Deep Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Unlikely
- Dimensione
- 2
Evidence of a lingering persistent slab problem continues in the form of some unstable snowpit tests on isolated near and below treeline NW-N-NE aspects. Observations and data indicate that breaking the persistent weak layer and triggering a persistent slab would be difficult to do, but that if it does break, the resulting avalanche could be large (up to D2 or D3) and destructive. Significant uncertainty and variability exist concerning where the persistent slab problem may or may not linger. Data and observations have not provided a clear explanation for the variations in stability between similar terrain at different locations.
Due to the uncertainty, variability, and potential high consequences of this difficult to trigger (low probability) avalanche problem, avoiding terrain where persistent slabs may exist represents a prudent choice. Near and below treeline NW-N-NE aspects sheltered from the NE winds hold the best potential for a lingering persistent slab problem. Collapsing and whumpfing, unstable snowpit test results, and handpits/probing into the snowpack to feel for a loose layer of weak snow under frim slab layers can help identify where persistent slab problems may still exist. Keep in mind that snowpits dug high on the slope may miss evidence of this problem since it is more likely in the mid to lower portions of the slope.