Looking back at the ECM 00z op run, it very nearly went the way of the GFS 12z op, but a Canadian shortwave trough sneaked across into the Atlantic, preventing the ridge into Greenland and instead developing low heights there, leaving us looking to the east as the Atlantic jet dug southward.

Considering that was still a fairly promising run going forward from day 10, the walling off of the Canadian shortwave would be like taking a shortcut in some ways.

I really can't be sure from the day 5 to 6 progression whether UKMO is headed for a walled off solution or not. There's a strong ridge coming out of Canada/Newfoundland and the shortwave on the western flank of the Atlantic trough could 'prop it up' across Greenland, but it looks like tight margins to me.

A seriously important ECM run coming up tonight.

Oh and one thing not mentioned in the previous post was that the polar vortex is left in shreds by the end of that GFS op run. A strong ridge is centered west of Iberia but with polar heights rising that would be likely to build north to Greenland as the jet stream weakens further.

Hi David. I've witnessed it back in the late 1970s, on the Lleyn Peninsula in North Wales. Very heavy snow show right near the coast, very close lightning and loud thunder and my dad even witnessed what he called a ball of lightning going into the sea.

Indeed, but the op is a distinct outlier in the extended arctic northerly stages , which means its chances of verification are slim, sadly:

I wouldn't go that far - although there's no consistent timing, there is a theme (which occurs at different times depending upon the perturbation) for amplification and northerly winds.  It's almost as if the system is trying to build a block and a northerly, but different instances succeed on different attempts (where an attempt is the SE movement of the low pressure).

23C is exceptionally rare though, in January for instance the SSTS down the E coast are about 7C, but it will be much colder than that if there has been prolonged cold during December. with 7C to get 23C you need an 850hpa temp of -16C, and that virtually never happens. The problem is cold air masses are often accompanied by cold SSTs, 1947 didn't have a chance the SSTs were virtually 0C! 2010 was very close and it regularly got up to 21C but that was chiefly because the snow happened so early, there is a drop of 3C during december of average SSTs. 

Snow beginning to pile up for parts of Scotland - the highlands in particular. I would expect a southward progression of that later in the day and early on Monday. But this below chart is as far as it goes on this EURO4 run.  

Hi Quantum, it's interesting that you mention 2010 as I do recall hearing about some thundersnow events at the end of November that year, when the big freeze started. Here is a YouTube clip of a flash of forked lightning and rumble of thunder seen in Dundee at the end of November 2010. I have seen thunder occur many times in the past with hailstones, but never with snow to my recollection.

https://www.youtube.com/watch?v=7aNmGrkk5rM

http://www.meteociel.fr/modeles/ecmwf/runs/2014120512/ECH1-168.GIF?05-0

ECM so far, not quite what GFS is showing

http://www.meteociel.fr/modeles/ecmwf/runs/2014120512/ECH1-192.GIF?05-0

Misses the straight Northerly GFS delivered

Cold still dragged across us

http://www.meteociel.fr/modeles/ecmwf/runs/2014120512/ECH0-192.GIF?05-0

Maybe my interpretation is wrong here, but that to me looks as though some of the polar vortex will be directly over Scotland!

I think the thundersnow event has only been mentioned on here about a thousand times every winter since it happened, so I  can understand how you missed it David 

http://youtu.be/qJt4nV6hM1Y

Thats thunder snow US style 

If it had also happened where I live I'm sure I would remember it. We also missed it at the end of November 2010 when parts of eastern Scotland, Dundee being one of them, had thundersnow. We had tonnes of snow at the same time here as did virtually everyhere, but there was absolutely no thunder with it whatsoever.

http://www.meteociel.fr/modeles/ecmwf/runs/2014120512/ECH1-240.GIF?05-0

HP ridging in, LP in the N Sea

http://www.meteociel.fr/modeles/ecmwf/runs/2014120512/ECH0-240.GIF?05-0

Looks like a toppler to me at T+240.

11 hours of thundersnow here on 28th Nov 2010 plus a couple of claps on the 29th. It is rare but can happen with very cold uppers coming in over a warm North Sea.

Edit. Sorry just realised I was in the model thread so going a bit off topic.😉

Very close to walling off the Canadian trough on the ECM run. The transition across Greenland still occurs but it's at day 7 so nothing nailed on yet either way.

Even with the transfer, the mid-Atlantic ridge proves sufficient for a sharply digging trough days 9-10, in fact so much so that there's room for the ridge to build over the top of the trough in the North Sea as it drops south, particularly given that the jet is also digging well south in the western North Atlantic.

Apart from GFS being flatter in the Atlantic as usual, the day 10 N. Hem profiles are actually quite similar as far as the major features go.

If I have my theory right, the stronger Siberian High and deeper Aleutian low on the ECM run should bring about even more strat. warming than the GFS run developed.

I figure the MJO is worth a look again today. Clearly UKMO and JMAN have trended towards the ECMF solution, but by contrast the ECMF solution now takees the MJO to phase 8 and it almost hits the amplitude of around 1.0 beyond which the atmospheric response tends to be much stronger. There's then a brief, weak venture into phase 1, after which it does head into phase 4 and amplifies, but by that time phase 4 is less detrimental to blocking to the NW (it actually favours it come January).

This, too, should encourage even more promising strat. developments in the extended ECM.

GEFS is being stubborn with the higher amplitude MJO but at the moment a meeting in the middle ground looks plausible. That would actually be fairly good going.

While basking in waves of positive developments this evening, I do wonder if this apparently smooth track might actually turn out to be a roller coaster as it so often does... but there's no denying that today's trends are the most encouraging of the past month or so 

Now 1,001 times (12 times by me) Feb 1982 - 48hr non-stop snowfeast in

South Wales, accompanied by the one and only period of time that I've seen and heard a few bolts of lightning claps of thunder

 "Thundersnow"

How come this hasn't been backed up by the Met Office or BBC!"??

Hmm indeed, I wonder why the BBC have not mentioned the GFS 12z operational run chart's low resolution t2m output 15 days in advance.