Regions
South Coast Inland.
Alpine Danger may be Considerable in localized areas that receive more than 20 cm of new snow.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
THURSDAY: Cloudy with 5-10 cm of new snow(10-15 on Coquihalla). Light to moderate Southwesterly ridgetop winds. Freezing level around 1200m.FRIDAY: Mostly cloudy. Light Southwesterly ridgetop winds. Freezing level around 1200 m.SATURDAY: Sunny. Light southwesterly ridgetop winds. Freezing level around 1400m.
Avalanche Summary
On Tuesday, a size 1.5 cornice triggered avalanche was reported on a north aspect at 2200 m in the Duffey Lake area.
Snowpack Summary
The forecast snow and wind on Wednesday is expected to create fresh wind slabs in exposed terrain at treeline and above. On sun solar aspects and at lower elevations, numerous crusts exist in the upper snowpack which are generally well bonded. Cornices are large and remain a concern: Saturday's fatal accident near Lions Bay illustrates the danger of them breaking off, and the large avalanches they can trigger.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.