The feature runing across England this evening is probably about nailed by NAE and Euro4 now (NAE doing what it does best adjusting south a bit). A farily sharp baroclinic zone will generate deepish convection running ENE with the greatest potential for intensity induced snowfall on it's Northern edge - say S Wales across the Midlands after dark.
I wouldn't expect anything more substantial than an hour of wet snow especially higher up, and the decline of the feature will continue as it pushes quickly east.

For the next five days the unsettled theme continues unabated, and I still can't see any sustained signs of a break in the zonal set-up. although trending cooler.

http://www.wetterzentrale.de/pics/Rtavn1021.png

My wife's flight to Chicago on that day the plane would have a bumpy start to the flight as it will cross over this deepening LP. 

Indeed, the ECM +240 is a horrow show for 'coldies'

http://www.wetterzentrale.de/pics/Recm2401.gif

Not exactly a mild fest though is it! http://www.wetterzentrale.de/pics/Recm2402.gif

And looking from above there is a decent pressure rise over the N Pole with the PV almost split in two by 240hrs.

http://meteociel.fr/modeles/ecmwf/runs/2013121900/ECH1-240.GIF?19-12

I'm certainly not pessimistic about the chances of a decent cold/snowy spell in January.

There have been persistent indications from various models of a pressure rise over the Pole towards the end of the month. Quite what effect that would have on weather in the UK is open to question, but it does look as though the Polar Vortex and consequently, the Polar Night Jet, is going to be disrupted. Will be interesting to see how it pans out.

http://www.meteociel.fr/modeles/ecmwf/runs/2013121900/ECH0-240.GIF?19-12

I wouldn't call that a horrow show ?

And GFS ENS Pert #7 wins the award today for what 'could' happen around the New Year should heights be allowed to get to the North of us.

http://www.meteociel.fr/modeles/gefs_cartes.php?code=7&ech=360&mode=0&carte=0

CFS I see also having another go at a Scandy height rise in the first week of Jan but it's been doing this for so long now you wonder if it's worth paying any attention.

I rather like the Fax 120......

GFS 12z is a nightmare. 90mph+ winds north west Ireland, Northern Ireland, west and north Scotland, Western Isles, Northern Isles, Essex and Kent

Yes thats a nasty looking storm on Monday

http://www.wetterzentrale.de/pics/Rtavn961.png

and then Tuesday for the south east. Oh dear.

http://cdn.nwstatic.co.uk/gfsimages/gfs.20131219/12/180/h850t850eu.png

Well then. That secondary LP is swinging a lot further south on this run! In fact it could undercut the HP to our NE, which is what perturbation 7 of the 06z GEFS did...

...could still slam the SE with some strong winds too.

What on earth will be ECM's reaction to GFS' exploration today...? Stay tuned to find out (6-7pm today).

Jet stream ending up well to the south on the 12Z, height rises in the arctic, with a -ve AO developing. At this rate we might be on track for some decent blocking by january. 

Great to see some entertaining GFS op runs at last 

This run really does take the polar blocking to the next level, with a more robust Arctic High established by the end of higher-res... the PV is then split and beaten down to a sorry state by day 14. It's a little hard to believe that things could progress that quickly up there, but you never know I suppose.

The evolution for the UK has the Atlantic being a real bother, first aligning poorly and then aligning well but positioned too close to the UK... such drawn-out, painfull evolutions are certainly possible, just to warn anybody watching and/or posting in the forums who has not been through the silly season before! 

Regarding GFS's output for the 24th, methinks it's been on the Red Bull again. Yesterday, it was showing a vicious-looking "daughter low" running along Southern England on the 26th, now the latest update shows things being almost dead calm for that same time period.
  I think the models are strugging to keep a firm grip on it all where anything beyond 56 hours becomes FI land, never mind 156 hours. The only common trend is for things to be changeable and temperatures sticking close to average values for the next seven days at least, while of course the threat of damaging gales will never be too far away.
  It's as if our climate has decided to do what it does best at as it switches to "Classic Mode".

And yes, I'm hoping for any downgrades on charts showing 90 mph-plus winds for the South East. One St Judes-type system is enough of the year for me.

GEM also very similar to GFS. UKMO looks good too for a white christmas for some up north

All we need now is for ECM to get on board!

12z gives us a colder run , plenty of wintry potential flying around

The thought of ECM 'reacting' to GFS is somewhat amusing. The model runs are as far as I know completely independant

In attempting to scrutinise detail on the location and timing of any 'severe' end conditions over the next week, I would advise not being to concerned with fine detail run to run. Because of the volatility and parameters responsible for the genesis of these systems the synoptics must be given some width regards detail.
I am issuing a forecast for Christmas tomorrow and will be lacing the text with an extra helping of caveats on the timing of any storm events.

I just hope the weather doesn't prove to be too much of a problem on Tuesday (Xmas Eve) up here; I'm planning a trip through to Edinburgh by train on that day and don't really want the trains to be disrupted!

Not too sure it is that cold

http://modeles.meteociel.fr/modeles/gens/run/gensnh-17-0-360.png?12

15 has a huge block marching towards the UK

http://modeles.meteociel.fr/modeles/gens/run/gensnh-15-1-384.png?12