scotland Scotland - Alba Regional Discussion 20/03/13 21z ------>

[November13]

Sunnier morning in Campsie with a cover of snow remaining and the hills looking great. 1.4c/-4.2c.

Good agreement for cold to continue throughout the coming week. It looks mainly dry with the wind dying down a bit over the next few days which will bring some hard frosts. Shower risk should increase as we move through the week, moreso for eastern areas. My attention will be on the end of the week and the next attempt by the Atlantic to bring in Spring. Scotland is favoured to stay on the cold side with any precipitation remaining as snow.

The GFS, as is often the case a bit progressive, UKMO less so and ECM the best option for those wanting to stay in the freezer.

GFS by Saturday:-

UKMO

ECM

Think you are right frontal snow Friday Saturday.Mildish on Sunday then cold kicks back.

[Benvironment]

Don't know Scotster,but I bet it's accompanied by this!!

Too right! And if anything it's more keen than yesterday. Hovering around -1C again here and with the last of the loose snow scoured from all surfaces, we've just got ice everywhere. If this all ends with a slow thaw with rain then it's going to be hellishly slippery.

Took a walk up East Lomond yesterday. The 'before and after' couldn't be more stark. Three days ago there was lovely even cover pretty much everywhere. Now, there's very little left on the uplands and they're more brown than white. The western slopes of East Lomond are loaded with dense wind-blown snow and there are some wonderful drifts in any depressions. I can't help thinking about what might have been, and how bonkers it would look if we too had got 1ft of snow blown on 50mph winds.

Oh well. I ain't complaining. The hill road is officially closed and it makes for a wonderfully bizarre drive for provisions

It's funny. Down in Leslie there's no hint of why the road is closed:

But after only a mile or so you're in a different world!

My east facing windows are very salty this morning!

Yes I'd noticed that too. I only cleaned them last week

[Snowplough33]

Well it's plain and simple today. Baltic and grey. Snow gates remain closed so now action unfortunately. Charts are interesting later in the week for sure. Be a fantastic finish to get buried North of England and Wales style. I am aware that doesn't suit NL and such people, but it's a possible solution. A fun week watching the charts. Be surprised if we don't see a snowy spell before summer.

I think this is the 7th day in a row it's snowed here.

Edited March 24, 2013 by Snowplough33

[FrenchScotPilot1]

The following is theoretical knowledge gathered from various sources. I don't have any operational forecasting experience and I'm very keen to learn more. So, here goes my humble take.

To answer the query above, clouds occur when dew point line and environmental line are close to each other, i.e. high relative humidity. Where the 2 lines separate, air is dry and cloud free.

The inversion (cap) is where the temperature increases with increasing height and marks the top of the convective layer, this is where air gets warmer.

So you want the 2 lines to stay close to each other for a bit to ensure sufficient cloud thickness.

For organised heavy showers, you need instability, wind/fetch, favourable wind shear, moisture.

Instability: For the vertical transport of moisture and heat, an absolute instability is required. As a measure for this instability in the boundary layer, the temperature difference between sea surface and 850 hPa is used. The temperature difference needs to exceed 13 °C. Affected indirectly by this, is the inversion. If it is found below 1000 meters, the boundary layer is considered to be too shallow for the development of convective showers. If the inversion is below 2500 meters (higher than 850 hPa) usually (heavy) snowfall may be taken into account.

Wind/Fetch:

Another factor playing a role in the formation of the cloud streets is the wind. Sufficient wind must be available allowing the polar air to flow over sea and affecting enough moisture in the direction of the coastal regions. More wind means a better exchange of moisture between the "warm" seawater and the cold air above. Too much wind however is not ideal as it would mean less exchange of moisture. The wind direction at 850 hPa helps determine the areas which are likely to be affected by snow. The direction also helps to determine the fetch. The fetch is the distance the showers move over relatively warm water; the longer the fetch the more active the convection will also will be. For serious convection the fetch needs to be at least 80 km.

