snowking

Was just about to post similarly Steve - hi res models picking up on some light flurries through the estuary this afternoon, doesn't look like anything major at the moment though. I had underestimated how much has fallen overnight here - similar to Dan's report from Rotherhithe, about 6cms so pretty impressed for London. Thursday still very hit and miss across modelling suites, it will be a case of wait and see but I suspect with the strong flow it might be a little more intense than currently predicted. Friday still looking good for now. Bet we'll wish we were over in the westcountry though

I woke up just at the right time. Probably had an inch come down in Greenwich, very impressive snowfall rates - this is what happens with a proper continental feed Just a shame everything is now moving WNW as I had my eye on one last hurrah heading into Essex but that will probably miss us here now I have to say, when you look at the shape and the timing of the precip and look back at my post from earlier this evening, this has been exceptionally well modelled by the hi res charts tonight Enjoy everyone - very jealous of the amounts @Daniel Smith has had!

@Paul Sherman - hopefully this is just moments away from you

New amber warning in force for Eastern most parts for tonight

Yep, looks like -9c now

Hmmm. Need a few more frames through until 9pm but the flow seems to be turning a little quicker than forecast at the moment. The showers quite scattered in the estuary but it might give more the region a chance at least a little earlier than expected

Euro4 and ECM both wanting to go for a repeat performance for this evening from today, just a little accelerated. We see the streamer re-establish across Eastern-most parts of Essex running into Kent But then, a little quicker than today, we see the flow switch to more of an Easterly once again, pushing the formed precipitation westwards: So some heavier falls once again in the east but the chance of another covering into the London area by morning too. Perhaps a greater chance of a covering in East Anglia tonight as well. This is pretty unanimous across most hi-res models too: Thursday and Friday is then our next watchpoint - very uncertain even at this stage. Initially we have a warm front head North - this won't warm things up at the surface and will produce snow but it's tricky to tell just how much precipitation it will have on it. Here it is shown on the FAX charts: Most of the precipitation will be ahead of this first front. The latter frames of the Euro4 not that keen to introduce too much precipitation to our shores: However, it could be that it picks up more precipitation than expected as it comes across the channel and especially into the estuary with a strong flow in association with this. ECM and ARPEGE similar too: So some patchy outbreaks of snow I would expect through Thursday - we can all hope that it's a little more intense than currently modelled. ECM continues to bring in spells of snow through the day though with Eastern parts generally remaining drier. ARPEGE and ECM much keener on some more significant precipitation on Friday: As you can see, whilst the ARPEGE a little more keen on rain close to the coast, the ECM brings an all day snow event, which could be rather fun. So lots to keep an eye on for the rest of the week - Friday is the day with most potential beyond the next 12 hours and could give much of the region a very decent covering indeed. All to play for.

As Steve has already alluded to:

I was just about to go and grab the EURO4 forecast for this morning but someone on twitter beat me to it - just shows how much of an underestimation there has already been:

That is, of course, assuming that the very narrow convergence zone as modelled is indeed that narrow If you look at the areal spread of the showers already today vs what was modelled by the EURO4 even yesterday, it will be interesting to see if the streamer tonight is actually a little wider than currently modelled

Well that 12z ECM livens things up a bit for the end of this week - outbreaks of snow pushing North through Thursday, a mixture of snow and freezing rain overnight Thursday before another, heavier front of snow pushes North through Friday, which remains entirely as snow. A very messy picture so I think it will be wednesday before we have much clue as to where this is heading. Fortunately there's plenty to keep us interested before then!

Yes it will certainly be interesting to see how this plays out. If we go by what is currently modelled then outside of the two amber zones you would think that chances would be very hit and miss. However that is assuming what is currently modelled is what plays out - as Darren alludes to, we quite often see some surprises crop up which are not modelled in these scenarios The big problem for anywhere west of the amber zone right now is that the flow is so variable. When we do see a more perfect flow to push stuff further inland on Tuesday, we then see that little disturbance run just in to the North-West of the region which one would suspect will lower the showery activity further south across us - just unfortunate timing really. But let's see what happens - it's not that outside of the amber zones I'm not expecting a cm or 2, but for the serious snowfall amounts this currently looks a little less widespread (pre-friday at least) for our region than say 2009. Anyway, let's see what plays out!

6z Euro 4 bringing in some snow flurries through the early hours of Monday: Probably in association with the cold front shown on the FAX charts this morning. Little wash streamer setting up just to the North of the region too:

I suspect, as is often the case with the GFS in these situations, that it's far too keen to blow away what is an incredibly dense cold airmass for the time of year in place across the UK. Generally I tend to have more belief in the ECMWF in such situations as it tends to be the best of a bad bunch in terms of resolving anything cyclonic coming into a blocking situation so will be interesting to monitor this through the week, but I would expect most model runs to bring this feature as far north as the 6z in the next few days before slowly correcting South through the rest of the week. It's a bit unique because usually we are talking about systems disrupting from west to east, but one would assume the same modelling physics apply here. Anyway regardless of that, looking at modelling for the middle of this week: We are likely to be in for some very snowy surprises with such a strong flow in conjunction with the intensely cold air in place. The flow by Thursday morning looks a little too SE'ly for us here but through Wednesday with the more direct E'ly flow I suspect we may see some more organised features heading inland which may be pretty poorly modelled - a completely different flow but Jan 2003 springs to mind here in terms of surprise features.

