Freshly formed storm slabs are expected to remain reactive to human triggers, especially in wind effected areas at treeline and above.
Confidence
Moderate - Timing of incoming weather systems is uncertain on Sunday
Weather Forecast
FRIDAY: Cloudy with flurries / Light southwesterly ridgetop winds / Freezing level around 500m.SATURDAY:10-15 cm of new snow / Light to moderate southwesterly ridgetop winds / Freezing level around 700m.SUNDAY: 25-40 cm of new snow / Strong southwesterly ridgetop winds / Freezing level rapidly rising to 1800m.
Avalanche Summary
Over a dozen explosive and human triggered storm slab avalanches up to size 2 were reported on all aspects and elevations near Whistler on Wednesday.
Snowpack Summary
30-40 cm of new snow on Thursday morning brings recent storm totals to around 170 cm which continues to be redistributed by strong southeasterly winds. Last weekend's storm likely created dense storm slabs lurking in lee and cross-loaded features. Impressive cornice growth is also expected to have occurred.200-250 cm below the surface you'll find a crust that was buried mid-January and is present at all elevations. This crust is thin on northerly aspects and up to 3 cm thick on solar aspects. Most reports suggest an improving bond at this interface, but the load of the new snow may tip the balance and reactivate this layer in isolated terrain. Below this, the snowpack is generally strong and well-settled.
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.