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Avalanche Forecast

Archived

Dec 28th, 2024–Dec 29th, 2024

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

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir.

Continue to make conservative terrain choices while the storm snow settles and stabilizes.

Uncertainty lies deeper in the snowpack, where dangerous weak layers may be at play.

Confidence

Moderate

Avalanche Summary

Skier traffic produced small loose dry avalanches on steep slopes at treeline throughout the region Saturday.

On Friday, a large persistent slab (size 3) was observed at 2000 m in the Bonnington Range. The trigger is unknown, but the propagation was wide.

Recent natural widespread avalanche activity was reported in Stagleap Provincial Park where numerous storm slabs (size 1 to 1.5) were observed from steep terrain.

Snowpack Summary

Continued snowfalls adds to the 25 to 45 cm of recent snow. Moderate southwest wind has redistributed this new snow, forming deeper deposits on leeward slopes at higher elevations.

Below this new snow, a thin crust is present near the surface below approximately 1600 m.

Weak layers of surface hoar or facets and a crust may persist in the mid-snowpack, and snowpack tests continue to indicate potential instability.

The lower snowpack is generally strong and well-bonded.

Weather Summary

Saturday Night

Cloudy with 5 to 10 cm of new snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -4 °C.

Sunday

Cloudy with up to 5 cm of new snow. 10 to 20 km/h northeast ridgetop wind. Treeline temperature -5 °C.

Monday

Mostly cloudy with isolated flurries. 10 to 20 km/h northwest ridgetop wind. Treeline temperature -6 °C.

Tuesday

Mostly cloudy with isolated flurries. 10 to 20 km/h souhtwest ridgetop wind. Treeline temperature -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • In times of uncertainty, conservative terrain choices are our best defense.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.