Regions
Northwest Coastal.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Thursday should be relatively dry before the next frontal system reaches the coast on Thursday evening. Precipitation is expected for Friday and Saturday. Heaviest amounts are expected for the south of the region.Thursday: Cloudy, dry conditions during the day, snowfall in the evening, freezing level am: 500m pm: 900m, ridgetop wind light S-SWThurs. Night/Friday:Snowfall10-25cm, freezing level am: 500m pm: 900m, ridgetop wind 30-50 km/h S-SWSaturday: Snowfall light to moderate, freezing level am: 500m pm: 1000m, ridgetop wind light to moderate S-SW
Avalanche Summary
Widespread natural avalanche activity is being reported on Tuesday and Wednesday.
Snowpack Summary
Storm slabs continue to build. In the north of the region, the storm slab is up to 1m thick. The south of the region had less snowfall and the slab is roughly 60cm thick. These slabs sit on a weak layer which may consist of any of the following: hard wind slabs or wind-scoured slopes in exposed terrain, a thick layer of faceted snow on sheltered, shady slopes, isolated surface hoar on sheltered, shady slopes, and sun crust on steep solar aspects. Expect moist or wet snow below roughly 1000m elevation. The mid February weak layer of surface hoar or a crust/facet combo is typically buried over 1.5m deep. This layer continues to react in snowpack tests, primarily on sheltered north aspects at or below treeline. The weight of the new snow and rain has the potential to reactivate this layer resulting in large, destructive avalanches. Basal facets and/or depth hoar remain a concern in shallow snowpack areas in the northern part of the region.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.