Confidence
Fair - Intensity of incoming weather is uncertain on Saturday
Weather Forecast
Thursday: Continued moist precipitation. 25 -30mm water expected. Freezing Level: 1800m, lowering throughout the day. Wind: Strong, South.Friday: Occasional light showers/flurries. 5mm water expected. Freezing Level 1300m. Wind Moderate, SW.Saturday: Another pulse of moisture makes its way inland. 20mm water expected. Freezing level tops out around 1400m in the afternoon lowering to 800m Saturday night. Wind: Light, SW
Avalanche Summary
Reports from Tuesday include numerous Size 1.0 to 2.0 storm slab avalanches running easily on recently buried surface hoar and sun crust at treeline and alpine elevations. Most avalanches were human-triggered with explosives or slope-cuts but a few naturals were observed in the afternoon out of steep rocky treeline terrain with a temperature spike. Numerous natural loose moist avalanche up to Size 2 were also observed on all aspects at treeline and below in a coastal area.
Snowpack Summary
The storm has delivered around 50 cm as of Wednesday afternoon and another 10 - 20 is expected overnight. This new snow is bonding poorly to the previous snow surface, which includes faceted snow, surface hoar, and/or a crust, but is most concerning where surface hoar is sitting on a crust on previously sun-exposed sheltered treeline slopes. Around a metre below the snow surface is a layer surface hoar buried on February 20th. Although this layer has a history of producing large avalanches, triggering this layer has now become difficult, and would most likely require a very large trigger on a steep, unsupported slope. Below this interface, the snowpack is 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.