Avalanche Forecast
Issued: Dec 17th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
TRettie,
Avalanche Canada
Avoid "thick to thin" areas and steep roll overs, Especially in treeline terrain. Persistent slabs are challenging to manage, if in doubt choose conservative terrain. If you observe more than 30cm of new snow consider the hazard rating to be high in the treeline and alpine.
Summary
Confidence
Weather Forecast
Friday: Low of -17 at 1500m. No new snow expected and moderate Southwest winds.
Saturday: A storm arrives bringing 15 to 30cm of new snow with the highest snowfall in the Southwest corner of the forecast region. Winds will be strong from the Southwest. High of -10 at 1500m.
Sunday: High of -11 at 1500m. light snow in the morning. Strong Southwest winds in the morning becoming light in the afternoon.
Monday: No new snow expected. Moderate wind from the Southwest and a high of -16 at 1500m.
Avalanche Summary
One natural size 2.5 was observed in the Monashees on Wednesday on a West aspect at 2150m. This avalanche failed on the early December facet/crust combo. The crown was one meter deep, a good indicator of the high consequences of triggering this layer.
Snowpack Summary
The incoming weather will form new wind slab in the alpine and treeline.
The defining feature of the snowpack is a widespread crust that reaches as high as 2200m and now sits 60-120 cm below the surface. In some places overlying snow is well-bonded to the crust but in others weak faceted grains have been observed above it. The facets above the crust are most prominent at treeline where the crust is thinner. We expect the incoming weather to increase the likelihood of triggering this layer.
Average snowpack depth at treeline is 250cm.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Persistent Slabs
The faceting above this crust is most prominent at the treeline. Avoid "thick to thin" areas and steep roll overs where sensitivity to triggering this layer could be greater.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
The incoming storm will form new wind slab in exposed terrain in the treeline and alpine.
Aspects: North, North East, East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 18th, 2021 4:00PM
