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Avalanche Forecast

Archived

Nov 29th, 2022–Nov 30th, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
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, Shuswap, North Okanagan, Whatshan.

Dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential. Recent snow overlies various layers that could 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 most likely to be small and found on isolated terrain features, but it will likely become a more serious problem when new snow arrives Tuesday night and Wednesday.

Snowpack Summary

Early season conditions exist with low snow amounts and crusts found at lower elevations and a deeper and drier snowpack approaching 1 m at treeline and alpine elevations.

Around 30 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.

The remainder of the snowpack is faceted as shown in this MIN, but is likely still intermixed with rocks, brush, and trees.

Weather Summary

Wednesday Night

Cloudy with flurries and 1 to 3 cm, 40 km/h wind from the southwest, treeline temperatures -12 °C.

Thursday

Cloudy with snowfall, accumulations of 10 to 15 cm, 70 km/h wind from the southwest, treeline temperatures warm to -9 °C.

Thursday

Partly cloudy, isolated flurries with trace amounts of snow, light wind from the north, treeline temperatures around -15 °C.

Friday

Clear sky no forecast precipitation, 10 km/h variable wind, treeline temperature -10 to -15 °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.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.