You always carry all of your gear because you might end up saving someone else not in your group, or vice-versa. Duh. Most packs have a dedicated pocket for b / s / p anyway so why bother taking them out?
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You always carry all of your gear because you might end up saving someone else not in your group, or vice-versa. Duh. Most packs have a dedicated pocket for b / s / p anyway so why bother taking them out?
The Sheep Creek incident is fascinating to me because it seems to be a bit of an outlier in terms of the information available to those involved.
http://www.americanavalancheassociat...3_Feb_2014.pdf
Normally, message fatigue and uncertainty are really big issues with DPS problems. In the Sheep Creek incident, the forecasts were kinda shouting that uncertainty was decreasing and the likelihood of triggering a deep slab avalanche was increasing. I think it's rare to have that kind of in your face beta for that kind of problem.
But I don't have the old forecasts at hand, so I may be wrong.
That's how I remember it. Even before Sheep creek, there was almost a daily report of a big slide in that area. The Vail pass fatality right before Sheep creek perfectly demonstrated low probablility/ high consequence since it didn't release until something like the 40th track. I'm not sure how much more the CAIC could have done the morning of Sheep creek, though there are a few suggestions in the TAR article.Quote:
Originally Posted by covert
Off topic, but perhaps an interview with Elizabeth Lamphere on Slide would be a good episode some day. This is at our avy awareness night this year: https://www.youtube.com/watch?v=kfvHGfhtTR4
The CAIC recently posted a blog where they discussed how they determine whether a problem is a PS or DPS:Quote:
Originally Posted by klar
More detail here (cover article): http://www.americanavalancheassociat...2_Dec_2012.pdfQuote:
Originally Posted by CAIC
Very interesting, thanks. Much clearer now.Quote:
Originally Posted by adrenalated
I do this mentally when DPS is among the problem list, I also think it would help others to see it in writing. I don't think it would be too difficult for forecasters to differentiate.Quote:
Originally Posted by goldenboy
I think this is the crux of the issue. Esspecially now with so much being shared through social media. If I see bold lines skied left and right online, it continues to test my patience while mitigating a DPS. Somebody else said it here a while back but, humans suck at making high consequence low probability decisions. It's just in our blood.Quote:
Originally Posted by goldenboy
Covert has referenced Daniel Kahnmen a few times so far in the podcast. If anyone else is interested in a physiologists take on decision making, I highly recommending picking up his book "Thinking fast and slow". I found a used copy on amazon for $4
I tried the book and it was too dense for my ADD brain. Here's a good summary: http://www.nytimes.com/2011/11/27/bo...ok-review.html
And I guess I am honestly very pessimistic about human's ability to get educated away from being tempted to tease the deep slab problem. We talk mindsets, better writing the forecast, better education, and so on and so forth. I think that the "young immortal" is going to think that he (she?) can get away with it for many many reasons, which are the same reasons that we draft that age group to go to war for us. They don't individually learn restraint vicariously until someone/ thing very close to them impacts their life. So in my mind the whole "Project Zero" or "Backcountry Zero" is a farce. And I teach avalanche education for a living.... with a dark mindset, honestly.
^^^ Thanks for writing what I was thinking.
Yep, +3Quote:
Originally Posted by homemadesalsa
That's a great book too btw.
I wasn't in this party, but knew the deceased and one other member in the group. This had the most profound effect on my decisions with both snow and terrain assessment as well as choosing appropriate touring partners.
https://utahavalanchecenter.org/avalanches/18137
RIP ALX88!
IMO at Sheep Creek multiple things broke down for that group resulting in a total collapse of protocol and judgement. Not paying attention to the potential for DPS was part of it but also terrain management and travel protocol were absent. If they would have either traveled one at a time or used effective terrain management all or most of them would have been alive today. I have skied at and around LL pass a hundred times and never have gone into this area - terrain trap.Quote:
Originally Posted by covert
So IMO to say that lack of paying attention to DPS slide potential is only a smaller part of the story there.
Overall for education skiers on deep instabilities - more and more detailed stories about deep slab incidents are a great way. Videos, text, 1st hand presentations, etc. to get the message across that this is real and as an olderish school skier I remember the days when Avy materials and Avalanche courses included the pictures of the badly mangled avalanche victims. I know that now adays no-one wants to show pictures of the dead, but it sure was effective in locking into my brain the real consequences of getting the decisions around avalanches wrong. There is so much positive feedback on social media and the Ski Porn world showing how awesome the skiing is but it very little gets put in front of kids to counter balance that, other than the random name on a newsite or internet forums. Why do we only make the first responder deal with the ugly reality of the results of poor decisions. If you're picking up a book on avalanches to learn or taking a class, you should be ready to see the ice mask on the dead guy or the twisted into abnormal form of the lower body of a victim with skis still attached. Those are the chips that are on the table, the players should know what the result may very well be. That teaches respect of DPS.
Re: Sheep Creek - they did travel one at a time, just not far enough apart. Of course their line choice was the bigger problem.
