think the key is potential cold, always going to be unlikely to be on Xmas day (not saying it won’t) but would be happy still if it was after

Richard?  😉

HP building over GH and Easterly flow established over the UK.

This is still shown today on models

The snow / rain boundary will continually move N and S with each run as it’s too far out to be clear

The LP track will be the main thing to focus your eyes on. It looks like the pattern is relatively consistent so there’s no point looking too much into the pattern, we can see where the pressure systems are going to be sitting next week

You need to keep looking at that LP and how it moves in, for those looking at cold in the South and snow you need that low to dig south to pull down colder air.

If the boundary line is Central England it will be very messy and mostly rain away from Northern England

It seems to me that beyond T144, the models seem to scan the horizon for macro changes in the atmosphere, pick up on one, "fiddle" with it (micro changes) and then either develop it or discard it (which the GFS Op run did with the Atlantic push through a few days ago). The more cross model agreement, the more likely this macro change will be adopted. My hypothesis is this. where the macro change is developed, rather than discarded, it also gains confidence in the outcome and gains momentum, ie, the time-frame to that part of the forecast, arriving in reality, shortens. A recent great example of this is the demise of the robust high currently over with which was - until three days ago - due to sit over or close to our shores until after Christmas, perhaps then sinking south into Europe. Now it is forecast to both decline and to shift quite a long way northwards. Over the last few runs, that macro change has gained cross model support and has gained momentum (it is accelerating) BUT ..... we are still outside of T144. I can see that there is room for one more macro change prior to the forecast for Christmas firming up.

One caveat to all this is that sometimes, a macro change can occur as near as T96 - and we all have memories of those!

Just food for thought.

Jeff

Looking at the GFS 850 ensembles for London there is now starting to be a distinct split into two camps rather than the random spread of recent days. Overall the colder perts are in the majority and if it goes that way it still looks very promising after Christmas.

I think for us southerners the cigar is gently being put back in the case for this Christmaas. It's a different story further north.

Interesting?

Very interesting.

6z looks very good. White Christmas back on for the South? Loads of uncertainty still. 

Hi Brian. You appear to put quite a bit of emphasis on Mogreps. What are the validation stats compared to say ECM or UKMO? Is it really any better than the 'big three' or does is it just as variable after a certain range?

Wow! snow showers in eastern coastal counties and northern Scotland. Where is the GFS confetti when it is needed.

I doubt whether there is a great deal of difference with GEFS, GEM ENS or ECM ENS. Generally the UM verifies a little ahead of the GFS and as all of the UK Met Office grids  (e.g. UKV, Euro4, Global, see https://www.metoffice.gov.uk/research/approach/modelling-systems/unified-model/index ) are basically the same internally I would expect the same to apply with MOGREPS vs GEFS. 

Keep calm....Next!

The continuation continues for Christmas to be cold but the 06z looks much less favourable for a cold period , more of a cold snap

It will change again but the pattern is slightly different on the 06z

Indeed. My thoughts entirely. Move on.

The 6z Op is a shocker.

Again, it builds high pressure over Iberia/North Africa, forcing the lows right over UK, and forcing the block to the north into retreat.

I would imagine this 06z Op sits high (ish) in the suite but the trend for northward correction continues to evolve into a diluted affair.
Where’s Gandalf?

edit: oh dear- seems supported:

https://www.wetterzentrale.de/en/show_diagrams.php?model=gfs&lid=ENS&var=2&bw=1&geoid=49069

How many times have we seen that in the modern era? I've already seen comments along the lines of if we can't get a proper cold spell now then when can we.

All in all, the models are in turmoil at the moment, and I can't believe for one minute we will be nudging 60F on the last day of the year.

Best christmas model watching in years, even if it doesnt come off