Avalanche Forecast
Issued: Dec 24th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Uncertainty around buried weak layers is best managed through conservative terrain choices.
Avoid wind-loaded areas and steep open slopes where buried surface hoar may be preserved.
Summary
Confidence
Avalanche Summary
A natural avalanche cycle occurred on Friday evening. Several large (size 2 to 3) wind and storm slabs were reported from the alpine and treeline on a variety of aspects.
On Saturday in the Monashees south of Valemount, numerous size 2 to 3 persistent slab avalanches were triggered remotely by skiers from up to 1 km away! These avalanches occurred in a shallow snowpack area in the alpine and are suspected to have failed on basal facets.
Snowpack Summary
Recent storm snow has been redistributed into wind slab near ridge crests by strong southerly winds. Below treeline a new crust is on or near the surface.
The mid pack contains several layers of note; a layer of surface hoar and a crust down 20 to 40 cm, a significant crust from the early December rain event down around 50 cm and a layer of surface hoar down 50 to 90 cm.
The make up of the lower snowpack is variable throughout the region, in shallower snowpack areas, basal facets exist. This is most concerning in shallow alpine areas in the eastern part of the region.
Weather Summary
Sunday Night
Clear periods with no new snow. South alpine wind, 30 to 60 km/h. Treeline temperature -8°C.
Monday
Cloudy with sunny periods, no new snow. South alpine wind, 30 to 70 km/h. Treeline temperature -5 °C.
Tuesday
Cloudy with snowfall, 1 to 10 cm of accumulation. South alpine wind, 30 to 70 km/h. Treeline temperature -6 °C.
Wednesday
A mix of sun and cloud, isolated flurries. Southeast alpine wind, 20 to 40 km/h. Treeline temperature -2 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Keep in mind that human triggering potential persists as natural avalanching tapers off.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
Wind slabs have formed on lee features in exposed terrain at treeline and above. Avoid wind-loaded areas and watch for fresh, reactive slabs forming throughout the day.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A layer of surface hoar is down 50 to 90 cm and is still concerning where a significant crust is not found above it.
In the eastern part of the region near Valemount, basal facets have shown reactivity in recent days.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 25th, 2023 4:00PM
