Avalanche Forecast

Remember, even as natural activity trends downward, we just received a huge volume of water in a relatively short amount of time, creating unstable conditions. Strong winds up to 58 mph the past 24 hours added additional areas of unstable snow. Alpental Pro Patrol reported between 7 to 10 inches of fairly cohesionless wind affected snow above 4500 feet on Wednesday, with deeper slabs in low to moderate angled slopes where the new snow had drifted in. This tells us the distribution of wind slabs is more widespread than being isolated to ridgelines. Expect to encounter larger and more reactive wind slabs along with deeper and drier snow as you travel up in elevation, particularly above Tuesday’s rain line. Fresh cornices, blowing snow, and smooth pillow-like features are signs that wind effect has taken place and wind slabs are likely. If these signs are present, avoid slopes greater than 35 degrees and don’t travel below fresh cornices.

Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.