Don't forget that rather annoying habit they have of showing temperatures in the major cities.  Out in the other 95% of the land area it will be typically at least a degree lower and in the case of London probably 2-3 degrees lower.

At least when they're discussing overnight minima they do show rural/countryside vallues but they don't bother with daytime maxima.

WI was, as far as I can see, referring to prone northern areas generally. If this is a snow over 1000ft only scenario I still have a lot to learn. http://www.wetterzentrale.de/maps/ECMOPEU12_120_1.png 

Here for example 500-1000hPa are sub 520dam and that is the case for a swathe of the country. I understand caution but when psychology starts to trump real analysis I am less convinced. 

Here's the Friday 0600 chart - freezing level around 1,000 feet for all but western and coastal areas.   It is a physical impossibility for it not to snow below 1,000 feet.

When you take into account the surface temperature I would suggest there's limited scope for any snow to turn to rain.  Obviously intensity can be a factor but I would be amazed if this set-up didn't deliver a wintry mix at the least.

Some weird post creeping in it has to be said, maybe I’ve missed the last 50 years in which Decembers always brings some big snow events and bone chilling cold every year, otherwise this projected cold spell does look like a cool blip compared to previous Decembers.🤪

you have to say some of those gfs members look promising for wintry potential just before mid month

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=180

With that usage of English I have to assume that you're baseline is a Dickensian winter....

I think that the main factor here might just be the blocking high to our west that has been coming and going recently and which as has been said before, is largely helped by a lack of any high pressure to our south. This would result in a north to south pattern of the jet stream which could work in one or two ways since we could either be on the western side of that block with the jet stream running northwards (which would result in us getting some really mild air coming up from the south), or we could be on the eastern side of that block with the jet stream then running back southwards and resulting in us getting cold northerly winds from the Arctic. So far, we have been lucky enough to be on that eastern side of the block with the jet stream running from north to south.

Generally, weather systems upon following the route of that jet stream around that block with then be diverted northwards on the western side of the block which in this case, would probably be just off the American seaboard. Those weather systems would then move around the top of that high pressure and thus approach us from the north-west before diving southwards across the country as it continues to follow the jet stream.

Basically, these weather systems are effectively just returning to their original latitudes and whilst crossing the UK, they might bring slightly less cold air for a time with cold northerly winds then coming in behind then. If there is also some high pressure to our south though, that would stop those weather systems from being able to get back south but if that high pressure isn't there, these weather systems can return south more freely and I don't think that this would require any further blocking to our east or north-east in order for that to happen.

Yes I know what those charts mean for here. 

OT the Beeb going for NW sliders with the risk of rain or snow 

Now that’s not what he said ...don’t spoil a good story  with the facts 

He said rain or snow as cold air is always close by 

i saw it too but you are cherry picking the negatives. 

Fake news?

http://www.meteociel.fr/modeles/ukmo2.php?ech=120&carte=2000

120h fax for Friday.Air flow shifting towards NW suggesting an early cut off of direct arctic air.

As is often the case it looks siniliar to the UKMO chart for the same time (in other words in this case cold). 

No, that's going to be a simple capitulation: the angle at which the LP and trough are advancing says it won't be a slider.  

Very different across NE Canada with a more coherent chunk of the vortex.  Hopefully the 18z has this wrong, otherwise we end up the wrong side of the jet for most of the country.