scotland Scotland Regional Discussion - Autumn 2013

[Hairy Celt]

Hmm, I was in two minds about it.  Because I had to drive home afterwards I didn't really want a huge day in the hills, so initially thought I'd go only as far as the first horn.  That would still have been a great walk with grand views.....but once up there with Sgurr Mhor rearing up ahead I just couldn't resist

 

DSC09747.jpg

 

That said, clambering over those pinnacles under conditions like that is probably at the limit of what I feel comfortable with without ropes and other people with me.

Nice one. One of my favourite hills, and the one where I got my intro to winter hill conditions rather a long time ago. You got better conditions than I did then - piles of melting slush up to about 800m then rime ice everywhere!

[LomondSnowstorm]

We're really firming up on the northerly now, GFS 12Z has sub -5C from Monday midday:

 

to the end of high res:

 

A whole week of snow potential, with winds varying from WNW through to NE.

And from this position, every chance of a reload when the next chunk of PV decides to drop down to our east:

(although with that slightly pessimistic caveat I posted earlier about chilly damp easterlies if/when the first upper cold pool dries up until the real cold arrives)

I haven't seen charts this promising in November since 2010, although with the glutony of synoptics riches we've been treated to just in the last 12 months you'd be forgiven for thinking these are pretty 'standard' winter charts - they aren't. We may be on the cusp of yet another major cold spell, in spite of a cold stratospheric vortex and in spite of most of the signals going into this month indicating exactly the opposite for the first half of winter.

The MJO is likely to help us out, with most forecasts putting it back to a low amplitude phase 8/phase1:

 

 

(cheers for these ScotlandWx/Lorenzo!)

Anyway, we'll have to wait and see how the UKMO and ECM shape up, but I haven't seen anything genuinely mild in the longer term in the last week and I suspect that's how it'll stay.
It's coming folks.

LS

[Benvironment]

Nice one. One of my favourite hills, and the one where I got my intro to winter hill conditions rather a long time ago. You got better conditions than I did then - piles of melting slush up to about 800m then rime ice everywhere!

 

Gawd, can't say I fancy those steep slopes in slush and ice.  What a savage introduction!

 

In other news, beautiful sunset here in Fife.  Nice and still.  It has that wintry feel about it.

[Buriedundersnow]

small question LS with regards to snow as i'm not as clued up on what perameters we need.

 

if we are under the 528 dam or lower do we still need to have the uppers so low for snow or can we get away with slightly warmer uppers and still get snow.

[LomondSnowstorm]

small question LS with regards to snow as i'm not as clued up on what perameters we need.

 

if we are under the 528 dam or lower do we still need to have the uppers so low for snow or can we get away with slightly warmer uppers and still get snow.

 

850s up to(but not above) 0C are technically fine for snowfall under certain circumstances, mostly if the cold is deeply embedded at the surface and is cooling the lower layers of the atmosphere up to around 900hpa. 950hpas upwards MUST be sub 0C for snow to fall, which is why that's the parameter I tend to use, unless pressure is extremely low i.e. the Braer storm where 950s were probably around 1-2C but 950hpa was pretty much ground level. 528 dam thickness is probably a better indicator than -5C uppers, 1290 on the 850-1000 thicknesses is even better (anything below that and snowfall is almost guaranteed) and dewpoint at or below 0C/Wet bulb temperature below about 1C are also fine indicators but none are entirely fullproof so it's just a case of checking all the variables and seeing if they all tick the box. And then we have to hope there's some precipitation around.

