If the threshold is -8c at 850hPa then I make it 12 out of 32. A few more get to -6c, so 50%.
 
Against that, very few bring in mild conditions; the balance are just around average.

Buts that’s the thing. You need the block In place which we will do, you then need it to move. This is a high risk and high reward game. 

The only trend I am seeing is a block which may or may not retrogress. No signs of an Atlantic onslaught. I have seen charts at this time of year a billions times worse.

Yep, HW, we've got charts like this at Day 6 from ECM... not a lot to be concerned about really!

Indeed. Looking at the control and mean, the GFS ensemble has shifted markedly in the 00z, away from a sustained upper ridge. 

So far ECM looks OK out to T+168 but subtle changes look to reduce the odds on the colder air advecting west.

Yes and the opp a cold outlier on GFS, feels like it will be game over very soon on this..

Have a look at the GFS ensemble suite; definitely a shift in the probability of cold weather.  Of course it’s just one run but the trend is becoming clear. The trend can switch back but currently what we’re seeing is what the Met Office has been seeing - the block getting squeezed out by a renewed burst of the jet stream 

To be fair to you and to Taylor when I made my earlier comment I hadn’t seen the pressure charts. It does at this stage look like we will be losing the influence of the high and thus we are playing with fire. The 0z GFS shows how it can work in our favour, but it’s fine margins and as we all know, fine margins never often go our way.

Don't be fooled by the op run this morning. There has been a notable shift in the GEFS with more runs bringing wetter and milder conditions. I suspect this fits in better with the ECMENS 00z mean from yesterday that left me a tad puzzled. 

Thanks.  

ECM underlines the problem: although better than the GFS mean, it’s still pushing the LP further east and on a slightly more northerly path. There’s cold air ahead but it’s marginal. Maybe a brief snowy transition? 

Yes, that’s about it.  The GFS op shows how it could still play out whereas GEM op, ECM op and the GFS ensemble mean show the change in emphasis/odds.  It’s a familiar question: have the models misinterpreted the new signals?  As you say, it’s far from resolved at the moment.

To use the cliché: more runs needed.

Yup, A definite improvement this morning IMHO for cold prospects but the wait for the weekend 120/144 charts continues, as FI is clearly in the 120 range so all to be played for.  My only advice to festive model watchers is have No Expectations, then whatever transpires you wont be disappointed.  

Absolutely! Although that is probably also some of the best advice for every winter in the UK. 

I’ve been watching the ensemble’s for days too and I’m now seeing modifications rather than a collapse of the high.

The latest ECM op backs this up, but still a single run of a model. the gefs ensembles are progressing in the right direction for a colder spell though. Maybe some precipitation after Christmas could be on the cards too ❄️

The ECM mean seems to agree with you both, looking a bit slidy to me post this though - high risk / high reward. 

At least what we can see is that it should be pretty dry and settled for the next five or six days which is a bonus for this time of year. The rainfall chance seems to have increased on the GEFS this morning after the 23rd, but with limited runs showing cold at the moment I can’t see that magical white Christmas appearing. 

Definitely an exciting 48 hours coming up. The change in the GEFS is better shown in the data tables today.

https://www.theweatheroutlook.com/premium/gefs-tables.aspx

The GEFS 12z (14/12) and 00z (15/12) show the move away from a colder solution more clearly than the graphs. They show forecast 850hPa and 2m max temperatures from all of the runs in the ensemble. (Available here https://t.co/cWraMTHdt6) NOTE: Not decided & could easily revert pic.twitter.com/UF3AmvqYIf

— TheWeatherOutlook (@TWOweather) December 15, 2021

CMA runs to 21/22nd December with high pressure dominance, thereafter we diverge.

Its definitely a case of the models sniffing energy in the atlantic threatening what originally looked like a high pressure dominated Christmas. The 240 mean is worthless as the range of options on the table for the big day is significant.

It 'feels' to me that we are moving into slider territory. The question is can we advect some cold air off the continent first before the battle commences.

Lots to keep an eye on and enjoy.