First class summary IMO.  As I said the other day I think it would be hard to find examples of very cold winters where the Bores high was strong, but it can lead to average conditions with marginal interest. Better than a slug sitting over the Alps.

Yes, those  "Berne Winters" daily posts from Dawlish back in 2006-8 about MSLP in Berne being greater than 1016mb still haunt me.

First major snowfall of the year (potentially)

Now this chart taken at face value may not look overly promising, but it has to be taken in the context of the airmass that is over the UK. This does have a chance (abeilt a small one) of producing a notable snow event in Scotland and perhaps even N england. Previous to this chart an unusually direct westerly imported cold air from canada with rather cold upper air temperatures. Now the upper air temperatures themselves are unremarkable (generally -4C to -6C at the 850hpa level) although barely cold enough to produce some wintry showers in the far west and more generally above 200m or so. However, in the wake of the next depression a ridge could cause cold air to stagnate at the surface, if this happens enough then a warm front pushing into that air could give significant snowfall. Some key factors are:

Strength of the warm front. Perhaps the most important, the weaker the warm front, the less likely snow will fall; this MUST be an ana warm front, a kata warm front will give rain without a doubt. Weak occluded fronts or secondary warm fronts ahead of the main warm front will be extremely counterproductive; this needs to be a clean division between a mild moist, and cold dry airmass. To this end the chart isn't that ideal; the red area gives likely snow coverage, but the front could do with being a little further south, because the tail is just too weak to produce snow, however this could easily be modified closer to the time.

Nature of the airmass the front pushes into. It needs to be both cold and dry for this to work, the more significant the ridging before the warm front incursion, the more likely snow will fall; i.e we need southerly winds, not southwesterly winds in an ideal world. It really is up in the air at the moment, but this is something I will be keeping a close eye on; I think it has the potential to catch a few people out.

Sod any cold weather for now We need that to carry on further North that has the right air mix to be a very nasty Storm for the North indeed!!

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=138&mode=0

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=186&mode=0

It makes a nice change to see ECM and GFSP looking fairly similar at 8-9 days range.

A chilly northwesterly, looks cold enough for some snow with elevation, perhaps to low levels overnight. These being in the form of showers in the polar maritime air mass.

Beyond this, perhaps an period of interest to keep an eye on for the warm air advection (WAA) aligning more N-S or even NNW-SSE:

GFS just throws energy over the ridge beyond this point but ECM has a hint of negative tilt to the trough (i.e. aligned NW-SE) and the right sort of WAA to encourage a ridge of high pressure NW of the UK, possibly extending east if the trough across the UK continues the southward motion seen from day 9 to day 10.

This does depend on the low off the East. U.S. Coast days 7-8 being far enough west to merge with a trough exiting Canada, which was not being shown this morning. The behaviour of that low has been changing with every run so yet again we are looking for the kind of luck which we have been granted in the past month. GEM's 12z run still has the low coming our way, but tracking quite far south. This means the Atlantic jet flattens out but the trough still aligns in the right way for height rises to occur over Scandinavia.

If we get the luck (hard to bet on that after the run we've been having), we open the door to either another dose of Arctic air from the north - the best we could manage from where GFSP is at day 10 - or some continental cold as the Russia/Scandinavia High extends westward, which ECM seems to be leading toward.

I think the height rises to our east would benefit us most in terms of strat. impacts. Perhaps a source of some comfort that such height rises are the Achilles' Heel of GFS/GFSP.

As with the November opportunities, we're still taking about conditions conducive to snow that are more regional than national and persist for at most a few days - nothing like the scale of events seen in December 2009 or 2010. If we ever manage do that this winter, it's not likely to be before week 3 of December at the very earliest, and that's probably pushing it.

Looking at ECM from the NH perspective though, it seems the model is up to it's old teasing ways with regards to continental cold advancing towards the UK - the trough is actually starting to head beneath the continental ridge:

Maybe one day one of these will verify 

That gfs opp seems to be all over the place in about 6 days as do its members maybe a joey run James

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

30% chance of snow for me on Sunday 

http://modeles.meteociel.fr/modeles/gens/runs/2014120112/graphe6_1000_257_41___.gif

The warm front snow really showing up on the Inverness GEFS with all 20 members going for it. I'm really surprised there isn't more interested in this event, warm fronts can really deliver; -5C isotherm in a Nwerly isn't going to unless you have a bit of elevation.

Dont think ive seen so cold 850,s reach that far west on that jap run

http://www.meteociel.fr/modeles/jma.php?ech=144&mode=0

Indeed PL. Another chart on the JMA run shows even colder air moving into Ireland & other western areas with widely -6 & -7 uppers, some snow no doubt even for low levels I would have thought. Beast from the west??? 

The max on the snow row is 23.

OK my bad, I guess the OP, Control and Pall; but still its fairly impressive, I think even newcastle has about 8. I can't understand why there isn't more interest in this, slack northwesterlies with uppers barely at -5C only deliver for the far north west and the high ground, but warm fronts can be major events; why are people concentrating on the former and not the later even if the former is somewhat more likely? 

As I expected a nasty looking storm on the pub 18z parallel

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=156&mode=0&runpara=1&carte=1

There is a moderate signal for some wintry ppn on Sunday night at elevation in the North I agree, but it's December! I don't think too many are as enthusiastic about it as you are. Not saying it's a bad thing, but if a few sleety showers on the Cheviots get you this excited I fear you won't last the winter

But this is the point, it isn't a few sleety showers, I'm not talking about the unstable polar maritime feed, I'm talking about the warm front on monday or tuesday depending on the model. There is the potential, and I admit it is very tenuous at this stage, but it does exist, for significant widespread snow for as much as 12, even 18 hours. Hell if everything goes right Aberdeen could get 20cm; and while I think this is highly unlikely it is possible, and no where short of 400m up is going to see accumulating snow out of the showers before and after.  

Perhaps a bit less than 200m but a small window Q

Q quote=Quantum;647994]

First major snowfall of the year (potentially)

Now this chart taken at face value may not look overly promising, but it has to be taken in the context of the airmass that is over the UK. This does have a chance (abeilt a small one) of producing a notable snow event in Scotland and perhaps even N england. Previous to this chart an unusually direct westerly imported cold air from canada with rather cold upper air temperatures. Now the upper air temperatures themselves are unremarkable (generally -4C to -6C at the 850hpa level) although barely cold enough to produce some wintry showers in the far west and more generally above 200m or so. However, in the wake of the next depression a ridge could cause cold air to stagnate at the surface, if this happens enough then a warm front pushing into that air could give significant snowfall. Some key factors are:

Strength of the warm front. Perhaps the most important, the weaker the warm front, the less likely snow will fall; this MUST be an ana warm front, a kata warm front will give rain without a doubt. Weak occluded fronts or secondary warm fronts ahead of the main warm front will be extremely counterproductive; this needs to be a clean division between a mild moist, and cold dry airmass. To this end the chart isn't that ideal; the red area gives likely snow coverage, but the front could do with being a little further south, because the tail is just too weak to produce snow, however this could easily be modified closer to the time.

Nature of the airmass the front pushes into. It needs to be both cold and dry for this to work, the more significant the ridging before the warm front incursion, the more likely snow will fall; i.e we need southerly winds, not southwesterly winds in an ideal world. It really is up in the air at the moment, but this is something I will be keeping a close eye on; I think it has the potential to catch a few people out.