This is a big improvement on the ECM

Note the yellows over scandanavia, height rise is more important than surface pressure. 

Hear hear.

Agree better upstream pattern also

http://www.meteociel.fr/modeles/ecmwf.php?ech=168&mode=1&map=1&type=0&archive=0

Even in the GFS run some of the energy runs over the top, which is why the block doesn't hold sufficiently to keep us on the cold side of the jet.

The key is whether the block can withstand the pressure from the deep LP to the west of Scotland.  UKMO pushes the low pressure critically a few hundred miles further east and ECM seems to be somewhere in the middle at T+144.

At T+168 the block is noticeably less intense, but against that there is much more of a flow of Arctic air down its eastern flank.

http://www.meteociel.fr/modeles/ecmwf/runs/2015122412/ECH1-168.GIF?24-0

NWly cold from ECM

would feel cold in the wind from what we have had

I should have added.... flowing down about 1,000 miles east of where we would want it ideally.

T+192 shows more of the same; a block in place but the battleground looks like being the Baltic, not even remotely close.

Nonetheless, at least there are some decent signals for a major block to develop to the east/north-east.   Whether it will evolve more favourably for those wanting a cold spell or not remains to be seen.  The form-horse says no, of course.  That's why we have the climate we have and Scandinavia has something more continental and therefore more 'extreme'.

hints to the s/e also Peter of pressure slowly falling

http://www.meteociel.fr/modeles/ecmwf.php?ech=216&mode=1&map=1&type=0&archive=0

Indeed.

500-1,000 hPa thickness values of around 524dam for London.  Cold enough for something wintry except that the airflow is from the west.  The Midlands northwards could be quite interesting with strong westerlies and 500-1,000 values in the low 520s.

J F F

J F F

J F F

February cold from CFS

Hints from the Japs I like that drop of pressure to the s/e 

ECM 12z ends similarly, in as much as although it still shows us under the influence of the atlantic, the HP to the north-east looks to bemoving into a position that may be more promising for us at a later time.

This is the Start of FI, ecm has taken a big step torwards GFS today we need it to take a few more tomorrow. Probably still odds against a New Year cold spell but we have a chance at least.

Aye, ah awiz nu a cold spell wiz comin!

P.S Apologies for the bad Rab C Nesbitt impression.

I almost feel sorry for the polar vortex, constantly attacked; is this it finally accepting defeat?

Okay, how much brandy have you guys had? 

Just look at that intrusion of relatively warm upper air temps high into the Arctic. A big clue as to how disturbed the vortex is looking to become.

The 850's manage to reach the Siberian Arctic while holding on to values in the mid-single (positive!) digits. Very impressive.

The two big blocks are well positioned to perform a pincer move on the vortex there - but more significant is their impacts in the stratosphere, helped along by that persistent Aleutian trough (around the Dateline).

GFS is very similar for day 10 and goes on to produce some artistic 10 hpa charts later in the run. The best of the warming occurs on day 15:

This warming has been showing up for at least a dozen runs in a row now, so it's looking likely to manifest to some extent or other. It's strong enough to seriously trouble the vortex and has great potential to set the stage for a SSW later in Jan. 

The counter-point here is the cold nature of the strat; -80 is at the lower end of the temps you'll see at the 10 hpa level. However this point is weakened considerably by the fact that those colder temps have become displaced and seriously elongated, suggesting that the vortex is becoming stretched and prone to splitting off a 'daughter vortex' as some call it. That's basically a secondary, weaker vortex that can lead to a notable export of cold to one lower-latitude region near and at the surface. Such was observed over the U.S. a couple of winters back (or it may have been last winter in fact). Typically the daughter remains loosely connected to the parent and the two merge again before too long, but that winter in the U.S. was unusual in that the stretch/split scenario stuck around for ages, aided by persistent strat. warming but nothing substantial enough to drive a SSW.

A SSW will either take the above scenario further (a 'wave 1' event), with the location of the displaced vortex crucial to what we experience here in the UK, or work to drive a wedge of high temps (and heights) into the vortex (a 'wave 2' event), leading to a proper splitting event with the remnant circulations set well apart and held that way for between around 2 and 6 weeks (or something like that). 

'Wave 1' occurs in response to a single blocking high such as the one over Siberia. 'Wave 2' involves two blocking highs and could be achieved based on the day 10 12z ECM and GFS op charts, provided that high over the U.S. is able to gain some latitude at times with ridges up toward the pole.

So concludes my last outpouring of thought prior to the traditional inebriation period. Merry Christmas everyone 

Nil carborundum illegitimi

That's way better than the unedited post and entirely in keeping with the intended tone.

Meanwhile, the ECM is all over the place by Day 6, with great uncertainty bang over our neck of the woods.

24 hours later and the greatest uncertainty sits over northern Norway, so plenty to play for in terms of the potential block.