I had never heard of Project Zero before I read about it in Backcountry today... my first thought was, good luck with that.
They didn't travel one at a time. They just increased their interval. Not the same at all. One at a time means only one person exposed to the hazard and everyone else is waiting and watching.Quote:
Originally Posted by TahoeJ
Yes, I understand that. I mis-remembered because three of them were waiting on their "island of safety" for the others to arrive, but you're right that they just spread out by 50 feet and kept going. Everything about that incident is just strange - I'm not sure it really makes for a great case study to be honest. http://www.americanavalancheassociat...3_Feb_2014.pdfQuote:
Originally Posted by AaronWright
Yes, they also had even read about DPS as the primary avalanche problem that morning so the more experienced members of the group even had consciousness of the risk. There was a lot in common between that accident and several others over a few year period, including lacking travel protocol and treating trees as islands of safety. Because of the time cost of one at a time, it can be hard to manage a larger group, among other things, but it is a good case study on multiple levels.Quote:
Originally Posted by AaronWright
Another curious thing is why they would choose and "island of safety" on the same slope they were concerned about with no real prominence. I could understand if it was a sub ridge on the slope with significant prominence from the general slope and travel to it one at a time, if that was the only option. This isn't meant to imply they should have been there in the first place.Quote:
Originally Posted by SkyIsland
Makes for a great case study for decision making, route selection, and human errors. They had the forecast, understood it as much as they possibly could, having it explained to them by Scott Tepfer, a CAIC forecaster the night before and reviewed it that morning as well. Where things broke down was their travel protocols and decisions making. They were trying to access a different slope, and didn't give enough thought to the slope they were crossing even though it was the exact thing they were trying to avoid completely. Almost every other party that day was across the highway skiing Trelease, a S facing, low angle slope with very little avalanche hazard.Quote:
Originally Posted by TahoeJ
I guess I just mean that the incident lacks any nuance and it's more of a big "what were they thinking?"
So one of the deadliest avalanches in CO history doesn't have enough "Nuance" for you? In a thread about PWLs and DPSs, I'd say it fits right in. A lot to be learned from mistakes made and why they were.Quote:
Originally Posted by TahoeJ
IMO the CAA does a great job with its special bulletins. http://www.avalanche.ca/blogs/danger...itions-brewing
If anyone cares, the appropriate information is in circulation.
This is a great example of one of the bits of "nuance" to be gained from looking at the incident.Quote:
Originally Posted by AaronWright
While we don't have a record of their specific conversations, there was and is this idea floating around that trees = safety. The last 20+ years may have seen efforts to change that notion, but it's still out there. While it's possible that they chose the grove of trees simply as a visual marker, I think it is much more likely that they just plugged in "trees=safe" and headed there.
A tragic result doesn't necessarily make an incident nuanced. Blatant disregard for the specific hazards emphasized in the avy bulletin (which said specifically to avoid travel beneath or adjacent to steeper slopes due to many observations of remote triggering) and some very poor decision making, isn't nuanced IMO. There are plenty of other incidents where as you read along you're saying, okay, I can understand where they were coming from. This was not one of them. But whatever, that's just my opinion and you don't have to agree with it.Quote:
Originally Posted by ULLRismyco-pilot
I think almost every accident or near-miss has nuance that is frequently downplayed or overlooked. By definition, nuance is less than obvious, you have to look for it.
"how do you do that voodoo that you do do"?
I always thought that couloirs were safer than big faces, from an avie standpoint.
But I never came up with a reasonable reason, except perhaps better anchored.
Now, I think it's because the snow is deeper in a couloir than on an adjacent face, because snow sloughs off the walls into the couloir.
And with deeper snow, you have a lower temperature gradient, so a buried weak layer has a better chance of healing.
Maybe.
I'm no expert, so bear with me here........ My understanding is that (and of course this is a simplification):Quote:
Originally Posted by rod9301
A lower temperature gradient will reduce the chance of some kinds of weak layers forming within the snowpack (at the bottom primarily, or beneath ice layers), but it will not affect the rate of bonding within the snowpack. A buried weak layer will primarily heal because it in some way or another turns into a melt form and refreezes.
Ok, fire away....
Is it possible then that the faceted layer will never form?
Again, I'm no expert, but yes; given the same temperature in an area, a locally deeper snow pack should produce less depth hoar. If your theory about snow falling from the rock walls leads to a deeper snowpack is right, then there should be less depth hoar. But a little bit is still dangerous. And as you know, any number of other factors affect the snow pack. For example; sunlight/heat, or the lack of it, will be one factor affecting stabilization. Or; If a couloir is sheltered from wind, maybe surface hoar might survive and produce a weak layer just as dangerous as the depth hoar, etcQuote:
Originally Posted by rod9301
In another words; I feel this is a bit hypothetical.
If a person said to me "I'm not going to ski that powder field today, but in that couloir I should be fine", based on only this.........no bueno.