 

I'll run through a quick example for Lerwick on Monday midday based on the 12Z GFS:

Uppers -6C *check*:

 

Thickness 522 dam *check*:

 

DP sub 0C *check*

 

850-1000 around 1295 *passable*:

 

Now we check the skew-t for any nuances between 850hpa and surface level that might lead to a problem for snowfall, including it being too dry:

Confirms DP is sub 0C (actually -1.9C), Temperature is a bit high *but* 0C line is about 950hpa so it should be ok, along with the fact that the cloud level is very low (maybe 900hpa, check out John Holmes' guide on the learning area for how to read skew-ts) and the CAPE is extremely promising (cloud development above 500hpa) so showers would be very, very likely to form, with a high chance of troughs embedded in the flow. Given this tendency for heavy showers air temperatures would be pushed down readily during showers since the relatively high air temperature is a function of ground heating by the sun so we'd expect pretty much all precipitation there to fall as snow, although probably not lie given the high initial air temperature.

So, in summary, it depends

Edited November 14, 2013 by LomondSnowstorm

[edo]

Lol humorous ending but great analysis LS

OTR no one speaks any more keich than me so followed u will be....I love the short sharp nature of twitter and there are lots of weather people to follow...just click on who Matt Hugo follows and select some...I will tweet u some people later to follow if I get the 4 strong posse to bed with some energy still left!!

Great potential for many but IMBY not too much excitement to be gained from northerlys as always dies out over the hills unless it is a major front coming down....anyway there's always a first time to see decent snow from the north!!

Oh and I was Madonna not Debbie Harry....had the Lacey bra like a virgin poster on my wall #goodtimes

Edited November 14, 2013 by edodfc

[Buriedundersnow]

think I will just check in with you over the winter for snow prospects LS  

[Scottish-Irish Skier]

Just arrived in Carrbridge, central highlands. Log fire on. Dinner cooking. Cold beer in hand.

 

Drive up was good with the A9 quiet northbound. Leon was allowed a good bit of freedom...

 

The views were absolutely stunning with the sun setting. Largely clear, deep orange skies really lit up the autumn colours of the forests around Blair Atholl. Then there was the snow capped peaks to follow at Drumochter. Quite a site to behold. God's own country to coin the phrase. As far as I'm concerned one of the most beautiful countries on earth.

 

Bloody camera was in the boot though.

 

While the borders is lovely, Edinburgh a cool city... coming home (was born and grew up in Carrbridge) to the Highlands is always special. 

 

Chilly oot; was 3 C when I exited the car.

 

 

EDIT. Not now obviously, but gets some great snaw. Not sure I'd be brave enough to jump off it now (in the summer!).

 

 

Oh, and this is how we deal wi snaw here:

 

 

Quality

Edited November 14, 2013 by scottish skier

[Buriedundersnow]

note caution for anyone thinking we are in a good position from the 12z runs because we might not be and will be hoping for a either a second bite at the cherry or things can go horribly wrong in a hurry

 

Greenland or bust

 

 

here I will show you from the ECM 12z and note the bit I have circled in this first chart and this is our killer for getting deep cold with this first bite and why we don't want Scandinavia

 

 

now if we do see the heights heading for Scandinavia the two highs will link and as we can see from the arrow in this chart it will clearly cut off the cold uppers

 

 

this is why we have been seeing anomalies charts like these over the past while because of that big high pressure out toward Russia which only leaves us with a window to deep cold through a Greenland high as the high to our east will kill everything else and will leave us looking for a second bite at the cherry if one ever comes along as it will sink any height rises over Scandinavia.

 

 

so we want Greenland people and nothing else for a chance at prolonged deep cold at this stage

[Buriedundersnow]

to show is the ECM against the GEM and for you CATCH the GFS even though I don't rate it

 

ECM

 

 

GEM

 

 

GFS

 

 

to me the ECM looks worse and might sink the high where the GEM and GFS has it looking better and for once I hope the GEM and GFS is closer to the mark and ECM is having a wobble towards the end and not trying to lead like it does a lot

 

hopefully sorted so can flip through charts instead of it changing screen

 

Edited November 14, 2013 by Buriedundersnow

[LomondSnowstorm]

You're right BUS, that was basically what I was warning about earlier - amazing synoptics for January aren't any use unless there's a cold pool to tap into. However, it's still worth keeping the heights around because sooner or later they're bound to try and set up for another go at the retrogression (although the GFS is inching ever closer to achieving that in one go, which would be nice). Otherwise, it's just a case of whether it's crisp and cold with a very limited chance of any snowfall or an easterly which squeezes every last drop of our cold pool until there's nothing left and have a slight chance of getting something epic if it holds. Either is excellent in terms of the longer term synoptics but the latter would feel like such a waste, to a much greater extent than the very cold and quite snowy but 'so gutted it wasn't 6 weeks earlier or it would've been worse than '47, '63 and December 2010 combined' spell this March.

