A few years ago, Brian's servers would be buckling by now!

Indeed. A more sensible and educated theme is definitely prevalent on here compared to the old days when all most saw were blue colours on a chart and instantly got excited. 

brutal cold in North America

http://modeles.meteociel.fr/modeles/gfs/runs/2015012406/gfsnh-1-240.png?6

http://modeles.meteociel.fr/modeles/gfs/runs/2015012406/gfsnh-1-252.png?6

starts to sink just as we finally tap into the proper stuff

A rare set of charts - cold on both sides of the Atlantic at the same time. Pity they are in deep FI.

A very nice cold and snowy run from GFS. Also a good strat warming as well.

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=240&mode=10&carte=1

Explains why the north Atlantic ends up with a -12 850 temperature anomaly - the vortex is split and pushed our way.

The past couple of days has seen a great trend to heavily disrupt or even block off the main jet in the 7-10 day range 

GFS seems to be finally getting there on the 06z op after getting close on the 00z, and there were some tasty looking ECM and GEM 00z op runs to wake up to 

Interesting that ECM has dropped the distinct area of low pressure crossing the Atlantic days 6-8, instead holding it back on the far side of the North Atlantic from us. This really allows the northerly to become locked in with a strong mid-Atlantic ridge, the cold finally becoming established at low levels right down to the far south by day 9 and persisting day 10 with little sign of much interruption on the following day or two.

GEM does allow that low across, but keeps it very weak, consistent with yesterday's 12z op run.

The broad theme is the most encouraging I've seen since those epic GFSP runs in the middle of December last year.

Good to see much stronger support for the better end of the charts this time around, and a trend to improve things further.

It looks like a good example of how a highly amplified pattern can deliver deep cold across the U.S. and a cold spell across the UK simultaneously when the longwave pattern is compact enough - the jet is weak and meandering enough to allow for two sharp troughs and a strong ridge in between instead of just one massive trough across the Atlantic as was the case last winter when the jet was far stronger.

Now we just need the pattern to verify with the right positioning for the UK to benefit in terms of cold, snowy conditions nationwide... easier said than done.

Whatever we end up with could stick around for quite some time, as there is a growing signal for the atmosphere to be in a generally low-momentum state for at least a fortnight.

I see the GFS 06z is a big step in the right direction day 9-10 for importing and entrenching that cold air 

Yes they are crap no question but it was a good cold run and I'm sure most would see some snow. With a very good UKMO and ecm people should be optimistic about the forthcoming cold spell.

I think I spotted it fairly early on, its hard to say though whether its just luck. My impression was that given the position of the jet stream and the LP over Scandinavia a reload was more likely than a complete topple, this was more from my experience of the charts themselves than for any other reason. I posted this stamp sequence two days ago which seems to now be supported by some of the models.

I'm glad to see my excitement wasn't in vain, though still a long way to go. What I really want to see is the arctic airmass residing near svalbard move into scandanavia. 

I would be astounded if Eastern and Southern parts saw anything of note from that.

Gavs vid last week stated a huge warming in stratosphere  come Feb.  Maybe this could be what we have been waiting  for since March 2013.

Had missed that. Tks

There's a lot of snow forecast for the north in the later stages of the ECM run. Of course thickness and 850s are a lot lower than on the GFS.

ECM snow charts for N Scotland, courtesy IMO - change the time stamp - it's in six hourly increments.

http://brunnur.vedur.is/kort/ecm0125/2015/01/24/00/ecm0125_djup_msl_2t_850t_snow_2015012400_180.jpg

Me too , to be honest

Gibbies update on NW is mentioning snow for many

Wasn't Quantum talking about "record low thicknesses" from this northerly?

Again it was just a potential, I was referring to the unusually southern position of the Arctic airmass, obviously its still quite difficult to tap into.

NASA GEO5 comes closest 

Note the white area over Svalbard.

EDIT: also one further point, thickness is never going to be a record low in a northerly. All I meant was that it has the potential to be record low for a northerly, I think the full thickness was lowest at around 504dm in the western isles, and I think this record is the one potentially under threat, not the 498 in SE england during a fridid easterly.

The potential too - due to the northerly source.  The thickness of which was progged to be very very low.  Not sure the currrent whereabouts on that now though.  Scotland would get nailed if it did.

I'm not sure what sort of thickness this would correspond to, my guess is that it would be lower than a -12C easterly feed, because the upper part of the atmosphere will be modified less, I'm sure this is getting on for 510dm.

been many a year since we saw -12s hitting the uk.

Yeh, and when was the last time it happened in a Northerly? March 2013 and 2010 were both from Scandanavia. I mean given the right situ we can get -20C uppers in the UK but never from the north, the -10C line on that chart is flirting with the south coast! It is pretty impressive.

Control run is fantastic