Is that air cold enough even down south?

GEM turns into quite an entertaining run FWIW:

Indeed miles better than the GFS certainly no immenant breakdown there. In wetter. Bin this GFS run doesn't have a clue.

http://www.wetterzentrale.de/pics/Rukm1441.html

Probably not for snow. I make it 525-526 dam in London, and highish pressure.

but that's yesterday's run...

I quoted the 500-1,000 hPa thickness values and 850 hPa temperatures and those are within the 'sleet and snow' parameters.

Above 528 snow is unlikely, low 520s and rain is unlikely.  I don't know if it's a weak cold front or just a trough but it's certainly not a warm front so the likelihood of drizzly nothingness is zilch.

 but the metoffice are not the Beeb.. What the Beeb say is up to them regardless of what the met say. Didn't the Beeb & metoffice part ways last year??

so, even the better model has rain down here...    that's little comfort to be honest.

It's showing today's for me?

Says the 8th for me.

Clearly my machine is caching the old charts.  

As far as I'm aware Beeb get info from Met.

yes - the Beeb have confirmed they will go else where for the weather forecast.. but that wont happen until their contract runs out in a few years.

And for me. What Neil says re. uncertainty at quite an early stage is probably the key message tonight.

Will the op GFS run be another one of the much milder options on the 12z GEFS suite? Will the 12z ECM throw out a cracker, will it all end in tears. Stay tuned to the next exciting instalment of ...(read in dramas tone) "When models go wrong!" 

Edit: Surprisingly after all the rain last night the snow in my garden and indeed on my car has not melted significantly if at all today.

Keep with UKMO  GFS is doing its usual 'whatever' for most of the run. One run in what is likely to be a massive degree of scatter in the ensembles after t120. 

UKMO looks well set up for cold  Nothing too extreme of course, but at least it's a change! 

From: http://weatherfaqs.org.uk/node/152

In the course of work to compare various predictors, Boyden gave the following figures. 500-1000 hPa TTHK

5180 gpm: 90%
5238 gpm: 70%
5258 gpm: 50%
5292 gpm: 30%
5334 gpm: 10%

In the course of this work, Boyden confirmed what others have already pointed out, that the 500-1000 hPa thickness parameter is the poorest discriminator for rain/snow. The best was height of freezing level and surface temperature, both difficult to forecast in 'critical' situations, and the next best/least worst was the 850-1000 hPa value, though Boyden devised the correction 'factor' that we all now use to take account of mean sea level pressure and local height.

So, at or below 525dam snow becomes more likely - but other factors are important and we won't know them until nearer the time.  But the UKMO T+144 chart, if it verified, would produce a wintry mix at the least.

It must be

I still think there is a chance for the cold to hang on for longer but chances appear to be dropping.

The warning sign I always look out for is the pressure difference between Gibraltar - Reykjavik.

at t+144 as an estimate

UKMO: 1020mb (Gibraltar), 1025mb (Reykjavik)

GFS: 1025mb, 1022mb

ECM: 1024mb, 1020mb

It may sound daft but in mid winter the pressure difference between these two sites are strongly correlated with temperatures over the UK. The reason why the UKMO would lead to something more persistant is because the Atlantic is Gib - Ryk sum is negative and hence opposite to what we would expect in the typical UK climate (W/SW winds and a positive gradient).

From my reading of the situation, it seems that the models are still trying to resolve the behaviour of the LP over us or just to our east next week. UKMO seems to have moved more towards what ECM and GFS were showing this morning. If the models are still having difficulty with developments for next week, how on eart can we be anywhere even approaching confident wrt what happend after that?

GFS, for what it's worth, seems to be all at sea to my mind, based on the wild swings of it's past few runs.