Scotland Regional Discussion - January 14th 2013>

[Norrance]

Light snow here just now. 0C. A few flakes only but worth a look at the lamp post!

[spindrift1980]

Sorry to say that the 18Z NAE gives even the west a much reduced precipitation total for Friday and appears to be siding with the GFS ... 18Z NAE total ppn

A bit of a shocker - everything seems to have shifted west . No accumulated snow at all through most of the central belt on this chart- is this beginning to go pear-shaped?

[Buriedundersnow]

A bit of a shocker - everything seems to have shifted west . No accumulated snow at all through most of the central belt on this chart- is this beginning to go pear-shaped?

is that not the 12z

[Snowplough33]

is that not the 12z

Yeh, that the Wednesday 12z (12:00) plus 48 hours, so image of Friday 12:00.

[Buriedundersnow]

Yeh, that the Wednesday 12z (12:00) plus 48 hours, so image of Friday 12:00.

aye but the 18z should be out by now should it not

[Highland Snow]

Mair eye candy for the boys. Ear candy too (raise the hairs on the back o yer neck).

Who is the female soloist SS?

[moffatross]

Yeh, that the Wednesday 12z (12:00) plus 48 hours, so image of Friday 12:00.

But my link wasn't the 12 Z I'm afraid. Plenty of time to change favourably again though.

[lorenzo]

18z rolling out and shows ppn accumulation to the end of the 48 hr period, rest of the parameters are updating. Projects the band further West so not joining in with the Snowmaggedon fun this evening.. It will probably have flipped back 50 miles East by the 00z...who knows !

Over to the trusty pub run to see if GFS decides to follow THE ECM into the next ice age..

Edited January 16, 2013 by lorenzo

[Highland Snow]

So what we looking at this weekend then....

this

or this

No Cheggers, this would be more like it!

[M1245]

Not a good run from the 18z regarding the eastward progression of Fridays snow. Seems to stall in central areas and move back West. Disappointing.

Edited January 16, 2013 by M1245

[A Winter's Tale]

Tonight - for the western half of the country in particular it should be a cloudy night with the influence of a front situated around the Irish Sea - this could bring some light rain and maybe a touch of wintryness further inland a higher up to Galloway, Kintyre the islands of the Firth of Clyde and maybe affecting the hebridean islands - possibly as far north as the Isle of Mull. Possibly in some inland and higher parts of Dumfries and Galloway there could be a little bit of light snow but it won't amount to much. For Aberdeenshire, Moray, the Northern Isles, Caithness and eastern parts of the borders, here in particular in should be a clear and starry night with a frost. The coldest temperatures tonight may be recorded in one or two spots in the Borders but I'd say that the north east should see the lowest values - in the glens and around Deeside and Glenlivet it could get as low as -8C. There could also be some fog in some parts of the Grampian region. Temperatures generally in towns, typically 0 to -2C, -4C or lower in some eastern parts and a degree or two above freezing in western coastal fringes. Temperatures could be around 3 to 4C in the outer hebrides with the risk of some patches of light rain and drizzle.

A similar picture for Thursday morning. A cold start, particulary in eastern areas where clear skies and cold upper air temperature should combine to create a widespread frost with low minimum values around dawn - just before 8am. Generally cloudier further west across Scotland and just a wee bit of patchy rain affecting Galloway and some of the western isles. Should be a lovely start to the day in Orkney and Shetland.

For lunchtime- glorious winter sunshine may be more widespread - eastern areas in particular enjoying clear skies and possibly northern and central parts of the highlands could enjoy some sunny intervals. Possibly some sunshine for the central belt, particulary further east but generally further west it may stay generally cloudy. Some spots in the east may still be below freezing.

Into the afternoon and I'm optimistic that sunshine and clear skies will be more widespread with only the south west, western end of the central belt, Argyll and some of the hebridean islands perhaps staying generally cloudy but even here there could be a few clear intervals. An ice day for a few locations, highs generally 0 to 2C, 4 to 5C in some coastal settlements and islands.

