeles16.meteociel.fr/modeles/gensp/run/gensprobuk-26-144.png?6

And then  2 days later it has increased a little to: https://modeles16.meteociel.fr/modeles/gensp/run/gensprobuk-26-192.png?6 

https://www.wetterzentrale.de/topkarten.php?map=1&model=gfs&var=1&run=6&time=264&lid=C00&h=0&mv=0&tr=6#mapref 

Good point. The op runs have been on the Grinchy side.

I think the input data would be affected in the same way any other model would be. I guess we will see any pattern establish or clarify for the New Year period by the weekend.