Scotland - Weather Chat

[lorenzo]

GFS P looking pretty similar to Met Office Faxes for Thursday strength and depth of system, more creaking hooses overnight..

 

 

As for GFS Parallel - 

 

 

 

?????????

[edo]

Lorenzo loving the SIG Hansen reference in MT last night....my favourite fisherman

Charts looking good and easterleys starting to show with quite a long fetch....will wait to see if there still there in a couple of days before getting excited

Edited January 12, 2015 by edodfc

[Northern Strath]

Temp slightly up to -0.1 and light snow

[November13]

Cold air moving North to South now. In theory the north west should be coldest right now.

[Hairy Celt]

Temp here now at 2C, clear sky. Alarm set early

 

Some wishful thinking on the MT (so what's new?) this evening.  The most relevant comment under the 1984 comparisons sub-plot was to look at how SST have gone up over 30 years.

[scott_anthony_glasgow]

Plently of precipitation about. Hailstones atm. Colder air arriving shortly. See how it goes

[November13]

Did a quick scan of traffic Scotland. All the higher level routes are now showing snow where rain before. So temps dropping away now. Hope tomorrow brings a white covering. Off to bed now as main action will be early hours.

[edo]

Pishing down here big style

[LomondSnowstorm]

A lot of uncertainty about the outlook, short, medium and long term tonight, even as far as what happens overnight. I'll take a look at the NMM and NAE (18Z NMM, 12Z NAE since the latest one isn't out yet) to give a better idea of what might happen.

 

While the precipitation within the front is moving northeast the front itself will sink southeast, turning gradually to snow as it does so:

The 12Z EURO4 had this sinking more quickly, giving less in the way of snow to the southern half of Scotland but still with more snow piling into the Highlands on SWerly winds:

 

Temperatures by early morning subzero for the Borders and Highlands but more like 0-2C elsewhere:

After that the Highland Boundary fault shower line establishes and grows southwards, leading to showers occasionally getting further south and east through the day, but generally the main events through tomorrow morning will be (unless this all moves a few miles further south of course) a sort of Helensburgh-Dundee streamer along with a decent dump of snow for the Great Glen northwards including Inverness:

 

(at this point, LS realised there was a Scotland only map on the NMM but couldn't be bothered going back and changing the previous charts)

Temperatures at most maybe 3-4C around coastal Fife and Edinburgh, but most places struggling to get above 2C through tomorrow. NMM has a bias towards overcooking coastal modification for the east coast, and hilariously this is the same whether it's a locally sourced easterly or, in this instance, a southwesterly, while the NAE does go a bit over the top with the chill, so a good idea would be to split the difference:

 

 

 

Now comes the bit where there was previously a lot of disagreement, particularly between the GFS models and the NAE on precipitation placement, and while I was wary of taking the NAE's side purely on the basis of it being a higher resolution model the 18Z NMM looks to give at least a bit of support to the more wintry option for the central belt.

The main problem for me is the direction of the flow - the more southerly, the more likely the precipitation is to end up tracking too far north for many of us, and the more of a direct westerly it is (ideally a sort of westerly 'kink' enhancing the precipitation) then the better the chance of the main band of snow being further south.

The GFS P has the flow just south of west, but with no discernible kink in the flow:

 

However, the NMM, with its higher resolution, has locally something more like a straight westerly flow, as the NAE does:

 

Consequently, although also perhaps an issue more generally with its resolution, the GFS P shows precipitation struggling to very far east at all, although still pretty good for around Glasgow:

 

 

The NMM, while still not showing huge totals, has quite a lot managing to get through to Fife and the Lothians and even at points up into Aberdeenshire, while also showing an improved picture for snow for Inverness:

 

This ties in well with the latest NAE, which has snow for many central areas between around 4 and 8pm:

 

 

 

One thing which isn't in too much doubt is the temperature - widely 0-1C, freezing level sub 400m, so a good chance that what falls will settle:

  

 

 

 

Accumulation estimates - very tough to be too specific when a 20 mile movement southwards (i.e. absolutely nothing in global terms) makes such a big difference. If the main band remains around that Highland Boundary Fault-ish line for all of tonight, tomorrow and tomorrow night then they're going to get absolutely pelted, perhaps a foot for southern Perthshire, perhaps more like 1-2 inches all told at the end of the line in Dundee (maybe more but it's not that clear how heavy the precipitation will be by the time it gets that far east) but north Fife and Perth could sneakily end up with 2+ inches, partly because I'm in Edinburgh but also because the Lomonds and Ochils often act as a boundary in these setups. Lothian and the Borders' chances are contingent of the overnight band turning to snow quickly enough before it disappears, then either the main band setting up around the central belt into the evening or at least a separate stream of showers managing to break out of the Perthshire snow nexus after dark. Not going to predict accumulations for Edinburgh, even though it's entirely possible, because the city is cursed with a snow shield which only intensifies if the wind is even slightly south of west, but West Lothian always gets snow, and Falkirk/Stirling (moreso the latter) might do well too tomorrow evening. Again, I wouldn't go higher than an inch but some of these places bookmarked for less will end up with more and some will almost certainly end up crying in the corner at the end of night with none. Around Glasgow looks decent at times, moreso to the north of the city and immediately west and east (Inverclyde could do alright, depending on the alignment of the frontal stuff). It doesn't lie often in central Glasgow but it might just tomorrow night, with precipitation about and temperatures pretty close to 0C, outwith the city a good chance of getting something, North Lanarkshire and East Dunbartonshire looking like being potential hotspots if the front doesn't just avoid the central belt altogether.  Further south is a difficult call, the models have it curiously dry for Ayrshire and D+G although temperatures aren't too bad if something does arrive.

