Northwest Coastal

Concerns for wind slabs in steep terrain and buried weak layers warrant careful terrain choices.

Riders triggered small wind and storm slab avalanches at treeline elevations on Saturday. Small wet loose avalanches were observed below treeline.

It has been a week since the last reported avalanche on the weak layers described in the Snowpack Summary. These layers are increasing in strength, but could still be triggered in specific areas.

Recent strong southerly wind formed wind slabs in lee terrain features near ridges. The recent 20 to 30 cm of storm snow continues to settle in sheltered terrain. Moist snow or a hard crust is found below around 800 m.

Several persistent weak layers may be found in the top meter of the snowpack. These include a surface hoar layer buried on Dec 28 found 40 to 60 cm deep and a facet layer buried on Dec 23 found 60 to 100 cm deep. In alpine terrain, triggering one of these layers is most likely on steep rocky slopes where they present as facets. In treeline terrain, the layers are most likely triggered on steep slopes in open trees where they present as preserved surface hoar.

Sunday Night

Cloudy with trace precipitation, 20 to 30 km/h southeast wind, treeline temperature -3 °C, freezing level 600 m.

Monday

A mix of sun and cloud with no precipitation, 20 km/h east wind, treeline temperature -3 °C, freezing level 700 m.

Cloudy with snowfall, accumulation 5 to 10 cm, 20 km/h southeast wind, treeline temperature -4 °C,

A mix of sun and cloud with no precipitation, 20 km/h southeast wind, treeline temperature -1 °C.

More details can be found in the Mountain Weather Forecast.

• Be especially cautious as you transition into wind affected terrain.
• Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
• Use conservative route selection and resist venturing out into complex terrain.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.