Avalanche Forecast

Issued: Dec 25th, 2019 5:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate.

Avalanche Canada dsaly, Avalanche Canada

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Snow continues to settle over a deep persistent weak layer, which very recently produced very large avalanches. Any additional load, such as a smaller avalanche, cornice failure, or person, could trigger large and destructive avalanches.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Wednesday Night: Mostly clear and starry. Alpine temperature -10 C. Southwest wind, 10-15 km/hr.

Thursday: Mostly cloudy with isolated flurries. Alpine temperature -10 C. Southwest wind, 20-30 km/hr.

Friday: Mainly cloudy with isolated flurries, trace to 5 cm. Alpine temperature -12 C. West wind, 15-25 km/hr.

Saturday: Sunny with cloudy breaks and isolated flurries. Alpine temperature, -10 C. West wind, 10-20 km/hr.

Avalanche Summary

Snow accumulation over the weekend overloaded deeply buried weak layers. A natural storm slab avalanche cycle to size 3 occurred Saturday and Sunday following intense and heavy loading from snow/rain and wind.

Explosives triggered very large (size 3-3.5) avalanches Saturday and Sunday, these avalanches failed on a deep persistent weak layer with some avalanche crowns over 2 m. On Monday and Tuesday explosives continued to produce large (size 2-2.5) deep persistent slab avalanches.

Snowpack Summary

The massive load of recent storm snow is settling around the region. More recent flurries have left 10-30 cm lower density snow on the upper snowpack. Winds are slowly redistributing loose snow. Between 1400-1600 m, this loose snow overlies a rain crust. Below 1400 m, a previously isothermal snowpack is recovering.

Weak facets and decomposing crust layers from November and October can be found 80-140 cm below the surface. The intense loading of storm snow overloaded these weak layers, producing very large (size 3) avalanches on Saturday and Sunday triggered by explosives. A complex avalanche problem has developed, check out latest forecaster blog here.

Snowpack depths range between 60-160 cm at higher elevations and taper rapidly below treeline.

Terrain and Travel

  • Cornice failure may trigger large avalanches.
  • Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Valid until: Dec 26th, 2019 5:00PM

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