Avalanche Forecast

Issued: Nov 27th, 2022 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs.

Avalanche Canada mconlan, Avalanche Canada

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Cariboos, North Columbia, South Columbia, Blue River, Clearwater, McBride, Premier, Quesnel, Clemina, Esplanade, Jordan, North Monashee, North Selkirk, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, Retallack, Valhalla, West Purcell, Grohman, Norns, Renshaw, Robson.

All the recent storm snow will take some time to bond to the snowpack. Conservative terrain travel is recommended until the snowpack has time to heal.

Summary

Confidence

Moderate

Avalanche Summary

Many slabs were reported to have released on the weak layer described in the snowpack summary this weekend. The avalanches were mostly triggered naturally during stormy conditions and ranged from small to large (size 1.5 to 2.5). They occurred between 1800 and 2300 m on all aspects.Looking forward, a cooling trend may decrease the likelihood of natural avalanches but similar avalanches to the above could be triggered by riders.

Snowpack Summary

Around 40 to 80 cm of snow has accumulated from progressive storms over the past week. The snow fell with southwest wind which is forecast to switch to northeast wind for Monday. Isolated pockets of wind slabs may be found on all aspects in lee terrain features in the alpine.

The storm snow is forming a slab that overlies persistent weak layers formed mid-November of sugary faceted grains and surface hoar in sheltered terrain as well as a hard crust on steep sun-exposed slopes. The most likely areas to trigger this layer are where the snowpack appears relatively smooth and uniform.

Average snowfall depths are around 40 to 70 cm below treeline and 100 to 150 cm in the alpine.

Weather Summary

Sunday Night

Partly cloudy with isolated flurries, accumulation 1 to 3 cm, 10 to 20 km west to north wind, treeline temperature -14 to -17 C.

Monday

Mostly clear skies with no precipitation, 20 km/h northeast wind, treeline temperature -15 to -20 C.

Tuesday

Increasing cloud with isolated afternoon flurries, accumulation 1 to 3 cm, 10 km/h southeast wind, treeline temperature -17 to -20 C.

Wednesday

Cloudy with snowfall, accumulation 10 cm, 20 to 40 km/h southeast wind, treeline temperature -15 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Closely monitor how the new snow is bonding to the old surface.
  • Make observations and assess conditions continually as you travel.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Around 40 to 80 cm of snow from the past week is forming a slab that may not bond well to the underlying snowpack. The interface of concern formed during mid-November and is composed of faceted grains, surface hoar, and a hard crust. To date the layer has been most problematic above 1800 m. Be cautious in lee terrain features where wind has deepened and stiffened the storm snow.

Avalanche hazard is unlikely anywhere snowpack depths have yet to overcome ground roughness like brush, trees, and rocks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Valid until: Nov 28th, 2022 4:00PM

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