Avalanche Forecast
Regions: Birkenhead, Brandywine, Garibaldi, Homathko, Sea To Sky, Sky Pilot, Spearhead, Tantalus.
Soft snow over a robust crust is making for decent treeline riding, and lower avalanche danger.
Caution in steep, wind-loaded alpine, especially on rocky slopes with variable snow depths.
Confidence
Moderate
Avalanche Summary
On Tuesday in the whistler area, a few small, human triggered wind slab avalanches were reported in the alpine, some of them running far on a hard surface underneath.
Surprising, large avalanches were occurring late in December on a weak layer over a crust down 50-100 cm, but this layer seems to be bonding, and no related avalanches have been reported in the new year.
Snowpack Summary
25-35 cm of new or settling snow over a frozen crust formed around the new year that may exist up to mountain tops. This crust seems to be thick, and supportive to the weight of a human south of Whistler, and more variable in thickness and strength to the north, where it thins out above 1900 m.
Below this crust, facets or isolated surface hoar are sitting on another crust 50-100 cm below the snow surface. This layer produced surprising avalanches late in December, but it appears to have gained strength, or is being shielded by the newer crust, and is now less of a concern.
The lower snowpack is strong and bonded. Treeline snowpack depths are in the 60-100 cm range, decreasing rapidly below treeline.
Weather Summary
Wednesday Night
Cloudy. 5-10 cm of snow expected above 600 m. Light south or southwest ridgetop wind. Treeline temperature around -3 ° C.
Thursday
Cloudy. 5 cm of snow expected above 800 m. Light to moderate south or southwest ridgetop wind. Treeline temperature around -4 °C.
Friday
Mostly cloudy. 10-15 cm of snow expected above 500 m. Light to moderate south or southwest ridgetop wind. Treeline temperature around -6 °C.
Saturday
Partly cloudy. 15-20 cm of snow expected to near valley bottom. Light northwest ridgetop wind. Treeline temperature around -7 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
- Carefully evaluate steep lines for wind slabs.
- Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
Avalanche Problems
Wind Slabs
Small, rider triggerable wind slabs may linger in steep terrain below alpine ridgetops and in cross loaded gullies.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 1 - 2
Persistent Slabs
Most likely in wind loaded terrain, and anywhere the snowpack is thin and/or variable. Less likely where a thick, supportive crust is down 20-40 cm (south of Whistler, this supportive crust may exist to mountain tops).
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3.5