Well if you are looking for straws, UKMO is not all bad, especially the 168 Chart, let's see what the met update says today 

I haven't been able to see the GFS 00z run this morning as for some reason it hasn't updated on WZ. As far as ECM goes though, while it certainly looks to be unsettled it doesn't look to be a particularly mild run either. As I commented last night, it doesn't look a million miles away from the kind of pattern than we had through much of December, January and early-mid February of last winter.

While it would be a less good set-up for southern areas as far as cold is concerned, I would not rule out the chances of some wintry precipitation at times in northern parts if ECM were to verify.

Now I am getting interested - something happening on 16th - will it grow?

P.S. From what I have been reading, the mere presence of HP cells over Scandi and northern Russia increase the pressure on the Strat.

It should be interesting to follow the Strat forecast over the next week - it is far more accurate than trop forecasts a week ahead and more.

Out of interest, did the EC46 pick up accurately the SSW of February this year which led to the Beast event at the end of that month/beginning of March?

I can clearly recall that SSW event being talked about in this forum at least 2-3 weeks before it actually took place (think it happened around mid-February but am not 100% sure about that).

I have been wondering that too David, I remember the long range met updates were very bullish about a cold spell post the ssw well before it happened and well before any models we see picked up on it.

It’s all rather complicated and a warming at 10HPa as per above isn’t necessarily a prelude to an SSW, though the UKM seem to think it will lead to one this time.

Timings look to be around the 22-25th Dec, which if there is a vortex split or displacement any benefits we might see would be around New Year on.

Doesn’t help much I know but that’s my understanding.

It does seem any cold spells in this country are now dependent on these events as they can override the supercharged Atlantic as we saw briefly last Feb/March

But any effects will only be felt in January so December is looking very mild to top off a record hot year globally

I just want it to stop raining so I would be happy to see a Euroslug to at least keep the SE dry

I agree with this. Its the rate of change in temperature in the stratosphere that seems to be the key.

Last February was 'sudden' in every sense of the word. IIRC it was something like 50C warming in 24 to 36 hours which had a huge impact on the troposphere about 10 days later. A gradual warming or a slow splitting tends not to have the same impact on hemispheric patterns as we had last February.  Blocked or more slowly progressive patterns are typical of more muted stratospheric events - not all of which deliver classic cold weather to the UK. The probability of SSW is also less when we move into a westerly phase of the QBO. 

All of this of course is not to rule out cold patterns that develop via another route.  

Hmm, well the chatter about this gathers pace as on the other side John Hammond 's forecast now mentions the impacts of an ssw.

What a dire set of GFS Op run on 06z if it's cold and now you're after! - Sick 

A POTENTIAL SSW at end of FI from the Siberian SIDE infiltrating into the Arctic looking at the 06Z run - the only hope we have at the moment seeing as there is nothing cold this side of Xmas:

A lift up of some 40c in the space of 3 days if this comes off and potentially more if we could have run on!? A big if though.

https://www.bbc.co.uk/weather/features/46476591 

I actually think this is sensible, despite the output. From experience blocks never maintain strength all the way through all the output... typically winning out with only a day or two before T=0.

Further to this, I have now read his forecast, very promising for coldies 

Win some & lose some but it does leave a sour taste in the mouth but the up-coming wave 1 activity on the strat elongating it & pushing it towards Russia could be the reason why the blocked pattern for next week has been blown away. Injection of vorticity/cyclonic pattern N Atl. pic.twitter.com/KNyTUuy9re

— Matt Hugo (@MattHugo81) December 7, 2018

Not much sign of cold and blocked outcomes. Perhaps the ECM is very different or otherwise the Met Office may want to see if there is a bug in Decider. 

Yes remarkable comeback another 100miles west and that's a decent snow event for the UK

http://old.wetterzentrale.de/pics/Rukm1441.html

Yes, funny how the 12Z runs have changed the balance back from a lost cause to a possible chance.

Still looks odds on the Atlantic winning out next week, but not so nailed on as in the 6z runs - trough disruption and the block fighting back are apparent in the latest runs from UKMO and GFS.

Wonder what makes the difference?

I wonder if the possbile SSW being predicted by some for later in December could be starting to cause a few headaches for the models.

From what I recall of following the models in February in the lead-up to the Beast from the East at the end of that month, my memory is that for a time, the models that we can see were all over the place, with some showing the block to the NE coming into paly and delivering the Beast while others showed the atlantic staying in control of things. My recollection is that it wasn't until about a week before the Beast struck that there was any real consensus among the model output that it was on the way.

Entering the more reliable timeframe i would have thought 

Lower heights over the Med? Lack of shortwave development from the Low?

Strat starting to get toasty at 384h 

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=204&code=0&mode=10&carte=1

More importantly, initiation now creeping towards the day 10 marker. 

Still all looks to be coming together for an early Jan cold spell...