Regions
Northwest Coastal.
Heavy snowfall and strong winds are forecast for Tuesday. Avoid all avalanche terrain, free from overhead hazard.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
A storm arrives early on Tuesday with heavy snowfall and strong winds. TUESDAY: Snow (20-30cm). Ridge wind strong, southwest. Temperature near -2. Freezing level 500 m.WEDNESDAY: Cloudy with sunny breaks. Ridge wind moderate to strong from the north / west. Temperature -5. Freezing level valley bottom.THURSDAY: Snow in the afternoon. Ridge wind strong from the west. Temperature -6. Freezing level valley bottom.
Avalanche Summary
On Saturday, natural wind slab avalanches to size 2 were reported on east aspects (due to north westerly winds) at higher elevations near Terrace.
Snowpack Summary
Strong and variable winds occurred throughout the long weekend, redistributing last week's storm snow and creating fresh wind slabs at higher elevations. Beneath the storm snow lies a 5-20 cm thick crust that was buried early February and can be found 60-110 cm below the surface on all aspects up to 1400 m. A weak layer buried in mid-January is 120-150 cm below the surface and remains a concern. In most areas this layer is a crust, but it may also be surface hoar in sheltered areas at tree line and below. This layer may remain reactive as it adjusts to the weight of the new snow.In thinner snowpack areas (north and inland), deeper crust / surface hoar layers that were buried in December and early January may still be a concern. They are buried over 150 cm below the surface, but could still be reactive and triggered from shallow spots.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.