Regions
Northwest Coastal.
Snowfall amounts for Thursday are uncertain, if amounts received exceed forecasted values the avalanche danger will be "High".
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
THURSDAY: Snow. Accumulation 5-15 cm. Ridge wind moderate to strong, southwest. Temperature -6. Freezing level 300 m.FRIDAY: Mix of sun and cloud, light flurries. Accumulation up to 5 cm. Ridge wind light, south. Temperature -7. Freezing level 400 m.SATURDAY: Mix of sun and cloud. Ridge wind light to moderate, northeast. Temperature -9. Freezing level 200 m.
Avalanche Summary
Numerous professionals across the region are reporting that intense loading during Tuesday's storm triggered a widespread natural avalanche cycle up to size 3, with at least one avalanche running beyond it's historical runout distance.
Snowpack Summary
Approximately 40-60 cm of new snow has fallen across the region since Tuesday with the highest snowfall amounts in the Terrace area.This new snow sits on a wide array of surfaces - including wind scoured from strong and variable winds during the long weekend, and fresh wind slabs at higher elevations on lee (downwind) slopes as well as facets and surface hoar in sheltered locations at treeline and below, and suncrusts on steep solar aspects.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.