How it could redeem itself is by doing this:

 

Which would make the week of dank drizzly 'North Sea' airmass worthwhile, but at the moment it looks like some kind of holding pattern will be required if we are to get retrogression to Greenland.

It's worth remembering that we had a similar build up to November 2010, with a not all that cold easterly to start with before the cavalry showed up from the Siberian Arctic. This chart, for example, is pretty similar to much of what the ECM has churned out in its later stages:

 

 

This was made irrelevant by the vortex dropping into Russia and two days after the verification date of that chart we were staring down the barrel of an exceptional cold spell:

 

Anyway, there's little point worrying about FI for the moment when we're looking at a good 4 day cold spell at the very least Monday-Thursday next week.

Edited November 14, 2013 by LomondSnowstorm

[Buriedundersnow]

I was hoping we would see upgrades LS and I suppose we have today but the ECM there has me worried as I would rather be putting my eggs in its basket rather than the GFS or GEM but we will just have to wait and see how the ECM mean and ensembles work out.

 

hopefully that high to the east doesn't kill us but i'm sure in the next few days we will find out.

 

and your right at the end wait for FI to sort itself and just look forward to next week just now and hope for more to come.

[LomondSnowstorm]

I was hoping we would see upgrades LS and I suppose we have today but the ECM there has me worried as I would rather be putting my eggs in its basket rather than the GFS or GEM but we will just have to wait and see how the ECM mean and ensembles work out.

 

hopefully that high to the east doesn't kill us but i'm sure in the next few days we will find out.

 

and your right at the end wait for FI to sort itself and just look forward to next week just now and hope for more to come.

It's all a bonus anyway I suppose at this time of year, just nice to see some proper blocking on the charts this early in the season. Possible that the models are overestimating the heights over Russia too as they did in January/February 2012, which ironically would be a big boost whereas then it was a major hinderance!

[Buriedundersnow]

GEFS mean has been dropping today and snow chances on the increase which is a good sign

 

 

GFS anomalies chart going colder aswell still shows the need for Greenland though with higher anomalies out east

 

[Buriedundersnow]

GEM mean looking good for us as well

 

[Cheggers]

Wow I go away for a day or so and miss weather upgrades and DEBBIE HARRY,,  although I was more a Kelly LeBrock fan, shame the weird science theory was not real...

Snaw better not arrive till Monday night at least as I am in Scouse land again.

Edited November 14, 2013 by Cheggers

[A Winter's Tale]

A pleasant day and a spectacular wintry sunset with pink/orange/peach/purple cirrus clouds against the blue evening sky. Failed to reach double digits. During the first 10 days, this happened on 9 occasions - since 1973, this has never happened before in November at the airport. It's great to see the first proper, arctic sourced cold spell of the season. This incursion early next week doesn't happen every year in November (and November snow isn't a perennial event for everyone aswell). It would be even more pleasing if we all see some snow during next week. The last time I saw snow here in November was in 2010 - the first accumilations arriving late on the 26th and before that the earliest I had seen lying snow was briefly on the 25th Nov 2005. This spell will sure bring winter excitement into the thread and with a bit of luck it might bring some very early lying snow for some. The cold, fresh air and crisp conditions should make things feel and look very festive aswell as greatly adding to the cool weather we've achieved so far this month.

