Avalanche Forecast

Good - -1

Wednesday: Continued very heavy precipitation with up to 60-80cm of new snow expected for immediate coastal areas, but less as you move inland. Freezing levels as high 1700m but dropping throughout the day, and strong to extreme southwesterly winds. Thursday: another 10-20cm possible but tapering off throughout the day. Freezing levels as high as 1000m and moderate to strong southwesterly winds. Friday: Relatively dry, cold and calm.

Persistent slabs and wind slabs are primed for human-triggering and heavy loading from snow wind and rain will likely cause natural avalanches. Three separate serious incidents that are relevant for the Sea-to-Sky region occurred on Monday afternoon in the Duffey Lake and Southern Chilcotin areas of the South Coast Inland region. All of incident sites had similar terrain characteristics with north through east facing steep treeline features. Two of the avalanches likely involved the mid-December persistent weakness, while the third was reported to have released on basal facets in a shallow snowpack area with a 50-75cm depth. All of the avalanches resulted in serious injury and at least two of them were human-triggered.

The snowpack structure is highly variable and complex. Gusty winds are keeping wind slabs and cornices fresh and weak. Slabs overlaying various old snow surfaces, including crusts, facets, and surface hoar, buried mid-December are primed for avalanches in many parts of the region. The surface hoar is lurking generally down 80-100cm in sheltered treeline areas and below. In exposed treeline and alpine areas, weak facets with associated crusts are down generally 80-120cm, but wind-loading has resulted in highly variable slab thicknesses. A recently buried thin hard rain crust that extends into alpine elevations is also providing a poor bond to the overlying slab. Basal facets remain a concern in shallow snowpack areas, especially where the snowpack is overlaying summer firn on slopes that have already produced deep persistent slab avalanches and have been reloaded.