For clarity, both of those are from last night's 12z, not today's 0z.

And from the actual 0z ECM ensembles, we can see that for London the 850s weren't an outlier.

This backs up the SW Netherlands ensembles, of course, which showed that the ECM op's easterly solution was part of a minority cluster. The next attempt a few days later has rather more members, as shown by the spikes down to -14C in the "absolute min" 850s. (EDIT: and the 10th percentile drops a bit too, reflecting said cluster.)

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

06z ICON has rain turning to snow over higher ground as it moves south during Thursday morning. Could get very nasty across Snowdonia, the Pennines and Lake District.

http://modeles.meteociel.fr/modeles/icon/runs/2019011206/iconeu_uk1-2-120-0.png?12-10

http://modeles.meteociel.fr/modeles/icon/runs/2019011206/iconeu_uk1-16-120-0.png?12-10

http://modeles.meteociel.fr/modeles/icon/runs/2019011206/iconeu_uk1-1-120-0.png?12-10

http://modeles.meteociel.fr/modeles/icon/runs/2019011206/iconeu_uk1-42-120-0.png?12-10

Just slightly different to this morning's ECM lol. This to be fair is much more likely though.

I'd describe that 6z GFS as very messy , very snowy for some and completely unforcastable. 

I have been eschewing the model output for the past week in the hope of something better being on offer by now.

The output has improved in the last week, but to be honest, the jam is always tomorrow - never getting into the reliable - always at day 10 - sickening really, since this is probably going to be the story of this winter - stellar, snowy output never making it into the reliable timeframe.

The only positive to be had is that Shannon Entropy is evident in the models which are pretty clueless about synoptics beyond about 6 days ahead - a consequence I guess of the recent SSW.

On the topic of the SSW, the PV is torn to pieces, but the danger for the UK is that the end result is a west based NAO and we all know that leads to winter purgatory in the UK (i.e. miserable and snowless).

Meanwhile, southern Germany and Austria are having all our snow.

Maunder, the comment about the timescale is totally untrue. Unless you were cherry picking very cold and snowy charts, which were always in isolation. The trend has always been a change to unsettled midmonth with colder interludes. That scenario and timing has not changed. There is no agreement on the precise synoptics, extent or duration of any cold.

The 06z GFS op epitomises this perfectly but I have little confidence in it due to massive changes by day 7 compared with the previous run. The GEFS data have been rock solid, no delays no significant changes.

Interesting final chart on the high res section of the GFS6z. No doubt it will be gone on the next run.

A significant rain to snow event being shown for most of England, Wales and N Ireland

T234 rain for most except in NI

http://modeles2.meteociel.fr/modeles_gfs/runs/2019011206/234-779UK.GIF?12-6

Dew points still fairly high across the south and south west

http://modeles2.meteociel.fr/modeles_gfs/runs/2019011206/234-101UK.GIF?12-6

But all change by T240. Very windy as well so would be blizzards

http://modeles2.meteociel.fr/modeles_gfs/runs/2019011206/240-515UK.GIF?12-6

http://modeles2.meteociel.fr/modeles_gfs/runs/2019011206/240-779UK.GIF?12-6

http://modeles2.meteociel.fr/modeles_gfs/runs/2019011206/240-101UK.GIF?12-6

the O6Z op run doesn't bring the -10c isotherm through the country at any stage until the 00z!? But does try to build to HP over Scandinavia but because of it's positioning it brings up milder air and southerly winds instead of easterly in FI!?

I wonder if this is a milder outlier - i am keen to see the ensembles?

I'm happy with the latest GFS run, snow hitting various part next weekend , widespread as you go through the week 

No doubt you are correct doctormog - I have not been following the charts for a few days. I was hoping for something better than the models are showing today on resuming attention and hence I am disappointed to say the least. We are not seeing a quick trop response to the SSW which favours the UK and I think the problem is the lump of PV which is still present on the Canadian side of the Pond. What is missing, is HLB which could open the door to sustained UK cold and snow, even though we should anticipate it given the SSW. It appears the AO is trending heavily negative, but that does not help us if the NAO does not go negative too, in a position which stops mild sectors from being thrown across the UK. Getting brief cold incursions and transient rain to snow to rain events, does not float my boat - I would rather have mild and dry than cold rain.

Yep agree with all that. I am still of the optimistic that we will be in a very cold east/north easterly airflow by the 25th but looking at the variability from the models this morning its like pinning the tail on a donkey time.

The only thing the models agree on is that it is going to get colder. I suppose though when a lot of the attention is post t192 then it is hardly surprising. Also the 22nd is roughly the date of the downwelling to the trop which the models are struggling to come to grips with.

The output is messy and mehy (if I can say that) for the southern half of the UK but I wouldn't discount the possibility of a significant snow event. Also there is a greater than average chance of the cold period lasting into February. 

The pattern is interesting and patience is required. Its been a long wait but we shall find out very soon (next 2-5 days IMO)  

With model watching observing what is happening previously is as important as observing what may happen in the future.

 Cold shots have repeatedly surged SE'wards over eastern and then central europe at weekly intervals since Christmas as our high pressure sticks close by. Each PM cold shot is getting closer.

The next cold shot planned on Thursday is the first one that brings the risk of some wintry precipitation. The fact that most models show some appreciable precipitation with this shows that our HP has finally been eroded sufficiently by this next shot.

I don't believe this westward retrogressing pattern is tied in with the SSW though (this pattern started around 23rd December before the SSW had even occurred) !

The long term signals from the JMA, CFS and ECM scream something significant and cannot be ignored. These have picked up the troposphere response following the reversal of zonal winds in early January.

23-26th of the January should be the period that we should start to see high pressure inflate over Iceland after the next cold shot around 23rd January if this is all going to happen. A few minority ECM members are starting to show this. 

Its not a done deal though as the atmosphere is fighting against a newly established westerly QBO and SST profiles that promote a positive NAO pattern.

Whatever happens it isn't likely to be too mild. The NW/SE jet alignment will ensure some cold zonality meaning that many northern areas could do quite well at times. For the north its a win win. For the south we are relying on that tropospheric response.

Key is that height rise over Iceland circa 24th January ish.

We will find out very soon. In model land that's around 300 hours at the moment  

I think that is a good analysis Steve. Scotland will probably do well whatever happens and the northern Pennines might get in on the fun, but for lowland Britain in the south, we need HLB to become established - fingers crossed.

This really is totally just for fun but it’s not often you see snow cover that widespread (even in the fantasy island virtual world of the models. 

Please do not read into this post that this is what I expect to happen!