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Avalanche Forecast

Archived

Jan 20th, 2024–Jan 21st, 2024

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Crawford, Moyie, St. Mary, Kokanee, Retallack.

Temperatures and freezing levels will continue to slowly warm and rise, expect this to increase the sensitivity of wind slabs to human triggering.

Confidence

Moderate

Avalanche Summary

On Friday, both natural and explosive controlled large (size 2) wind slab avalanches have been reported at elevations above 2200 m and on north aspect terrain. On Thursday extensive explosive control at a number of professional operations, produced large both wind and storm slab avalanches up to size (2.5).

Snowpack Summary

10-25 cm of recent new snow has covered weak, faceted snow in many areas and wind-affected surfaces in open areas at all elevations.

A layer of surface hoar is found down 70 cm in sheltered, north-facing terrain. This layer appears as a sun crust on south-facing slopes. As temperatures slowly warm expect this layer to become reactive to human triggering.

A thick crust deep in the snowpack largely protects any weak layers further down in the snowpack from being triggered.

Weather Summary

Saturday Night

Mainly cloudy. 1 to 5 cm of snow expected. Light to moderate southwest ridgetop wind. Treeline temperature around -5 °C.

Sunday

Mainly cloudy. 1 to 5 cm of snow expected. Light southwest ridgetop wind. Treeline temperature around -1 °C.

Monday

Mainly cloudy. 1 to 5 cm of snow expected. Light southwest ridgetop wind. Treeline temperature around 0 °C.

Tuesday

Mainly cloudy. 1 to 2 cm of snow expected. Light southwest ridgetop wind. Treeline temperature around 0 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.