kold weather

FWIW those 850hpa temps are pretty comparable to the Feb/Mar 18 cold. I'd suspect that is at the extreme end of what is possible in this pattern, certainly maxing out what we have on this run for sure!

Great run. Could be even more interesting down the line again, maybe an attack from the NW followed by another pressure rise towards Greenland a the PV lobe moves up and out.

Kinda, but instead the low blows up in a big way and does a anticlock-wise rotation through northern France then back into the SE, basically 36hrs of snow, but I'd guess its the same feature that the ECM ensembles are picking up.

Got to say that the GFS 18z op looks very similar to a majority of the ECM ensembles around 240hrs, that's good news that despite some differences at the start, we end up at a similar place...

There is that snowy set-up at 216hrs that the ECM ensembles have been highlighting for a few suites now, not too exceptional this run but decent snowfalls, probably 3-5 inches on that NE edge of the precip core would be my guess, but sbnbow extends the whole way south eventually.

Well a slightly more convoluted way of getting into the cold spell and more risky (shortwave fun and games) but a pretty solid run coming up, indeed may turn into a really great run down the line ad the Arctic looks supportive this run.

The key thing with the ensembles is to watch the trend, if you start getting more and more members per run jumping ship and joining that outlier OP, then you 9/10 have a big problem, as we saw with the easterly. Still not too sure what to make from the 18z GFS. It looks ok to me, just a variation of the broad theme. Little shortwave feature extending from the upper low to our east may limit what is possible this run. but broadly looks fine.

Quite the different pattern over NE America now from the 18z GFS, not really sure if its for the best or not though at the moment...

That is really rather close to again introducing a E flow, indeed the surface flow may well turn briefly easterly anyway. Interesting. Nick S, I think you are right, we are always battling against marco set-up right now.

Very interesting gFS so far and throwing yet another curveball, not a bad northerly actually by 114hrs. Our neck of the woods look REALLY sensitive to changes that would normally not cause the models issues. Certainly interesting, wonder how it will effect the pattern down the line. I tend to agree with Catacol, FI probably start somewhere between 96-120hrs at the moment, mad as that seems!

Well that is an interesting signal, the thing is there is more volitilty out there that its quite possible a small feature crops up and changes things as early as 72hrs! Doesn't always have to be bad things that crop up!

A bit of lateral thinking?! In all seriousness, only 1-2 runs that look like the ECM from the ECM and both deliver a very zonal flow by day 13. I think its pretty certain the ECM op follows those examplers given where it sits within its ensemble range. But the fact there is literally only 2 that I can find kind of speaks volumes as to the likelihood! (One GFS para run in the last 36hrs also pulled a similar track and looked dreadful by day-13 as well).

Given how extreme Feb/Mar 18 was, I think that's probably wise to say its not as likely to get quite that extreme, sounds more like the long term models are more going along a DecJan 10/ December 2010/ March 2013 type event, long lasting but without the extreme blast of Feb/Mar 18.

Right the 18z GFS is up and running. Pleasse GFS, no 12z ECM OP nonsense, I don't want to have to look at the 00z through my fingers!

Certainly right to worry about the flow bending back to a southerly, that is a risk and it is well reflected in the GFS ensembles as well. Also, still a decent snow signal for the 29-31st from the ECM ensembles.

LP to our north is much stronger on this run and more organised, which may mean a slightly stronger cold push earlier on.

Well only one word I can use for the ECM ensembles: Stonker! Seriously that is amazing set of ensembles, just for reference just 6 out of 50 do not create a decent Azores ridge into the Greenland area by the 31st Jan. Several of those end up with decent northern blocking a few days later. I think there maybe some outrageous looking charts for the UK in this set of ensembles.

12z ECM control run now takes the biscuit as the most extreme snowfall I've ever seen from a run, just fwiw (widespread 9-12 inches, SE and the north of England upto 15 inches...) Anyway that is probably highly unlikely, but a bit of fun for sure!

Control run from the 12z ECM gets better and better, 240hrs looks 100X better than the OP run (probably no surprise given it was a big outlier) and then evolves into a cyclonic easterly, really great run. I wonder where that sits on the ensemble range. Hopefully the 00z ECM op run falls inline at least somewhat.

I'm personally still 0 for 30 years form a NW airflow, but then again the chances always were there for some snow as this was a very cyclonic NW airflow and that trough feature was neat. Indeed, that trough should show that just because a set-up doesn't look 'that' snowy, it could become one in a cyclonic airflow, which is highly likely to be the case if we do get the GFS evolution. ECM control run out to 29th looks very good, much better than the OP. Rest of the individual members should be out soon so will be good to tell.

Looks like there has been a lot more snow around than was first expected by the models. Sadly here we got screwed out of it by the drier slot that was in place on the back part of the trough, just as the trough started to widely transition to snow. I probably needed a delay of 1-2hrs to have had snow as the system was just turning sleety. Ah well, you win some and lose some, and this was a lose for me, but a big win for plenty of others, congrats and keep sending in those lovely photos!

On all fairness, the 12z ECM ensembles mean IS good tonight, when people said it was good I wasn't sure, but they were 100% right on that one. Now we really do need a good ECM operational tomorrow, because the OP ECM can be pretty problematic once gets its teeth into something, an outlier now may not be that way in 24-36hrs time... Anyway I'm interested in how each of the individual ensemble members look, that will be telling.

THAT however does ease some fears for sure. Heck of a mild outlier suggests the 'cleve' pattern isn't at all supported by the ensembles, thank goodness! Indeed the eCM is just about the warmest run throughout the entire thing.

Yep...what worries me a little and itd nagging me is that the ECM op was one the first to spot the move away from the cold easterly. The ensembles were still on board but more and more jumped off ship. The GFS has been like that, with near total agreement a few days ago, we are now in a situation where only about 50-60% dive the LP far enough SE to relaly get the most out of the cold air. I think a cold shot is just about certain, but I think about waiting this long...I want...more...

Such a slow evolution to cold on that 00z ECM though and I think the whole thing is going to be put under a lot of pressure by the NE Canada lobe. Thr 12z is even more progressive on that front and WILL end with a toppler situation shortly after the cold air has dug in, probably at 288hrs. The 500mb thickness charts show very nicely this if you run 6hr increments between 216-240hrs. PS, great mean as others have said though!