| What it is | Dense slab from wind-deposited snow |
| Where | Leeward slopes, below ridges, gullies |
| Behavior | Often reactive soon after forming |
| Signs | Pillowy/chalky snow, drum sound, drifting |
A wind slab is a dense, cohesive layer of snow formed when wind transports and deposits snow onto leeward (downwind) slopes, packing it into a stiff slab over softer or weaker snow. Wind slabs are a common avalanche problem, especially near ridgelines and in gullies, and can be very reactive soon after forming. Signs include smooth, pillowy, chalky, or drum-like snow and visible wind drifting.
This is general educational information, not avalanche training.
Wind-built danger
A wind-formed slab avalanche problem in the snowpack; the same wind sculpts surface sastrugi.
Frequently asked questions
What is a wind slab?
A wind slab is a stiff, dense layer of snow created when wind picks up snow and redeposits it on sheltered, downwind (leeward) slopes, packing it into a cohesive slab. If that slab sits over weaker snow, it can release as an avalanche, making wind slabs a frequent and often touchy avalanche problem.
Where do wind slabs form?
On leeward slopes — those sheltered from the wind — especially just below ridgelines, on the downwind sides of terrain features, and in cross-loaded gullies and bowls. Because wind can deposit snow far faster than it falls, dangerous wind slabs can build quickly even without new snowfall.
How do you identify a wind slab?
Look for signs of recent wind transport: smooth, rounded, pillow-like or chalky snow surfaces, cornices and drifts, snow that sounds hollow or drum-like, shooting cracks, and stiff snow over softer snow. Recently formed wind slabs are often reactive, so suspect them near ridges and on leeward aspects after wind.
Sources
- Wind slab problem — Avalanche.org
- Wind loading — American Avalanche Association