Jackfrost

You can see Emma approaching on this radar, currently across Central France: http://www.weathercast.co.uk/radar/europe.html The precipitation is further east than I expected, but I suspect that that doesn't tell the whole story as the bulk of the system is to the west, out of radar range.

Yes, a mountain in the UK is classified as anything above 610 m (a molehill compared to the Himalayas and Andes!), and the Valleys are generally between 150-350 m or so, making this area most definitely hilly in that sense, but I've still never been sure what forecasters are referring to when it comes to "heavy snow on the hills; when people think of the hills of South Wales, they think of the Beacons and Black Mountains.

Here's something I've always wondered: when they refer to "the hills", are they talking about all hilly areas (because the Valleys are very hilly) or just the Beacons, Black Mountains etc?

Agreed @bradythemole, the 12Z is a last minute upgrade and I'm interested to see a secondary low forming to our southwest come Saturday.

With the amount of disruption these warnings have already caused, what with preemptive school closures, if the forecast does go horribly wrong then there'll be some explaining to do. That said, GFS is holding steady with tomorrow's snow but it brings RAIN into West Wales. Eek!

I really am hoping for a slight eastwards correction for Emma, for all our sakes.

Just to add, I feel like a fairly small area will see the greatest depths between tomorrow morning and Saturday, roughly the areas within the red line. 25-30 cm widespread, but likely more.

Something else of note: the temperatures. -6Cs and -5Cs throughout tomorrow meaning that a) the snow will be fine and will blow into drifts thanks to gusts approaching 50 mph and b) March daytime maxima records could surely be broken.

A further 0-15 cm possible on Friday and Saturday. I think we can be confident that South Wales is in the sweet spot over the coming days, so we can expect towards the upper end of those estimate. ~30 cm depths come Saturday can probably be realistically expected in South Wales, if not a little more, and not necessarily only on high ground.

I'm going to get things thrown at me for this but while I'm looking forward to the snow (beginning in around thirty-six hours and hopefully lasting for thirty-six more!), I'm also looking forward to this being over and normality resuming. I've noticed over the last week, more than ever, people on Netweather getting very worked up over will-it, won't-it minutiae and IMBY concerns and actually getting into arguments over it. Personally, I'm finding myself on edge with each model run and feeling either disappointed or elated. That can't be healthy, can it? So, let this weekend be winter's last hurrah: even if we don't get a warm, sunny summer, the abundance of greenery, flowers, long days and walking opportunities in the lovely Welsh countryside will be there to be enjoyed, and with none of the winter snow anxiety!

It's looking serious indeed up here in the central Valleys, with snow falling uninterrupted between early Thursday morning and Sunday lunchtime*, much of it heavy and coupled with sub-zero temperatures and winds gusting close to 50 mph. * Not set in stone of course as the output is mostly computer generated, but the signal has been there for days for heavy, prolonged and drifting snow.

I have to say that that was perhaps my favourite Derek broadcast ever, my dream forecast, and something I never thought I'd see/hear: him pointing to a picture of the 1982 event and saying "... and we could be seeing scenes like this later in the week." And all this from a man who has never been prone to ramping.

Was that a deliberate pun, Andy? A bloody good one if so.

Is anybody old enough to remember the forecast in the days leading up to the infamous, era-defining blizzard of January '82? I've searched on Youtube for archive forecasts but... nothing.

Stick with the Met Office, not because it's showing what we want to see but because the computer-generated output on the BBC's website beyond the next day or two has been woeful since they switched data providers. They've also, I believe, done away completely with the heavy snow symbol. Just teething trouble, hopefully.

Pretty decent ECM for us this morning!

Agreed. The GFS is highly rated, and rightly so, but anybody placing all of their eggs in one particular basket is not going to get the best informed view of what's going on. Let's see what this morning's outputs, updates, forecasts and tweets bring. As things stand, like Andy said, all sources (except for the GFS) are still going for a major event on Thu-Fri.

An admittedly poor 00Z with the worst of the snow going through Ireland and the Irish Sea, leaving a six hour spell of moderate snow over Wales followed by a thaw from the south. Still, perhaps the 06Z will be an improvement.

So, given that some serious weather looks like commencing come Thursday, would anybody be brave/foolish enough to single out where they think the sweet spots could be, based on current evidence? Don't hunt me down if this map isn't entirely accurate or if the model output changes, but I'll go with locations inside the red line seeing significant snow with places outside of it (Swansea, for example) also potentially seeing some. The southern half of the RoI is also included, and if there weren't so many doubts about less cold air filtering into the far south I'd also include inland Cornwall, Devon, Dorset and Somerset.

Big improvement on the 06Z for prolonging the snow over Wales - the milder air never makes it as far north as us - with more snow on Sunday. And encouragingly, all of Wales, not just inland parts with elevation, get in on the action.

It is, yes! One thing to bear in mind: most of us (and I'm assuming all of us here on Netweather) will be enjoying the cold and snow since we have the luxury of being able to wrap up warm before returning to our cosy homes. Not everyone is so fortunate; I felt genuinely upset reading this story: http://www.bbc.co.uk/news/uk-england-essex-43181603 Especially with the forecast windchill and nighttime lows (-4-6C, even in urban areas), anybody on the streets has a real chance of hypothermia. There are a lot of homeless people in Cardiff, Swansea and Newport in particular, so if you do one good deed this week then buy a rough sleeper a hot drink and a warm pastie or pie! In an ideal world we wouldn't have such a heartless and incompetent government and this wouldn't be an issue, but alas. Also, our furry friends will appreciate a warm coast when out for walkies this week.

Perhaps I was being needlessly negative and going solely by the GFS 12Z output. It's true, most of the models are now hinting at a breakdown for the South by next weekend but it's all far from resolved, and before then we have potentially the heaviest snowfall in years to contend with!

The end of next week seems to have gone from a thirty-six hour snowstorm followed by a reload of the cold easterlies to a twelve hour affair followed by a thaw. I despair.

The real damage will be done when frozen cabbages and broccolis begin raining down.

Derek has now mentioned the 1982 event in relation to the end of the coming week several times. It's very rare that he mentions snow potential so far in advance; he really isn't a ramper at all. I think "tantalising" is the correct word to use here!