Regions
Northwest Coastal.
A gradual improvement in avalanche danger is expected over the weekend.
Confidence
Fair - Due to the number of field observations
Weather Forecast
Expect a change to cooler conditions on Friday and through the weekend. Light to locally moderate snowfall is expected on Friday, tapering off on Saturday. Winds remain light to moderate from the south-west.
Avalanche Summary
A naturally triggered avalanche cycle was observed on Tuesday and Wednesday. At low elevations, many of these were wet and dug deep, failing to ground, up to size 2.5. At treeline and above, storm slabs and wind slabs were reported. In the north, large explosives triggered slabs up to size 3 failing on the November crust layer, with wide propagations at alpine elevations.
Snowpack Summary
Heavy rain which recently saturated the upper snowpack resulted in wet, loose, and cohesionless surface snow as high as alpine elevations in the southern part of the region. As freezing levels drop, this may freeze into a solid surface crust with fresh wet snow stuck on top, depending on elevation. Meanwhile in the high alpine and as low as treeline elevations further north, as much as 70 cm of recent snow and wind has formed new storm slabs. These have overloaded previous weaknesses buried within the snowpack, such as the mid-November crust-facet layer.
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.