Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Wednesday
Weather Forecast
Tuesday: Light SW winds. Alpine temp -15. A few cm snow.Wednesday: Strong to gale S winds. Alpine temp -10. Moderate snow (~20 cm).Thursday: Moderate S winds. Alpine temp -9. Light snow.
Avalanche Summary
Size 1-2 sluffs were running in steep terrain on Sunday and skiers were triggering numerous size 1 soft wind slabs on lee features. A skier also triggered a size 1.5 soft slab at treeline, which failed on a layer of stellars and surface hoar down 30 cm in the Duffey Lake area.
Snowpack Summary
Low density storm snow has been shifted by variable winds into soft slabs in the alpine and at treeline. A layer of surface hoar and stellars buried on Dec 10 exists at treeline in the Duffey Lake area and may be more widespread. Recent snowpack tests produced hard to no results on a deeper surface hoar layer from late November, buried down 70-100 cm. A consolidated mid-pack overlies the deeply buried November crust/facet layer, which gives occasional sudden planar compression test results. This layer has not been observed in the Coquihalla area.
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.