Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 2
Triggering a large, 1-2' thick avalanche is most likely on slopes with the following characteristics:
- Slopes steeper than about 35 degrees.
- Well-developed facets in the middle of the snowpack.
- Where wind has stiffened the snow in the upper part of the snowpack and/or formed hard drifts on the surface.
- Slopes that face W/NW-NW-N-NE-E-SE. These aspects are where the majority of our recent avalanche activity has occurred and harbors the ugliest underlying snowpack structure.
Because the weak layer is more deeply buried in this zone, it's getting more difficult to trigger avalanches. Unstable slopes may not give you obvious "red-flags" like snowpack collapsing, shooting cracks, or poor instability test scores. Unfortunately, when you find the wrong spot, the resulting slide will be large and dangerous.
There's a real chance of remotely triggering slides—from areas below, above, and to the sides of steep slopes. Be aware of the terrain you are in and the terrain above you.
ADDITIONAL DISCUSSIONSince Wednesday night, up to 8" of new snow fell in this zone with very little wind. Loose snow avalanches are possible on all aspects in very steep terrain. These slides may be triggered by you, or occur naturally as the sun warms a slope.
(12/27/2020) Large natural avalanches are visible on McDonald Peak (foreground) and Parks Peak (background). These slides broke hundreds of feet wide, failing at the end of the storm on Saturday.