Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
The more recent weak layer in the top 2' of the snowpack is showing signs of giving up the ghost. As a result, our attention returns to our old, familiar friend—the December facets near the base of the snowpack. In the western portions of this zone (Soldiers, Dollarhide area) and at upper elevations, the snowpack depth is greater and this layer is buried beneath a 2-3' thick slab and is becoming difficult to trigger. Where the snowpack is a bit thinner, the facets are even weaker and may be more easily affected by your weight. Throw in the effects from last week's wind event, and you have a highly variable snowpack. If I were to make some generalizations and describe two areas where you are more likely to trigger a slide, they would be:
- Steep (over 35 degrees), rocky, wind-affected, "prime-time" terrain. On the western side of this zone where the snowpack is deeper, this type of terrain will have more trigger points where your weight can more easily impact the deeper weak layer.
- Where you find old, harder wind slabs from the recent wind event. Especially where the snowpack remains thinner, these stiff wind slabs may be sitting over weak, faceted snow. Yesterday, a rider between Wells and Dollarhide Summits triggered an avalanche on a slope that likely had a snowpack that matched this description.
(2/12/2021) This avalanche was triggered by a rider NE of Wells Summit in the Soldier & Wood River Valley zone. The slide broke around 40' wide and carried the rider about 100 yards. A section of the cornice also released in the slide.