As has already been mentioned to some extent, I think there's a tendency to associate danger rating with the severity of the slide. People see "high" and think the avalanches will be really dangerous that day, but the rating really only conveys probability. People see "moderate" and assume the avalanches themselves won't be that dangerous that day, but again the rating is for probability, not severity. I feel this nuance is too often ignored and the rating becomes associated with severity rather than probability, which is a result of human psychology to some extent. Given that, I don't really know how deep slab problems can be better conveyed in a way that will lead people to make better decisions.
This is sort of a variation on the trees adding to risk theme. How much gets added to consequence is going to be very couloir-dependent. On average I think it's fair to say your probabiity assessment needs to take into several factors, and may or may not be lower versus higher. But, your consequence is normally going to be far higher. Possibly not as clear a case as steep trees in terms of piling on risk, though.Quote:
Originally Posted by rod9301
Right. I'd much rather go for a ride down an open bowl than get flushed through the choke of a rock walled couloir. Cornice hazard is also much greater since there's not much of a chance of dodging it compared to an open face (assuming you are booting up the couloir).
You have it sort of close. Snow Metamorphism is interesting as a subject but is probably way over emphasized, especially for the recreational skier.Quote:
Originally Posted by sf
To clarify that statement.Quote:
A lower temperature gradient will reduce the chance of some kinds of weak layers forming within the snowpack (at the bottom primarily, or beneath ice layers), but it will not affect the rate of bonding within the snowpack. A buried weak layer will primarily heal because it in some way or another turns into a melt form and refreezes.
A lower or smaller Temp. Gradient will encourage the formation of smaller and more rounded grains. Due to shape and size those grains will tend to form bonds between the grains and overall the snow layer should gain strength.
A higher or stronger Temp. Gradient will encourage the growth of larger and more squarish/faceted grains. Because of the larger size and shape there is less contact area between the grains so the bonds are weaker and there are less of them and generally speaking this is a weaker structure.
Unless the grains temperature rises above 0 Deg C there isn't any melting, just water vapor transport which is always happening within the snow pack but is driven by temperature gradients or the lack of them.
A strong Temp Gradient (> 1 Deg C/10 CM) will generally tend to form faceted grains.
A weak Temp Gradient (< 1 Deg C/10 CM) will generally form rounded grains.
Does that make sense?
As for facets, they will usually always be present during the early part of the winter, the exception being in a Maritime regime but that is a maybe yes, maybe no.
As the snow pack depth increases, the Temp. Gradient should become smaller or less and the facets may tend toward rounding and gaining strength.
Note all the qualifier words used in the explanation.
Since I like skiing couloirs, I thought about consequences a lot.Quote:
Originally Posted by TahoeJ
Assuming the couloir is straight, without a dog leg, once the avie reaches the apron, the snow will spread over a much larger area, so you have less of a chance to get buried.
I think hitting a tree in an avie is a lot more likely than hitting the walls of the couloir.
Cornices, no doubt, as are upper walls that take sunlight.
I was only talking about the much deeper snow in a couloir as producing a lower temp gradient than in an adjacent face.
And not all couloirs will have deeper snow, some are gullies without high walls, or the walls are too vertical.
To get deeper snow, the walls must open up, so the couloir is much wider at the top of the walls than at the bottom.
In other words, the walls must have an angle, not vertical, say 60 degrees, then all the snow that falls on the walls will slough off into the couloir, adding to the snow depth.
And by the way, I was thinking of a maritime climate. Even though, I could see that if you have a depth of 3meters in a couloir (vs half m on an adjacent face) in a continental climate, the snow could act more like a maritime, or in between, because of the lower temperature gradient.
Similar to high elevations close to the coast where the snow pack will have more continental features.
My take on this super hypothetical discussion: If the snowpack in a couloir is significantly different than on an adjacent, open slope, I suspect it has more to do with differences in the compaction/settling process due to snow falling in from the walls (mechanical, destructive) and the assumed much larger snow depth (weight/overburden) than with facets that may or may not form due to different temperature gradients.Quote:
Originally Posted by rod9301
Not sure if this fits your definition of a couloir but for me this was one of the more educational examples of persistent weak layer avalanches I've seen. Several people had skied it before someone else triggered it. A lot of similar terrain got skied that day without issue.
https://c1.staticflickr.com/2/1576/2...3445f44b_o.jpg
https://c1.staticflickr.com/2/1637/2...0e685d24_o.jpg
I like couloirs because I find them less complex than open terrain.
The North American Public Avalanche Danger Scale actually addresses Likelihood, Size, and Distribution.
http://www.avalanche.org/danger_card.php
The danger rating can never be more than the broadest of brush strokes though. The useful information is always in the problem descriptions and the discussion.
http://i619.photobucket.com/albums/t...psvifaasma.jpg
2005 Annual SPA Conference at Highlands in Aspen the theme was: Aspect is Everything
I would add Weather and Elevation. I was happy that a bit of molecular physics was introduced
to the conversation. It's a move toward a UnificationTheory of Backcountry Travel or to quote Frank:
http://i619.photobucket.com/albums/t...psao6excrl.jpg