Avalanche Forecast
Issued: Feb 28th, 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.
swerner,
Avalanche Canada
Overnight winds from the northeast may form fresh wind slabs on unexpected slopes and be sensitive to human triggering. Take a cautious approach and investigate the bond between the new snow and the old surface before committing to your line.
Keep in mind that if triggered, wind slabs may step down to the deep persistent slab problem resulting in large avalanches.
Summary
Confidence
Moderate
Avalanche Summary
On Monday, loose dry sluffing from steep terrain was seen as well as a remotely triggered wind slab avalanche size 1.5 that reportedly failed on facets below the recent storm snow.
Last Thursday, two size 3 deep persistent slab avalanches were observed just north of the Hurley summit. One was on a north-facing alpine face and the other an exposed, east-facing open slope at treeline.
Last 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.
For a deeper dive into last week's conditions leading up to last 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. In some areas, this new snow has bonded poorly to the stiff wind slabs and near-surface faceting 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
Tuesday Night
Clear periods. Alpine temperatures -13 °C. Ridge wind northeast 10 to 20 km/h. Freezing level valley bottom.
Wednesday
Cloudy with flurries up to 5 cm. Alpine temperatures reach a high of -10 °C. Southwest wind 30 km/h and freezing level valley bottom.
Thursday
Snow amounts 10 cm. Ridgetop wind 40-70 km/h from the southwest. Alpine temperatures reach a high of -10 °C. Freezing level 600 m.
Friday
Cloudy with sunny periods and isolated flurries up to 5 cm. Alpine temperatures near -11°C. Ridge wind southwest 20 gusting to 55 km/h. Freezing level valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Wind Slabs
15-30 cm of storm snow has been redistributed by southwest winds into wind slabs in lee areas. Changing winds overnight Tuesday may form new wind slabs on opposite slopes and terrain features. Wind slab reactivity may persist for longer than is typical due to the weak surface they are sitting on.
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: Mar 1st, 2023 4:00PM
