Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Monday
Weather Forecast
Monday: Light rain, with snowfall possible only at very high elevations. Freezing level around 2600 m. Light to moderate south-easterly to south-westerly winds.
Avalanche Summary
Several size 1-2 avalanches were triggered by people and explosives on Friday following overnight snow and wind. These failed on a crust or within recent storm snow layers. Natural avalanches were also triggered by sunshine on solar aspects, and a size 2 natural slab was observed on a NW aspect in Garibaldi Park. On Saturday, similar activity continued.
Snowpack Summary
20 cm of snow which fell on Thursday night was shifted into wind slabs on slopes lee to the south or south-west. Around 50 cm of snow now overlies a buried crust, which has been acting as an easy sliding layer. Solar warming de-stabilized new snow above this crust on Friday and Saturday. Warm temperatures through Saturday night didn't allow the snow surface to refreeze. This pattern is likely to continue for the next few days, which could lead to a weak, wet snowpack at all elevations. A deeper crust layer from late March, buried within the upper 2 m of the snowpack, remains a lingering concern for big avalanches, particularly during times of intense or prolonged snowpack warming. Large cornices threaten slopes. Glide slab releases are a possibility, especially in steep rocky terrain.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.