Wind shear:

Directional shear is one of the most important factors governing the development of the cloud streets; environments with weak directional shear typically produce more intense convection than those with higher shear levels. If directional shear between the surface and 700 hPa level is greater than 60°, hardly any convection and showers will be experienced. If the directional shear between the surface and 700 hPa level is between 30 and 60°, weak lake-effect bands are possible. In environments where the shear is less than 30° strong, well organized bands can be expected.

Moisture:

High relative humidity upstream moisture is needed.

Synoptic conditions: Cold air advection at mid levels will also help by increasing the instability (parcel temperature warmer than environment). Maximum vorticity advection aloft will help by increasing the the large scale upward motion (positive vorticity dissipation out of a trough leads to upper level divergence which draws surface air upwards to replace the upper mass depletion).

I hope it helps a little.

A little addition...

When the 2 lines are close together but only for a short depth of the atmosphere, the clouds are shallow.

This is what is happening right now: light snow showers from stratocumulus/cumulus clouds with very limited vertical extent, 2000-3000 feet at most.

When the right conditions are present, deep convection create towering cumulus and cumulonimbus clouds with 8000-10000 feet extent, able to support large updraughts and creating heavy snow showers.

[Hairy Celt]

Dry, grey, very cold, very fckn windy as usual. Patience is wearing thin.

[NUT]

The sun came out shock horror! I don't believe it! Defo looking a hell of a lot brighter today

[Buriedundersnow]

nice to see the sun poking its head out from the clouds today if it wasnt for that wind it would feel no too bad outside

[edo]

Well the remarkable spell continues with this being the 9th day in a row of snow recorded equalling the Nov/Dec spell of 2010 which I never thought I would see equalled never mind in March....ok we have never had more than 2 inches lying in that spell and its never lasted beyond lunch....even more remarkably that's us up to 30 seperate days of snow falling only 2 behind 10/11 yet the deepest snow has been 4 or 5 inches in the Friday 18th Jan snow to rain event....and have only managed 2 decent sledging trips with kids due to it never lasting or no decent depth...

I will always remember this spell for the sheer cold of the wind and constant dandruff snow falling and never again write off what can happen beyond February especially seeing the photos of wales.....

So whilst no massive snow disruption for many in Scotland this winter it is clearly far from the benign winters of which we hav had so many in the last 25 years...maybe last year was a blip in what is becoming a prolonged spell of proper winters...here's hoping anyway but here's also hoping for decent summers

Edited March 24, 2013 by edodfc

[Sunny Leith]

Different type of cloud today, bit more cumulusy and the sun makes a fleeting appearance now and again.... Also seeing tiny snow blowing about in the wind again, so just possibly the start of a long-haul over the hours and days to something a bit more snow-showery.. Maybe!

Edited March 24, 2013 by by-tor

[LomondSnowstorm]

Just to show how exceptionally cold it is this is a photo not from Hudson Bay but from Barvas on Lewis on the Atlantic coast:

[Hiya]

I went for a walk, very impressive wind chill and a very dramatic snow line at about 70m asl, I will see if I can upload a picture. I'm starting to get a bit fed up with this winter, no real snow fall, a lot of near misses, a lot of bad driving conditions caused by piddley little snow icing over and now no spring.

Well the remarkable spell continues with this being the 9th day in a row of snow recorded equalling the Nov/Dec spell of 2010 which I never thought I would see equalled never mind in March....ok we have never had more than 2 inches lying in that spell and its never lasted beyond lunch....even more remarkably that's us up to 30 seperate days of snow falling only 2 behind 10/11 yet the deepest snow has been 4 or 5 inches in the Friday 18th Jan snow to rain event....and have only managed 2 decent sledging trips with kids due to it never lasting or no decent depth...

I will always remember this spell for the sheer cold of the wind and constant dandruff snow falling and never again write off what can happen beyond February especially seeing the photos of wales.....

So whilst no massive snow disruption for many in Scotland this winter it is clearly far from the benign winters of which we hav had so many in the last 25 years...maybe last year was a blip in what is becoming a prolonged spell of proper winters...here's hoping anyway but here's also hoping for decent summers

I was just thinking about this this morning actually, I remember years ago before the return to colder winters complete depression on the model thread in mid-February when there was no cold on the gfs before the end of the month because "you can't get any proper snow in England after the last week of February." Oh how things have changed.

