Having said that, it’s quite possible that the normal route has changed a bit since I was looking at it what with glaciers retreating etc
I've only been to the top Domes de Miage and not skied down the Armancette glacier and don't recall the exact layout. I was probably thinking of the traverse along the ridge to access the top of the glacier. But basically we agree that it is ski down which is what the groups were doing at the time of the avalanche.
Last edited by Poster: A snowHead on Wed 12-04-23 15:28; edited 1 time in total
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
@davidof, don't forget UIAGM guides have their own intranet as it were, where guides post details of trips etc that they've done as well as contacting their contemporaries who might be specialists in any given region.
But three groups pretty well sums up that conditions were believed to be alright.
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?
Arno wrote:
davidof wrote:
There was no reason not to ski tour that route like that on the 9th, especially as the route was done as a traverse from the Refuge des Conscrits so the glacier was being tackled descending, although they would have climbed to the summit.
I’m pretty sure the normal route for this doesn’t involve retracing your steps at all (ie you climb up on one side and ski down the other)
I attempted this many years ago and got turned back by avalanche danger. Wasn’t much doubt about that decision - we were up to our waists in fresh snow which would need a few days to settle. IIRC a typical route was to traverse the Domes de Miage then ski the Glacier d’Armancette. It’s certainly a beautiful route and I can see why it’s popular
Correct, that is the classic route. I think there is a route via the col de Berangere that could mean you climb to Miage and retrace your steps a bit though.
@davidof, don't forget UIAGM guides have their own intranet as it were
the wires have been glowing red hot since the incident I'm told. The guides already know the conclusions of the investigation on the ground.
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
davidof wrote:
Was such an avalanche predictable ? Yes, it was mentioned in the avalanche bulletin as a risk.
Just to clear something up. Predictable is maybe not the best choice of words. The avalanche that occurred wasn't predictable, just the general case that an avalanche of the type that occurred was a possibility that should have been taken into account.
Here are the snow profiles taken after the avalanche:
There is 275cm snow depth. The first column test got a result at 215cm with four taps, a second test got a result with 1 tap (or whatever the test methodology was - will check this) - so quite sensitive to triggering however the slope had been skied that morning without a result. A snow profile found a very thin layer of facets at this depth.
2. At 3300m there is 500cm of snow. Note a sand layer at 50cm depth (this was noted in some Swiss avalanche incidents too). This helps date the layer, there was sand on my car about a week ago but checking the news they talk of February however someone in Chamonix said 4th April which corresponds to what I observed.
A column test got a result at 390cm - CT1 was 2 taps, CT2 was 8 taps. So less sensitive on average than the first slab. So weak layer at 110cm under the surface. This would be the PWL mentioned in the bulletin.
3. At 3100m there is 500cm of snow. A big snow/sand layer between 440 and 455cm. The weak layer is now at 370cm (130cm under the surface). CT1 didn't get a result, CT2 got a result with 8 taps.
So a slab that was relatively easy to trigger at 3500m that propagated down-slope. I would guess that these secondary slabs are the result of the March snowfall and not "old slabs" that had been in place since the start of winter at the guide Pierre Muller suggested. But that is a guess.
Note that a saw test didn't get any results - this is where a column is isolated with a saw and the weak layer is touched - this will often cause a collapse of the whole weak layer like a house of cards. See video.
It is ten days since you posted the snow pit data @davidof, and it shut the thread down.
Some of the column test numbers appear, to me, to be incredibly low and indicative of a very dangerous layer.
I have spent quite some time contemplating the overall scenario and have drawn no conclusions at all.
Experienced mountain guides got caught out in this tragedy and I am sure their knowledge is far superior to my own.
Is it reasonable to think that the depth of cover above the weak layers was deemed to be sufficient to bridge/ distribute load and avoid triggering?
I think I read that the slope had been skied earlier in the day obviously without incident.
Classic reassurance from other tracks.
Six fatalities is dreadful and I feel deeply for those who lost loved ones. That said, examining these incidents is the only way we expand our understanding.
Then you can post your own questions or snow reports...
Then you can post your own questions or snow reports...
Rogerdodger wrote:
It is ten days since you posted the snow pit data @davidof, and it shut the thread down.
That wasn't my intention. I hoped it would spark some more debate.
I imagine the whole thing will be tied up in disputes between insurers about who, if anyone, is to blame.
After all it is free
After all it is free
@davidof, that video is quite scary...there's hardly any incline on the slope by the looks of it, or will a saw test propagate a result like that more so than tapping?
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.
Rogerdodger wrote:
Is it reasonable to think that the depth of cover above the weak layers was deemed to be sufficient to bridge/ distribute load and avoid triggering?
That is a *very* good question.
As I understand:
i) Once snow is >2m deep then you reduce risk of triggering a weak layer below.
ii) But the load on slope obviously increases as snow pack gets deeper.
Because snow does not sit / drift uniformly across the mountain side there is no correct answer.
A skier hitting a "hot-spot" can trigger an entire slope. Think of it like a game of Jenga.
Removing the wrong block releases the entire tower. But other blocks can be removed without consequences.