 

Thereafter, looking at the conditions presented by the models - some frost, fog and cold, crisp conditions again would make for a fairly traditional, cold November ending with some settled, quiet winter weather without the snow and potency we'd be more likely to experience later in the season. Synoptically, it is 'gripping' again with some very decent and solid signs. However how such factors evolve during the days will create more model drama. This feels familiar, roughly this time last year - without a lot of solid stratospheric support - we witnessed high pressure make progress into interesting areas. There was a small window for 'big-freeze' like synoptics/conditions but instead the model saga went on and the result was a nice, festive, cold start to the winter with high pressure ending up just to our north. At the moment, I'd say things look a lot more promising for a more significant cold/or wintry start to winter than last year there are many hurdles in the way and options on the table. If we don't achieve a proper Greenland high the first time round, then it's likely that the interest in the models will continue with a possibility of further attempts. LS this evening has posted a few charts going back to Nov 2010 when around 5 days before the cold spell really got going, synoptically it looked promising with blocking already in place but it did take time for the conditions to follow. 

 

The GFS 12z looked pretty good with the WAA into Greenland during an earlier stage - fingers crossed for more upgrades and support from other models during future runs. The high looks like moving towards Scandinavia - possibly liking with the Russian high - on some runs. ECM 12z and some other runs offer stunning synoptics with winds coming from the east but with lack of a cold pool over the continent. Such charts would bring unbelievable conditions during the middle of winter. We would need a section of the polar vortex to plunge south into the continent and then we would really be in business. BUS recently posted about 'GOB' and how the ECM 12z at face value doesn't look that great - but looking at the wider picture, any block that sets up around Scandinavia or Iceland could potentially retrograde to Greenland. Anyway, some decent winter conditions for late November is on the way - including some snow - and the winter model-watching madness has well and truly started. 

[LomondSnowstorm]

Good to see some familiar names returning to the forum again, hopefully even more will be back along with some newcomers as the northerly gets into 'telly forecast' range. If you're a newcomer or just a more occasional poster from years gone by who's lurking then come and say hi and join in with the discussion - we're friendly folk, honest!

[edo]

ah kelly le brock what a great shout and one of my favourite films.....just falls short of ferris buellers day off!!

[Buriedundersnow]

Wow I go away for a day or so and miss weather upgrades and DEBBIE HARRY,,  although I was more a Kelly LeBrock fan, shame the weird science theory was not real...

Snaw better not arrive till Monday night at least as I am in Scouse land again.

 

I've been told by the nosey pain in the f-a-r-t-e-r other half to ask you why CHEGGERS lol

[edo]

good question BUS..... why cheggers why??????

[lorenzo]

Wow, bit of an epic 24 hours of model runs, looking at some of these charts is eye watering in the midst of a proper industrial 2 day hangover. Too old for mid week partying til 4am !

 

Insane Control Run. A real box of frogs.

 

This is a pleasure to see at just 144hrs out. -9.7 850hpa temps on tonight 12z.

 

Some crazy, crazy model watching the propensity of High Pressure to develop across the NH in that control run is one of the maddest things I think have seen..

 

Some great, great posts today. Superb analysis, Debbie Harry, Kelly LeBrock - ooft ! magic Video Ben and a whole bunch of wild charts in the offing. Cannae beat model watching in Winter.

 

Though we might get something exciting, certainly did not expect a 2010 revisited.. Very interesting from here creeping into Fax range.

 

 

 

[Cheggers]

I've been told by the nosey pain in the f-a-r-t-e-r other half to ask you why CHEGGERS lol

Not this honest.   Family forum and all.

http://en.wikipedia.org/wiki/Naked_Jungle

[Buriedundersnow]

Not this honest.   Family forum and all.

http://en.wikipedia.org/wiki/Naked_Jungle

 

that was her guess keith chegwin is that the reason

[edo]

 

only 4 days away and cold air arrives...... thought better post 1 chart and will now leave the rest to the experts

 

4am Lorenzo???? lol thats hardcore.... I see a lot of 4am but its bottles and nappies!!...... local inn from 9-12 is my limit these days apart from the obligatory office xmas nite out of course