I always like using this tool in times like this: http://meteocentre.com/vigilance/france/vigilance.php?ens=naefs&run=00&map=SN&day=all&lang=en&area=fr It's a Met Office warning-style chart created using the NAEFS ensemble system (a combination of the GFS and GEM models for anyone unfamiliar) - it shows the probability of various parameters as an average of all the ensemble members. Below, yellow indicates the probability of more than 2cms snow and orange more than 5cms. That's probably still a very conservative estimate on a regional scale but given this is an ensemble average it makes for pretty impressive reading for much of the UK.

In NW Essex we certainly did. I can remember two fairly substantial snowfalls, the one that sticks in the mind the most was on a Sunday afternoon where we had somewhere close to 6 inches come down (helps that we had a little bit of elevation) Yet despite all of the incredible snowfalls of those winters, our absolute largest was actually in Feb '12, where we had somewhere between 9-10 inches of powdery gold.

I'm exhausted, I've never seen anything like this in some 16 years of internet weather watching. I'm off to Amsterdam tomorrow and will be glad of the break to be honest to try and recover a bit! I think we all have to accept that even what we are seeing here feels unlikely to transpire exactly as depicted by our 'stella' friend the 18z, but if anything even close to this comes off then the mood in here this time next week will be very buoyant. Anyway, where is @lorenzo - isn't this the pub run you've been waiting for Tony?

-17c into parts of the south I would say breath-taking...but taking breath could get quite tricky in those conditions

Just the smallest hint of the unspeakable "TS" word off the back of that 12z ECM run Though nothing especially impressive totals wise it should all of course be taken with a huge dollop of salt at this range

Only 1 run with more twists and turns to come I'm sure so we should keep this in perspective, but I must confess that when you compare things to yesterday's 12z: I couldn't help but give out just a little

It will be either per 3 or per 6 hours, depending on the timescale the TWO charts use. If their charts are displayed in 6 hour intervals then it will be per 6 hours...ditto 3

Okay, we're splitting hairs then over terminology here as to what constitutes "cold" and "very cold" in a long range text forecast which has no official terminology key to equate the prose used to specific parameters (and for a good reason - no forecast at that range is going to be specific enough to give exact temperature profiles, wording will always be a little deliberately vague), but in the 16-30 day outlook: "At the start of this period it is likely to stay cold for most" I.e. - the cold already in place from the previous forecast period remains in place at the start of this next forecast period. So I think you're having a bit of a worry about nothing, there's nothing in that forecast that is any different from the expectations we already have at this stage Yes, I find it more fun these days to sit and obseverve the chaos and just chip in where I think it might be helpful. The main nuances we have seen in recent days stem largely from the energy distribution of the jet stream over the Atlantic crashing into the high around our shores and beyond, particularly through to Wednesday. For this reason, and in addition to the current happenings in the stratosphere, I'm still waiting until then to be absolutely confident of just where our high is headed to and what may be allowed to slide underneath it as a result. That said, I just have that feeling that we are on the verge of something special, as I think I mentioned when I last posted in the MOD thread earlier in February. Back then, when you looked at the scale of the stratospheric warming event in conjunction with the near record tropical forcing, it was pretty clear that we would have to be exceptionally unlucky, even by UK standards, to not get at least some notable cold for the time of year in. If everything goes well in the next few days, we could have something even more special than that Fortunately I'm in Amsterdam Tue-Thur so either way, I should be able to keep myself occupied...

I'm not really sure how you managed to conclude that from the forecast you posted. The 'dry' part applies to the first few days of the forecast period - ie Friday to Sunday, as is currently expected anyway. They then mention the risk of snow start to increase, especially for the South and East, into the following week - ie the week commencing 26th February - as is also currently being modelled. So for this region, a pretty extraordinary update really and I'm not sure we could really expect more than that at this stage.

It's probably worth re-iterating Nick's comment from earlier (as in BA Nick....Mr T's long lost cousin) that the EPS do tend to have a habit of following the op rather closely at times with a rather mixed track record. But when you compare the EPS mean and op side by side: For what looks like almost all of the 51 perturbations to be incorrect at such a short lead time, if the entire suite is wrong then I don't think we could ever learn to trust it again. At least if the UKMO climbs down we're just looking at a couple of deterministic runs having been wrong. And in time, with snow shovels in hand, we could learn to forgive and forget and at least remain friends.

Sadly, I think we know by now Tim, those Weather.us charts are hugely overblown. I tend to find that if you go into the settings and convert the scale from inches to cms, for some reason you get a slightly more realistic view (of course as a male I would usually advise converting from cms to inches...) That yields this at +240: From experience this winter so far, that tends to be about 75% true. So with 2-5cms generally shown at lower levels, I would advise more realistically perhaps 0-4cms, with the undercut towards the end of the run clearly visible in the South-West. @Nick L usually has some ECMWF access with a far more realistic scale. I'm only theorising here as to why the Weather.us charts are so wild with their estimates, but I imagine there is a fair bit of parameter configuration available when building out these charts and it may be that when viewing these with the inches scale, the more typical US snowfall ratios of around 10:1 (snowfall to rainfall equivalent) are used, where as when converted to cms for a more metric scale-ified europe, the ratio is changed to something more realistic for these parts.