You know what I mean. 😀

remember what happened in Dec 2009 - we had cross model agreement for quite a few days and the weather ended up delivering in quite a spectacular way.

We’ve seen all too often - if one model doesn’t like an evolution, as outlandish as it may seem - it can prove correct. 

Meteociel has 850hPa temperature charts for the UKMO run: http://www.meteociel.fr/modeles/ukmo2.php?nh=0&carte=1007&ech=144&archive=0

Cool thanks, that is handy, though the fussier me would prefer to see them on the classic WZ European charts as it is the style I have become accustomed to over the years. 

Not from Canada this time, but it was at the time of my posting in which I said it was. 

Thanks for the link Rob K. 

If the GEFS are anything to go by, there’ll be no complaints about lack of cold air this time.

Some very cold charts on offer.

http://www.wetterzentrale.de/maps/GFSP05EU06_144_2.png

This is P5 and many others are similar. 

The t850hPa mean in NW Scotland reaches -10°C on Friday on this ensemble set.

I was going to post the link and say that Meteociel provides three different map views; the one you prefer was added to their options earlier this year - or perhaps late last year.

Interesting set of runs again overnight and this morning. It seems to me that what isn't on offer is a mild south-westerly flow or a Euro high. The favoured safe options appear to be a flow from the north and some form of blocking in mid-Atlantic.  How sustained, how cold and how much snow are all still up in the air, IMO.

ECM 00z ensemble suite for London shows growing support for sustained cold out to day 15. The op was very much a mild option on days 9 and 10

06z GEFS at T+144

http://www.wetterzentrale.de/maps/GFSPANELEU06_144_1.png

There are a few which have a mid Atlantic High (no real link to Greenland) but a clear majority go for something similar to the op. 

Let's just agree to disagree on that, shall we.

I have to say the charts are stunning today...and already just 120-144 hours away. Key to this is the extension of the arctic high. This allows for a direct arctic  and prolonged source and stabilises the Greenland block.

The door has been banged 4 or 5 times now in recent weeks. Each northerly is getting that bit colder.

I see we are bringing down -40c (500Hpa) air..such deep cold is a recipe for disturbances and polar lows.

This week's recent northerly and light snowfalls was a taster.

The outlook is a wintry one. 

Never know this as I rarely use Meteociel tbh, but now I know.

EC15, as you say, keeps troughing in the North Sea going right up to day 15, but with a stronger Atlantic push towards the last couple of days, but even then, still a very high uncertainty regarding this. 

And we could go one further and agree to agree, if only you would agree that I was right.. which I was. 

Yep, most of us have and a very sensible viewpoint although it is understandable to have more enthusiasm for the current output than most we get.

Awesome set of ensembles. Snow row of 12 in London next Saturday is significant at this range.

Such a wintry outlook has put me in the festive spirit. As a result the decorations are going up today. The missus is off to Sainsburys to buy the mulled wine ! 

What does the snow row actually mean? I have never understood it. 12%, 12mm, 12cm –– what? Cheers.

48 hours ago this looked off, with a brief cold snap before a return to the norm. Now things look very, very interesting for later next week. I think I’ll use the benign weather over the next 72/96 hours to get things done outside, as a very dramatic change looks likely. It may well be moderated in terms of deep cold, but it looks nailed on to be very unsettled, and quite likely very wintry for a good few...possibly most.

GEFS now has that look about it. Things could change quickly but at the moment you would bet on December being colder than average. As for snow events it's best to wait and see. Even in winter 2009/10 (the most severe since 79 for most of the UK) there were "only" 3 significant snow events in the Chilterns. It's not scientific but my benchmark is that approx one in six snow opportunities will materialise in this part of the world. The ratio improves as you head northwards.

I believe it means that 12 of the 23 available perturbations are showing that the combination of 850Hpa and precipitation combined is supportive of snow. 

I explained it recently here:

https://www.theweatheroutlook.com/twocommunity/default.aspx?g=posts&t=18340

it means 12 of the 22 ensemble runs show snow at that time.

Meteociel shows it as a percentage instead. http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&lat=51.5085&lon=-0.12574&ville=Londres

Spot on Brian. Get the cold in place and let the synoptics follow.  Depth of cold and longevity is key.

That's not quite right as I explained in this thread:

https://www.theweatheroutlook.com/twocommunity/default.aspx?g=posts&t=18340

Cracking ones for Liverpool too. 

Snow row of 23. 👍👍

https://www.theweatheroutlook.com/charts/gefs/gefsens850liverpool0.png?cb=43

yep, don’t see that often around here!

Martin