Into the evening and much of the northern half and east of Scotland should have a wonderful clear, frosty evening but you can't rule out the odd shower clipping the coast of Aberdeenshire. It's more likely to be generally cloudier in Dumfries and Galloway, around the Firth of Clyde into some western parts of the central belt, parts of Argyll and Loch Lomond and Trossachs National Park and some of the hebridean islands - but Skye and Lewis/Harris could be on the clear side - but even still there should be some clear intervals here but there could be some rain for Galloway in the evening.

Thursday night - another cold and frosty one with general lows of 0 to -3C, above freezing for the islands and coastal towns and villages. Dry away from Dumfries and Galloway, Arran, Kintyre, Mid-Argyll, parts of Cowal, Islay and Jura. Away from the rain and there should be clear intervals.

Then we come to Friday......and it's looking interesting but details will chop and change between now and then. Since the weekend, we have a blocking high situated to our NE which has helped to bring cold air to the British Isles and we've seen some low temperatures - as low as -13C at Braemar and Aberdeen/Dyce recorded it's coldest night since the historic December of 2010. The atlantic has tried fight back but has so far failed but later this week it'll put up a better fight against the block. The chart below from GFS 12z shows this well: Block to NE, tightly packed isobars and a southerly flow across the British Isles, cold uppers in the east; milder uppers in the west. This = a battleground situation and dividing the two sides is a front - a band that would bring heavy and persistent precipitation to a widespread area. With cold surface temperatures and uppers, dew points probably favourable too then the precipitation for Scotland is most likely to be snow - away from western coasts, Galloway etc...The next problems that may not be sorted until just before it arrives is where precipitation from this front is likely to fall, how heavy the precipitation will be and where, and how long it will last. There is a general consensus across the models, NAE included that a snow event is very likely to occur in western areas - having said that it could stay dry north of the Great Glen - and most likely into the central lowlands and southern uplands, but we don't know how far east the front will get. I would confidently say, that if you those living in northern parts of Dumfries and Galloway, western parts of the Borders, much of Ayrshire away from the Firth of Clyde, most of South Lanarkshire, possibly Renfrewshire and parts of Argyll and around Loch Lomond then you should probably prepare yourself for a distruptive snowfall. Glasgow, Dunbartonshire, North Lanarkshire, a good chunk of Stirlingshire, possibly Falkirk and West Lothian should also be prepared for snowfall and probably accumilations and the possibility of significant accumilations that could be as much as 10cm or even 15cm. Further east across the Borders, Edinburgh and the rest of the Lothians, Fife, Perthsire and southern parts of the highland region - be aware that there is a risk of snow from this band edging north eastwards and it could be significant and would result in accumilations that could be distruptive - further west the higher the risk, furth east the lower the risk is. There could be some significant snowfalls for south western parts of Perthsire and Fife. For the north west highlands - parts of the Lochaber region west of the Great Glen could see some snow but it isn't likely to be significant and close to the coast and it's likely to be rain. There may be some precipitation reaching many of the islands but it would probably be rain. North of Kyle of Lochalsh and there isn't a high risk of significant snowfall. The front may not get as far north as the Cairngorms, so for Moray, Aberndeenshire, Inverness, the northern isles and much of the highlands north of the Great Glen there isn't really a risk for snow from the front for Friday but it's very far from impossible. And for Aberdeenshire, parts of Angus and Caithness with strong southeasterly winds coming off the north sea and uppers of around -6/-7C then there is a risk of convective snow showers. Ahead of the front, on Friday there could be some sunny intervals. It's likely to be a pretty cold, feeling very cold combined with the strength of the wind and with no sunshine where the front is located. Temperatures across large parts of country may only be as high as -1 to 1C, more like 2 to 4C near the coast. Keep an eye on the latest forecast - if you are in the high risk zone, my advice is not to travel unless it's important and AVOID upland routes such as M74 and the Rest and be Thankful.

