A natural avalanche cycle is headed our way. Be aware of changing conditions as the storm intensifies.
Weather Forecast
Rogers Pass looks like it will get thumped. Thursday night and into Friday we should see 30-40cm, strong/extreme SW ridge-top winds, and freezing levels rising to 1600m. Saturday is somewhat uncertain, but another 50cm may fall, with strong alpine winds and freezing levels around 1600m. Perfect conditions for a natural avalanche cycle!
Snowpack Summary
20-25cm of storm snow overlies widespread surface hoar at all elevations. SW winds have begun to create slabs in lee features at alpine and tree-line. As the load increases and the slabs become more cohesive, the surface hoar will become reactive. Rocks, stumps, and trees are still poking through the surface, so early season hazards still prevail.
Avalanche Summary
The size 3.5 avalanche off of Bruins Ridge on Sunday opened many eyes. Winter and, along with it, avalanche season are here. Yesterday, numerous loose and soft slab avalanches up to size 2.5 were observed on Mt MacDonald, pulling out of steep, alpine terrain.
Confidence
Due to the number of field observations
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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
Wind Slab avalanches are the 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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.