Windcrust???

[ak_powder_monkey]

Up here we have pretty much everything with windcrust, lots of windcrust. Should I be worried about a 2 inch layer of crust thats hard as rock? What happens when it gets compressed by snow? Usually I see many soft snow avys right after it snows on higher angle stuff but never anything big. In this part of the chugach we don't really have snow on windward slopes so I'm skiing leeward almost always, anybody have tips that will help me keep safe? Do I need to be worried about this crust or just the new snow? I know these questions are vauge and you cant see but any help will hopefully keep me from dying

[AltaPowderDaze]

well i'm not too sure what you have up there but when any crust gets new snow on it you need to assess how well the new snow bonds. if it comes in heavy and wet then it has a better chance of bonding. after the snow piles up and you can dig a pit profile you should notice that the crust is now bridging the snowpack on top of it. this is because the crust and the snowpack below it settle at different rates. as that snowpack below settles it allows space between it and the crust where facets can flourish. the vapor barrier created by the crust and the open space is perfect for that. you can often find facets both above and below the crust depending on the weather conditions in the days/weeks after the development of the crust.

i'm still not really sure what you're looking to find out but if you can be a little more specific then i might be able to answer your question.

[ak_powder_monkey]

i'm still not really sure what you're looking to find out but if you can be a little more specific then i might be able to answer your question.

Usually the snow doesn't bond at all to the windcrust and the top few inches of new snow (cause we never get more then that) almost always goes as a soft snow avy expecially in areas that load it up and make it a bit denser. I'm wondering more of the old windcrust. Should I be worried about this layer (supportable crust ~2-10 cm thick).

[AltaPowderDaze]

I'm wondering more of the old windcrust. Should I be worried about this layer (supportable crust ~2-10 cm thick).

the layer itself poses no problem. you have to have snow on it to slough or a slab on it to slide. it will be a weak interface but i'd rather deal with that than buried surface hoar anyday. a better answer is dig and you shall see.

[Lurch]

Usually the snow doesn't bond at all to the windcrust and the top few inches of new snow (cause we never get more then that) almost always goes as a soft snow avy expecially in areas that load it up and make it a bit denser. I'm wondering more of the old windcrust. Should I be worried about this layer (supportable crust ~2-10 cm thick).

You need to dig a pit to see how that layer has bonded to the lower layers to know if it's going to be a problem. You should take a local Avy 1 class to get the skills and knowledge needed for your snow pack.

[AltaPowderDaze]

However, especially for thinner crusts (less significant rain events) the snowpack beneath the stiff layer often continues to settle. sometimes substantially. The ice layer bridges the snowpack. But at some point the fact that the underlying snow will continue to settle and the stiff slab above (in this case ice layer) doesn't creates the potential for future problems iff the ice layer weakens through faceting or warming. For a 12" layer that probably requires a relatively long period of faceting similar to Canada in late 2002. Once weakened, the fact that the stiff crust hasn't settled means it is now storing gravitational geopotential energy, it is elastic and slab-like. How much energy it is storing depends on the slope angle, shape and the load overlying the now faceted or weakened crust. Strange stuff. The once strong and settled layer becomes the layer that is capable of propagating energy.

there are some very good topics covering stuff like this over at t-tips.