Regions
Northwest Coastal.
Conditions remain primed for both natural and human triggered avalanches. Avalanches can be triggered in lower angle terrain and have the potential to propagate very widely.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Friday: Cloudy with 5-10 cm of new snow. The freezing level is near 600-800 m and winds are moderate from the SW. Saturday: Mainly cloudy with sunny breaks and a chance of flurries. The freezing level is near 600 m and winds ease to light. Sunday: Mainly cloudy with a chance of flurries. The freezing level is around 400 m and winds are moderate from the southeast.
Avalanche Summary
Explosives control in areas near Bear Pass and northeast of Terrace produced numerous slab avalanches, size 2-3.5, likely failing on the January 9th interface. Some had very impressive propagations. Other areas reported small skier triggered size 1 slabs and some remotely triggered slabs. Thursday's weather may not have been enough to tip off a widespread natural avalanche cycle. Rider triggering and triggering from a distance remain a concern. The size and likelihood of avalanches will be on the rise as the slab continues to develop with more snow, wind, and milder temperatures.
Snowpack Summary
Thursday's weather affected the Northern part of the region more with some areas receiving up to 20 cm of new snow. Southern sections saw less snow (around 5 cm), but moderate-strong S-SE winds and milder temperatures were common throughout the region. This puts the January 9th surface hoar/facet layer down 50-70 cm in most places. Approximately 10 cm below this weakness you might find the Dec. 26/31 surface hoar layer. Reports of remote triggering, whumpfing, and sudden "pops" shears are all indications that both these layers could propagate well if triggered. Deeper persistent weaknesses buried in December have the potential to wake-up to heavy loading, rapid warming, or avalanches stepping-down.
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.