Tis possible.

I did nearly have a punt the other day on an initial cool/chilly unsettled flow turning easterly as the jet petered out - wish I had now, given some of the MO, might have looked like I know what I'm talking about

I still reckon there's a decent chance of a cold spell in the mid to long term and still a reasonable chance of seeing some falling snow out of the initial cooler spell, although not much more than some snow mixed in at the back of the front down here given slight trend to less cold 850s and more variability (still looking good for some up North though!).

One thing I don't think likely is a mild, zonal spell but there's obviously quite a few ways the UK manages to dodge cold air so need the ducks to stay nicely lined up if we're to get lucky this time. I am a wee bit more optimistic than you at the moment though I think

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It remains a poor performing model in its current guise Neil - below its Canadian cousin now.

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BBC wrestling with GFS v ECM too, it seems.  Uncertainty abounds.  All to do with "low pressure system across the USA" on Sunday.

https://www.theweatheroutlook.com/charts/gfs/18_63_preciptype.png?cb=1501201918 

Many a cold spell have been ushered in with an under discussed / under acknowledged snow event. 2013 had many sliders that appeared in the charts but looked relatively weak until 24 hrs before.

One to keep a neye on. Especially the timing. Gfs has friday 9am. Icon has it as friday 5pm.

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Or tomorrow night depending on location https://www.theweatheroutlook.com/twodata/chart.aspx?chart=///www.theweatheroutlook.com/charts/gfs/18_30_preciptype.png?cb=779 

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

2m temps not quite as cold as the 0Z, but mean daytime maxima for London are between 2C and 3C for over a week.

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And GFS 18Z seems to have a better profile across Greenland at 168.

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18z lining up ok so far 

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Much more energy heading south on this run akin to the ECM.

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GFS looking ECM esque at day 7 looks like a snowy slider. Can we get an easterly as well?

 

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Reluctant to show an Easterly 

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it could be an easterly in the making, just poorly modelled.

Not perfect at day 9 but a big shift to the ECM tonight from the GFS. Marginal uppers for snow though.

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A bit messy

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Huge northern blocking again in far FI a good sign.

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The GFS has almost done a full turnaround and joined the Euros in its outlook, a pitiful performance from the American model over the last week. Now we need to see those heights push into Greenland allowing troughing to our East to back westwards. I still think we’ll see more twist and turns in the next day or two but it’s now looking like we’ve got a consensus on where we are heading.

JMA absolutely stunning run tonight proper  beasterly 

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An impressive ECM 12z ensemble suite for London if you're looking for solid support for a very cold spell. A cluster heading towards less cold at the end, but still below normal.

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GEFS has some impressive members, P1 is a corker. Still lots of scatter and a rather unimpressive mean though.

 

CMA is almost as good as the JMA tonight... and CFS has the -15C isotherm hitting the southeast as early as 954 hours 

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Hmm - last night's ECM extends the SSW by two days (to the 22nd), has one day of very weak normality (+0.24 m/s), one day of reversal (-0.3) then back to weak normality again (+0.2).

As I mentioend yesterday, I reckon if those winds were to recover quickly instead we'd see a much faster downwelling. As it stands, it just about makes it to 70hPa for one day.

https://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html 

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An awful GFS 0z today and these ensembles look pretty terminal for a cold spell.

http://old.wetterzentrale.de/pics/MT8_London_ens.png 

No point polishing a turd. If ECM falls into line today, which I am sure it will do, this will bring an end to the hopes of prolonged cold spell.

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Variation of theme. GFS is still playing catch up. High pressure still looks like building to the NE. The ECM is model to watch right now

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