More snow and wind arriving Wednesday means avalanche danger will be High. Persistent slab avalanches are primed for rider triggering.
A weak layer of faceted grains above a melt-freeze crust buried 50 to 100 cm deep is a recipe for large, high-consequence avalanches. This snowpack setup will take some time to strengthen.
Storm slabs are likely to remain reactive to human traffic, particularly where they sit on problematic weak layers or hard surfaces. Giving the snow time to heal is warranted at this time.
Numerous natural and rider triggered storm slab and persistent slab avalanches size 1 to 3 have been reported the past few days in the alpine and treeline elevation bands on all aspects. Most of these occurred on the weak layer of faceted grains 50-80 cm deep sitting on a crust formed in early February. Several were reported as remotely triggered (from a distance).
Expect rider triggered avalanches to be likely as more snow and wind arrives Wednesday through Thursday.
60 to 100 cm of recent snow sits on a variety of layers that it may not bond well to, including surface hoar in wind-sheltered terrain, weak facets, or a hard melt-freeze crust on sun-exposed south and west-facing slopes. The wind has likely formed thicker deposits in lee terrain features near ridges.
A thick and hard widespread crust that formed in early February is buried 50 to 100 cm deep and is found up to around 2400 m. This crust may have a layer of facets above it, which makes it a troublesome avalanche layer.
The remainder of the snowpack is settled.
Tuesday Night
Cloudy with 5-10 cm of snow. 20 to 50 km/h west and southwest ridgetop wind. Treeline temperature -11 °C.
Wednesday
Cloudy with 5 to 15 cm of snow. 30 to 60 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1000 m.
Thursday
Cloudy with 15 to 25 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -6 °C. Freezing level at valley bottom.
Friday
Mostly cloudy with 1 to 3 cm of snow. 15 to 30 km/h southwest ridgetop wind. Treeline temperature -7 °C.
More details can be found in the Mountain Weather Forecast.
