LomondSnowstorm

It's certainly helpful that they're decreasing, although as it currently stands the flow on Wednesday is largely just about keeping the showers heavy for the east coast and inland south of the Forth. If we do get an extension of the easterly into Thursday though it would likely be on the slack side and something like that would go a long way to increasing the snow risk and maybe creating the conditions for secondary lows to develop (just speculating now but we'll see how it goes )

By the looks of both the models and the radar it seems like the convergence line will hover between Aberdeen and the Forth for the next 6-12 hours (cheers for posting that CMD! Helpful to see the breakdown by 12 hourly segments like that), if anything maybe moving a bit northwards in the next couple of hours. The flow is becoming a little more ENErly and the kink in the flow over western Scotland starting to be ironed out a bit so we may see a bit of a southwesterly extension, and I think that southern zone of precipitation seems to be extending northwards again too, so perhaps Edinburgh-Glasgow will see more over the next few hours from that. As far as Amber/red warning potential goes I'd say - Amber potentially tomorrow morning-afternoon from Aberdeenshire to Fife basically inland to the nearest Munro, tomorrow lunchtime to Tuesday morning from the Tay to Edinburgh-Glasgow, tomorrow night-Tuesday evening Forth-Clyde streamer line to the Southern Uplands and Tuesday-Wednesday lunchtime maybe a shade to the south of that. Red warnings aren't out of the question either, and I'd think could be anywhere from Tayside to East Ren as a northeast/southwest limit, and probably at some point from tomorrow lunchtime to maybe Tuesday night depending on how things shake out. Enjoy it folks

Latest UKV is a little better for Aberdeen, Tayside and Fife than the previous run, totals still very much on the stonking side (not to be taken too literally of course but as a rough indication of where it's distributing the showers over the next couple of days): The lines out in the North Sea seem to be getting longer - bit of a lull along the Forth-Clyde line as the 'pasting zone' moves south into North Fife/Tayside

Apologies, naturally Perth is included in that too

With the exception of some Forth-Clyde stuff (already!) it isn't getting too far west. I do think it's getting a bit further west than forecast though, and more streams to the south of the central belt than the models had for today, so I wouldn't be too disheartened - the west and southward extent on the UKV keeps growing run on run...

It does seem a lot of that is what it, for some reason, assumes is there now - presumably some of the peaks have close to those depths but even with a 1.5km resolution it's probably putting it in a significantly wider area than it should be.

Bit of a lull between streamers here. No lying snow to report in Freuchie (if I was there I'd be annoyed that Coatbridge got lying snow, albeit a dusting, before us ) but that next blob has Dundee/Fife north of the Lomonds' name all over it...

Seems to be fairly well on track, I've noticed a bit of a southward correction generally which I think is associated with a bit more of a northerly tilt to the flow, hard to pin down but certainly more than enough snow to go around for all of us

Nice wee streamer starting to arrive here, an actually visible dusting now although we're still towards the edge of where the showers are losing their intensity, for now. And yeah the boundary between the intense and lighter stuff is shifting south, I'd expect that to continue through the night.

Starting to looking interesting for the Lothians through to Glasgow with the way the next line of convection is lining up, looks pretty heavy and a bit larger than what we've seen at this latitude so far. Very light graupel here at the moment

Yet more upgrades further out, as well as bit more of a northerly tilt to the flow on Tuesday too, staying closer to the lower heights as well which will help with convection:

Snow on here properly now, not really heavy but you can see individual flakes settling nicely.

Basically the wet bulb is closer to the temperature than the dew point, so if the snow's heavy today it'll probably cause the wet bulb to lower and make the snow lie

Still looking promising for most places up to tomorrow night (with at least another 18 hours of good snowfall potential to come after).

Another point on the wet baws, as it's known - the best approximation for it at low temperatures is the "1/3 rule" where you subtract 1/3 of the difference between the temperature and dewpoint from the temperature. So for example, 2/-4 gets you to a 0C wet bulb temperature. However, if you have heavy showers, and the temperature and dewpoint start to converge as the humidity increases, you'd only need the temperature to drop 1C for every 2C the dew point rises in order to keep the wet bulb temperature at the same level, and obviously if the temperature drops a little more the wet bulb temperature will drop too. That's why I'd think that, even without the even colder uppers coming in, you only really need a heavy shower to end up with lying snow.

A few more indicators of how things are likely to shape up overnight. More -11Cs appearing in the uppers as the night goes on, at present it's a mix of -9C and -10C values, so more like 0C maxima inland and 0C wet bulb temperatures at the coast (it will lie with intensity now I'd think since the Twet isn't far enough above freezing that a heavy shower won't drag it down a tad, but this will help certainly): A couple of breaks in the cloud overnight. It's not massively windy now so with clearer spells temperatures will quickly drop below freezing. Everything otherwise looks fine, but today was quite well flagged up as the most disappointing day of the easterly. Snowing here on and off, but as elsewhere it's too light to settle and rather grey.

Should be getting heavier tomorrow through to Wednesday with lower thicknesses and I'd imagine that'll be enough for it to accumulate

I'm certainly hopeful it will - there's a bit too much of a southerly component today and the cold pool, while pretty cold, is still a bit shallow - from looking at the NMM soundings for today you could see a bit of an inversion at around 800hPa or so which is capping the convection, certainly Dundee southwards. By tomorrow we'll see colder air moving in at higher levels as well, and the thicknesses reducing: That's going to allow the deeper convection to build up and merge into more persistent bands. I'd think that this will occur overnight - you can see at the 700hPa level the humidity goes from around 40%, then there's potentially a bit of a clear spell allowing temperatures to drop properly around midnight or so, then the values really increase That's when we'll start to see far more yellow and potentially reds on the radar and a bit less grey snizzle.

The overnight UKV is rather tasty for a lot of us...

The good news is the coldest uppers are just making their way inland now (it was mixed with more -8/-9s overnight) so I would think it won't rise today, and if anything should drop a bit as the heavier stuff comes in

I think as far as falling snow goes Monday into Tuesday morning will have more falling snow especially further west (looking at the UKV it seems like there'll be a good amount of snow south for central areas too) whereas by Wednesday into Thursday it's more likely to be dry as the flow gets slacker, most likely.

I'd think so, aye:

I think marginal at the moment, probably non-marginal snow by 1-2am though I'd think

Looks like the dewpoints are starting to get there if nothing else: Drier than the Sahara at that (well, if the pub run is right)

The third easterly delivers one for the ages on the pub run: A total nonsense but always a fun ride