Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2–3
Weak snow looms below thick slabs of cohesive snow on most slopes increasing the chance to trigger an avalanche large enough to bury, injure, or kill you. Triggering a smaller avalanche from a wind-drifted area could provoke a larger, more dangerous slide that breaks deeper into weak, collapsible snow layers three to four feet below the surface and broader across slopes than you might expect. You may not see cracking or hear audible collapses on every slope, but if you do, it is an early warning sign of unstable snow below. The threat to trigger an avalanche from below a slope, or from a distance remains, so give yourself plenty of room if traveling around bigger terrain. Avoid all steep slopes unless you very carefully evaluate the snowpack and find an absence of buried weak snow layers.