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 may spill into the region by the afternoon. There is currently model uncertainty regarding how much cloud or sun the region will see Wednesday afternoon with one showing full sun and the other showing substantial cloud.
Tuesday Night: Mainly clear, moderate NW wind easing overnight, freezing level at valley bottom.
Wednesday: Mainly sunny in the morning, a chance of increasing cloud cover in the afternoon, light SW wind, freezing level high around 1700 m.
Thursday: A mix of sun and cloud, light to moderate SW wind, freezing level high around 2500 m.
Thursday night and Friday: Precipitation 5-20 mm, a chance of sunny breaks in the afternoon, moderate to strong SW wind, freezing level falling to around 1400 m.
An early report from Tuesday includes observations of a few natural size 1 storm slabs in the Coquihalla area.
On Monday, numerous natural storm slabs up to size 2.5 were reported in the north of the region, many of which likely occurred Sunday overnight during the peak of the storm. These were mainly on northwest through northeast aspects resulting from wind loading and were typically around 40 cm thick. Skiers and explosives also triggered a few small storm slabs in the north of the region. No new avalanches were reported in the south of the region but the number of observers is now very limited.
The recent storm typically produced 30-50 cm of new snow in the north of the region and 40-70 cm in the south of the region. 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 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.
