That's harsh Rob. It is recognised that SSWs often impact on the troposphere but I agree that some people seem to assume a guaranteed corrrelation where there isn't one.  But in this case it's premature to call the outcome now,

We know you don't trust computer models, so you're being remarkably restrained.

So

That tells me it could well be mobile with colder air now and again , nothing Easterly or too severe , which you well know 

I will nip over to the right thread to see if you have replied in that 

My source of certainty is the net , I haven't seen a model that has consistently shown anything severe , I have looked at Tweets , I have read the Met forecast , there ( currently ) is absolutely nothing that shows anything very cold or severe coming our way ( at this time).

Unless you can point me in the direction that does, if you cant then its safe to say at the moment nothing very cold or severe is heading our way in the next 3 to 4 weeks …………..now in 5 days times that might change but at the time or writing there is nothing ,...…………..or is there ?

Please show me otherwise 

You'll know that milder, wet and windy interludes can come from an easterly set-up with weather systems pushing in at times. But it's all just speculation for now.

Indeed, I'm sure the feeling is the odd ridge will allow some frost/fog to form, but systems from the NW bringing colder conditions.  I don't read that as zonal and agree there could be an Easterly element (but no Beast sighted yet...)

ECM 12z ensemble suite for London 

Some colder options appearing but almost anything is possible. I wonder what Synoptics produce an overnight -11c?

I wasn't sure if I knew of anything called an SSW back in 2013 but it did occur early Jan and during the 2nd into 3rd week of January we already saw this pattern - and this could be what we see with this SSW? This lead to a colder than average Jan and Feb and a really blocked SNOWY March 2013 as we can all remember very well! At least this SSW is occurring earlier in winter! It's rare to get them in Jan let alone December! If this work out well and to plan this could be like the winter of 2012/13 as the SSW is around the same time  or 7 days earlier this time than in the winter of 2012/13.

Little baby steps, but perhaps worth keeping an eye on.

https://weather.us/forecast/2643743-london/ensemble/euro/temperatur850 

Even during the last week of Jan it only has a cold anomaly for central and northern parts of the UK. In the south and for much of north western Europe there is no anomaly. To me it suggests the idea of a Scandi high leading to a long fetch easterly no longer has a great deal of support. You would expect Exeter to update today, although because of the NY I'd not be entirely surprised if they hold off until next week. 

I don't think they'll change their wording significantly, but not because it's coming up to the New Year. The EC-46 continues, as it has done for a while now, to show increasing signs of a marked shift to a colder outlook. Here are direct links to the relevant charts:

http://brunnur.vedur.is/kort/ec-ens/2018/12/27/00/ec-ens_nat_taem_msl_t850_anom_2018122700_0768.png

http://brunnur.vedur.is/kort/ec-ens/2018/12/27/00/ec-ens_nat_taem_msl_t850_anom_2018122700_0936.png

http://brunnur.vedur.is/kort/ec-ens/2018/12/27/00/ec-ens_nat_taem_msl_tprate_anom_2018122700_1104.png

The same run also shows (as it has done for weeks now) a marked blocking pattern setting up over the North Atlantic. Here's the week 5 chart (end of Jan / beginning of Feb):

http://brunnur.vedur.is/kort/ec-ens/2018/12/27/00/ec-ens_nat_taem_msl_anom_2018122700_0936.png

A strong +ve anomaly to the NW, a strong -ve anomaly to the SE... at the very least, that'd be a large high parked close by, with lows running much further south than usual.

I don't disagree with your analysis but:

1) It still suggests the signal for a Scandi high / long fetch easterly in January has more or less gone

2) The colder conditions are increasingly focused on February. So it means they have been pushed back again. 

I think the Met were at one point talking about it turning cold in December. Then it was moved into January and now the focus is rapidly shifting towards February. Given the El Nino pattern there is some evidence for a "back loaded" winter, however the correlation between a mild Nov/Dec and mild winter may be as strong. 

ECM 00z was one of the colder runs in the ENS but within the bounds of plausibility. It's still possible eastern Britain will flirt with the cold air for a time next week.

I’m not sure the Met Office forecasts have ever mentioned a long fetch easterly, certainly not explicitly. They talk of the risk colder but unsettled conditions in the N and E from the second week in January but mild before then (with no mention of it being cold inthe south before the 11th - the end of the first section of the forecast). This has been very consistent with the colder more unsettled weather in the north preceding more general and widespread cold later in the month.

I would be surprised to see them change that outlook or start to explicitly mention a long fetch cold easterly.

Output like the new GFSP (and EC46 of course) if anything add weight to the Met Office outlook. The FI section of the GFSP run fits well with the second week of January being cold and unsettled in the north.

All of this could change and given the timescales involved all we can do is wait and see what is shown in the coming week or so when the time period in question enters the range of more of the models.

if as you say uncertainty about potential for colder in the short term I would not place any sort of faith in the longer range with so much going on in the atmosphere at the moment. We still have potential for a cold spell, the way the HP is floating around beginning next week

Given that in the UK sustained cold periods, sufficient to acculiate cold pools, or receive advected cold air from the continent are rare events, and I can remember pretty much all the ones that affected the south and east back to the 60's (geek alert admitted), would you all consider - as respected and admired experts - that these events ( including mega winters of 47, 63 & 79), were precipitated by Stratospheric Warming events? 

Outside of equinox periods, where blocking is more common, as we saw this November, during the mid winter period when the jet is strongest, do we need a SSW event to put the breaks on for us?

your thoughts would be appreciated as ever

The majority of evidence and forecasts suggest any high pressure related cold is at least 2 to 3 weeks away. There could be some colder more unsettled weather in about ten to 15 days or so, initially in the north.

at least should be dry and mild for the south once the high sinks into a euroslug

UK Outlook for Thursday 3 Jan 2019 to Thursday 17 Jan 2019:

The beginning of this period most likely brings further dry weather in the south but showers and longer spells of rain in the north. However, the unsettled weather may extend to all parts for a time in early January. There is low confidence in the forecast thereafter, although we will most probably see a colder and drier period with the potential for easterly winds and a chance of some wintry weather for parts of the UK. We may also see occasional frontal systems try to make inroads, bringing the chance of further wintry weather in the west. However, despite this potential shift to colder weather, wet, windy and mild weather may still be possible at times.

They mentioned a chance of Easterly winds but nothing prolonged 

I believe that reanalysis has been performed on here and it showed no significant link (around 50% of ‘very cold’ Easterly types were preceded by an SSW of notable amplitude). Conversely, not all SSWs lead to U.K. cold. In other words, it’s the roll of the dice where the SSW induced blocking sets up as to whether the U.K. goes cold as a result of it.

 I think if you rewind further they were talking about the potential for colder weather in December. I remember attending the Festival of Light in Berko on 25/11 and discussing the possibility of colder weather in the run up to Xmas. There was also chatter in the media with journalists contacting me directly to see whether I would add to what (I believe) was coming from Exeter.

Apologies I thought from your comments thatt you meant they may change the current forecast not the one from days or weeks ago?