[Scotland/Alba weather discussion - Jan 2021 onwards]

22 minutes ago, Bullseye said:

How is this one looking @LomondSnowstorm on the latest runs? So much going on over next few days so apologies if you haven't had chance to have a wee look 

I actually decided not to be lazy and had a wee look . Got it (I think) and looks good still? 

 

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 )

 

[Scotland/Alba weather discussion - Jan 2021 onwards]

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

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 

[Scotland/Alba weather discussion - Jan 2021 onwards]

1 minute ago, edo said:

About time they had perths name on it

Apologies, naturally Perth is included in that too

[Scotland/Alba weather discussion - Jan 2021 onwards]

2 minutes ago, jellybaby1969 said:

Checked the radar looks like plenty of showers packing in Edinburgh / borders and then North of Perth....few making inroads west.

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...

[Scotland/Alba weather discussion - Jan 2021 onwards]

1 minute ago, Hairy Celt said:

Seems a bit too 'experimental' - the north-west Highlands aren't going to get pasted like that. Or, at least, it would be rather strange. But not unwelcome!

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.

[Scotland/Alba weather discussion - Jan 2021 onwards]

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...

[Scotland/Alba weather discussion - Jan 2021 onwards]

9 minutes ago, aggy said:

Same here lovely bonus 

 

I just hope this dosent effect Tuesday snow

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

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. 

[Scotland/Alba weather discussion - Jan 2021 onwards]

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 

[Scotland/Alba weather discussion - Jan 2021 onwards]

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:

 

[Scotland/Alba weather discussion - Jan 2021 onwards]

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

Just now, Blitzen said:

Whit?!!   I wish they had a cross eyed emoji!   Suppose this will do!

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

2 minutes ago, aggy said:

Has any one got updated ukv or ppn forecast or snow depth chart so I can see what I’m in for 

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

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. 

[Scotland/Alba weather discussion - Jan 2021 onwards]

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. 

[Scotland/Alba weather discussion - Jan 2021 onwards]

10 minutes ago, Michael Kaii said:

Been snowing off and on all day just nothing is lying although last shower was quite heavy @LomondSnowstorm what’s it looking like from tonight onwards?

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

19 minutes ago, Sunny Leith said:

Well its early on in this easterly, but so far its the wrong type. Grey and fairly uniform cloudsheet here, very light snow blowing in the wind, bloody freezing. Hopefully it changes in character over the next 24 hours, as a few days of constant and grey just above freezing snizzle would be very unwelcome. Seen a few of these too, and quite often in the 1970s.  We need the drama!

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. 

[Scotland/Alba weather discussion - Jan 2021 onwards]

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

2 minutes ago, Hawesy said:

Morning all,

There are about 5 flakes of snizzle in the air but that’s something, right? Air temperature is 1.7c, which is a little bit above where I thought it might be with such low uppers. Let’s see how things pan out today!

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 

[Scotland/Alba weather discussion - Jan 2021 onwards]

1 minute ago, aggy said:

Good luck everyone!!! 
 

I have a dilemma . I’m due to work in Ayrshire tomorrow until Tuesday morning however I can change this to Wednesday into Thursday. What is the general consensus snow wise ? As I don’t want to miss any and obvs don’t want to risk travel if I can get away with it should I change to Wednesday as Monday into Tuesday is looking much more promising for here 

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. 

[Scotland/Alba weather discussion - Jan 2021 onwards]

2 minutes ago, Hawesy said:

Yes dew point looks fine, air temperature not so fine...ach, it will be okay by morning!

I'd think so, aye:

[Scotland/Alba weather discussion - Jan 2021 onwards]

1 minute ago, Michael Kaii said:

 so does whatever fall here according to the dewpoint will be snow or is it just a bit marginal ?

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

[Scotland/Alba weather discussion - Jan 2021 onwards]

3 minutes ago, Hawesy said:

Still 3c here on the Fife Riviera. <Drums fingers> 

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)

[Scotland/Alba weather discussion - Jan 2021 onwards]

The third easterly delivers one for the ages on the pub run:

A total nonsense but always a fun ride