Northwest Coastal

Given the very limited information on hand for this bulletin, I would tread cautiously and take the time to gather snowpack information as I go. Please submit any observations from your day to the MIN.

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The arctic front will gradually weaken and move east as the week progresses. Unstable weather off the coast will bring  snow accumulations 10-20 cm with freezing levels near 500 m tonight through Tuesday. Ridgetop winds will blow moderate from the southeast. Wednesday will mostly be cloudy with some flurries.

A skier triggered size 1.5 slab avalanche was reported from the Shames area yesterday. This occurred on a north aspect and propagated 25 m across running 150 m in length. This was reportedly in an area with a little more wind effect, so potentially a stiffer slab running on a buried surface hoar layer. With forecast snow and wind natural and rider triggered avalanches may be on the rise.

Snowpack depths are variable across the region and significantly peters out below 1000 m opening it up for many early season hazards like open creeks, rocks, downed trees and below threshold for avalanche hazard. The average snowpack depth at treeline is 60-100 cm with 150 cm plus in the alpine. Surface snow tends to be variable with low density fluff to exposed areas of wind effect. I suspect wind slabs may be found on leeward slopes at higher elevations. Buried surface hoar crystals up to 10 mm have been found down 30-60 cm. This layer is reactive to snow pack tests showing sudden planar results and whumphing. The mid pack is generally moist to ground with a series of crusts. When traveling in the mountains Id maintain an investigative approach and dig down to test for weak layers before committing to a slope. If you've been in the mountains, please share your observations on our Mountain Information Network.