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Avalanche Forecast

Archived

Dec 29th, 2024–Dec 30th, 2024

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.
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.

Don't let good riding lure you into complacency.

Potentially dangerous weak layers still exist deeper in the snowpack.

Confidence

Moderate

Avalanche Summary

Skier traffic produced several small loose dry and soft storm slabs on steep convex slopes throughout the region Saturday.

Avalanche activity was reported over the weekend in Stagleap Provincial Park where natural storm slabs (size 1 to 2) were observed from steep terrain.

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.

Snowpack Summary

Continued snowfalls add to the 30 to 50 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. Professionals are still concerned about the potential instability of this layer.

The lower snowpack is generally strong and well-bonded.

Weather Summary

Sunday Night

Cloudy with up to 5 cm of new snow. 10 to 20 km/h northwest ridgetop wind. Treeline temperature -6 °C.

Monday

Cloudy with up to 5 cm of new snow. 10 to 20 km/h northwest ridgetop wind. Treeline temperature -6 °C.

Tuesday

Mostly cloudy with isolated flurries. 20 to 30 km/h souhtwest ridgetop wind. Treeline temperature -8 °C.

Wednesday

Cloudy with up to 5 cm of new snow. 20 to 30 km/h souhtwest ridgetop wind. Treeline temperature -10 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Uncertainty is best managed through conservative terrain choices.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Problems

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.

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.