The recent storm snow is expected to remain reactive to human triggering, especially in wind-loaded terrain. With extended sun exposure on Wednesday, any unconsolidated storm snow may settle into a more cohesive slab and become increasingly reactive.
Cornices have grown large during the recent storm and may be fragile on Wednesday, especially with extended exposure to the sun. Falling cornices are a likely trigger for slab avalanches on the slopes below.
The recent storm snow is expected to remain reactive to human-triggering on Wednesday, especially in wind exposed terrain and on steep, convex or unsupported terrain features.
Loose wet avalanches should be expected from steep, sun-exposed slopes during extended periods of sun exposure.
A ridge of high pressure brings sunny conditions for Wednesday morning but cloud from a storm system impacting the north coast is expected to spill into the region in the late afternoon.
Tuesday Night: Mainly clear, light variable wind, freezing level low around 500 m.
Wednesday: Mainly sunny with increasing cloud cover in the afternoon, light to moderate SW wind, freezing level high around 1700 m.
Thursday: Mainly cloudy with sunny breaks, light to moderate SW wind, freezing level high near 2500 m.
Thursday night and Friday: Precipitation 30-50 mm, sunny breaks in the afternoon, moderate to strong SW wind, freezing level falling to around 1400 m.
An early report from Tuesday includes several size 1-2 explosive-triggered storm slabs and a remotely-triggered size 2 storm slab which was triggered from 2 m away.
On Monday, evidence of a recent natural avalanche cycle was reported which had occurred during the storm. Ski cutting and explosives were triggering storm slabs up to size 2, some of which were failing on the melt-freeze crust below the storm snow and some of which were failing on interfaces within the storm snow. Of the avalanches which failed on the crust, many were in the 50-60 cm thickness range in sheltered terrain and up to 100 cm thick in wind loaded terrain. A couple of the avalanches were remotely triggered from a short distance away.
The recent storm produced 60-80 cm of new snow in the Whistler area. This storm snow has buried a firm crust which extends to mountain top on solar aspects and to around 2200 m on northerly aspects. Strong to extreme southwest wind has redistributed the new storm snow in exposed, high elevation terrain forming wind slabs up to 150 cm thick and developing large cornices. Windward slopes have been scoured down to the crust and the alpine snow surface is expected to be highly variable.
The middle and lower snowpack are generally strong and well bonded.
