Stormy weather continues, creating dangerous avalanche conditions at upper elevations.
Expect the storm slab problem to increase in depth and reactivity as more snow accumulates with strong winds. Slabs will likely be larger and more reactive in northerly, wind-loaded terrain.
On Saturday, riders and explosives triggered size 1, storm slab avalanches. As winds increased, ridgeline lee features became increasingly reactive through the day.
On Friday, explosives triggered size 1-2 storm slab avalanches, which failed about 20-40 cm deep within the recent storm snow. The few size 2 avalanches were triggered in steep, wind-loaded lee features.
Strong southerly winds have left a variety of surfaces - wind slabs and loaded pockets in lee features, scoured rock in open terrain, and storm slabs and softer snow in sheltered areas.
Approximately 50 to 90 cm of wind-affected storm snow has accumulated recently, and covers a melt-freeze crust at 2200 m and below. The depth of this crust is highly variable due to extensive recent wind transport.
A crust with associated facets, formed in mid-November, is buried an estimated 80 to 150 cm deep. With limited observations, especially in the alpine (which did not have the same mid-pack crust development), we're not ready to rule out this layer of concern quite yet.
Sunday night
Cloudy. 10 to 30 cm of snow. 40 km/h south ridgetop wind. Treeline temperature -3 °C.
Monday
Cloudy. 20 to 40 cm of snow. 30 km/h south ridgetop wind. Treeline temperature -5 °C.
Tuesday
Mostly cloudy. 15 to 25 cm of snow. 30 km/h south ridgetop wind. Treeline temperature -5 °C.
Wednesday
Mix of sun and clouds. 1 to 2 cm of snow. 20 km/h south ridgetop wind. Treeline temperature -4 °C.
More details can be found in the Mountain Weather Forecast.
