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Avalanche Forecast

Archived

Dec 30th, 2024–Dec 31st, 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.

A calm weather day marks the end of the year.

Surface instabilities and deeper weak layers may remain reactive to riders.

Choose low-consequence terrain and watch for signs of instability.

Confidence

Moderate

Avalanche Summary

On Sunday, skiers were surprised by the storm snow at treeline and alpine on northerly slopes, with several avalanches (size 1.5 to 2) in the Bonnington Range and around Whitewater Resort.

Evidence of a natural avalanche cycle was also reported over the weekend throughout the region.

If you head out in the backcountry, let us know what you are seeing by submitting a MIN report!

Snowpack Summary

30 to 50 cm of settling snow can be found in sheltered areas. Previous moderate southwest wind has redistributed this snow, forming deeper deposits on leeward slopes at higher elevations.

Below this recent snow, a thin crust is present 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 its potential instability.

The lower snowpack is generally strong and well-bonded.

Weather Summary

Monday Night

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

Tuesday

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

Wednesday

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

Thursday

Mostly cloudy, with isolated flurries. 20 to 30 km/h southwest 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.
  • Keep in mind that human triggering may persist as natural avalanches taper off.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Pay attention to the wind; once it starts to blow, sensitive wind slabs are likely to form.

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.