kold weather

Very good 144hrs, though probably would signal rain after a brief snow front edge for the south. Still the MAIN thing is getting the pattern in and its a very good sign from the ECM. I'll gladly take it at this stage. Ridge coming in behind the low should help to slow the PV over Canada down a little as well and keep the LP on its way ESE.

That would be my best guess yes. LP on a good looming angle, very similar to the UKMO I have to say which gives us confidence. Hopefully it weakens a little as it moves ESE...but even if not, the shape and angle should mean the cold is still close by if worst comes to the worst.

Game on the ECM at 120hrs.... Indeed worth noting that the 120hrs chart itself is very good and cold aloft, I'd bet there could well be some surprises with that type of flow. ps, will probably be a more northern based run due to there being a lobe of the PV splitting off, but its got a good angle still.

I will 100% take that right now then if that is broadly what you think will be happening, cold with multiple snow opportunities beyond the ones that are within the week. Some decent northern blocking starting to emerge on the ensembles as well deep into FI right in my ballpark time of 5-10th Feb. Still a long way to go till that point though. Your idea of a Scandi high is starting to show its hand.

In the right set-up even those above -5c could well be snow given the right wind direction, etc.

Yeah its a really solid set, but with still quite a lot of variation, other than to inform us of what is possible, not sure they are too much benefit! Still, some REAL eye candy, I'm sure a couple of those would give some 1ft type snowfall for someone.

Yeah this is a far mpopre complex situation than what we had with the easterly and so we may find that even a less than optimal ECM output may well still do the job. Several of the GFS ensembles looked poor at 144hrs but by 192hrs they are looking quite snowy, so plenty to play for!

It will be slightly slower but it will get there, the key thing to note is the areas of purple (ish!), as long as the NE one is stronger, that will be the dominant feature in any fujiwara and ensure that complex moves broadly E/ESE. The runs that go wrong phase move some of the PV energy from Canada into the Atlantic and then starts to deepen, meaning by the time it gets to that point, the westerly area is stronger, so that means it rotates towards ENE instead and shunts in SW/WSW winds. Ensembles still a little all over the shop but still snowy for most places on all but 2 of the ensemble runs. A couple are more northern based but even they do bleed down colder air into the flow pretty quickly (within 24hrs) so they aren't a disaster. Roughly 20% of the 23 members (including OP+para) phrase the low, so similar levels to the 00z ECM ensembles. By the way, a couple of blizzards show up on the GFS ensembles, at varying times. Small risk but it is as much a chance as it going completely wrong, due to the high risk, high reward nature of this, the ceiling is very high....the bottom...very low!

Yep, its a good run as it keeps the cold nice and close by for all and gives a good spell of snow. The exact location of the low has yet to be decided, so for now just the trend of the low developing in that way is Most important. Not too fussed where it ends up providing it doesn't usher in a large WSW fetch! I just know the ECM is going to throw a curveball, that's just how this winter has been so far!

Yep, and it was that one that turned out to be right Anyway several opportunities as you mention, some of the models are still toying with perhaps back edge snow as the front clears out on Sunday, the models seem to be at least trending that way for say the east coast/East Anglia. Also I'm fairly confident that providing we manage to get that NW on Sunday/Monday that it would be yet another active flow, so good chance of a trough or two being embedded in the flow. Who knows, 29 years with no snowfall from a NW could be broken at long last if that does come off...nah who am I kidding

Certainly a small risk, but then again the easterly would have had similar failure risk at this time as well and we know it was that 10% that won out of that occasion. Never underestimate our ability to snatch defeat from the jaws of victory!

Great looking GFS so far, and the UKMO was also very good. GEM and ICON both destroy hopes of a long lasting cold spell, so feels like we are back at that all or nothing place we were same time last week! Whilst they are not as good as the UKMO/GFS, still is a possibility they are right. ECM going to be a pretty important run to see which side it sits.