The mitigation is not to take the Grands Mulets Petit Plateau route. I note the fall happened at 4.30am which brings home that Serac falls are really unpredictable. The Chamoniarde were warning not to take this route a few days before this incident due to the risk of serac fall this spring. They suggest using climbing by the north ridge of the Dôme du Goûter (marked with dots on the IGN map below) but the route is technical, requiring cramponing but it is not exposed to ice fall. The recent incidents possibly show that too many people are following "trade routes" without analysing the current risks.
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
davidof wrote:
The mitigation is not to take the Grands Mulets Petit Plateau route. I note the fall happened at 4.30am which brings home that Serac falls are really unpredictable. The Chamoniarde were warning not to take this route a few days before this incident due to the risk of serac fall this spring. They suggest using climbing by the north ridge of the Dôme du Goûter (marked with dots on the IGN map below) but the route is technical, requiring cramponing but it is not exposed to ice fall. The recent incidents possibly show that too many people are following "trade routes" without analysing the current risks.
Yup : I have done both...
North ridge of the Dôme du Goûter seems to be have become the "modern" ascent route for Mt Blanc.
Interestingly the 2nd time I did Mt Blanc all the guided groups went that way.
Takes longer but probably on balance a little safer.
Though because it takes 1-2hrs longer it has its own issues (returning to midi later in the day).
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.
Haggis_Trap wrote:
Interestingly the 2nd time I did Mt Blanc all the guided groups went that way.
The guides are exposing themselves a lot over the long term so that makes sense.
So if you're just off somewhere snowy come back and post a snow report of your own and we'll all love you very much
So if you're just off somewhere snowy come back and post a snow report of your own and we'll all love you very much
davidof wrote:
jmr59 wrote:
It's striking that instead of saying 'limité' they say 'très faible' (and 'faible' / 'low' is level 1), even though it was a level-2 day.
I'm not sure that at 3500 meters, with cold, fresh snow and strong winds on Saturday you'd really describe the risk as 'très faible' which is why I imagine the bulletin was set to 2 / Moderate above 2400 meters.
You might say the risk of a very large avalanche was 'très faible' and maybe that is what they are trying to say.
It's just some self-defencive wording, imho. But it is true, avi risk level 2 is as good as it's get's on a north facing glacier like this.
I must say, I was very surprised by the avalanche risk given. We have been skiing with friends and family in the Tarentaise (Grand Domaine) the week before the accident. Last ski day for us was saturday. On sunday, the day the accident happened, we have been to Chamonix.
As you all know, snow was scarce throughout this winter. As I more or less planned this trip for a total of 17 people, I felt a bit responsable for the overall conditions - unpleasant, to say the least - and as a result followed the snow reports as closely as I would normally only do going skitouring.
So, what did we got? After a very long period of nothing, heavy on and off snow/rain from thursday March 30th onwards. Mind you, that's at resort level Valmorel (1400m). Last day of precipitation was saturday 1st of April. Over 2500m this all came down as snow, something in the ballpark of 1m-1.5m. So that's a lot. We ended up with around 15cm at 1400m (from saturday evening) and a little bit more higher up. From then on, no more snowfall until friday 7th. But for the time of year quite chilly temperatures. As a result you could ski powder on north facing slopes throughout the whole week. Even below the Col de Madeleine the snow stayed fresh. We are talking now about the 2000m-1800m range. Friday 7th was once again snowy, with 10-15cm fresh, last snowfall coming in in the evening accompanied by heavy winds.
Saturday 8th was a blue bird day, no clouds at all. As I mentioned above, I was very surprised seeing them flying the green flag (Valmorel side of the resort tops out at Col de Mottet 2400m). So we had 10cm fresh on top of about 5-10cm sunken powder, which in gutters gives easily rise to 30cm+. I never in my life skied this much loose snow on a level 1 day!
valais2 wrote:
avalanche warnings are interesting but could be totally irrelevant to the specific location to which you are going.
Yes! ...and no.
On a factual level you are, of course, completely right. But imagine yourself for a moment in the guide's boots: You got two clients (the maximum for this route, if you go with a local agency; I looked it up). Each of them shelled out €560 plus other expenses. They actually did ask you beforehand, if this route was feasable, to which you (or your agency), based on the avalanche bulletin, agreed. Only because of that did they hire you, only because of that they are now with you. Together you scramble through the woods for a long time, until you can finally use your skis - commonly between 1200m (parking) and around 1700m. The next day, once you reach the top of Miage and look down the other side, you think, "That's a hell lot of powder. Damn!", while your clients might think, "That's a hell lot of powder. Woohooo...!"
It is a really tough call, then to say, "Okay guys, looks great, avi bulletin says it's safe, but I got a bad feeling. Let's get down by the crusty side of things..." All that while everyone else will ski the nice side. Mind you, in almost all of these cases there will be no avalanche. If there is an avalanche, kudos to you. But if there isn't, your customers will feel very bad about themselves, because all the other guys in the hut will have the best time of their lives, while they are fighting bruchharsch with you. Btw, this involves for non-expert skiers normally taking a tumble or two, which ironically entails a real - maybe slight, but non-negligible - risk of injury. Even if this doesn't happen, what are the chances that your clients will be happy with your service?
Damn, in a case like this I can even imagine me as a client complaining. That's the difference between the alps and take say Kamchatka.
FAQ
Poster: A snowHead
That's the difference between the alps and take say Kamchatka.