[Norrance]

Light snow and snow pellet flurries continuing today in the string Easterly. Not as frequent as the previous two days with wind a little lighter. No sign of sun here. 1.7C so up a notch on yesterday.

Like SP33 this is the 7th consecutive day of snow falling.

Edited March 24, 2013 by Norrance

[Buriedundersnow]

When are we likely to see the shift to a more ENE flow rather than the ESE we have at present, Sun/Mon?

little post for u as u were asking about an ENE flow well today both ECM and NASA go for one later in the week but GFS/UKMO are not going for it so could go either way

ECM

NASA

NASA even going for some shower activity again ignore the snow hatching marks there useless on this model but this will be snowy

now remember this is only two models so could still go another way but thought i would put a little smile on your face and show u an ENE flow might be on the cards

Edited March 24, 2013 by Buriedundersnow

[applemint]

The wind has blown most of the snow off the tops of the Pentland Hills as well: http://www.eastsidecottages.co.uk/webcam/

[Sunny Leith]

Will mean some serious depths in the gulleys though, will keep the hills snow-streaked for weeks to come.

The wind has blown most of the snow off the tops of the Pentland Hills as well: http://www.eastsidecottages.co.uk/webcam/

[Polar Gael]

Some amazing aerial shots of Arran - including power line poles snapped like twigs. They've been truly whumphed by that last front. It's March - in name only!

http://www.bbc.co.uk...otland-21917708

http://www.bbc.co.uk/news/uk-21915774

Hope the folk there stay safe, keep warm and that they get their power back on soon.

Edited March 24, 2013 by Polar Gael

[Bullseye]

Can anyone direct me to the basics of the weather link to understand the more about the weather? Thanks.

[Buriedundersnow]

http://forum.netweather.tv/forum/69-learners-area/

there stuff here dont know if LS or LORENZO will know other threads to go to

[mistyqueen]

Afternoon all! Freezing cold wind here, and hee haw snaw. Poor Arranites! That's some dump of snow they've had!

[lorenzo]

Can anyone direct me to the basics of the weather link to understand the more about the weather? Thanks.

The netweather guides is a good place to have a look

http://forum.netweather.tv/forum/5-the-netweather-guides/

The Winter set ups guide is probably some good reading to start with, seen as we appear to still be in Winter !

Met office have a learning page here also http://www.metoffice.gov.uk/learning

Would advise looking here also to begin with http://www.metoffice.gov.uk/learning/learn-about-the-weather

A couple of links from the metoffice learning page particular to now..

Snow http://www.metoffice.gov.uk/learning/snow

Wind http://www.metoffice.gov.uk/learning/wind

Really depends what you are looking to find out about as there is just about everything you could wish for on this site, feel free to pop questions on here and we will try and point you to some useful material.

[applemint]

Cairngorms this year: http://www.christownsendoutdoors.com/2013/03/retreat-from-lairig-ghru-cairngorms-in.html

https://www.facebook.com/CairnGormMtn/photos_stream

Cairngorms same time last year: http://tms.nickbramhall.com/blog/2012/03/atholl-forest-and-western-cairngorms-traverse-day-2/

[LomondSnowstorm]

Cairngorms this year: http://www.christown...rngorms-in.html

https://www.facebook...n/photos_stream

Cairngorms same time last year: http://tms.nickbramh...erse-day-2/

Incredible, there was more snow in July last year than in March:

http://tms.nickbramhall.com/blog/2012/07/derry-cairngorm/

[Snowplough33]

Quite a few flurries since lunch time. Last couple have been nearly worth watching. Still brief but a little heavier than this morning.

[Hawesy]

Just back from a weekend at Loch Lomond. There was snow down to loch level, nothing deep just a cm or two. Ben Lomond looked stunning today.

Back in Crail, it's cold and windy with some snow grains blowing about, as would appear to have been the case since I left on Friday! 2.3c currently.

[FrenchScotPilot1]

Who's for battleground situation for Easter week end as the Atlantic weather system makes its way in?

White Easter anyone? I know it is a long way away but it is interesting to speculate...

Edited March 24, 2013 by FrenchScotPilot1