It’s worth noting that heights to the south don’t guarantee mild weather much more than heights to the north guarantee cold: it depends on the positioning and other factors.  If the zone of upper heights to the south is displaced south or west it’s not an issue.

In that snapshot the high is off the coast of Northern Africa.

06z maintains the north/south split for temps as it has done for a number of days now

The ECM 00z ensemble for London:

As with yesterday's 12z there is a clear cooling trend from the very mild conditions at times in the coming week to progressively colder next weekend. The main cluster keeps it cold thereafter, with daytime maxima under 5C and overnight frosts. Another cluster develops are returns us to average temperatures for mid-December.

After the current rainfest fizzles out it becomes drier:

There's quite good agreement at T+168 for low pressure over Scandi and high pressure to the east of Greenland, supporting the marked cool down evident on the ensemble.

GFS 12z looking promising fro a Scandi at T210!

I would prefer it to hold between Iceland and Scandi.  If the heights topple east then there's the risk of the jet breaking down the block.

Here at T+228 it is looking OK.

-10c @ 850hpa on this 12z run knocking on the doorstep of Northern Scotland!?

Uk would have had enough Pizza Express slices by then.

Eye candy only at this range but looking pretty good at T240!

Where did that come from?

Some variation on that evolution has kept popping up in recent runs - but there's no consistency yet.

As ever, it will be interesting to see how the ensemble looks - and how ECM evolves, as the mid-Atlantic surge of upper heights gets going by day 8.

Potential support for the 12z Op in the short ensembles!

That said... it does feel like we are inching our way towards something colder be it by an easterly or northerly.... i can smell cold weather...

Half a dozen runs in support of the Op and an interesting finish to the Control.  Probably the best ensemble run I've seen so far this winter.

Hah- before I read your post Brian that was my exact question- to the letter, literally. High thinning and stretching northwards, then leaning east, rather than toppling east as soon as it took hold. Wintry around the coasts, but the max temps still forecast at 2 or 3 C.

I'll have a look at the ENS now to see if the op is just partner-switching at the ball.

One of those occasions where the ensemble suite flips to cold.

I'll be interested to see if that signal is maintained tomorrow!

just goes to show a high confidence in any output is futile at the moment although given the pattern this year HP being close has to be slight favourite 

Winter is only a day old 🙂 So no surprise on that!

But yes more promising for cold and snowy winter fans - we needed something to give us hope!

I still expect more chopping and changing though/. What is evident is that there is a ridge /block as we head towards mid month and some models have us on the milder pizza slice side of the block where as others have us on colder side like on the 12z run.

Look forward to the ECM update and what the 18z run shows and see if this trend is consistent and has cross model agreement by tomorrow? 

Another 'in' MO terminology that I have never heard nor know the meaning of, but I'll pretend to just to stay 'hip'.

ECM 12z for next Saturday looks very similar to yesterdays 12z

End of the ECM 12z run

Some consistency in wanting to push upper heights to our north.  Not as significant as GFS but some support nonetheless for this kind of evolution.