 Poster: A snowHead
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Weathercam, interesting - sounds like a good course and maybe a good time to be doing it if you are looking at worst case (or near to) conditions
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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At least the weather looks good all week for your course.
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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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You need to Login to know who's really who.
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Weathercam, that's the scariest thing I've seen.
I understand from Bruce Trempers book avalanches due to depth hoar are hardest to predict and ones that catch best guides out.
It seems unfortunately, many resorts (except southerly ones) just don't have enough snow cover to bridge it and prevent weight of one skier triggering, and won't for forseeable future.
Hmmm. Anyone with half sense would say off-piste skiing this year is madness (said by one booked to do just that in Valais next week, which would appear to be only worst affected region in worst affected country right now)
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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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| peanuthead wrote: |
It seems unfortunately, many resorts (except southerly ones) just don't have enough snow cover to bridge it and prevent weight of one skier triggering, and won't for forseeable future.
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The issue isn't lack of snow cover, the issue is that that faceted layer is likely to remain there for the rest of the season, no matter how much or how little snow lands on top. The only thing that's going to significantly stabilise it is if that layer somehow gets mixed up with upper layers as would happen when a piste is groomed, or for a melt-freeze cycle to cause the layer to change it's structure or for enough liquid to percolate down and refreeze that it allows those crystals to bond to each other.
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| Quote: |
| Anyone with half sense would say off-piste skiing this year is madness |
And others with their whole senses would say that's at best a melodramatic half truth and that it would be a completely Alpine-centric one too. 
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You out with Dave Meyer (aka diverskify) as he posted the same on FB. Offpisteskiing also posted a link to the snow profile.
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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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Weathercam, there's a difference between explaining slope steepness as a percentage and as degrees. 30% is only around 16 degrees. Units are important!
Also why not just ask the person who posted the thread what the avi conditions were?
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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apologies if this is referenced somewhere in this thread (tho I couldn't see it), but I received a circular from the eagle ski club today warning about off-piste conditions across the Alps. I hope no-one minds if I post it verbatim :
Alpine snow pack instability: many recent fatal avalanches.
Eagles need to be aware that the winter started with a shallow snow pack in
the Alps. This has led to a weak layer that has caused many recent
avalanches.
Andy Perkins comments that rearranging the following words into a well-known
phrase is good advice!
Necks
Your
In
Wind
For those interested in the details read on:
The Swiss snow and avalanche research institute (SLF) describe conditions as
“critical”.
http://www.slf.ch/dienstleistungen/news/lawinensituation/index_EN [1]
BMC
https://www.thebmc.co.uk/alpine-avalanche-experts-explain-current-snow-c...
[2]
There are summaries of recent fatalities in Switzerland here:
http://www.slf.ch/praevention/lawinenunfaelle/lawinenunfaelle/unfaelle_a...
[3]
and fatalities and accidents in France here:
http://www.slf.ch/praevention/lawinenunfaelle/lawinenunfaelle/unfaelle_a...
[4]
One of the above fatalities was the hut guardian of the Refuge du Grand Plan
who many Eagles will have met.
We all need to remember that it is possible to remotely trigger avalanches.
The photographs of the avalanche at Mase (where a guide died) show the
release point high above where the group were travelling:
http://www.lematin.ch/faits-divers/victimes-mase-suivaient-cours-avalanc...
[5]
Graham frost says:
“As well as avalanche risk there's a much higher than normal risk of
hitting rocks when skiing or falling, and some popular descents are virtually
un-skiable. Obviously this also increases the consequences of being
avalanched too - 3 of the 4 deaths at les Masseray were from trauma, not
burial. I've been avoiding any big slopes and definitely avoiding steep shady
slopes. However, I'm skiing with Eagles in Grimentz this week and we've still
found plenty of good snow”.
