Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
A thick slab of snow sits above various weak layers on most slopes (video at right/below). Your odds of triggering an avalanche are greatest on steep, rocky slopes on the north half of the compass. Although these avalanches are hard to trigger, these avalanches will be large enough to bury and injure you.
You're most likely to impact these layers where the slab is thinner. Thin spots are common at the edge of a slab, near ridgelines, or along rocky, mid-slope ribs. Remotely triggering an avalanche from flat terrain near steep slopes remains a possibility.
Additional discussion: Consistent NW winds over the past 24 hours have transported snow and formed thin wind slabs on leeward slopes. Keep an eye out for wind-affected surfaces near ridgelines on E, SE, and S slopes and think twice if you’re seeing shooting cracks.
(12/31/2024) Explosives-triggered slab avalanche on a NE-ESE facing bowl @ 8,400'. The avalanche broke ~300' wide and 2-3' deep. Shoulder of Peak 2 in the Soldier Mtns. Photo: Sawtooth Avalanche Center