Yesterday's ECM control run is largely snowless outside of Scotland until 264, whereupon the Midlands northwards gets a good inch or so. There's a dollop of snow right at the end (354 and 360) which means the whole of the UK sees snow.

i just said exactly the same on NW -

the overnights have perhaps now just started to get a grip of the energy distribution around 144-168 - hence the cold is being teased further west

In terms of the ECM ENS I would go with 30 -40 % very cold for debilt & 20% into the UK

S

Some of the runs lately, notably this mornings ECM, remind me of a few years back where disrupting lows were sliding in to a cold block to the East.

IIRC there were a few snow events and GFS in particular really struggled with getting to grips on where the energy was going and kept throwing it North, rather than south east as actually occurred.

Be interesting to see if there's a repeat - it does have that messy look about it currently, rather than the classic easterly set up.

Of course the cold option is still in the minority at present so plenty of scope for the milder majority to win although it looks fairly certain Decembers exceptional warmth will be washed away at last.

Yes Hippy, its about the models attempting to calculate how much energy goes under the block.  Another issue at the moment is that the block does not quite extend far enough westwards.  Still time for things to change, but a rain sodden, milder outcome is still the most likely outcome, little comfort though this will be for flood affected areas.  The NW will be crying out for an easterly where it is traditionally more sheltered from that direction.  We can hope...

Although the ECM ensembles are a degree or so colder today (compared to last night's 12z), it's perhaps unsurprising that the op was one of the coldest options this morning. Also, bear in mind this particular EPSgram is for Reading, in central southern England. I reckon it would be a colder set of ensembles for the far SE, as is the case with GEFS.

http://oi68.tinypic.com/x3ihj7.jpg

Nonetheless, the majority of runs are now showing below-average temperatures towards the end of the run.

The -5 850 line getting tantalisingly near the east coast on the ecm mean chart by day 10. It's getting colder folks.

http://www.wetterzentrale.de/pics/Reem2402.html

Looking at ukmo this morning the high moves way too far north to introduce cold enough air to the U.K. Instead we would end up with lows passing north of Scotland bringing yet more rain to the north west.

Yes about the best I have seen this for a long time - azores high displaced well to the SW and blocking on ECM across the arctic too:

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Here's the Antwerp (SW Holland/ NE Belgium) ens.  Very poor really in terms of ensemble support for the outlier cold  op and control...

edit - although there is a second coming of cold ens members on 5th Jan, but its only a trickle whereas the main stream of members stay wild and milder.

I think clearly the ECM OP and Control runs are outliers; and more significantly the METO don't even forsee the sort of battle that could ensue with either the GFS or ECM scenarios - they must see everything several hundred miles further East.

We should see subsequent runs showing the Scandi block retreating NE and the jet advancing further East.

Don't the Op and the Control run at a higher resolution than the other ensemble members and therefore, when at variance with the ensemble mean, aren't they the more trusted output?

Just saying.

I imagine that prior to Xmas Eve, you wouldn't have anticipated, nor would a lot of people, that the models would be showing pressure rising over Scandi as they have been over the past 2-3 days! It is easy to make assumptions, but assuming anything is an unwise thing to do IMO.

Yes, the hope for the flood victims and others in the firing line is that the higher resolution op and control are picking up the energy balance better than the 'minion' ensemble members.  We all know colder air can hold less moisture and an easterly flow would shelter the western up-slopes.  Not the form horse though...

The HP cell seems to have changed orientation a bit around 120 hours on the GFS 06z; a clear Easterly develops along its S flank and the -10 upper line starts a struggling march westwards.

A much fresher start to 2016 , it would feel almost Brrrrrrrrrrrrrrrrrrrrr lol

The low to the SW at 153hours on GFS 06 looks as if it is preparing to undercut, with a SE component to its straight side,but I notice also a nose of HP also pushing in from the SW- will that prevent an undercut?

Cold air being pulled in.

[quote=White Meadows;746788]Going to be a nice looking run this. Snow for the Midlands north from 2nd Jan [/quote]

I'm not too sure about that ?

A right battle going on , deep into FI by now though

Definate brrrrrrrrrrr feel to the weather ..............................................JFF of course

Only needs that ridging over Scandinavia to intensify, maybe generate a satellite HP cell.

What makes you think that so clearly?  I'm sure the MetO will not say anything publicly until it is nigh on certain... we are talking probabilities here. As discussed in various other replies, it would be helpful if you could post some charts in support of your arguments.  I see signs of an undercut as early as t144: