scotland Scotland Regional Discussion 05/02/13 08 -------->

[snow1975]

Snow started here at 0630h when I left for work. Continuous snow until 1415hr. Proper dry snow fell this morning with temp below zero. Min -1.0c. Got home from work around 2pm. Total depth at 14hr, 6.5cm. Snow then turned to transparent ice pellets until 1530hr. Temp 0.5C, wet 0.0C so warm layer aloft. Ice pellets turned to rain around 4pm. Temp rising to 1.5c. I think a woman has been killed in a road accident up the Cupar road, A916 near Ceres/Craigrothie. It doesn't help when the Met Office forecast was so poor, not even a yellow warning in Fife. In hindsight, ought to have been a yellow, maybe amber warning because most of the snow fell with temps below zero.

I should add 1-2inch of snow fell in the at sea-level in the coastal towns of Leven and Buckhaven.

Edited February 13, 2013 by snow1975

[Allyw12]

I know, I know, it's too soon, you've just had to deal with the last failed easterly and you don't need another abject failure to contend with, BUT, the big difference with this one, hypothetically, is that it's actually driven and preceeded by a proper block and the shortwave would be coming out of the east, rather than the west. Another difference is that this forcing would make it more likely that heights would (finally)retrogress to Greenland:

GFS getting there too:

Hope the trends continues, It would be a great end to this Winter

[Norrance]

Here now changed to a mix of rain and small icy pellets. Pretty wet underfoot but not much dripping. Temp 0.8C.

Re the Edinburgh snow shield I had a look at the longer term averages for snow lying days and edinburgh

Is less than one day fewer than Dundee and Inverness and about two days more than Glasgow. Taken from fifties to nineties. Don't have figures since 2000.

All are well below Aberdeen though.

[LomondSnowstorm]

Snow started here at 0630h when I left for work. Continuous snow until 1415hr. Proper dry snow fell this morning with temp below zero. Min -1.0c. Got home from work around 2pm. Total depth at 14hr, 6.5cm. Snow then turned to transparent ice pellets until 1530hr. Temp 0.5C, wet 0.0C so warm layer aloft. Ice pellets turned to rain around 4pm. Temp rising to 1.5c. I think a woman has been killed in a road accident up the Cupar road, A916 near Ceres/Craigrothie. It doesn't help when the Met Office forecast was so poor, not even a yellow warning in Fife. In hindsight, ought to have been a yellow, maybe amber warning because most of the snow fell with temps below zero.

I should add 1-2inch of snow fell in the at sea-level in the coastal towns of Leven and Buckhaven.

The warning not being extended to Fife was an utter joke when it was clear that coastal marginality wasn't going to be prohibitive to snowfall in this instance. There was snow lying on the road in Freuchie certainly from 8.30 am onwards and I do hope the council didn't refer solely to the MO warnings otherwise they would have been badly caught out. 2+ inches for parts without so much as a yellow warning given that the NAE and the NMM both showed accumulations of that magnitude is quite hard to justify IMO

[Blizzardo]

Pouring rain all the way back from Glasgow. Car thermometer temperatures dropped relative to the amount of lying snow - 5c Glasgow city centre, 3.5c bishopbriggs, 3c Kirkintilloch and 2c in Campsie. I'm really surprised how much snow I still have lying - comfortably 10cm. Exact temp now 2.2c/1.3c and lashing down.

[snow1975]

The warning not being extended to Fife was an utter joke when it was clear that coastal marginality wasn't going to be prohibitive to snowfall in this instance. There was snow lying on the road in Freuchie certainly from 8.30 am onwards and I do hope the council didn't refer solely to the MO warnings otherwise they would have been badly caught out. 2+ inches for parts without so much as a yellow warning given that the NAE and the NMM both showed accumulations of that magnitude is quite hard to justify IMO

I didn't see one gritter/snowplough today. It's always easy in hindsight. Going back to yesterday, the air was really quite cold and dry. The dewpoint T was -5C, rh 60% and a SE wind at 09hr/12th. With the SE wind backing S to SSW ahead of the approaching Atlantic front, further cold and dry air would mix with the precip.

[Scottish-Irish Skier]

Snow stopped here a few hours ago. Bit of dripping going on but no rain. Strange as radar suggested decent prep.

1.2 C with most cover retained.

[Cheggers]

Heavy rain here now, but snaw cover holding. Roads really wet.

[Allyw12]

Rain here also, surprised its rain to be honest as the temp 0.6/-1.9 ?

[A Winter's Tale]

Pouring rain all the way back from Glasgow. Car thermometer temperatures dropped relative to the amount of lying snow - 5c Glasgow city centre, 3.5c bishopbriggs, 3c Kirkintilloch and 2c in Campsie. I'm really surprised how much snow I still have lying - comfortably 10cm. Exact temp now 2.2c/1.3c and lashing down.

It was 7cm here. Any ideas on the depth in areas surrounding Torrance?

[LomondSnowstorm]

Rain here also, surprised its rain to be honest as the temp 0.6/-1.9 ?

The uppers must be above 0C now over Perth so regardless of the dewpoint or even the air temperature it will be rain. Actually more worryingly with that profile is that it's most likely freezing rain. Enjoy.

[Guest]

Rain here also, surprised its rain to be honest as the temp 0.6/-1.9 ?

The upper air must be too warm now, but the surface temperature is still low.

LS will testify to my experience a couple of years back on Christmas Day, the temperature at Glasgow Airport was reading -5ºC and rain was recorded. That rain turned all the vegetation black, my kids called it "the black rain".

When we were heading back tonight the temp over Soutra was -0.5ºC on the car thermo yet it was lashing rain. Horrible driving conditions and plenty of accidents to match. Once the upper air is too warm it doesn't matter what the surface temperature is, unfortunately.

The uppers must be above 0C now over Perth so regardless of the dewpoint or even the air temperature it will be rain. Actually more worryingly with that profile is that it's most likely freezing rain. Enjoy.

Beat me to it! Freezing rain is 'orrible stuff!!! A lot more common in this country than I ever used to realise.

[BleakMidwinter]

When we were heading back tonight the temp over Soutra was -0.5ºC on the car thermo yet it was lashing rain. Horrible driving conditions and plenty of accidents to match.

Probably teaching my grandmother to suck eggs, but... heading south from Edinburgh, through the first snowgates and it curves left and there's a sharp right almost on a promontory? Be really careful with that one - my folks have lost two people over 30 years on that bend, and I once worked nearby and asked the locals about the Soutra road in general and they said that first sharp right-hander took most of the deaths.

Blawin' a hoolie here, gusting wildly from all directions, black as pitch and lashing with spattery rain. Me, I'm in and I'm staying in!

[Blizzardo]

It was 7cm here. Any ideas on the depth in areas surrounding Torrance?

I

Theres actually still a good cover in most places but more so as you head towards the campsies. I'm on the road to strathblane and it's lying quite thick on on the road at parts. My temperature is back down to 1.9c with the dew point at 1.0c still heavy rain but it feels like its threatening to turn back to sleet.

[Sunny Leith]

Aye, no coincidence I suppose that larger population centres tend to be in geographically and climatologically advantaged locations. Our ancestors weren't daft eh...

Still gives me a bad attack of TOORP though. When we were 90% of the way home and exiting a snowy Fife, I was thinking that there was no way Embra couldn't have been hit as well. Get to the Forth Bridge and a total reality check meets the eyes. Doh!

Anyway, not not too upset, we may yet have another bite at the cherry with an easterly it seems. But will all the elements be in place... Here we go again !

I think it's a mix of factors, including:

1) Urban Heat Island Effect

2) Coastal modification off the Forth and the North Sea during an easterly flow

3) topographical issues - being in the lee of the Pentlands and the Lammermuirs means precipitation totals are significantly lower than the surroundings with southerly wind vectors.

4) The same issues with northerlies that the rest of the central belt and mid Scotland has aka the Grampians.

5) proximity to sea level, certainly for the middle of the town and up towards Leith and Western parts too to an extent.

Its site may have done a good job of keeping the English out during the middle ages but it also does a very good job of keeping the snow out. Somewhere between an east and northeasterly wind is probably the ideal setup for here, which is actually the same for Freuchie, but without some of the added hang ups listed above.

[A Winter's Tale]

It might not be too long until the rain eventually clears. If conditions were more or less perfect, I wonder what sort of conditions and distruption we would have experienced if this was an all snow event.

[Guest]

Probably teaching my grandmother to suck eggs, but... heading south from Edinburgh, through the first snowgates and it curves left and there's a sharp right almost on a promontory? Be really careful with that one - my folks have lost two people over 30 years on that bend, and I once worked nearby and asked the locals about the Soutra road in general and they said that first sharp right-hander took most of the deaths.

Blawin' a hoolie here, gusting wildly from all directions, black as pitch and lashing with spattery rain. Me, I'm in and I'm staying in!

Aye, it's mayhem up that bit of road most nights, a mad scramble up Soutra to get ahead of the slower vehicles. Fine on a summer's night but not today. Some people need their heads looked at, we saw so many examples of plain mental driving today, glad to be home. I can't believe that I used to drive from Kelso to Paisley and back every day. I must have been mental

Edited February 13, 2013 by CatchMyDrift

[Guest]

Aye, no coincidence I suppose that larger population centres tend to be in geographically and climatologically advantaged locations. Our ancestors weren't daft eh...

When I studied for my MSc I made that point to a senior lecturer...he didn't agree! I agree with you though

[Scottish-Irish Skier]

Probably teaching my grandmother to suck eggs, but... heading south from Edinburgh, through the first snowgates and it curves left and there's a sharp right almost on a promontory? Be really careful with that one - my folks have lost two people over 30 years on that bend, and I once worked nearby and asked the locals about the Soutra road in general and they said that first sharp right-hander took most of the deaths.

