 Poster: A snowHead
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Spotted this in Les Arcs today. Will this have been the result of a full-depth slide or snow creep?
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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woah!
Whereabouts is that Rob?
Those tracks coming on from the LHS - did they possibly cause it, or was it an " ohhh sh... turn now, that's NOW!" moment?
Or possibly just going for a gander.
But yet again mother Nature shows some capriciousness. Little temptress.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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to my barely educated eye, it looks like a full depth west snow slide - have things warmed up a lot over there?
mind you, if you asked me exactly where the line between creep and a slide is, i would struggle
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Arctic Roll, It's on the Arc 2000 side of the Arpette ridge, just below the point where the Arpette and Bois de l'Ours lifts meet.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Arno, yes, it's about 10 degrees warmer and that slope is West facing.
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You'll need to Register first of course.
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rob@rar, still seems a bit early in the season for wet slides. suggest you ski over and get a closer look 
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Arno, it does need further investigation. I'll send Jane I think, she's the closest I have to a Scandi Bomb at the moment.
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rob@rar, got it - so those tracks are on the Bois de l'Ours piste Natur.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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rob@rar, saw Rudi Mair (who does Tirol avalanche bulletin) was tweeting about the threat of Gleitschneelawine this morning with the increasing temperatures. The ground beneath the slide looks relatively smooth?
Last edited by You'll get to see more forums and be part of the best ski club on the net. on Fri 23-12-11 15:33; edited 1 time in total
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Arctic Roll, no, that is on the far side of the ridge as you look at the photo. To reach this slope turn left off Bois de l'Ours lift and ski along the ridge for about 60m, then drop off to the left by ducking under the rope - you will ski down to where the Lac red and Edelwiess blue meet.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| nozawaonsen wrote: |
| rob@rar, saw Rudi Mair (who does Tirol avalanche bulletin) was tweeting about the threat of Gleitschneelawine this morning with the increasing temperatures. The ground beneath the slide looks relatively smooth? |
I think it's relatively smooth under the snow, but couldn't be certain. I suspect that the ground is still relatively warm as there was not a prolonged period of cold before the heavy snow arrived, and that slope faces West. That plus the rise in temperature might mean a little bit of melt has lubricated the snow/ground interface.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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rob@rar, how steep is the slope at the crown? 35* ish?
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You know it makes sense.
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Arno, yes, thereabouts.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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| nozawaonsen wrote: |
| rob@rar, saw Rudi Mair (who does Tirol avalanche bulletin) was tweeting about the threat of Gleitschneelawine this morning with the increasing temperatures. The ground beneath the slide looks relatively smooth? |
Yep, looks like that. The English translation is (according to that site) "glide crack". So, it has not fully released (yet), but it's not a good sign.
It's not really the same as a wet snow slide because the slab has remained intact and there's no debris as such.
Didn't know about the twitter account for the Tirol - will take a look!
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Poster: A snowHead
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From my almost non-existent understanding this scenario arises from warm conditions.
Firstly under warm conditions the slow consolidates quite rapidly. As it's a steep slope, the snow is supporting itself - all piled up from the bottom to the top, and effectively all resting on the lowest bit of snow. As it warms and consolidates, therefore, a pile of snow collapses like a souffle - fresh snow is possibly 90% air, just like a souffle. Given this is all piled up in a slope the snow mass shrinks, and the big gaps open up at the top.
This is all encouraged by a layer of water under the snow - as a result of the warm temperatures, and moreover a warm slope underneath. The layer of water acts as a lubricant so that as the souffle collapses, it slides easily and gently down the slope. This is a slow process, all helped by being very well lubricated, hence its being described as creep.
This also helps explain the peculiarly clean (snow-free) slope that has been left behind in Rob's pictures.
The classic material that creeps is lead, when employed in a vertical position. This building http://www.c20society.org.uk/botm/archive/2008/the-new-museums-site-building-by-arup-associates-1966-74.html has lead facing on parts of it - the grey bits. Over the last 40 years the lead has been creeping, hence the ripples you can now see in it.
If I've got this all wrong, doubtless somebody will comment.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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James the Last,
Not convinced - if it is wet, causing consolidation, you would see a disturbed top surface of the slding mass - you only get the consolidation and densification because the increase in moisture leads to weakening of the dendrites on the crystals leading them to shear off, the snow particles then more closely resemble rotund particles, and hence there is a massive reduction in volume. That process would lead to a collapse of the mass into itself, and that would break up the surface.
Thsi picture appears to show that the upper part has slid as a continuous block/slab.
The tension cracks/fractures also look very sharp suggesting there is more inherent strength in the clab that one might anticipate in a wetted up mass
That's my tuppenth worth and i bow to the ones who really know 
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| Quote: |
| If I've got this all wrong, doubtless somebody will comment. |
I'd say this wasn't far off... (similar caveat applies about me not being an expert etc)
Snow doesnt just rest on snow lower down though, there is more structure to it, so snow above and to the side contributes to the forces holding the pack in place. This is why the snow above the fracture is still there. When this structure fails you have problems, from the fairly benign slide in that picture to a major slab avalanche. [/quote]
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rob@rar, What was the altitude there ?
Just reading the Aosta avalanche forecast and they note that they have had poor overnight refreezing to 2000m resulting in wet slides during the day.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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AndAnotherThing.., the crown is about 2,350m. We had a reasonable freeze overnight at 1,800m.
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rob@rar, your photograph gives me the willies.
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Which is ironic, because your willy gives me the photographs.
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| paulio wrote: |
| Which is ironic, because your willy gives me the photographs. |
You're imagining a level of dexterity that I just don't have
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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Clever dick.
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FAQ
