So I've been working on a lot of pet projects recently. Here is one of them that I finally think is good enough to use.

For midnight tonight from the 0Z GFS (for some reason the 6Z GFS and the GFSP have all gone down - I really hope they fix this before the 12Z runs this evening). Low level snow probability forecasts, its based on a wide range of parameters incorporating the properties of the atmosphere generally below cloud level. It would work very poorly for American weather with their large upper warm layers but should do quite well for marginal situs in the UK, at least that's what I'm hoping.

I think volatile and chaotic sums up the situation after Christmas. I think a lot of the uncertainty is linked to a possible rapidly bombing LP near/over us due to dramatically contrasting airmasses, with the meeting place possibly being Blighty.

These energetic bombing LPs can't be predicted with any accuracy at this range and the development or lack of may significantly alter the following weather. So I expect there'll be be several more days of uncertainty WRT a cold spell until we get into reasonable range.

Some of the bombs on the GEFS

Rapid cyclogenesis in sub -5c 850's and sub 528dam would be fun!

I do want to see a truly catastrophic snowfall event at some point in my life; national emergency and all that.

There was one in the early 19th Century. January 1838 I think it was.

Gavin's old enough to remember it

Off-topic,  but in my opinion, one would almost be forgiven for thinking that catastrophic weather events happen regularly in this country, given the way the media seem to insist on sensationalising  bad weather & everything else these days. The stormy spell in the middle of last week is almost a case in point.

Perchance did your last life happen to end in January 1838?

Hi all,

Here's today's video update;

Post Christmas Cold On A Knife Edge + JMA Friday;

http://www.gavsweathervids.com/

So many questions, not many answers.

Quite so David, that'll be the weather bomb that brought a massive 10 mm of rain and a strong breeze down here then. lol

GEFS a blooming tease, wish it wouldn't give a snow risk till it at least passes 25% 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=306&y=141&ville=Londres

What's the link for the bit of Meteociel where you enter your location & it gives the ens?

(or, if I've imagined that function, would someone provide the link to the list of locations you can see the ens for)

Probably won't happen, a few yrs ago I remember Tomasz Schafernaker talking to a middle aged guy live in Braemar and Tomasz asked him what was the worst snow he's seen there and he said "about 2 feet"

I was quite surprised to be honest. I would have thought more than that.

I suppose 2 feet in NW England is catastrophic 

I'm hoping for Yellowstone to blow

http://www.meteociel.fr/modeles/gefs.php?carte=1

i would expect a track slightly further north- these systems are usually slightly further north than originally progged. This could well affect any cold snap that may develop after- it's certainly on a knife edge. Let's hope it downgrades and just passes casually to the north. 

Yeah, as long as you are safely at home at the time. I remember December 1st 2010. I was stuck in a traffic jam for hours. Had to get out and piss in front of everyone. So embarrassing

http://www.meteociel.fr/ukmo/runs/2014121912/UW96-21.GIF?19-17

Crunch time approaching on UKMO

GFS similar to the 06z.

Knife edge. High pressure to south is still a real concern

http://www.meteociel.fr/modeles/ukmo2.php?ech=6&carte=1021

Yer, that would teach the "septics" ... oh wait !

http://modeles.meteociel.fr/modeles/gfs/runs/2014121912/gfsnh-0-162.png?12

Still almost identical to the 06z out to 162 hours which is remarkable considering the choas that was taking place yesterday evening through to this morning.

The main differences are that the U.S. low is deeper (but still with the same position and angle which is what really matters), and the shortwave coming along from the SW is a little slower so the resultant low after phasing with the one to the NW will have a different appearance.

http://www.meteociel.fr/ukmo/archives/2014121912/UN144-21.GIF

UKMO has the shortwave to the NW already visible at day 6 so slightly faster than GFS.

Meanwhile the positioning of the U.S. low by UKMO is perhaps better for 'trapping' the blocking high over Greenland as a more east-based -ve NAO setup like yesterday's ECM 12z op run did... though with the risk of the low pushing through Greenland as per the ECM 00z op run.

Obviously that's as far as should really be read into that run given the uncertainties at play.

GFS is looking violent going into the 27th...

We may have to all go out to see around the UK at t240 on the 6z 

http://www.meteociel.fr/modeles/gfs-para/royaume-uni/precipitations-hd/240h.htm

OUCH.

Euro High starting to fade away - this could get even more interesting...

I'm thinking you just looked at an old run from yesterday or something...?

http://modeles.meteociel.fr/modeles/gfs/runs/2014121912/gfs-0-204.png?12

-5*C and below across the whole UK by end of 28th and progressively colder going forward from there. In dramatic style too!