Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 2
The Valentine's Day storm has built a dense, cohesive slab on top of our weak, underlying snowpack. On northerly aspects, the entire snowpack is faceted through with varying degrees of hardness, but a layer of fist hard facets exist directly beneath the slab. Outward signs of instability such as collapsing and whumphing have decreased significantly but they are still being observed and stability tests remain reactive. The bottom line is that human triggered avalanches up to 2 feet deep or more, failing on this weak layer remain highly possible. The danger is most prevalent on northerly aspects near treeline but don't think you can outsmart it by changing elevation. For the foreseeable future, I'll be avoiding all slopes steeper than 30 degrees on all northerly aspects.
As you wrap around to west, the problem still exists and it's a fine line between shady and sunny. Many westerly aspects still present as northerly if there are trees to provide shade. West facing slopes should be considered guilty until proven innocent, and a slope by slope analysis is required.
South facing slopes are now cooked off or crusted over and we should be through with concerns there. The exception is on upper elevation, SE aspects. Due to the high altitude, these slopes often present as easterly, thereby preserving weak, faceted snow. We don't have much current information from these areas so they should be assumed guilty until proven otherwise.
Photo illustrates very poor snowpack structure on a northeast aspect at 10,700'. An extended column test produced results of ECTP 24.