North Columbia

Buried weak layers will likely cause dangerous avalanche conditions to persist.

Ensure your route planning accounts for overhead hazard and avoids travelling under large slopes.

The avalanche cycle continued on through the past week, with many large storm and persistent slab avalanches failing deep within the snowpack, either below the storm snow or on the crust from November.

The larger avalanches (size 3-3.5) were running from the alpine into the valley bottoms, well below treeline.

50 to 120 cm of snow has fallen this week and has rapidly settled . This new snow overlies a weak surface hoar layer and/or weak faceted snow.

Surface hoar is most likely to be located in tree openings sheltered from the wind, whereas faceted snow may be found in wind-exposed terrain into the alpine.

Facets may be associated with a hard melt-freeze crust that formed in the middle of November. This layer has recently produced large avalanches due to ongoing snowfall and increased loading.

Friday Night
Mostly cloudy. 4 to 10 cm of snow. 30 km/h west ridgetop wind. Treeline temperature -6 °C. Freezing level 700 m.

Saturday
Cloudy. 3 to 5 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1200 m.

Sunday
Mostly cloudy. 4 to 10 mm of precipitation as snow or rain at treeline. 40 km/h southwest ridgetop wind. Treeline temperature -1 °C. Freezing level 1900 m.

Monday
Mostly cloudy. 15 to 40 mm of precipitation as snow or rain at treeline. 50 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 2000 m.

More details can be found in the Mountain Weather Forecast.

• Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
• Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
• Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.