https://www.meteociel.fr/modeles/gefs_table.php?ext=1&x=&lat=51.5085&lon=-0.12574&ville=Londres 

Hi Darren - good to see you posting.

Very early season and a NNE flow that favours a long fetch across a seasonally warm North Sea. An ENE in late January would deliver something quite different I’d imagine, or at least in theory!

Several drivers (currently low to neutral u-wind and a weak ENSO, among others), might work in our favour this December but as with most old puzzles you’ll always be searching for a few missing pieces.

GFS; agrees with Fax; then a spell of W-ly influence but unlike yesterdays' output conjures up a general decrease in pressure from Sat 22nd  eventually resulting in a depression 980mb Wight Tue 25th moving SE-wards, followed by a toppling ridge of HP 1030mb Thu 27th before mild SW-lies set in lasting into Dec.

ECM; makes less of the above LP Tue 25th but instead brings LP down from Iceland to E Scotland 985mb Thu 27th with strong NW-lies, and sign of a ridge of HP on that date.

AIFS; London maxima about 3C at the end of this week, rising to 8-10C for most of the rest of the forecast but a milder couple of days Sat/Sun 28th/29th, rain at regular intervals from Sun 23rd. Edinburgh maxima 3-6C until Thu 27th, then a couple of milder bursts ca 12C Fri 28th and Mon 1st. Significant rain now (wet snow?) and after Wed 26th, but some at other times.

GEFS; in the S cold (5C below norm) to Sat 22nd, then mean temp near norm (most ens members milder but mean held back by some cold outliers) Rain in many runs from Sat 22nd onwards, perhaps a little snow (snow row 20/33 Brighton) tomorrow but the quantity isn't there except possibly E Anglia. In the N temp profile similar, rain not setting in until Mon 24th and then more sporadic; high chance of snow tomorrow plus some quantity (snow row Scotland mostly 33/33, upper 20s N England)

Hope Brian's winter forcast reveals a few surprises although I'm not expecting Siberian Express to be mentioned...

https://www.theweatheroutlook.com/twodata/ecmhrai.aspx 

FWIW, I believe the physics based precipitation type charts are still considered better, at least at short ranges. 

This upgrade marks the most substantial enhancement to our global and regional model systems in over three years. It introduces improvements across atmospheric, oceanic, and coupled systems, including:

Enhanced precipitation realism

More accurate forecasts of cloud cover and cloud base height in the UK

Advancements in our UK winter temperature forecasting 

Stronger tropical cyclone intensity forecasts

When you consider it hasn’t changed much on a fundamental level in the past 15 years, I wouldn’t hold out for any breathtaking upgrades. 

The ECM 10hPa zonal charts continue to show an SSW lasting several days, followed by a gradual rise closer to (but still below) normal by the end of the year. My understanding, assuming it comes off, is this is the first SSW in November in the satellite era (since 1979). There was one in 1968 which lasted a couple of days, and a one-day wonder in 1958.

https://csl.noaa.gov/groups/csl8/sswcompendium/majorevents.html 

https://charts.ecmwf.int/products/extended-zonal-mean-zonal-wind?area=nh&base_time=202511180000 

The ECM weekly outlooks now show a cold week for most next week (it's been trending colder each day), and the return to milder conditions doesn't quite reach the far SE - which remains near normal right 'til the end of the output. It remains a promising outlook for coldies as it's a world away from the more typical pinks and deep pinks we see at this time of year.

https://charts.ecmwf.int/products/extended-anomaly-2t?base_time=202511180000&projection=opencharts_europe&valid_time=202512010000 

Last night's op run ECM, FWIW, failed to achieve an SSW - going down to +0.1 m/s. So near but so far!

https://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=10&forecast=f216&lng=eng&hem=nh 

Do please continue - this is fascinating  and the chart of data is worthy of study in its own right. With some additional digging, I note that all the major cold winters and those with major snowy events coincided with La Niña, La nada or Just occasionally very weak El Niño. The correlation to QBO is less clear but easterly is most common in winters of notably cold, although some with W had changed recently from E. This year we have LaNina and an E QBO, so if the SSW comes off - as you say - this winter is one to watch. And I agree - each model run downgrades the return to mild weather. The sub -5 air comes back in to the east twice in the last run.

GFS; carries on where FAX leaves off and takes the LP from Sun SE-wards to Dover 1000mb Tue 25th, with more NE-lies esp for England but not connected to any cold air mass. Even as this drifts out of the way, pressure remains low over Britain with the next development being 985mb off NW Ireland Sat 29th and a trough in advance to S England. This fills but then there is a re-load 965mb Tue 2nd before LP takes itself off to Iceland with SW-ly gales for all of Britain by Fri 5th.

ECM; differs from GFS after 25th , with low pressure established to the north of Scotland 960mb and SW-lies for Britain Sat 29th, no rough established.

AIFS; London, maxima about 3C now, rising by fits and starts to 13C by Tue 2nd, significant rain Sun 23rd and Sat 29th. Edinburgh, similar temp profile but with something of a dip Sun 30th interrupting the general rise in maxima, rain mostly Mon 24th, Fri 28th and Wed 3rd 

GEFS; cold to Sun 23rd, then mean temp not far from norm well into December (cooler at first, milder later). Rain or snow now, dryish for a day or two, rain on and off from Sun 23rd

Following on from Retron. 

Judah Cohens weekly blog details how this could well evolve. It gives some historical incidences of how rare an SSW is at this time of year with some evidence showing that when it has, what follows should please the majority of those who frequent this great platform. 

Not in the bag yet, but certainly worth keeping an eye on. 

https://published.aer.com/aoblog/aoblog.html 

Indeed, some extremely cold air for the beginning of Winter pushing into Eastern and Central Europe.

It was a bit of an outlier in the ensembles so I'm not expecting anything but interesting to see at least.

Instead is nothingness at 9 or 10c

Last night's 12z ECM op isn't available yet on the Berlin site, but I wouldn't be surprised if it no longer shows an SSW either. 

https://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=10&forecast=f216&lng=eng&hem=nh 

At least there's still a bit of interest!

It actually snowed yesterday on the same day as last year and I remember saying then to my mate, it would be funny if that was the only snow we would see. I wasn’t laughing at the end of winter, despite some very slushy snow flakes falling in January.