Avalanche Forecast
Regions: Bonnington, Crawford, Grohman, Kokanee, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Rossland, St. Mary, Ymir.
Mixed precipitation will further load a snowpack that is still recovering. Uncertainty is best managed through conservative terrain choices.
Confidence
Moderate
Avalanche Summary
A widespread large natural avalanche cycle of wet loose to size 2.5, and persistent slabs up to size 4. While activity peaked on Wednesday, human triggering is possible where there is no thick melt-freeze crust.
Read the Forecaster Blog for an opportunity to reflect on this week's widespread avalanche activity.
Snowpack Summary
Wet flurries have deposited 15 to 20 cm of storm snow at upper elevations and have buried variable surfaces of a melt-freeze crust or moist snow, depending on freezing levels.
Several weak layers are found in the middle and lower snowpack:
Facets/surface hoar/crust from early March buried 50 to 80 cm deep,
Facets/surface hoar/crust from mid-February buried 110 to 130 cm deep, and
Facets/surface hoar/crust from late January buried 120 to 160 cm deep.
Weather Summary
Friday Night
Cloudy, wet flurries, 10 to 15 cm. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -1 °C. Freezing level 1700 m.
Saturday
Partly cloudy, isolated flurries 2 to 3 cm. 10 to 20 km/h west ridgetop wind. Treeline temperature 0 °C. Freezing level 2000 m.
Sunday
Clear with increasing cloud in the afternoon. 15 to 20 km/h southeast ridgetop wind. Treeline temperatures 0 °C. Freezing level 2000 m.
Monday
Cloudy, flurries 5 to 8 cm. 20 to 30 km/h southeast ridgetop wind. Treeline temperatures 0 °C. Freezing level 1800 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- In times of uncertainty, conservative terrain choices are our best defense.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Keep in mind that human triggering may persist as natural avalanches taper off.
Avalanche Problems
Storm Slabs
Mixed precipitation and convective flurries will develop storm slabs forming over a moist surface or melt-freeze crust. Storm slabs will be more reactive where wind has accompanied the storm.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
Several persistent weak layers exist in the upper meter of the snowpack. Forecasted precipitation will continue to load these layers.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 2.5 - 3.5