Regions
Northwest Coastal.
Avalanches will remain very likely in the wake of Tuesday's massive storm. Avoid all avalanche terrain, free from overhead hazard.
Weather Forecast
We'll have unsettled conditions in the wake of Tuesday's awesome storm. WEDNESDAY: Cloudy. Ridge wind moderate to strong from the north / west. Temperature -5. Freezing level 400m.THURSDAY: Snow in the afternoon (5cm). Ridge wind strong from the west. Temperature -6. Freezing level valley bottom.FRIDAY: Cloudy. Ridge wind moderate to strong from the north / west. Temperature -5. Freezing level 400m.
Avalanche Summary
We haven't received reports (yet) but we anticipate a widespread natural avalanche cycle occurred on Tuesday.
Snowpack Summary
Phenomenal snowfall amounts occurred on Tuesday, with 40-50cm falling in a 12 hour period near Terrace! Combine that with strong north west winds and temperatures near zero... it's a perfect recipe for widespread large destructive avalanches. All this new snow sits on a wide array of surfaces - either wind scoured from strong and variable winds from the long weekend, or fresh wind slabs at higher elevations on lee (downwind) slopes. 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.