Worth noting that the GEM super charges the low pressure over Canada between 36-48hrs, getting it decently below 955mbs. The GFS is gets down to 960mbs and the UKMO only to 965mbs. It may be that then GEM is overpowering the low which is suggestive its throwing too much energy into the flow, which obviously has its impacts on what happens downstream between 96-144hrs.

-5C isotherm is a fair bit north of even Scotland on this run, that's a massive drag down that is required to get cold enough for snow. IF GEM happens then only Scotland are within close reach, for the S.England thats probably a solid 5-7 days delay from 1st Feb IF the pattern is good afterwards.

GEM goes along with the ICON on this run. GEM is at 985mbs by 108hrs and phases with the PV lobe further east, indeed the LP that comes down at 120hrs never separates from the Canadian PV. A little reminiscent of the Easterly fail actually.

Looks like another very unstable flow, indeed the GFS has yet another strong trough over S.England. Maybe I may yet end up with my first ever NW snowfall! 150hrs GFS - snowfall on leading edge of front, rain for far south. Decent enough run though for the pattern! On that leading edge could vbe some big falls on this run, maybe some more snow on the back half for the south as it clears...if it clear.

Yeah no issues with the 12z UKMO, and no issues thus far with the GFS out to 132. BIG issues with ICON. So what odds guys that the ECM follows the ICON this evening...

Actually 144hrs UKMO is nearly a carbon copy of the 06z GFS, so perhaps better than even I was thinking. Anyway 126hrs GFS has a good shaped low extending and attaching around the broad circulation of the PV lobe to our north. Looks good so far!

UKMO is fine, probably not great for S.England verbatim but the shape is fine and mean quite a tight gradient of cold air to the northern edge of the low...so even if us in the south were on the wrong side, the cold air is still nice and close by... Compared to the ICON with the bowling ball strong low means any cold air is 100s miles north of the center. VERY hard to drag cold air down there without northern blocking to help, which isn't happening any time soon.

To be fair, does look like the ICON speed wise, but not phasing already like the ICON does (between 120-132hrs). 144hrs UKMO looks fine to me, nice elongated LP, compared to the circular 980mb low already present on the ICON.

Probably a similar number on the 06z GFS ensembles, it was there as option but hardly favourite. Of course with this winter, that 20% will definitely be the right option, everything has to be difficult system also is rapid on the 12z ICON, pressure already down to 975mbs in the Atlantic at 120hrs and south of Greenland and then it phases as you say. I highly doubt its going to come in either that fast OR that strong at that point.

Icon looks much too strong for the south unfortunately with too much mild air coming into the south. May even be too much for Midlands as well but we will see. All complex is still moving ESE nicely. ICON looks WAY too strong, pressure below 965mbs which seems highly unlikely and blows our cold pool to kingdom come! If it is that strong, it will probably delay cold again for another 4-5 days given the way the flow behind it slackens up....even the next slider would be screwed by that due to the lack of cold air!

I was 2 at the point, so yeah to young to really remember anything, my first tentative snow memory comes from probably 95-96, or maybe 97-96, I'm not 100% certain! Anyway won't be long before the 12z suite comes out. Don't get too hung up on the exact location of the LPs, they will shift around on these runs.

Its finny that Tom was posting about the 1927 blizzard yesterday, because the synoptics look quite similar to what we may receive, though obviously with the caveat that its a heck of a long way out yet. Good read Tom by the way!

Its actually a SE airflow, quite a strong one at that! Hence why the boundary level remained cold despite what looks like debateable 850hpa temps. As for 850hpa temps, they are a good guide but far from the be all and end all, just lasdt year in storm Emma 850hpa temps rose to about -2C but because the boundary level was so cold from the cold of the week, it still was powdery dry snow for the most part (the following day was wet snow). Indeed March 2018 was the first time I've seen proper powdery snow. Living previously on the Thames Estuary most cold was moderated to make it the wet variety. I'm sure Feb 2009 had powder, but I was unfortunately in Chichester back then.