Cheshire Freeze

I can only assume that there are really quite strong signals for a -AO as we approach mid December. IIRC the Metoffice have traditionally done well with picking out cold spells when us amateurs couldn't necessarily see it yet. I recall them picking up on the January 2013 snow weeks before it hit...I know this because a council employee had been in work and told us that they'd been briefed. That was mid December I think. The Metoffice are not known for sticking their head above the parapet RE cold and snow unless they have some solid signals to suggest it.

John Hammond is a brilliant forecaster...one of the best the BBC have at the moment in my very honest opinion.

N'ly ready to blow?

The UKMO run is actually fairly decent going forward from day 6..compare it to the GEM and they're night and day upstream...with the UKMO being fairly amplified across Canada.

Couldn't make it up Bitterly cold air flooding in from the N/NE BUT we don't get a sufficient undercut

It has been on many occasion when aligned S-N rather than SW-NE. It pumps warm air into the higher latitudes and displaces cold elsewhere, often building heights as it does so.

Ties in well with the period that I think Ian mentioned the Metoffice were seeing a potentially more mobile spell??

Borderline how this plays out at day 10...could do with a smidgen more WAA a day or so before to really put a wedge between that Canadian troughing and the lower heights east of Greenland. However it plays out, there is more potential there at day 9 than there was on the 0z run so I'll take that positive and say 'thank you very much'.

Yeah, funny how models are so good at predicting zonality via an Atlantic onslaught. Can count down to it like clockwork most times.

The control makes it....

The mean is now on board with the extra WAA at day 8.. Also digs the LP to S of Greenland further SE. Encouraging at least- there will be some decent perturbations in this lot.

Divergence will be stark in this pattern because you either get sufficient WAA and a stronger block that sustains or you don't. It's as simple as that. Knife edge stuff but the direction of travel today has been good with that low exiting stateside being held back more and more each run.

Aye, here drops the trough from the NE

Highlights the differences between getting a good pulse of WAA northwards and not....Getting WAA north is important going forward into December...which is what I tried to point out last week when it was obvious the first attempt was failing.

Atlantic looks relatively blocked off chaps (at least northern arm of jet)...we may see the trough descend from the NE this run...perhaps interacting with LP to SW as per Metoffice long ranger?

Surely SURELY that developing high pressure west of Greenland has a chance of gaining a sufficient foothold on this run as LP backs off even further than on earlier runs (which were an improvement each time) If it can't gain a foothold from there it's time to pack this weather malarky in

This isn't usual November weather though is it. Some areas further S must have seen 100mm+ over past 3 days or so. That's pretty exceptional. These 2 systems haven't been your usual zonal W-E warm front then cold front jobbys. They've been absolute rain makers. To rain for 10 hours solid is excessive...and it's still going.

Absolutely horrid day today. It has been raining for 10 hours pretty solidly with a brief respite between about 1-2. Surface water flooding on the roads, pretty deep in places. Absolutely vile. The wind is starting to whip up now as well.

That low across the Atlantic at or around day 8/9 is the common theme on most of the output and it is causing a nuisance i.e preventing Atlantic ridging to reinforce the fledgling Canadian blocking. You couldn't have picked a worse time for this to happen (synoptic progression wise) as in all the crap runs we've seen today, the common factor is this LP flattening the attempted Atlantic ridging...

Well that's great but not everyone has had snow (me included) and what has already happened has no actual effect on what will happen as we progress through winter. Personally I haven't seen more than 1cm of snow since 2013...that's coming up to 4 years ago.

Yes, that chart would do 2015 proud! It's far out and hypothetical to say the least, but once you get Euro heights like that they can be massively hard to shift. I guess that's in the back of everyone's minds.

We hear this same line trotted out every year though....then we end up at the end of February with most of lowland UK still waiting for a snowfall. Happens far too often. Seasons are far shorter than people think. I don't care about patience, I want some snowfall ASAP from now on in then the rest of winter can do as it pleases.

I feel the modelling has been going the 'wrong way' for the best part of a week now. It wasn't s long ago that we had all the medium and longer range products going for a near unanimous pressure rise just to our NW very end of November into December. I suppose, in a way, that signal is still there but what has changed (or beginning to be firmed up) is that the UK may well miss out on the cold goodies with far too many complications flying around the N Atlantic sector. The 18z GFS run is in that group of ensembles I mentioned earlier that were far from stellar

ECM follows that group of ensembles in the GEFS which sink the high SE into Europe. Mixed results as to what follows but this isn't the 'stellar' route,

850s ensemble graph doesn't look too bad, but doesn't tell the story RE the synoptics on offer. By 384 a lot are either 'messy' and unsettled or the last vestiges of a colder spell between 240-300 hrs are on their way out. Too many images to post but here are a couple picked at random