Avalanche Forecast
Regions: Birkenhead, Duffey, South Chilcotin, South Coast Inland, Stein, Taseko.
In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
10-20 cm of recent snow and light to moderate southwesterly wind may have formed small wind slabs on lee features below alpine ridgetops.
Confidence
High
Avalanche Summary
A couple cornice failures triggered loose dry avalanches up to size 2 on large alpine slopes on Friday.
On Wednesday, a cornice fall entrained a mass of snow which then triggered a size 3 deep persistent slab avalanche. It occurred at 2350 m on a north east facing slope.
A size 2.5 deep persistent slab avalanche was reported Tuesday in the South Chilcotin range, around 2200 m on a south-facing slope.
Snowpack Summary
10-20 cm of recent snow and light to moderate southwesterly wind may have formed small wind slabs on lee features at upper elevations.
Below the new snow is a melt freeze crust exists on all aspects at treeline and below, and on solar aspects to mountain top. The only exception is high north aspects which had a mixture of decomposing dry snow and small surface hoar in isolated locations.
The mid-snowpack is generally strong but the lower snowpack is a different story..
A weak layer of sugary facets is still prominent at the base of the snowpack. Small surface avalanches and cornice falls are the most likely things to trigger this layer, which would result in a very large and destructive avalanche.
However, there remains a significant concern for human triggering in rocky, shallow, or thin-to-thick snowpack areas at treeline and above.
Weather Summary
Saturday Night
Partly cloudy / 5 km/h northwest ridgetop wind / Low temperature at treeline around -7 C / Freezing level valley bottom
Sunday
Mostly cloudy / 10 km/h southwest ridgetop wind / High temperature at treeline around -4 C / Freezing level 1300 m
Monday
Mix of sun and cloud / 15 km/h east ridgetop wind / High temperature at treeline around -1 C / Freezing level 1500 m
Tuesday
Sunny / 40 km/h northeast ridgetop wind / High temperature at treeline around -1 C / Freezing level 1500 m
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Avoid exposure to slopes that have cornices overhead.
- Carefully evaluate steep lines for wind slabs.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Avalanche Problems
Deep Persistent Slabs
A layer of weak facets sits near the base of the snowpack. This layer is most likely to be problematic in steep, wind affected terrain where the snowpack depth varies from thick to thin. Especially in the northern part of the region around the Chilcotins, Birkenhead, and Hurley.
Recent natural avalanche activity was observed on this layer, likely triggered by warm temperatures and strong sunshine heating the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely
Expected Size: 2 - 3.5
Wind Slabs
10-20 cm of recent snow and light to moderate southwesterly wind may have formed small wind slabs on lee features at upper elevations.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 1 - 1.5