*How can we all manage this risk?* Rick Marchant comments:
“I have not dared to do any ski tours recently that go onto terrain where
the slopes crossed are big or prone to slide. I am only trying to choose
tours with no terrain subject to avalanches. i.e. nothing steep, no big
slopes, terrain traps, big convexities etc. Almost everywhere I have been in
the last 10 days has shown a very hollow and poor snowpack. I would advise
people not to expose themselves to any large slopes, which also means giving
a wide berth when traversing on flat ground with suspect slopes above.
Good spacing between members of a group is vital with these weak layers.
All that said, the warm weather this week is settling things down rapidly. I
have been amazed at the improvements in some places I have revisited in the
last days. It will improve the situation but many weak layers will remain and
they will cause problems throughout the winter and especially when the
isotherm rises dramatically as it often does in the spring”.
I am very grateful to guides Julie-Ann Clyma, Graham Frost, Bruce Goodlad,
Rick Marchant, Andy Perkins and others for input into this article.
Any comments can be made by posting on the website to a thread started by
Dave Wynne-Jones
http://www.eagleskiclub.org.uk/node/2575 [6]
Phil Jardine
Touring secretary
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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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I'm a bit busy today but I'll just post this before I carry on with some work. There was an interesting trip report on skitour.fr to the Grand Coin on yesterday. It illustrates how to navigate in avalanche terrain
Here they use the ridges to climb. You need to take a bit of care as there can be corniche danger and a slide, if it goes, can take the snow right of the summit of the ridge but it is relatively safe.
http://www.skitour.fr/photos_courses/arete-de-la-pallaz,52941-14.jpg
here you can see that they didn't ski the steep, shaded pitch with the rollover but stuck to lower angled terrain
http://www.skitour.fr/photos_courses/plaque-du-haut,52941-10.jpg
even so the slope remote triggered as they passed and the debris build up in the terrain trap was substantial from even a smallish slide. Given the slide in the middle did some of the skiers pass to close to the windloaded slope lookers left? If it had gone it could have deeply buried someone in the terrain trap right.
Same slide, another angle
http://www.skitour.fr/photos_courses/plaque-du-haut,52941-11.jpg
Still they skied down the flattish plateau before cutting across the bottom of the terrain trap
http://www.skitour.fr/photos_courses/plaque-du-bas,52941-8.jpg
and there, on a similar slope aspect, angle etc to the previous slide another remotely triggered avalanche, time to fit skins and climb to safety. Again given what they'd seen with remote triggering should they have descended so far in the second valley? How big could a slide have been from the left bank?
and the two slides
http://www.skitour.fr/photos_courses/les-2-plaques,52941-9.jpg
Did they ski into the valley at the end rather than down the sunny slope because of the snow quality (heavy powder/crust with the springlike weather)?
This scenario is typical of a risk 3 day, fragile medium size slabs but it is possible to negotiate around them if you plan your route in advance and then adapt on the terrain based on observations.
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You know it makes sense.
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Really useful and interesting post, davidof, thanks very much for taking the time to share. Nice case study in the things to think about when route planning.
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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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Think those photos davidof, posted show just how important choosing the right terrain is.
Today's exercise was a ski tour up to the Col du Galibier selecting a safe route to climb as well as descend, plus another snow profile to compare South facing snow pack vs yesterday's North facing
I did think that maybe we were being over cautious, but the exercise was to demonstrate the thought process involved in route selection, and then you come down and see those photos!
Gave a lift back to here to a La Grave piste patroller by the great name of Ullyses - very interesting chat as to what he does etc, he does not recommend Les Freaux which he did late afternoon.
Think we're back up LG tomorrow.
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Poster: A snowHead
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Weathercam, the first photo is a photo of a guy in the entry backside of Mont Fort. In case you are not familiar with it, this is a small bowl that divides into two chutes, one of which is quite narrow. I would estimate the slope angle at c.35 degrees. The bowl faces north east and therefore catches the prevailing wind. As you can see there is a small cornice and I'm guessing the first skier into the bowl triggered a 20cm slab. They may well have done that deliberately. I reckon c. 20 people have been through there before the party in question took the photo - based on counting the tracks in the second photo.
