Northwest Coastal

The chances of triggering a large slide may have decreased, but the consequences if triggered could be disastrous. Conservative terrain selection remains critical.

Moderate - Due to the number of field observations

Monday: Cloudy with sunny breaks and a chance of flurries. The freezing level is near 400 m and ridge winds are light or moderate from the NW. Tuesday: Mainly cloudy with a chance of flurries. The freezing level is near 400 m and ridge winds are light or moderate from the NW. Wednesday: Periods of snow. The freezing level is around 500-700 m and winds are moderate from the S-SE.

On Saturday, there was a report of a remotely-triggered size 2.5 avalanche that likely failed on the mid-January surface hoar. This slide occurred on South aspect at around 1200 m. Explosives control work in Ningunsaw Pass also produced numerous slab avalanches to size 3. Most of these slides were from N-E aspects in the alpine and at treeline. Many initiated on the mid-January surface hoar but then stepped down to deeper persistent weaknesses. This type of avalanche activity highlights the current challenge of dealing with buried persistent weak layers that are becoming harder to trigger, but if triggered they will produce very large and potentially deadly avalanches.

15-30 cm of lower density new snow overlies moist or wet snow, or previously wind affected surfaces in the alpine. Recent wind has been minimal in most places but pockets of fresh wind slab could be found in lee and cross-loaded features in the alpine and at treeline. The January 9th surface hoar/facet layer is down 70-150 cm in most places, and remains a concern on all aspects and elevations. Around the same depth you may also find a surface hoar/facet interface from around New Years. In the wake of the recent storm, there is a lot of uncertainty regarding the reactivity and distribution of this destructive persistent avalanche problem. A conservative approach to mountain travel is still required.