As for Aberdeen city, shire etc., you're relying on precipitation getting across the Cairngorms for the most part - not impossible but tough. Western Aberdeenshire will do ok, Moray looks to be on the fringes of the Highland snowmaggedon so again, maybe an inch or two there and definitely not too much of an issue with marginality (except in Rosehearty, which from memory of the MO obs site is perpetually 6C and raining but will probably be dry tomorrow anyway). As for the Highlands, you're in for it, You maybe avoid it on the immediate west coast where it might not settle or the likes of Wick which are sheltered from SWerlies but elsewhere, expect some serious snow, an extra 100cm of snow at the main ski centres (bar Glenshee and the Lecht) by Wednesday midday looks like a decent bet.

Wednesday morning then becomes the next point of interest after showers gradually die out (possibly) overnight, when the next front arrives, sometime between 7am and 3pm, bringing snow/sleet/rain/not arriving.

EURO4 has a very hefty front which runs into cold air, brings marginally less cold surface air for a time but still manages to keep it as snow inland:

   

 

With the super hi-res NMM only going to +36 we can't see what it does, but the GFS P and GFS both show similar, almost lazy chart with snow for the west not getting very far east:

 

And then the storm comes, melting our lovely snow (temporarily perhaps) and blowing us all to bits (scary charts on post below)

Edited January 13, 2015 by LomondSnowstorm

[LomondSnowstorm]

  

 

Anyway, as I was saying,

Going to be some eeriness with wind gusts dropping 60mph in an hour for some, with Lewis going through the 'eye' of the low with 70+mph gusts (i.e. beach weather compared to last Thursday) at either end.

Still never very warm, with precipitation transitioning between rain and snow (staying as snow entirely 500m+ but rain entirely at sea level from Wednesday afternoon) and back for about 24 hours, but by Thursday night we're back into the cold:

 

 

After that, more cold type west/northwesterly with resultant snow chances but with the outside possibility of something like this occurring:

 

What appears to be driving this is the MJO, which is staying at an amplitude in phase 6 (the 'nearly classic synoptics' phase) which we haven't seen before. This has thrown the models off a bit, and means that we're now more likely to progress into the properly awesome phases of 7,8 and 1, increasing our chances of getting something from either the north or the east before January's over:

 

So, essentially, snowy for some, possibly many, of us tomorrow into Wednesday, a bit less cold (still far from mild) but very stormy Wednesday night into Thursday, cold returns by Thursday evening, a similar pattern at least for this weekend with snow chances from the west and northwest and then either a continuation of the pattern or an MJO induced jolt into at least a toppler easterly. Certainly far from boring, and far from mild.

Edited January 13, 2015 by LomondSnowstorm

[NUT]

Now I can say the showers are sleety here

[Northern Strath]

Incredible stuff before I slink off to bed peeps, thunder, lightning and heavy snow

Epic

[Sunshineandshowers84]

Starting to snow here

[Polar Gael]

LS, that was an epic double post - thank you for outlining all the options and throwing a bit of clarity on the 'forthcoming attractions' over the next wee spell (am especially hoping that the 'foot of snow for southern Perthshire becomes reality).

An epic summary and hopefully some epic conditions for all fellow kilters over the next few days (and the remainder of the winter).

Hats off, LS!

'Mon the snaw!

[Polar Gael]

And bang on cue, the cold air has arrived: 1.1C/0C.

Goodnight from Kilter Outpost Zebra in the Shaky Toun.

[Polarlow]

White out in Dundee !!!!!!!!!!!!!

[Snow Monster]

Pelting down with snow here. Everything totally white in space of 5 minutes.

[Norrance]

Just easing off here now but has left a cover.Looks like a gap coming on the radar before the next lot arrives. (I hope).

good night all. 

[Polarlow]

A quick video of the snowfall in Dundee just now....

Nite all

[GraemeB]

It's pretty "mild" here in Stirling just now - certainly not as cold as it's been at night, plus, not a breath of wind.

[snowidea]

Just had a peek out of the window, just a dusting here on the cars and grass. Hopefully we'll see a bit more late afternoon. Think it'll be a short day at work for me so I can (hopefully) have a play in the snow with the kids.

[CoastRainbow]

Just had another hail shower ! Never known so much hail ! Anyhoo looked out window everything white hoping it continues

[Northernlights]

Still only a dusting of snow but ground frozen up by a strong freezing wind Hooray no mud. Currently -0.2c

[mistyqueen]

Morning Kilties! Was woken at 6am with a crash, bang wallop and flash of thunder, lightning and a very fierce hailnshower. All white out there now, but not due to any snow sadly! Temp 0.2c. I look forward to a very interesting few days of weather! Enjoy the white stuff if it arrives in your airt!

[snowidea]

Snowing now.