Is it safe? I'm biased here as I've skied with BobinCH a lot (see Verbier threads passim) and I think his hazard evaluation is good. The chimneys and Verbier in general see a lot of skier traffic and hence compaction. The main issue with this route is frequently how well newly fallen snow is bonding with the base rather than the stability of the snowpack as a whole. I'd be interested in how and whether that is true at the moment.
I think the first people through took a very significant risk if the slope was not deliberately cut. It is not a risk I would have taken. Otherwise, once the obvious slab was triggered the stability of the slope depends on the condition of the base, which cannot be observed from the picture.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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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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Davidof, the second photo chills me.
This is the front of Le Tour a couple of days ago, alt around 1600m and a westerly aspect. They are down to the turf, what was that about a weak layer.
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You need to Login to know who's really who.
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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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davidof, I read that article the other week when it appeared in the main paper. Well informed IMV - I hadn't realised he'd used your material!
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You'll need to Register first of course.
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Having said that, it's not the one I thought it was - this is more recent.
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| Sharkymark wrote: |
| Having said that, it's not the one I thought it was - this is more recent. |
It was le Matin's interviews which I'd translated key elements of into English which Peter then copied but he should have linked to Le Matin which made the interviews as a courtesy really.
http://pistehors.com/watch-out-say-swiss-mountain-guides-23147387.htm
http://www.lematin.ch/suisse/Faites-gaffe-disent-les-pros/story/19021732
As someone from the BMC said today "David from Pistehors.com has been talking about this weak layer since way back in November". It is easy to write pieces after a bad series of incidents, esp. in the Swiss Valais but Henry Schniewind, Andy Perkins, Alan Duclos and I stuck our necks out a bit by warning of the danger before the events actually happened.
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| jbob wrote: |
Davidof, the second photo chills me.
This is the front of Le Tour a couple of days ago, alt around 1600m and a westerly aspect. They are down to the turf, what was that about a weak layer. |
Hi
Are you up a le tour a lot? Sometimes these full depth slides happen all the time at certain spots. There is a 35 degree clearing in the woods near the col de Porte above Grenoble where the snow slides to the grass the second a certain depth is reached. Still Le tour is notorious for its avalanche incidents.
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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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| Weathercam wrote: |
Think those photos davidof, posted show just how important choosing the right terrain is.
Today's exercise was a ski tour up to the Col du Galibier selecting a safe route to climb as well as descend, plus another snow profile to compare South facing snow pack vs yesterday's North facing
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at least you got some sun
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davidof, very true
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| Weathercam wrote: |
There is a thread in the Piste section "Return of the Powder" and I'm very tempted to show a couple of the photographs to the guides asking their opinion, especially these two. Would have posted in the thread asking them what the risk was etc
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According to SLF avy level was 3/5 with risk elevated on steep North faces. As Gorilla correctly points out the pic is Mont Fort backside where top section is a steepish North facing couloir so we hesitated begore skiing it. However it was well tracked - you don't want to be first across the traverse to the entry - and we made the decision to go after a local Verbier guide took his group in. The main chimney had a big wind lip but the top slab had already been cut and several skiers had crossed into the second chute. This is narrow and was already well skied. After the top section the slope gradients are lower and the remaining risk is the dam traverse with big open slopes above for which you space out.
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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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The slopes in the Verbier pictures (i.e backside Mont Fort) see a lot of traffic due to proximity to the lift.
I suspect the reason those slopes were stable is because any deep weak layers and subsequent slabs were cut up by previous daily skier traffic ? Though to find this out you would need to dig a pit rather than just view the top layer. If you went somewhere more remote, like Rosablanche say, then the buried instability would probably remain.
Was in La Grave last week. Had a great week and the good news, despite the gloom, is there is still some great off piste to be found if you are cautious and pay attention to altitude, aspect and terrain. The snow pack is certainly becoming more stable with the recent warmer weather even though buried weakness remains in certain locations.