Friday night is particulary difficult to predict at the moment as we don't know for sure what the situation regarding the front will pan out earlier in the day. But it seems likely that precipitation, mostly in the form of snow will hang around and decay as the front stalls as it comes up against the block. During the early part of the night snow could continue to fall across the high risk areas - so that would include many areas south of the central belt and in west - but there is the possibility of snow continuing to fall across the central belt, Argyll and possibly extending a bit further north and east to affect the southern highlands, maybe the Lothians, Edinburgh, Fife, and Perthshire and possibly Angus but this remains only a possibility, not a certainty. And then there is the brisk southeasterly wind bringing convective snow showers fresh off the north sea. Much of the highlands could stay dry, maybe some clear intervals in some places and rain affecting some of the islands. A cold night but there is uncertainty regarding overnight lows, quite possibly lows could typically be -1 to -3C.

Some areas 9am Friday and 6am Saturday are going to be in for a serious snowfall.

The cold spell continues into Saturday, there maybe some precipitation around with the decaying front whilst in Aberdeenshire, Angus, possibly Caithness and the north sea coast of the Borders could enjoy snow showers in the easterly wind coming off the north sea so it's worth keeping an eye on that easterly flow and uppers as it will be very influential in determining the nature of the convective activity. It may be a mostly cloudy day for many but cold with highs generally 0 to 2C, 3 to 5C in some areas closer to the sea and possibly 6C in the outer hebrides.

Another cold night to follow with lows of 0 to -4C, a widespread air frost but possibly a degree or two above freezing near the sea in the east, far north and above freezing in the islands. Possibly some snow for eastern areas. Clear skies to be found further west.

When we get to Sunday, we can cleary see the differences between 12z rusn of the GFS and ECM. On the ECM 12z there is a deep area of low pressure situated in the atlantic west of Ireland. Both runs keep it cold, but the ECM is more favourable for snowy and cold weather from more of an easterly flow as that area of low pressure slides eastwards across the south of Ireland and England then into France.

GFS 12Z

ECM 12Z

Anyway, Sunday is looking cold with an ice day for some, typical highs of 0 to 2C, a degree or two higher near the sea. Probably a cloudy day with some light snow possible in eastern areas. The risk of snow in the east continues into Sunday night and it could be a very cold night in some places, another widespread air frost.

The cold spell (or Big Freeze) funnily enough looks like continuing into at least the first part of next week. GFS suggests a breakdown around Tuesday night/Wednesday morning and possibly temperatures in some areas could briefly exceed what I consider to be the threshold of a cold spell - maximum temperatures at 5C or lower - but considering how we've seen this cold spell be dramatically extended, then I wouldn't rule out this cold spell extending further, possibly as far as the weekend which would mark a two-week cold spell.

The ECM however is a cracker with shades of November/December 2010.

How about this for a chart - Monday

Continuing into Tuesday

and staying cold right up to the weekend - I think the term 'Big Freeze' would be suitable if the ECM 12z verifies. Of course there are variations across the models, but there is a signal for significant things to come beyond this week and possibly beyond next week with things a northern hemispheric perspective looking good - remember the effects of the SSW on the troposphere wasn't projected untl around the 25th January

- a really, really thrilling period of winter and weather in general coming up. Brace yourselves.

[Highland Snow]

Not a good run from the 18z regarding the eastward progression of Fridays snow. Seems to stall in central areas and move back West. Disappointing.

If the Easterly follows on then we will hopefully all get our white fix.

[Buriedundersnow]

well the weatherview forecast just now on bbcnews24 had the front moving in to the west on friday and when they showed saturday the front was stalled over the east but decaying

[GrangemouthBairn]

Just saw the latest bbc weather forecast and the snow is nowhere near as northeast as it was earlier on. Looked as if the western half of the central belt had snow but the eastern half didn't. But it then showed Saturday and the band had moved east to affect eastern and central Scotland and England. So maybe if you don't quite get hit on Friday, you'll get it on Saturday although it will be lighter by then.

[Scottish-Irish Skier]

Who is the female soloist SS?

