My take at that range is a number of the runs show a ******ised mid-Atlantic high extending northwards, but very few (2 or 3?) show a genuine Greenland high. I agree with both you and Michael, but think based on the GEFS a cold spell in the next 16 days remains unlikely. Colder incursions? Yes, mostly in the north as has been the case for much of this month. MOGREPS and ECM may indeed show a colder pattern, but the December CET could well finish above average.

What we do know is that the mild tropical maritime air will pushed away on the 24th by a cooler polar maritime airmass with the likelihood of a sparkling and seasonal Christmas Day and Boxing day with some wintry showers in favoured exposed areas after frosty starts.

The uncertainty starts at 168 hours. Some output still keeps High Pressure very close to our southern shores while others bring in a real brut of a storm system on the 27th December.

Confidence for widespread cold and snowy weather has diminished somewhat due to the fact that we never really lose heights to our south and southwest but there is always the risk of some back edge stuff around the 28-29th if the track of the low (yet to be determined) is close enough and strong enough to allow it to do so. 

Fresh off the press, here are the 0z ECM ensembles, with last night's 12z for comparison. From these it's fair to say that post-Christmas is still looking generally cold, with the exception of Saturday 27th - that reaches the dizzy heights of 8C, which is a degree or two up on average.

Looking at the scatter, it looks like the uncertainty revolves around that low on the 27th. It currently looks like a "blink and you'll miss it" warm sector, with median highs of 4C on the days before and after. That's likely to be cold rain territory (along with a moderate chance of some strong winds), but as can be seen by the length of the "whiskers" a colder day is more likely than a milder one on the 28th.

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SATURDAY DECEMBER 20TH 2014.

NEXT UPDATE SUNDAY DECEMBER 21ST 08:00

THE CURRENT GENERAL SITUATION A cool NW flow will back SW and strengthen further as a warm front sweeps East over the UK tomorrow, active in the North but very weak in the South.

MODELS-2 WEEK HEADLINE Remaining changeable with rain at times especially across the North and West. Possibly becoming more generally colder and unsettled post Christmas with some snow and ice in places, at least for a time and chiefly over the North.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Foreecast is for the flow to gradually be squeezed further South than currently lying near or to the South of the UK before a trend to shift it back towards the North somewhat later maintaining a pattern of Low pressure to the North of the UK and High to the South after a brief hiatus..

GFS OPERATIONAL The GFS operational this morning shows a mild SW flow in the run up to Christmas before Christmas itself turns rather chillier with overnight frost but bright crisp days as High pressure moves over the UK from the West. This then steadily collapses away SE in the post Christmas and New Year period with rain at times in the North and West spreading to all areas with a cold plunge of air from the North post Christmas with snow showers in places. This pattern then collapses South to reinstate mild and windy weather under a Westerly flow to end the run with rain at times.

THE GFS PARALLEL RUN The Parallel run also shows a shot of cold Northerly winds under a powerful Low pressure just to the East of the UK post Christmas with snow in places, considerable for a few. Later in the period the pattern resets and flattens as the Low to the East moves away with a cpollapsing ridge over the UK and a mild SW flow with rain at times returning as we move into 2015.

THE GFS CONTROL The GFS control run too shows a brief colder period when strong winds and some snow are possible across the North and East after Christmas but High pressure and frost quickly takes over from the West which in turn becomes followed by milder weather with rain at times under an Atlantic flow later.

THE GEFS ENSEMBLES The GFS Ensembles do show the temporary chance of cold weather from quite a few members post Christmas with the overlying trend thereafter for the cold to lift out in preference to milder Westerly winds between High to the South and Low to the North into the New Year.

UKMO UKMO today shows the weather turning colder as we move towards Christmas as High pressure lies close to SW England by Boxing Day with frosty nights but with any wintry showers for the North in the NW flow on Christmas Day dissolving away later as cloud reaches the NW at the end of Boxing Day with milder SW winds developing here.

THE FAX CHARTS The Fax Charts today show a sustained warm sector period of weather across Southern Britain between tomorrow and Christmas Eve as moist SW winds blow strongly with rain and drizzle over the hills. The fronts straddling the North will give heavier rain before they all clear SE over Christmas Eve to leave Christmas itself in rising pressure and a chilly NW wind with wintry showers for a time over the North likely on Christmas Day

GEM GEM today shows a much more classic Wintry evolution over the UK post Christmas as the chilly anticyclonic Christmas period gives way to a brief milder day or so with rain before cold Northerly winds with widespread strong and cold winds delivering plenty of snow showers to all areas especially heavy and substantial across the North and East with sharp overnight frosts for all. The end of the run shows High pressure strong and locked in across Greenland.

NAVGEM NAVGEM's run today shows a very similar Christmas to the rest before a deep Low over the North Sea brings rain and cold NW winds down across the UK post Christmas with wintry showers in the North and West but not as pronounced or severe as GEM.

