Scotland/Alba weather discussion - Jan 2021 onwards

[blitzen]

2.1c/1.8c/E/Calm. Light rain.   Temps / DPs been fluctuating a bit over the last couple of hours. Temp was down to 1.8c/1.4c but now creeping up again.   A bit misty.

[Penicuikblizzard]

Snow lying here now

[101_North]

Just now, Penicuikblizzard said:

Snow lying here now

Basically just lashing rain with blobs here! 

[Geordie Exile]

Here in Burnside (SE Glasgow) lampost estimate says 80% snow and we are at 90m asl. 

[Geordie Exile]

Edit. VAR check, now 100% wet snow. 1.4C and dropping fast...

[Penicuikblizzard]

6 minutes ago, 101_North said:

Basically just lashing rain with blobs here! 

[101_North]

1 minute ago, Penicuikblizzard said:

 

IMG_1884.MOV 38.54 MB · 0 downloads

Rub it in why don't you

[scott125]

Thin covering in East Kilbride, does not look heavy.

[metallikat34]

5 minutes ago, LomondSnowstorm said:

The ECMWF is coming out and again looks pretty reasonable for snow potential. One indicator that may be useful from their page is the 925hPa temperature - while I've previously used the 950hPa 0C level from the Euro4 for example as a decent indicator of where snow is likely the low surface pressure means 0C and 925 hPa is probably good enough in this setup to highlight where we're likely to see proper snow.

For tonight, this is what we have:

And the precipitation for the same timescale:

Comparing with the FAX charts from earlier:

 

Basically, the southern edge of the warm front that's currently edging northwards towards us is the dividing line between snow to low levels (well 50m or so and a bit inland at best) and rain. The other factor that's going to limit snow potential further east is the surface wind:

 

Dewpoints are likely to rise just a bit too much for snow in most of eastern Scotland even if you do get a bit of intensity, so you'll need a bit of elevation here for anything much tonight. Here's a comparison of the NMM forecast skew-ts for midnight tonight to illustrate, between North Lanarkshire and Fife:

 

While this isn't a massive difference on the face of it that 70m extra on the freezing level and slightly more 'stable' layer near the surface compared to the one on the left is probably enough to make a difference.

 

Comparing for the key timeframe tomorrow night, at midnight, and we can see that it's very finely balanced at the 925hPa level on the ECM:

There's a few factors impacting here - firstly the upper warm sector associated with the low, with the 850hPa 0C line not too far off the coast:

This is not too likely to impact away from the eastern Borders and coastal Aberdeenshire but because of the uncertainty over the track of the low any westward correction could lead to rainfall, most likely freezing rain, even to higher levels in the east.

There will also be the coastal modification at the surface, both in the northeast with the northerlies and potentially towards western coasts. This will depend on the shape of the low, which has varied a bit, as a more easterly flow would introduce additional areas of marginality on top of the upper warm sector.

In general, though, surface temperatures and freezing levels look reasonable enough on the NMM at least, sub 500m away from the northeast:

and surface temperatures around 1C on the ECMWF:

I'll do another post on the UKV, which I see has just updated, and precipitation totals later on, but I just wanted to give an overview of what to look out for in the next day or two from a marginality perspective.

 

I think it's starting to turn sleety here which makes sense with reports of temperature of 0C in Airdrie but primarily just wet for now - I wouldn't be surprised to end up with a slight covering by around midnight though.

 

 

 

 

Was just looking at the ECMWF as well. Definitely a more reasonable and likely snow scenario, and not as juicy as the GFS. One of the big differences between the GFS (top) and ECMWF (bottom) has been the position of the low pressure, shown here for 6am on Thursday.

ECMWF and the UKMet have had a much more progressive solution, with the low pressure being shunted further the south as it hits the water. GFS has been showing a position more to the northwest. The ECMWF/UKMet solution is more believable given the somewhat open nature of the low pressure wave. 

So a low pressure positioned a bit further to the south and east isn't a complete deal breaker as its still close enough and strong enough to produce precipitation. The 925mb temps are marginal, but may actually be helped to trend a bit colder given that low position. 

 

Expecting a sharp cut off somewhere between 50-100m, but should be a pretty good event for elevated areas. Haven't had a close look at the thermal profiles, so I am not sure how much sleet/grauple will mix in, even at higher elevation. Again, I am a big believer in the diurnal bump!  

Don't buy the GFS totals given the likely error in low position and the likely errors in the boundary level thermal profiles adding to a "juiced" up precipitation totals. 

I miss model watching for these events! Growing up in Boston in the US, this was my favorite thing to do pre winter storms!

 

[101_North]

I couldn't with any conscience even call this sleet

[Ross B]

An unexpected dusting of snow here 

[aggy]

Rain here in Cumbernauld 

[Eagle Eye]

The Beast begins, okay no it won't we'll have a second warming. 

Still hours of Snow on the GFS

Towards the end of the reliable time frame it does seem the loss of good uppers to the South, make the most of the next few days. 

Enjoy the Snow, good luck with getting outside lol hopefully a repeat of the 80s years. 

Xander

 

[Ceitidh]

Snowing lightly in East Kilbride. 

[Penicuikblizzard]

10 minutes ago, 101_North said:

Rub it in why don't you

No no  not at all

bizarre as we are at a similar height asl just a few miles along the bypass 

[Gadje]

Driving home from work heading west, watching the rain in Duns turn to sleet at Earlston to snow after Gala was brilliant. I believe for every raindrop that turns to sleet that turns to snow an angel gets their wings. Must be hunners of the wee buggers flying about tonight.

Oh and I've got a new used measuring stick.

[Norrance]

Temp at 1.0C here and the precipitation has arrived. It is rain of course.

[101_North]

9 minutes ago, Penicuikblizzard said:

No no  not at all

bizarre as we are at a similar height asl just a few miles along the bypass 

Just jesting

But yeah, it's a strange one. Doesn't happen often at all. Probably 5(ish) miles in a straight line! 

[Scottish-Irish Skier]

Aboot 2.5 cm here now. Gairden aw white again.

Snawin away happily.

Edited January 19, 2021 by Scottish-Irish Skier

[JoeShmoe]

5 hours ago, metallikat34 said:

Appreciate your assessment! And I totally recognize that I am the new guy (2 years now) here in the Edinburgh area. But I am not so sure I'd fully characterize this as a purely frontal event. Some really decent dynamics in place once that storm center hits the water early on Thursday morning. Could see a good 3-6 hour thumping of snow and the overnight timing helps with temperatures and precip type.

As someone said earlier hopefully at some point you’ll experience a proper fourth streamer in -10c uppers in a cold easterly. Last time was 2018 and we had a red warning 

Met Office issue Scotland's first ever Red weather warning for snow in central belt - The Sunday Post

WWW.GOOGLE.CO.UK

---

THE Met Office has issued its highest level of warning for parts of the central belt.

never forget that day, everyone shutting the offices early and a mad panic to get home as the blizzards started !

 

[Hawesy]

Nice to see some more snow reports!

4c and light rain here in the East Neuk. 

 

[mistyqueen]

Just popped ootside for a wee breath o' fresh air. Clear, starry sky, no wind -0.2c. Braw!

[Norrance]

Daughter says that it is snowing in Perth at least up towards Broxden roundabout?

[Glaswegianblizzard]

Solidly remaining as rain here in Cathcart, although was out for a run there and even in Giffnock theres patches of wet snow.

[JamesM]

Trying to turn to snow here now with a sleety mix.