Avalanche Forecast
Issued: Feb 26th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
zryan,
Avalanche Canada
New snow is bonding poorly to the underlying surface and human-triggered wind slabs are LIKELY! Keep in mind that triggering a deep persistent slab remains possible, especially in areas with a thin snowpack. Sheltered and shaded terrain will offer the best and safest riding.
Treat the avalanche danger as HIGH and avoid avalanche terrain and overhead exposure during periods of strong solar radiation.
Summary
Confidence
Avalanche Summary
On Thursday, two size 3 deep persistent slab avalanches were observed just north of the Hurley summit. These slabs are suspected of having failed within the last two days. One was on a north-facing alpine face and the other an exposed, east-facing open slope at treeline. A nearby operation was able to trigger two size 2 wind slabs with a snowcat groomer on northwest-facing terrain at treeline. Skiers were able to trigger small (size 1) wind slabs in alpine terrain on south-to-east aspects in the Birkenhead north of Pemberton.
On Friday, two large (size 3-4) natural deep persistent slabs were observed on south and southeast alpine faces in the Birkenhead. We suspect these slabs occurred as a result of wind-loaded from strong northwesterly winds.
Looking forward to Monday, fresh and reactive wind slabs are expected to exist in lee areas. Keep in mind that older, stiff wind slabs may now be hidden under the storm snow.
For a deeper dive into last week's conditions leading up to the weekend's storm, check out this awesome South Coast Conditions Report posted by Zenith Guides.
Snowpack Summary
Last weekend's storm brought 15-30 cm of new snow down to valley bottom. This new snow has bonded poorly to the stiff wind slabs and near-surface facetting formed by recent wind and cold temperatures.
A melt-freeze crust from late January can be found down 60-80 cm. At the moment this layer appears to be gaining strength though in isolated areas small facets can still be found above the crust.
There is a widespread weak layer of large sugary facets at the bottom of the snowpack. Recent avalanche activity on this layer has been confined to northern parts of the region in the Chilcotins. Snowpack depths around treeline range between 150 to 250 cm.
Weather Summary
Sunday night
Clear with cloudy periods. Alpine temperatures drop to a low of -14 °C. Ridge wind 10 to 35 km/h from the southwest. Freezing level at valley bottom.
Monday
Sunny with cloudy periods. Alpine temperatures reach a high of -9 °C. Ridge wind calm to 20 km/h from the southwest. Freezing level at valley bottom.
Tuesday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -10 °C. Ridge wind light from the southwest. Freezing level at valley bottom.
Wednesday
A mix of sun and cloud. Alpine temperatures reach a high of -11 °C. Ridge wind light from the southwest. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Wind Slabs
Up to 30 cm of storm snow has been redistributed by southwest winds into wind slabs in lee areas.
Keep in mind that older, stiff wind slabs from previous northerly winds may still be reactive to human-triggering and are now hidden under the fresh storm snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
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, unsupported, wind-loaded terrain in the northern part of the region around the Chilcotins, Birkenhead, and Hurley.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 27th, 2023 4:00PM
