Regions
Kootenay Boundary.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Sunday
Weather Forecast
Tonight and Saturday: Break in precipitation before the arrival of an intense frontal system late Saturday. Very light precipitation tonight, light to moderate southwest winds becoming light from the south for Saturday. Freezing levels rising to 1400 m in the afternoon. Sunday: Moderate to heavy precipitation is forecasted for Saturday night tapering off Sunday (~15 cm accumulation forecasted) before it picks up again Sunday night. Strong to extreme winds from the southwest. Freezing levels rising to 1200 m and falling to 700 m with the incoming and wake of each system.Monday: Strong westerly onshore flow keeps bringing low pressure systems over the province bringing some more precipitation and similar winds and freezing levels.
Avalanche Summary
Multiple skier triggered slab avalanches size 1 and 1.5 were reported yesterday. One of these events remotely triggered an avalanche size 2.5 on a northern aspect at treeline. Natural loose avalanches were also running out of steep terrain.
Snowpack Summary
Recent ~30 cm of storm snow has settled fast with mild temperatures creating a slab that is reactive to human triggering. Strong winds mostly from the southwest has also created windslabs on lee slopes in the alpine and immediate lee ridgetop at treeline. I suspect these windslabs will be prime for skier triggering tomorrow. 40-60 cm below the surface, exists a surface hoar or suncrust layer has been reactive even since it has been buried in late January. Natural and skier triggered avalanches have stepped down to this deeper buried weak layer in the recent avalanche cycle. This layer has now reached a critical load where big destructive avalanches can be easily triggered.The mid snowpack is strong and supportive. Deeper persistent layers have been dormant, however, they could be triggered by a load such as a cornice drop or a large slab avalanche.
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.