Persistent Slabs
N
NE
E
SE
S
SW
W
NW
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2–2.5
Cohesive slabs of snow resting above weak snow layers makes it easier to trigger a dangerous avalanche on, below, or adjacent to slopes steeper than about 30 degrees at upper elevations. An avalanche triggered from a wind-loaded, easterly-facing slope can break around you and wider than you expect, and could provoke a failure in weaker snow three to four feet deep. Deeply breaking avalanches will grow much larger in size, and be more of a challenge to escape. Shooting cracks and rumbling collapses are signs of unstable snow, and suggest moving to lower-angle slopes or areas sheltered from the wind. Smaller avalanches can turn into bigger problems if you get swept over a cliff or stuffed in a terrain trap.