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Archived

Avalanche Forecast

Nov 30th, 2022–Dec 1st, 2022
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Bonnington, Grohman, Kootenay Boundary, Kootenay Pass, Moyie, Norns, Rossland, St. Mary, Whatshan, Ymir.

Dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential. Continued snowfall is increasing the depth of snow that overlies various layers that will produce slab avalanches on steep terrain features.

Confidence

Low

Avalanche Summary

Over the past week, a few small (size 1) avalanches were reported south of Nelson. There were also reports of whumpfing and cracking suggesting the recent snow is poorly bonded to the mid-November weak layer.

Avalanches on this layer are becoming more serious as the forecast snowfall continues. Expect large avalanches on isolated terrain features.

Snowpack Summary

Early season conditions exist with low snow amounts and under snow hazards existing at lower elevations and a deeper and drier snowpack exceeding 1 m at treeline and alpine elevations. In wind-loaded areas, snowpack heights have been reported as deep as 160 cm with windward areas scoured down to as little as 20 cm.

Up to 75 cm of snow overlies a weak layer that formed mid-November that consists of sugary faceted grains, weak surface hoar crystals in sheltered terrain features, and a hard crust on steep sun-exposed slopes. Reported testing on this interface indicated moderate sudden collapse results.

Further details specific to the southern zone can be found in this MIN.

Weather Summary

Wednesday Night

Cloudy with snowfall, accumulations of 10 to 15 cm, 50 km/h wind from the southwest, treeline temperatures -9 °C.

Thursday

Cloudy with snowfall, accumulations of 5 to 10 cm, 20 km/h wind from the west-northwest, treeline temperatures cool to -12 °C.

Friday

Clear sky no forecast precipitation, 10 km/h variable wind, treeline temperature -18 °C.

Saturday

Cloudy with snowfall, accumulations of 5 to 10 cm, 20 km/h wind from the southeast, treeline temperatures -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Avalanche Problems

Storm Slabs

Around 70 cm of recent snow overlies various layers formed mid-November, including surface hoar, faceted grains, and a hard crust. The recent snow may not bond well to these layers.

Wind may have redistributed the storm snow at high elevations, forming isolated wind slabs in lee terrain features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2.5