Regions
South Coast Inland.
New snow and wind will likely build reactive storm slabs. Storm slabs may have the potential to trigger deeper weakness in shallow snowpack areas. Conservative terrain selection is key for the weekend.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
The weather pattern has finally shifted as a surface low moves onto the Coast bringing new snow through the weekend. Saturday: Snow amounts 10-20 cm with light- gusting strong southwest winds. Alpine temperatures near -4 and freezing levels 800 m. Sunday: Snow amounts up to 10 cm with strong southwest winds. Alpine temperatures -3 and freezing levels 700 m.Monday: Mix of sun and cloud. Ridgetop winds light from the northeast and alpine temperatures near -15.
Avalanche Summary
On Thursday, several size 1 loose dry avalanches occurred from steep terrain features. New storm slabs will likely have a poor bond to the old snow surfaces and be reactive to rider triggers, especially on leeward slopes that are more wind loaded. In thin areas to the north, storm slabs could potentially step down to deeper weak layers.
Snowpack Summary
New snow has buried a wide variety of old snow surfaces including stiff wind slab or wind effected snow at upper elevations, sun crust on steep southerly slopes, surface hoar and surface facets in sheltered locations. The mid-January surface hoar and facet interface is now buried 50-80 cm and the mid-December facets down 90-120 cm remain a concern especially in shallower snowpack areas like the Duffey, Hurley and/ or South Chilcotins. These deeper weaknesses warrant monitoring especially through periods of more load. In southern areas (Coquihalla), the lower snowpack is reportedly well settled compared to the North.
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.