I know it. There's an overtaking lane on the southbound carriageway, yet this bend is quite tight. If you don't know it's that tight can give you a fright as you've approached it accelerating to e.g. pass a lorry so are going faster than you should be for the bend potentially. The fact that you have two lanes suggests 70 mph should be the limit (not technically as its not a dual carriageway) although most folk would panic cornering that bend at >60. Add in some slippery conditions and that could be nasty.

A big problem I've seen on that corner is when drifting is pushing snow from the bank of the northbound lane onto it. The snow seems to emerge just at the apex of the tight bend in question. This can force people who didn't see it on approach to suddenly panic and try to shift out of the lane to avoid and so cross into the path of oncoming southbound traffic in the middle of overtaking. Not a good combination. Problem is, it's that or hit a snow drift a speed on the bend and spin out. I've seen the latter; arrived on scene a few minutes after. Thankfully nobody hurt.

Here's the bend in question looking southbound on approach.

http://goo.gl/maps/ydyxY

Edited February 13, 2013 by scottish skier

[mistyqueen]

Well, surprise surprise.....nae snaw! Helluva windy this morning though, wind up to 61mph, blew a lorry off the road. Nasty.

[November13]

well all over again so soon.7 days until the next cold spell.

[LomondSnowstorm]

It might not be too long until the rain eventually clears. If conditions were more or less perfect, I wonder what sort of conditions and distruption we would have experienced if this was an all snow event.

Very hard to say I suppose because you'd have to draw the 'stalling' line somewhere. Anywhere on the very eastern edge of that point would have seen 24-36 hours of continuous snowfall, probably totals upwards of a foot quite easily given the intensity, with places further east seeing more like 6-8 inches, though more locally. The line between tonnes of snow and not much would be very stark, potentially 10-20 miles between a foot of snow and total melt, though it would of course depend how much the low buckled under the high. Anyway, it was decent enough for what it was and we're still far from out of the woods yet:

ECM gives a very cold easterly to Englandshire with still probably just enough instability for some snow showers into eastern Scotland (bearing in mind the picture of low dewpoints and low overnight temperatures preceeding this).

And then, finally, what we've all been waiting for for the entire winter:

Not a bad cold pool:

Key things to note:

It's FI, as we all know, but again the building blocks are there from about +96/+120 onwards.

The ECM, while verifying relatively well, have tended to end up with the pattern being somewhat further north and potentially less clean than shown at long range. I'd far rather be sitting on the side of having the high pressure to close than having the cold uppers nearly missing. Any increase in shortwave activity or disturbances in the flow from that kind of position of a strong high just to the north would bring the potential for a very much more potent easterly in the interim and, especially if one that one from the east hit home, the opening of the floodgates to the northeast would be very much the favoured evolution, especially given that the Canadian vortex has finally drained.

Edited February 13, 2013 by LomondSnowstorm

[Snowplough33]

Quick post as in late due to road chaos on the A90.

Defo the best event this winter. Several inches lying. Second fantastic breakdown. Can't understand why no upgraded warnings....???

Some great charts showing up later next week. All FI but constant trends from UKMO and ECM. UKMO on its txt 2 to 4 weeker has not budged from cold spell for the last week or so.

[Snowplough33]

I am aware that not all areas had particularly impressive breakdowns, but many areas in the east, particularly north of Edinburgh but also SS and CMD land, have had 2 major events during the breakdown. Now the showers clipping the coast yesterday evening were marginal, yet today the event was dry snow (certainly early on). So was the main component of the event the dew points being very low, and are due points directly related to humidity as it felt extremely dry and cold this morning?

[LomondSnowstorm]

I am aware that not all areas had particularly impressive breakdowns, but many areas in the east, particularly north of Edinburgh but also SS and CMD land, have had 2 major events during the breakdown. Now the showers clipping the coast yesterday evening were marginal, yet today the event was dry snow (certainly early on). So was the main component of the event the dew points being very low, and are due points directly related to humidity as it felt extremely dry and cold this morning?

Dew points are a function of temperature and humidity, so when humidity is extremely low the dewpoint is markedly lower than the temperature (dewpoints in the Sahara for example are often sub zero even in the height of summer for example). The reason for the sudden drop in dewpoints was that the relatively moist easterly flow was cut off, which allowed both a drop in temperature and crucial a lowering of dew points, since the actual airmass in situ over the British Isles was very cold. The southerly wind enhanced that by dragging a dry localised continental flow from the south which meant dewpoints remained very low, even into this evening, and this ensured that when the snow started to fall it lay and dragged temperatures down (when precipitation hits the humidity increases but temperature also falls towards the dewpoint to the point where they converge) below 0C. Oddly enough all the decent snowfalls this winter, barring the northwesterly and earlier snowfalls in December, have come from essentially southerly continental-esque flows, even the freak snow streamer, while straight easterlies and maritime southeasterlies have been particularly poor for snow for lowland areas.