Flat Tops Wilderness Slide/1st CO Fatality

[BFD]

seems to question the validity of the ECT in cases of surface hoar. didn't scroll down far enough to see the profile.

[capulin overdrive]

Well, yeah, there is that too. And keep visual contact

Other than some learning to pick a better place to watch their bro highmark, or at least leave their sled running. BC etiquette has a ways to go in the motorized world.


Visual contact on snowbikes is often two guys 10 feet apart, and equally exposed. Physical effort is less than skiing, so will require more disciple to learn to space out and hit stuff one at a time. As taking a breather is more about giving your butt a rest, than your lungs.


That said, I saw plenty of WTFWTT stuff from skiers and sledders during the time of this slide. So all groups can/could do better.

[hatchgreenchile]

The usual bag of tricks aren’t working. No collapsing or cracking observed on low angle terrain, stability tests weren’t concerning, yet every slope we touched steeper than 33 degrees avalanched on surface hoar about 15-20″ deep"
]

Yikes. I imagine a "tests = useless, skiing = slide" scenario like this is pretty uncommon, but damn scary nonetheless.

[summit]

^SH is notorious for things like that... and killing experienced folks and avalanche pros. SH is the number 1 PWL for avalanche accidents involving avalanche pros. Particularly because it is so variably distributed and variably reactive. It can be on your slope but not in your pit, or vice versa. Or you can miss it. or it can react differently on your slope than in your pit. King of spatially variable weak layers!

Looking for SH in your pit is hard unless you already knew it was there or unless they are big big big SH and haven't laid down. If you have to look, tilt tap (burp the baby) or SS test... then you look. Sometimes your compressions will find it if you look at a clean shear plane, but don't usually expect to just see it in a pit wall. But really the best way to know about the SH is to look in your log book where you wrote down "saw SH" then "SH persisted in X Y Z areas on A B C aspects in W T F elevation bands" and then "snowed, don't think the SH all went away and is now buried *frowny face*" Or for most, CAIC says "SH is lurking in some areas." We don't normally get it like this in CO. BC is more familiar with this problem.

[hatchgreenchile]

^SH is notorious for things like that... and killing experienced folks and avalanche pros. SH is the number PWL for avalanche accidents involving avalanche pros. Particularly because it is so variably distributed and variably reactive. It can be on your slope but not in your pit, or vice versa. Or you can miss it. or it can react differently on your slope than in your pit. King of spatially variable weak layers!

Looking for SH in your pit is hard unless you already knew it was there or unless they are big big big SH and haven't laid down. If you have to look, tilt tap (burp the baby) or SS test... then you look. Sometimes your compressions will find it if you look at a clean shear plane, but don't usually expect to just see it in a pit wall. But really the best way to know about the SH is to look in your log book where you wrote down "saw SH" then "SH persisted in X Y Z areas on A B C aspects in W T F elevation bands" and then "snowed, don't think the SH all went away and is now buried *frowny face*" Or for most, CAIC says "SH is lurking in some areas." We don't normally get it like this in CO. BC is more familiar with this problem.

Thanks Summit, good stuff here.

[LightRanger]

Ditto that. We don't see it much in CA in terms of it hanging around. Usually if we do get it, it'll get warm enough to destroy it in (almost) all places before it's buried again, or it'll be destroyed as a cohesive layer by rain/massive amount of wet snow. At least those are my observations over the years. Quite rare that it becomes an issue.

[goldenboy]

For a while there, the thing to do was listen to the avie center and not even mess with the aspects and elevations that they were concerned about SH. Too easy to miss, too much variability. The areas that were the worst were the areas people usually go to in CO winter- lower 30 degree glade skiing, N through E aspects.

Not sure how or if I can embed a facebook video, but here's a good SH demo (and they couldn't ID it in a pit, either):

https://www.facebook.com/cbavalanche...4737542022860/