Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 1.5–2.5
We are currently experiencing significant spatial variability in snowpack and avalanche problems. One common theme is the buried weak/faceted snow that has been recently observed in all locations. Cold, dry, and windy conditions during December left a weak, faceted snowpack throughout the region. For the last several weeks, there has been a limited possibility for avalanche activity associated with this weak snow due to a lack of cohesive slab on top of it; however, this is beginning to change. Some areas throughout the pass now have 2 feet of dry storm snow or windslab, loading the weak faceted snow below. This has recently been causing widespread collapse in some of our observed areas. Large interconnected slopes over 32 degrees with deep storm snow or thick windslabs may be able to produce destructive human-triggered avalanches, especially as snow loads increase in the near future. Pay attention to how the recent snow has loaded the areas you travel in today and use protocols to avoid exposure to suspect slopes.
Many areas have over a meter of faceted snow at the base of the snowpack. This problem will likely stick around for a while until we get a wet heavy snowfall to crush it.
Wind Slab: Recently formed windslabs near the summit of Thompson Pass may be sensitive to Human Triggers today. Significant windslab formation is expected to be limited to the area adjacent to the pass summit, with less wind effect to the North.
Storm slab: In non-wind-affected areas, there is little cohesion within the dry storm snow; however, a few density changes within new snow have been producing failure. Expect the possibility of triggering small soft slab avalanches on isolated steep terrain