ECM ECM this morning shows that the mild SW winds after Christmas quickly become replaced by a chilly North flow with snow showers in places with a deeper dig of cold over Europe. The UK lies on the Western periphery of this with snow showers restricted to Northern and Eastern parts and frost at night more widespread rather than snow.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart is not as good for coldies today as the pattern is flatter with a NW flow across the UK rather than a direct Northerly. High pressure is stubbornly High down to the SW and pressure is becoming lower to the NW all spelling less cold conditions following any colder period post Christmas.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS Trends this morning show strong support for a cold post Christmas period with much disagreeance on how much, little and how long this influences the cold conditions across the UK post Christmas.

MY THOUGHTS The Jury is still out on the details surrounding the period Post Christmas with all models indicating cold weather coming to the UK over Christmas itself although this will be the largely dry and frosty kind of cold. Then as a milder blip crosses with some rain a more serious plunge of cold North winds is possible with gales, heavy rain and snow all possible for a time. It's at this point that all models show difficulty in finding an agreed solution to this phase of the weather with some hanging on to the cold and potentially snowy theme, notably GEM while GFS quickly changes to pattern back to a mild Westerly type as we move into the New Year, a theme supported by it's ensemble data too by quite a few members. ECM doen't look that alarming to me today and it, although being a bit divergent run to run like the rest lately is I believe one of the best model to use for guidance in these conditions.   So taking all this morning's data in a nutshell it looks like changeable weather with marked temperature variations will be maintained over the run up to Christmas and the period thereafter too with the chance of a strong surge of cold and potential snowy weather especially in the North for a time at least later. More runs are needed to pin down the detail of the events after Christmas and the New Year though if I was to put my spin on things today I feel that while a period of cold weather for all is coming post Christmas when we all see a little snow falling I don't somehow feel comfortable in saying anything other than it will be a more pronounced but short interlude of Winter than of late before the milder Westerlies return but I hope I'm wrong.

 Do you know whether the temperatures are max / min or mean values for the time step? GFS/GEFS gives forecasts for min, max and mean. For example, this plots the max and min for each run:

Sadly, the chance of a true Greenland high is almost gone. This cold spell never looked right from the start.

They're just listed as "2M temperatures" as far as I can tell - the EPS parameters available from the full-fat version include things such as surface equivalent potential temperature, but there's no mention of maximum and minimum temperatures as you get with GEFS.

Note that's via Accuweather Pro, so they may not be presenting all the parameters (although as they include such diverse ones as SWEAT index, moisture convergence, 850hPa vorticity and 850hPa absolute vorticity etc then I would have thought they'd have included them if they were available).

morning Beast.

I have to agree, a decent cold spell is now pretty remote but there may be a few frosts and seasonal days for those down South. It's the possible storm that's now catching my attention- it could be quite a nasty affair if it manages to interact with the jet as I fear it could. Plenty of  interest though in the model watching world over the next few days!

I never bought into a cold spell and always thought this would be a nothing but a short sharp blast before the inevitable westerly regime takes over and IMO it's looking like we could be stuck under such conditions for some while  until we get a SSW, and even then we'd be relying on the weather gods to be kind to us. 

That's easy to say now , unless you have been saying this over the last 2 or 3 days

Your back then

Reading on NW a SSW looks unlikely also

It was dead 3 days ago according to you Jacko , not sure if that was fantastic piece of chart reading or just dumb luck

As far as Global Warming mentioned in this thread last night. there is apparently due to be some stratospheric warming taking place during the days between Christmas and New Year. It'll probably be a while though before we start to see this have any visible impact on the model runs, assuming it does at all.

Goon, you know my chart reading skills are legendary!! LOL

Pure luck mate, though I did have that feeling that things just weren't quite right. Its so hard to lock into a cold pattern in UK. Still, this storm has grasped my interest- though to be honest I am hoping it just sails away to the North without troubling us too much at the festive period.

There's been a big uptick in solar output now whilst the lag periods for these are in dispute this will have a big say where exactly the jet stream will be anchored over the coming weeks. Of course colder incursions are still possible as is a cold spell such as Feb 1947 which had moderate levels of solar activity. There that's my straw clutching done and I'm the first this winter to mention 1947.

In some ways, this is more frustrating than last year. At least we didnt have carrots dangled before us only to be taken away. We knew we were locked into a mild and very wet pattern which  lasted all winter so we could accept it and pursue other interests

06z so far, At least it will feel seasonal this Christmas

http://modeles.meteociel.fr/modeles/gfs/runs/2014122006/gfsnh-0-108.png?6

Some ppn showing up for NW areas, Cheshire gap etc for the Big Day. Saint could get his White Christmas albeit the odd flake

Thoroughly depressing recent output.

Indeed , dry but chilly Xmas day will do

http://www.wetterzentrale.de/pics/Rtavn1261.gif

Agreed! Heck, Christmas Day is only a few days away and that's still to be pinned down, let alone the following week. The models will of course continue to flipflop around as they get a handle on the cyclogenesis in our part of the world.

As it is, the ensembles as of right now show the outlook beyond Christmas remains a largely colder-than-average one down here, let alone further "up north". And then there's the potential for some widespread gales in a week's time...