But usually when you get a mild flip, its stays, doesnt usually flip back.  Meltdown on netweather

No Darren this morning says it all really

Yes a growing theme of a fairly widespread snow event Tuesday night.

https://www.wetterzentrale.de/en/show_diagrams.php?geoid=50893&model=ecm&var=2&run=0&lid=ENS&bw=1 

Well, all the models flipped milder a week or so ago and then they went colder again, so it does happen. I don't look in at the other place very often but it melts down more often than a Russian nuclear plant...

Unless we get a clear signal for northern blocking, I suspect the ens will continue to wobble around but given it's an unsettled pattern, anything enough below the average line signals potentially interesting, even if only temporarily so IMO.

It may all collapse to a mild and wet pattern if the Atlantic revs up properly and the usual HP just to the south, NE tracking jet sets in but whilst some members play with that the majority in the ens suites aren't at the moment, so glass half full I reckon. 

As Rob/you mentioned there's currently a decent signal for something interesting circa 6th/7th Jan for those not already experiencing interesting weather. 

A quick IMBY look has:-

UKMO - Snow moving south.

ECM - wintry mix moving south (wet snow over higher ground like the Downs), second little feature bringing another wintry mix to Kent/East Sussex etc. from the NE.

GEM - rain from the main feature, snow North of London. Some secondary precip is snow presumably as the LP pulls colder air back in its wake.

UKV - band of mostly snow moving south down the country, poised to cross me at T120.

It's 5 days away in a still evolving pattern so may well disappear entirely but highlights the possibilities nicely.

Might be surprisingly a premature comment from you. Cold spells lasting without mild interludes very rare. Looks like a reload on GFS and areas further north staying on the cold side

I think the medium term range is still a bit of a mess with potential for almost anything, both mild or cold and settled or unsettled. As ever, beyond about 120 hours ensembles will be the way to go (or at least looking for run to run consistency).

I hope that this isn't off topic but my experience is similar. We've only had 3 air frosts this autumn/winter and none over the Christmas period, even on nights which were ostensibly suitable for frost like last night. I suppose that the apparent difficulty in getting temperatures to go sub zero is the counterpart of summer when we seem to get high temperatures even with fairly common or garden synoptics.

Nothing set in stone yet of course as regards future cold weather prospects and as you suggest, there is plenty scatter in the ensembles. However, I can't say that I like the direction of travel of the GFS control and op runs this morning. 

This is a genuine question, maybe one for Brian, but what do we think has led to this "powerful blocking" to be blown away so easily?

Whatever happens next week, and I still feel there will be more swings, there is no doubt that the super powerful block has been swept aside as easily as dust is swept from a doorstep. Why?

The models never suggested anything unprecedently cold. The lowest 850s down here are only modelled to be about -10, possibly -11C which is nothing too noteworthy. I am expecting some pretty sharp frosts over the next few days, but which I mean below -5C and possibly -10C in prone areas of the south. UKV has -8C not far away from me on Tuesday morning for instance (and -16C in Scotland by Wednesday).

Has it?

This is the current analysis chart. https://www.meteociel.fr/ukmo/fax/fax0s.gif?02-6

You seem to be taking model output for current reality. The block is there right now.

But it's not the super block that we were told was the strongest for nearly 5 decades, and the models are sweeping it away, every model doing so. May not happen of course, but if the models are correct, it hasn't been a particularly powerful block at all.

Because, like many on here, the Met Office models don't factor in history and what has happened to similar promising set ups in the last ten years!

That is a very good point! 

And just to keep us on our toes, GFS control run serves up a classic Channel low snowfest in a week's time 🙂

There's still a lot to play for.