New storm slabs continue to develop in the alpine and at treeline. Watch for conditions that change with elevation.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Expect 10-15 cm of new snow overnight combined with moderate southwest winds and freezing levels dropping down to about 800 metres. Saturday should remain cool with freezing levels below 1000 metres, with light precipitation and moderate southerly winds. Warmer air is forecast for Sunday bringing freezing levels back up to about 1500 metres combined with 5-10 cm of snow and moderate westerly winds. Monday is the warmest and wettest day, precipitation amounts have dropped over the last few model runs, but expect 20-40 mm with strong winds and high freezing levels.
Avalanche Summary
Cornices and storm slabs were released with explosives on Friday up to size 2.0 within the new storm snow in the Whistler area.
Snowpack Summary
Moist snow up to 1800 metres combined with strong winds on Friday, created moist slabs at treeline and storm slabs in the alpine. Variable new crusts formed in the alpine and at treeline on Thursday. Supportive crusts on solar aspects resulted in corn skiing in some areas on Wednesday. Breakable crusts were reported from Northerly aspects on Tuesday. Up to 30 cm of moist snow below crust on all but north aspects. Cornices are also reported to be huge and collapse has become more likely with additional loading and high freezing levels. About 50-90cm below the surface, you'll likely find a rain crust which formed on January 28th. This crust is widespread and exists up to about 2100m. Where it still exists, the mid-January surface hoar layer may be found between 130 and 200 cm below the surface. The combination of warm temperatures and subsequent gradual cooling is making avalanches failing on these deeper layers unlikely.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.