Scottish Cold Spell Discussion:

[snowmess]

Got colder across here, too - 2C, 75% Humidity, -1C Dew Point

It looks like 18z has made the spell of snow tomorrow last from early morning until evening. Perhaps all hope isn't lost (at my end)

Edited December 16, 2009 by snowmess

[Shandiman]

Hey! I don't live in Leith. Holyrood don't you know

And yes it is bloody annoying - I mean you can drive for 5 hours from London to Carlisle - how many English regions does that journey take you through? But five hours north from Edinburgh and you're only just over the Black Isle - and that's classed as one 'forecast area'. It is ridic.

Ah well, better placed to have a go at some of the influential players in the places that really hurt then .

[LomondSnowstorm]

Got colder across here, too - 2C, 75% Humidity, -1C Dew Point

It looks like 18z has made the spell of snow tomorrow last from early morning until evening. Perhaps all hope isn't lost (at my end)

Indeed, dewpoint here 0.1C: GFS 18Z claimed it would be 3C by now! Overnight precipitation turning to snow perhaps??

LS

[Mondy]

Hey! I don't live in Leith. Holyrood don't you know :lol:

And yes it is bloody annoying - I mean you can drive for 5 hours from London to Carlisle - how many English regions does that journey take you through? But five hours north from Edinburgh and you're only just over the Black Isle - and that's classed as one 'forecast area'. It is ridic.

Of course it's ridiculous, but have you said to the team to resolve this ongoing issue we have? Not picking at you, mate - but as a red one, you MUST have some say in matters!

Split us in two if easiest - North is north of Perth. South is south of Perth ! Be a good start

[shuggee]

It will be a pleasure to remind the team :lol:

Sub zero dew points creeping in from the east as I type

[bingobob777]

Gents,

any of you care to explain to me the significance of the 508-512 dams shown in Scotland early next week, do these relate to likely ground temperature or are the 850 temps a better indication of ground temperature?

[shuggee]

Gents,

any of you care to explain to me the significance of the 508-512 dams shown in Scotland early next week, do these relate to likely ground temperature or are the 850 temps a better indication of ground temperature?

Unfortunately (but as you might expect) there's no definitive answer to using either of those measures for temps at surface.

The significance of dam values is that the rule of thumb for wintry ppn is anything sub 528dam. But of course there are exceptions in certain set-ups. And remember the true dam value is only shown on the HGT 500-1000 charts - not the 500Hpa charts which many people get muddled up with.

As for the 850s - remember they are the air temps 1.5kms up. Again, a rough rule of thumb is to add 10ºC to get surface temps at sea level, but this is even less reliable than the dam thickness rule above!

[bingobob777]

Unfortunately (but as you might expect) there's no definitive answer to using either of those measures for temps at surface.

The significance of dam values is that the rule of thumb for wintry ppn is anything sub 528dam. But of course there are exceptions in certain set-ups. And remember the true dam value is only shown on the HGT 500-1000 charts - not the 500Hpa charts which many people get muddled up with.

As for the 850s - remember they are the air temps 1.5kms up. Again, a rough rule of thumb is to add 10ºC to get surface temps at sea level, but this is even less reliable than the dam thickness rule above!

That's cleared it up then!!! I'm curious why temps of -15 are shown in the North of Scotland next Tuesday/Wednesday when the 850temp is much higher, is it simply a result of lying snow, do the gfs temp charts take that into account?

[shuggee]

Yeah they do. I'll go have a look

[bingobob777]

Yeah they do. I'll go have a look

That sounds like a no then, thanks for your help

[shuggee]

Clear skies, lying snow, little wind - those are the major factors. Heat radiates away and Mr frosty frost comes out to play! The 850s are irrelevant in these circumstances bingobob

Here's all the relevant charts:

[Shandiman]

Just seen Rob on BBC late weather, and he is predicting a 'pasting' over the south-east corner tomorrow, but nothing here until Sunday, where the Edinburgh area is due to have snow.

He has said that by the end of the weekend just about all of the UK will have seen snow, 'then there is Monday, haha'!

Guaranteed to be flipping cold though for the foreseeable future .

[LomondSnowstorm]

Anyway, after that annoying long break, my dewpoint has gone up to 0.4C - perhaps just a hint of precipitation coming our way? I believe 0.4C in showers from the east would be enough for it to turn to snow, so all to play for tonight.

Hope to wake up with a weak orange light in the window from the heavy snow clouds!!

LS

[asjmcguire]

Just had a heavy sleet shower, 70% of which was wet snow...

Should of been all snow - but temp is a tad high

Looks like I'll be up all night watching the streetlamp then

[Cookie]

met office left trouser leg me off when we get lumped in with the highlands.

espcailly with snow fall!!

[glasgow-guy]

well the will it snow feature has been taunting me now for days. and I wake up and its gone but keeps promising more when is this snow going to arrive?

[LomondSnowstorm]

Dewpoint now 0C with a few sleety showers having passed through. Temps around 1C so perhaps black ice will become an issue, though I think the next showers will be of snow, given the low dewpoints.

[glasgow-guy]

Dewpoint now 0C with a few sleety showers having passed through. Temps around 1C so perhaps black ice will become an issue, though I think the next showers will be of snow, given the low dewpoints.

had some sleet about a hour a go looks like i may see snow today

[snowmess]

Got a little covering, stopped snowing...for now

Temp. - 1C

Dew Point - 1.3C

Edited December 17, 2009 by snowmess

[LomondSnowstorm]

Got a little covering, stopped snowing...for now

Temp. - 1C

Dew Point - 1.3C

Good. More showers to come through the day so you may do well today.

LS

[Highland Snow]

Nothing in Perth this morning. Temp. 1.5C Dew Point -0.1C.

Snowing away at Drumochter.

http://www.trafficscotland.org/lev/?mi=10

[Guest]

Parts of the east are going to get a pasting!! Keep us updated, photos as well please

[Hairy Celt]

temp 3C now; been heavy slightly sleety showers on and off all night. yuk

[Methuselah]

Aye, temps are definitely on the way down. Aberdeen now at 1C...

[snowmess]

Good. More showers to come through the day so you may do well today.

LS

Hopefully

Blooming freezing here!