LRD

Almost perfect. Just the odd tweak needed here and there such as getting that nose of orange out of Spain and Portugal (preferably to the south and south west of the Azores) and also getting the Scandi ridge ever-so-slightly closer to Iceland and bingo!

That didn't sustain though. The pattern soon collapsed after that. But on the face of it, you'd think that would have been the precursor of a great winter. An almost-perfectly aligned Scandi High that looks robust. Just goes to show that the flimsiest of highs can drive a pattern south while a strong-looking high can collapse quickly. It turned out an exceptionally mild winter, of course, especially in the new year and that ridiculously warm February

Equally you could say it's ridging to Greenland... despite the purple over northern Canada.

Yes, that's true but I just can't see a backtrack on the 18z. The general pattern is there. European low pressure. Once that establishes (if it establishes) then the rest is just detail so it's neither backtrack or, er, forwardtrack for me tonight. It might change in the morning of course and I'm worried it will but I'm just commenting on tonight's charts

Yep, looking at the southerly jet and persistent euro low on the 18z, my first thought was "backtrack". Or, to put it another way... no, it wasn't

Oooooh, matron

December 1981?

Those means are brilliant. Especially the last 3 frames

I thought it was a wedge of high pressure around western scandinavia that deflected and disrupted systems south east from the north west. But I could be wrong

To be fair it was NW to SE sliders that gave me (and many others) my last true wintry spell - January 2013. Nearly 5 years ago. I know the north did well in March 2013 from a more defined cold pattern. I find sliders to be more reliable than straight Northerlies

I commented the other day that I thought the introduction of milder weather was being put back to later and later in December by these Met Office updates and this one doesn't even mention mild now. Hopefully these will continue to upgrade the cold even further

Not a million miles from what the last frame looks like on the 12z GFS operational. Hmmmmm...

Indeed. That's because the long wave pattern obviously isn't quite right. It might be selective memory playing tricks but I'm sure those colder periods between 2009 and 2013 were seen by the models and then didn't really wobble much. Because the atmopshere was in a particular state during those years. This year it's obviously more ambiguous so the models are struggling a bit more

Agreed. I suppose if the amosphere is particularly well primed to help UK cold then the marginality can be taken out of it and it's comfortable to get the cold in as it seemed to be during the period from Feb 09 to Mar 13. Today, the atmosphere is obviously in a state where it's more knife edge for the UK, making your analysis even more valuable

Nice first post. Yes, the Met Office and, therefore presumably GLOSEA, are clearly seeing a stratospheric driver to enable mobility by mid December. What I would say, though, is that the predicted period of mobiity seems to be getting every so gradually pushed further back...

Agreed. Nick's analysis is still really valuable because we may not truly know what the atmosphere is set up to do (despite clues like QBO, solar activity, etc) until we look at and understand the smaller stuff... and then observe the reality.

Yes, Nuuk, Rekyavik and Oslo are the ensembles to look at but more for pressure trends. Obviously, for those locations, the higher the better

Exactly what I was thinking Chris. It's not really a case of the shortwaves destroying anything. It would be the general long wave pattern that allows those 'little' lows to break through or over ride northern blocking. In cold winters those areas of low pressure still exist but the overall pattern is more conducive to cold so they don't mess anything up. So, if things aren't properly set up then the shortwave pattern will be allowed to develop in a way that kicks northern blocking into touch. However, to be fair, we will only know if the pattern was ever conducive by observing the behaviour of the shortwave synoptics and seeing the reality unravel! Sort of chicken and egg but it's the long wave atmopsheric pattern that's the true driver

Interesting update. Dominant high pressure just where we want it (well, where most of us who like seasonal weather want it anyway). Persistent with the 'getting milder at mid month' message but it feels like the timescale for the milder weather to win out is being put back gradually. Gut feel and not based on any science whatsoever but I reckon it will be a cold, frosty December. I am not expecting much in the way of significant snow, unfortunately. Mild eventually winning out near the end of the month, perhaps even into 2018. And, from a cold, seasonal perspective, that could be as good as the winter gets

Nice one. Cheers

http://www.wetterzentrale.de/de/topkarten.php?map=1&model=ecm&var=1&run=12&time=240&lid=OP&h=0&mv=0&tr=24#mapref Dare I say... BOOOOOM!!!! Let's get it to 48 hours rather than 240! PS I tried to copy the URL and present it as an image but it wouldn't let me

http://www.wetterzentrale.de/de/topkarten.php?map=1&model=gfs&var=1&run=12&time=216&lid=OP&h=0&mv=0&tr=3#mapref - GFS http://www.wetterzentrale.de/de/topkarten.php?map=1&model=ecm&var=1&run=12&time=216&lid=OP&h=0&mv=0&tr=24#mapref - ECM ECM isn't as good as GFS but it ain't bad at all. General theme maintained. UKMO still a worry but it looks isolated

Oh yes quite agree but you were asking why December was mentioned in relation to a 6 day chart. That's why. It also works the other way, of course - the models (that we see for free) can be stymied by other models and the words that are then written in rersponse to those models we don't see. I s'pose we're trying to get our hopes up that UKMO is wrong tonight based on the Met's update

Because it is very difficult to see how today's 12z UKMO run would then go on to lead to what the Met are saying for the first half of December without some pretty unlikely amplification/synoptic evolution. So, it seems to be contrary to the latest forecast

Memory might be playing tricks but wasn't the UKMO the first model to pick up the cold this week or at least the cold over this weekend? I could be wrong of course and, yes, let's hope GFS is right. But I'd always favour UKMO over GFS.