Had a very interesting conversation with well known local LG guide over an apres skier beer. Here reckoned it takes *approx* 1m to 1.5m of new snow before the buried weak layer gets consolidated by weight of the snow pack above it. However until that happens any new snow just adds extra loading to the existing weakness - and in theory the 20th or 30th skier over such a slope could be the one that triggers the buried weak layer from 2 weeks ago. The real complication is that snow does not fall uniformly and weak "hot spots" could exist on thinner areas for a very long time.
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You know it makes sense.
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| Quote: |
The slopes in the Verbier pictures (i.e backside Mont Fort) see a lot of traffic due to proximity to the lift.
I suspect the reason those slopes were stable is because any deep weak layers and subsequent slabs were cut up by previous daily skier traffic ? Though to find this out you would need to dig a pit rather than just view the top layer. If you went somewhere more remote, like Rosablanche say, then the buried instability would probably remain.
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That would be my assumption also. The chimneys are also likely to have a deeper snowpack than the surrounding area right now. Were a full depth slide in play I would anticipate that the 1-2 tons released by the initial ski cut would be more likely to trigger that than subsequent skiers passing one at a time. Note "more likely".
I think Verbier is an interesting example of how poorly resort skiing can prepare you for hazard evaluation while touring or skiing somewhere quieter (like Zinal for instance). Similarly, while the chimneys might be safe, there is no way on God's good earth I would go near the Dena at the moment.
Glad you had a good time in La Grave.
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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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Cervinia, last week apparently.
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Poster: A snowHead
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rob@rar, I think that photo is from several years ago. It's intersting in that it shows pretty clearly that a slope which has plenty of tracks on it is no indicator of stability.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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nozawaonsen, possibly, I just spotted it on Facebook and found it very sobering.
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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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rob@rar, Is it a public link on FB or was it a friend? Got a link?
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You need to Login to know who's really who.
You need to Login to know who's really who.
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feef, public link, I think, shared by a couple of friends. Will try to find it.
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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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The photo is from Dec 07 at the latest. Davidof pulled it from camp to camp.
http://pistehors.com/news/forums/viewthread/70/
There is no way of knowing whether that's a skier triggered slide or whether, say, the temperature rose and the pisteurs threw charges at it until it did that. Given that it is virtually flat - note the poles in the right hand side of the picture I'm going with there being something other than just skier + slab + buried surface hoar in the mix.
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Virtually flat? If I'm right in thinking where it is (and the colour of the piste poles tends to confirm this) that is a black run...
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offpisteskiing,
The top of the piste is reasonably steep. Bottom left of the photo is clearly reasonably steep. The right bit is not steep. We're almost side on and the top of the lowest 2m high piste marker pole is roughly in line with the bottom of the one higher up. Assuming they are spaced 10m apart, that's not a steep part of that piste, yet 3m below on something that doesn't look like a wildly dissimilar gradient there's a 1m crown. Perhaps the photo is flattening my ability to judge the gradient but I'm surprised that something that looks clearly below 25 degrees - in that section of the slope has gone that big. Where is it btw?
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Looks to me like the slope that went is steeper than the piste, id guess 25 to 30 deg., those tracks look like boot deep powder turns that require a good gradient, if it was flat they'd be straight lines. There's no bomb crater, doesn't mean it wasn't triggered, but usually there's a crater near the crown. Could have been triggered by a bomb off picture, or maybe one above the ground (i think bombs are more effective when detonated slightly above the ground, e.g suspended from a cable).
anyway, its still sobering. I'll link to that next time someone argues that off piste close to a piste is "safer".
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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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It's a really old picture. We had that pic on snowheads at least six / seven years ago.
Sobering indeed! Would be interesting to see whether the slide respected the piste boundaries all the way down.
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sah,
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I'll link to that next time someone argues that off piste close to a piste is "safer".
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The fact that this kind of photo is rather rare suggests that close to the piste is 'safer' which for numerous reasons I am pretty sure is the case. It does not make it completely 'safe' though
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