Elysia Leech. Glasgow Opera singer is all I know.

[howham]

Temp here has risen from -3C at 7pm to -0.5C now...??

[sn0wman]

That's 2 runs and the NAE that have shifted further west now. Hopefully they will have shifted back to the east by morning. I seem to keep being on the boundary of snow events lately.

[Buriedundersnow]

UKMO 12z 120hr

ECM 12z 120hr

GFS 18z 120hr

wonder who has got it right i'm hoping not the GFS

better put the GFS in the same kind

Edited January 16, 2013 by Buriedundersnow

[Cheggers]

That's 2 runs and the NAE that have shifted further west now. Hopefully they will have shifted back to the east by morning. I seem to keep being on the boundary of snow events lately.

Aye but remember that it's the boundary to both hits this time, so we may at least see some snaw, or we could be buried by Sunday.

[gsteruk]

I know how you feel, had nothing in Cumbernauld and ive got a sinking feeling that thats going to be the same this weekend,hope im wrong!

[LomondSnowstorm]

Just looking at the 12z NAE as the margin issue is ongoing for us east coasters. So for Friday the dew points and the 950's both look sub zero as required for any snow.. The 850' s look to be around -8 or possibly -9 so it's possible the coast MAY be ok if the showers move in through Friday night and into Saturday. But it will be close. Also positive that the north sea is full of -9 and -10 uppers which should travel east as the flow backs more to the ESE with time.

I seem to have a memory from 2010 that -8 / -9 did the trick. Perhaps LS or By Tor may remember as it was the subject of moocho conversation.

Also to add the 12z ECM is something quite incredible. Don't think I've ever seen a run like it.

-8C is fine for the vast majority, although with the southeast flow parts of the Angus and Aberdeenshire coast might struggle a bit even with that. Most of east central would be absolutely fine with -8C or below though. -6C can sometimes work if the flow is slacker and you're inland a bit, but only usually with a more north of east flow, and -7C is sometimes ok as well, provided you have a mile or two inland and a few metres above sea level. This was the uppers situation yesterday morning:

And quite a few places saw some snowfall, albeit it was a bit on the marginal side. How far east the front gets isn't easy to say at this stage and I'd hold off making firm judgements until tomorrow's runs. Clearly there has been some westward movement but since that ECM high resolution looks very different to the off-form NAE who knows really.

[Sunny Leith]

Seems like a long time ago that us east-coasties had to obsess on these thing SP33 ! From memory, -8/-9 was good enough - right side of marginal - for a lot of the time we had snow in 2010. But we had a good easterly fetch, mega-convection and lots of intensity in these showers - all that thunder snow you had !

I'd think if the uppers don't quite achieve that then it could be a bit sloppy on the immediate coastal fringe/lower ground.

But doesn't seem much point in any easties worrying about it for another 36 hours or so Going with Lorenzo's nowcasting on this one !

Edit: I see LS just beat me to it in the post above

Just looking at the 12z NAE as the margin issue is ongoing for us east coasters. So for Friday the dew points and the 950's both look sub zero as required for any snow.. The 850' s look to be around -8 or possibly -9 so it's possible the coast MAY be ok if the showers move in through Friday night and into Saturday. But it will be close. Also positive that the north sea is full of -9 and -10 uppers which should travel east as the flow backs more to the ESE with time.

I seem to have a memory from 2010 that -8 / -9 did the trick. Perhaps LS or By Tor may remember as it was the subject of moocho conversation.

Also to add the 12z ECM is something quite incredible. Don't think I've ever seen a run like it.

Edited January 16, 2013 by by-tor

[BurntFishTrousers]

Do I detect a very small dose of TOORPing on here?

[edo]

i blame cheggers posting the snowy pictures #jinxedit

im looking more to the easterly anyway will be nervous wait to see how potent that is.... I do hope a lot of west coasters who are snow tarved get something from this much hyped front though

[snowy owl]

Holding my breath till tmrw, hoping for a little eastward movement.