What you are observing here is more that the Azores high is becoming increasingly influential in this part of the world, and i think that its influence is warming the seas in that it helps reduced vigorous zonality, thus allowing the ocean to retain heat, which in turn could be a downstream effect of a warming North American continent. No real cold air to drive those north Atlantic lows. 

When I saw the 06Z North Atlantic charts my first thought was "inversion" but then I looked at the 2m temperatures. 

I think, sadly, it's broken beyond repair! Just look at this - I've plotted the values available  from NOAA below:

https://ukwct.org.uk/weather/amo.jpg 

Quite telling that! Definitely shows how things are changing even if some don’t want to believe

Even major players like MJO indexing or SSW events can’t seem to put a dent in the UK ‘winter’ these days. 

I'm not a fan of inversions in the UK. They are usually dull, misty or foggy affairs that lead to freezing drizzle at best. I'd much prefer cloudy, mild highs sitting abit further south which at least give some hope of brightness or sunshine like we had for much of today. 

Even if inversions evolve into ice days they nearly always get blown away by mild Atlantic depressions . 

But every cold spell ends in something like that manner, it’s the nature of our climate.

I am unsure how to read that chart and what it denotes?

It is tracking the temperature of the Atlantic Ocean since 1840, showing the oscillation (AMO)  failing - just a steady warming trend.

When you put it that way, inversions sound good. I do enjoy a bit of anti cyclonic gloom, provided it's cold. Dull, foggy and cold sounds like proper dickensian weather to me. Doesn't look like the form horse but we'll see in a few days, I suppose. 

My point this morning was that day by day high pressure is being modelled further north and that if that trend continues we could end up under a high pressure cell or even get it just to our north.  It’s by no means a certainty but certainly an option.

A frosty "white" christmas is possible still, better than the mild dross we've had in recent years I suppose. 

Even in what looks like a stonewall westerly regime you’ll always have a few danglers in the extended range teasing inversions and easterly wafts (the new buzz word - we don’t get proper easterlies anymore). I agree however the UK high inversion scenario is a possibility and might be our best hope for a seasonal feel.

The majority view suggests average to mild up to and probably over Christmas. 

GFS - as yesterday with alternating HP and LP moving E-wards across Britain into Europe though perhaps more emphasis on HP later. HPs over France with ridge to north bring milder weather (1035mb France Tue 17th, Sat 21st blink-and-you've-missed-it, 1035mb Channel Wed 25th persisting, 1030mb Brittany Wed 1st  ; LPs moving into N Sea bring cooler NW-lies (970mb off Norway Thu 19th, again Sun 22nd, 1010mb - a weak affair - NE England, Tue 31st). Caveat with a persistent HP is that at this time of year frost and fog are possible.

ECM - very much like GFS

GEM - again similar though LP and HP follow each other more closely so windier in general, esp the NW-lies.

GEFS - temps  down-up-down to a cool point Fri 20th; then up-down-up to a mild period around Christmas Day. Ens agreement breaks up after this but mean, op and control all decline slowly to norm by New Year; a (very) few spectacularly cold outliers at this time. Some heavy rain at the end of this week for the S & W, otherwise random bits and pieces though rain is always persistent in the NW. 

Inverness has a couple of probable snow days 18th and 22nd (28/33 on the snow row) elsewhere single figures; and for the 25th itself England manages 1/33 or 2/33 at best, Scotland not much more.

They're more likely to be just nondescript nothingness, just some grey crap with temps around 12c

Which many of us would be perfectly happy with. With snow (and, probably, frost) likely ruled out in the populous SE quadrant, many would buy an offer of a dry and benign Christmas Day. It has been wet, windy and unusable from a Christmas-walk POV for the last six or seven years. Leading to being cooped up indoors even more than normal over the 'holiday'. 

Maybe, but looks like a foehn effect may set up in the Highlands.  Could easily see 16c if that happens. Maybe 15c or so in the South as well. 

On the face of it, at least for most its looking like a pretty much mild december as a whole.  For many feeling the pinch, thats a small blessing.  So lets just appreciate that for what its worth.

On another note though, Ive seen a HP dominated outlook quickly turn into a northern blocking one... so dont write off the xmas period as a whole, just yet.  a little bit of retrogression and the outlook could be pretty seasonal very suddenly

Later in the run a handful of perturbations bring some sort of high pressure rise to the west. Have a look a P17 from the 06z, which is the only one that actually delivers as we end the year.

Hey, the flame hasn't completely gone out, even if there's not much wick left!

The GEFS has this little number, for example, and there's another member which blows up a Scandi High (not exciting for you, more exciting for me).

https://images.meteociel.fr/im/20/27920/gens_29_2_216wef2.png 

(And of course while acknowledging the fact that a mild, WSW'ly Christmas is by far the most likely option right now, it's still good to see the likes of the above... a reminder that we are, of course, still 9 days away!)

On your last point, IIRC this is pretty much what happened in 2009. After the mild, wet and windy weather that dominated November that year finally abated in early December, we then had a spell of HP domination for a time around the middle of the month. This I think then merged with rising pressure over Greenland just after mid-month and, as the saying goes, the rest is history. I think something similar happened during November 2010 too as I recall that month being mostly dry in the lead-up to the freeze.