Storm slab occurs when which process?

• A. Meltwater migrating between layers
• B. New snow sliding on existing snow surface
• C. Dry loose snow release
• D. Wind slab formation

Answer: (B)

Storm slab is formed when the snow that falls during a storm does not bond well to the layer beneath, creating a cohesive block of fresh snow that can slide as a unit on the existing snow surface. The rapid accumulation and the conditions during the storm often produce weak bonding at the interface with the old surface, so when the block is later loaded or disturbed, it fractures and releases as a slab avalanche. This is different from a loose-snow avalanche (which involves a spray of individual grains) and from wind slabs (which are formed by wind transporting and loading snow into a cohesive layer). It’s also not primarily about meltwater migrating between layers, which talks about different weak-layer formation.