As storm slabs build and temperatures rise, natural avalanches are likely.
Avoid exposure to avalanche terrain and overhead hazard.
Storm slabs may involve moist/wet snow with possible rain, and rising freezing levels.
Slabs may step down to the buried surface hoar, producing larger avalanches than you expect.
On Monday, storm snow was sluffing and cracking in response to human triggers. A size 1.5 storm slab was triggered on an east facing treeline slope, stepping down to the buried surface hoar. Explosive control produced slabs up to size 2.5.
We expect reactivity to continue as storm snow continues to accumulate, with natural avalanches most likely in areas of heavy loading with snow, wind or rain.
By Wednesday afternoon, 20–40 cm of snow is expected falling on a rain crust. 50–70 cm of dense snow sits below. Higher elevations are likely wind-affected with deep deposits on north and east facing ridgelines. Lower elevation snow will likely be moist from rain or mixed precipitation.
A layer of faceted snow or surface hoar, and a crust from mid November is buried 70-110 cm deep. Additional crusts are present in the lower snowpack, and in some areas, weak, sugary facets exist near the ground.
Snowpack depths range from 90–160 cm and thin rapidly at lower elevations. In many areas, especially below treeline, slopes lack enough snow to cover ground roughness and produce avalanches.
Tuesday Night
Mostly cloudy. 10 to 15 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1200 m.
Wednesday
Cloudy. 10 to 25 mm of precipitation as snow or rain at treeline. Highest amounts are expected from Kootenay Pass up to Kokanee. 50 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing levels rise from 1300-2000 m over the day.
Thursday
Mostly cloudy. 2 to 20 mm of precipitation as snow or rain at treeline. 40 km/h west ridgetop wind. Treeline temperature -1 °C. Freezing level 1800 m.
Friday
Mostly cloudy. 2 to 5 cm of snow. 30 km/h west ridgetop wind. Treeline temperature -3 °C. Freezing level 1100 m.
More details can be found in the Mountain Weather Forecast.
