It is rare that we have as clear of evidence of a deep-persistent avalanche problem as we did the week leading up to this accident. Some of the group likely drove by fresh evidence of the problem in Straight Creek on their way to Saturday's event. Before their tour, the group read about the conditions in the avalanche bulletin and identified deep-persistent slabs as the primary avalanche problem. They selected terrain that was less likely to produce a deep-slab avalanche, but to get there they traveled through a dangerous area. At least 3 members of the group reached the "island of safety" they had identified, only to be subsequently caught and buried in the avalanche.
It is easy to underestimate the consequences of getting caught in a deep-persistent slab avalanche, because these slides are often much bigger than most of the avalanches witnessed by backcountry recreationalists. Deep-persistent slabs do not form every year, like storm and wind slab avalanches. The only effective travel technique for this avalanche problem is to avoid areas where deep slabs might release, or if the risk is deemed acceptable, expose a single group member to the danger. Spreading out often does not mitigate the risk to the group because these avalanches are always large and destructive.
http://avalanche.state.co.us/caic/me...505_5125-r.jpg
