Avalanche Forecast
Regions: Brandywine, Garibaldi, Homathko, Sea To Sky, Spearhead, Tantalus.
Keep your guard up! This isn't your typical 2-3 day wind slab problem. Slabs have formed over a dangerous mix of weak grains and Saturday's warming may increase their reactivity.
Confidence
High
Avalanche Summary
A combination of transportable snow, elevated winds, and weak grains sitting on the hard early February crust has led to a steady stream of small (size 1 to 1.5) and a few large (size 2) wind slab avalanche reports over the past few days. Natural avalanches have triggered on leeward slopes by wind transport but human-triggered avalanches have occurred on a range of aspects. Slabs have been averaging 20 - 30 cm thick, with some failing on buried surface hoar.
Snowpack Summary
Sun and wind are creating variable surface conditions. Exposed terrain is being scoured by northeast wind and forming wind slabs on south and west facing slopes.
Roughly 30 cm of snow sits above large surface hoar and/or faceted crystals at treeline and above. A widespread, supportive crust exists 30 to 40 cm below the surface. It is an excellent bed surface for slabs to form over.
The snowpack well bonded and strong below this crust.
Weather Summary
Friday night
Clear. Southeast alpine wind 30-35 km/h. Freezing level remaining near 1400 m.
Saturday
Increasing high cloud. Southeast alpine winds 20 - 30 km/h. Treeline temperature +2 °C with freezing level reaching 2000 m.
Sunday
Cloudy with flurries bringing up to 5 cm of new snow, light rain below about 1300 m. Southeast alpine winds 25 - 35 km/h. Treeline temperature -2 °C with freezing level around 1400 m.
Monday
Mainly cloudy with isolated flurries. East alpine wind 10 - 20 km/h. Treeline temperature -2°C with freezing level around 1400 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Wind slabs may be poorly bonded to the underlying crust.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
Avalanche Problems
Wind Slabs
Outflow wind has impacted open terrain on various aspects. This formed wind slabs that are bonding poorly to underlying surface hoar and facets on the early February crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Loose Wet
Daytime warming will rob cohesion from surface layers and promote wet loose avalanche conditions in steep, sun-exposed terrain, particularly where dry snow sees above freezing temperatures for the first time.
Aspects: South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2