Watch for signs of recent wind loading in exposed terrain. Wind slabs are expected to be reactive to human triggering on Wednesday.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Thursday
Weather Forecast
Unsettled conditions are expected for Wednesday with the potential for both light flurries and sunny breaks. Alpine wind is forecast to be moderate from the west to northwest direction and freezing levels are expected to reach around 800 m. The next storm front is forecast to arrive Wednesday overnight. 20-30cm of new snowfall is forecast by Thursday evening. Alpine wind is forecast to be strong from the southwest and freezing levels are forecast to reach around 1000 m. Friday is currently forecast to be dry and sunny.
Avalanche Summary
On Tuesday, explosives and ski cutting produced soft slab avalanches up to size 1.5 which were confined to the new storm snow. On Wednesday, wind slabs are expected to be the main concern. Ongoing strong southerly winds are redistributing the 20-30 cm of new snow from Tuesday.
Snowpack Summary
20-30 cm of new snow has accumulated since Monday. This new snow sits over a variable interface which consists of wind affected surfaces, faceted (sugary) snow, or surface hoar. The surface hoar has been observed up to 20 mm in size in the Whistler area and it is reported to exist at and below treeline. Recently strong southerly winds have formed new wind slabs in leeward and cross loaded features in wind exposed 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.