Storm Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 3
At least two human-triggered deep slab avalanches have occurred in the last 24 hours: one this morning at 11:30 am and one yesterday at 2:45 in the afternoon. Both were remotely triggered and both propagated across large areas and involved enough snow to destroy a car, a wood framed house, or maybe even a train (D3 to D4 in size). Human triggered deep slab avalanches are possible on near and below treeline NW-N-NE aspects where a facet layer (loose weak snow) is buried 4+ ft. deep in the snowpack. This layer and therefore deep slabs may exist in above treeline terrain as well, but some uncertainty surrounds whether or not the problem exists at those upper elevations.
These avalanches would have dire consequences and likely be unsurvivable. While the weak layer is buried deeply in most areas and may be difficult to trigger in some places, people can still cause this layer to fail especially around trigger points such as single trees, exposed rocks, and convex slope rollovers where the weak layer may be closer to the snow surface and easier to trigger. Large triggers such as multiple people on the same slope at once have a greater chance of triggering deep slab avalanches.
Due to the dire consequences of these deep slab avalanches and a reasonable possibility of triggering them, avoidance represents the best course of action. If traveling in an area where this weak layer may exist avoid this problem by staying on slopes less steep than 30 degrees without steeper terrain above.
