Persistent Slab

A persistent slab is an avalanche problem that is defined by a slab formed over a persistent weak layer. New snow that accumulates and consolidates over a persistent weak layer is normally first labeled a storm slab until the persistent nature of the weak layer becomes apparent over time.

Persistent slabs are most likely to result in dangerous human-triggered avalanches when the weak layer is buried 30-100 cm below the snow surface. When the layer is buried more than one metre deep, it usually becomes harder to trigger, but can still result in a very large, destructive avalanche. 

Management of persistent slab problems requires a strong grasp of the problem’s distribution, as clues about the problem are unlikely to be visible on the surface. It also requires a patient and diligent mindset, shown through the willingness to avoid suspect slopes for extended periods of time.