Wonder how Ian Brown is feeling now after that tweet to Fergie and this run from GFS

GFA @ T234:-

http://www.wetterzentrale.de/en/topkarten.php?map=1&model=gfs&var=1&run=6&time=234&lid=OP&h=0&mv=0&tr=3#mapref

Looks like a cold N'ly on this run from Thursday next week. A slight delay is all IMO as the weekend will be cold from this too.

I predict a cold December with some notable freezes along the way but this is the UK; there will be milder blips in-between. It is always going to be extremely difficult to have the mouth-watering eye-candy at all times.

Too many peeps jump ship too quickly.

 Rob but statistically I would bet that a couple of runs  trending mild are more likely to verify than cold.This is just because westerly flow is the norm and therefore is the default position.

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=192&mode=0

GFS 06h continues with a strong northerly with the LP further east than  the 0h.there is a tendency for models to start off with LP close to the east of the UK but with tim ethe northerly becomes more a glancing NW as the LP tracks further north and east.Hope we are not in for another failed northerly.

One thing that has been evident these past few runs, is theres is likely to be a very big temperature contrast across the country.

If there isnt going to be snow - there will be alot of rain to someone.

Someone is going to be in the sweet spot.  

I think your logic might be a little suspect here?  Yes, a flow of energy from a westerly quadrant might be the norm but I'm not sure that you can take that and just apply it to whatever synoptic pattern is being modelled.

Meanwhile, I've noticed a pattern in the GFS runs of late where as soon as the output moves past T+240 and into low res it steps up the rate of collapse of the block. The 06z does it again: the changes around Greenland are very slow up to day 10 and then within 48 hours the pattern flattens completely. 

I imagine he's immune otherwise we wouldn't get repeated instances on the same lines.

Surely not?

Next week's evolution seems to depend on two key developments: first, the two shallow LPs forming south of Nova Scotia at T+36 and T+54 and second the LP forming SE of Greenland at T+90. The former eventually help to waft some WAA northwards as they drift into mid-Atlantic.  The latter and it's subsequent track and evolution is key in driving the next blast of Arctic air south.  Remove either, and particularly the second one, and I think we'd see the pattern flatten.

Interesting times. 

Yes, the 6z has flipped back to give us a fairly potent, Northerly next week, but of course the 12z could easily flip back again. However, what seems clear in the current set up is that any Northerly will be transient as there is little or no energy heading South in the Atlantic so the mid-Atlantic block will continually collapse.  

So as we head into December it looks like a mainly dry and fairly cold spell of weather interspersed with cloudier, less cold interludes. No sustained cold and snowy weather but it could be a lot worse. 

This looks interesting for the many next Friday but all subject to change of course:

At the moment it looks like we have the northerly for 4 days Thurs - Monday. But this could be extended!? It keeps chopping and changing each run . What we want is the HP to slip westwards and even better northwards.

But that being said - Northerlies don't produce much if any snow for the south. We need a channel low or something.

Yes looks like it ! Nothing unseasonably cold or snowy. Just seasonal although we are not use to this after recent years. If models are right then, The second half of next week looks like a rinse and repeat of this week albeit colder as it's December.

It does look colder than average followed by a few days of average temperatures before potentially another northerly plunge of air for a few days before a transient ridge of HP brings in milder air off the Atlantic. The good news is that it's not SW winds and relentless cyclogenisis systems of low pressure from the SW. - All we need is the HP to the west of Ireland to move northwards a little!! 

Gandalf it should be possible take a large  sample of  winter cold synoptic forecasts and mild ones and look at how they verified If the answer is that mild verified better there may be other explanations apart from default but that's the best I can offer.

By that logic, there is no point looking at the models, because if any show cold they are wrong and the mild ones are right.

The spread has got even bigger, if anything.

I think this overlay of the latest four GEFS runs sums up the picture nicely:

We know pretty much what will happen up to the 5th, then.... ????

Im sure I had one of these to decode a password on a game i had on the Commodore 64

Looks like the model output has become random noise for the time being (At greater than t+120 hours in any case).

Just goes to show it all hinges on which way the High Pressure moves when 'pressed'.  I imagine it like pushing a bubble of air into water with a slightly concave surface, and eventually the bubble will need to escape back to the surface.  Will it go Westwards or Eastwards?

The postage stamps for T+192 (8th) show almost no evidence of zonality returning, at least.  There are variations on a theme of some sort of blocking up into the Greenland area - 18 out of 22 (including the control and op).  The two main variables are how much the high pressure to the south is displaced and how the LP coming SE is modelled.

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=192

Of course even the sum of all of the charts or any individual one doesn't quite reflect the actual weather. My daughter just rang to say it was snowing IN London. Number on the  snow row for London = 0. Bearing in mind it doesn't often snow in the middle of London - there is always hope! 

I think that approach is valid but only when the charts are into the period when there's a measure of consistency and the verification levels are reasonably high.  Certainly I wouldn't regard charts over a week away as sufficiently reliable to merit your suggested test.

The other key point is whether we're looking at the long wave or short wave position.  I think the long wave position should be clearer further ahead but we know the short wave position can change at quite short notice.

Now, the synoptics are generally different, imo, from the last few decades - but, possibly not very obviously so.

Last time I checked London had 70% and has been showing high chance quite a bit in gfs over recent days.