Avalanche forecast

South Rockies

Jan 3, 2019Avalanche Canada
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Archived · expired 8 years ago

Avalanche danger

Fri
Sat
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

New snow will load a weak snowpack. It will remain likely for a while that humans can trigger deep persistent slabs. Best to avoid alpine avalanche terrain and travel very cautiously at treeline and below, whilst limiting overhead exposure.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Touchy wind slabs are expected to form, as snow will fall with strong southwest winds.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3
    Snowfall on Thursday will load a weak layer of sugary faceted snow buried around 60 to 90 cm. Avalanches triggered on this layer will likely scour to the ground, resulting in large avalanches.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong west winds, alpine temperature -8 C, freezing level below valley bottom.THURSDAY: Cloudy with snowfall, accumulation 5 to 15 cm, moderate to strong southwest winds, alpine temperature -3 C, freezing level rising to 1300 m.FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest winds, alpine temperature -5 C, freezing level 1500 m.SATURDAY: Mix of sun and cloud, light to moderate southwest wind, freezing level 1000 m.

Avalanche Summary

A naturally-triggered large (size 3) avalanche was observed on Wednesday near Elkford, which likely released on Tuesday. It ran full-path to valley bottom. New snow on Thursday will increase the likelihood of observing such avalanches.

Snowpack Summary

Large variability in snow depths still exists in the region, ranging from practically no snow to almost 200 cm. Variable snowfall amounts are forecasted for Thursday, ranging from 5 to 20 cm. New snow will form fresh slabs across the mountains. Expect the deepest snow accumulation in lee terrain features, as the snow will fall with strong southwest winds. This snow will sit on previous hard wind slabs, a scoured and shallow snowpack on exposed southerly ridges, and generally soft snow in sheltered areasAround 60 to 90 cm of snowfall in December has formed a slab that sits on a persistent weak layer of weak and sugary faceted snow that formed during dry and cold weather in early December. This layer is most likely to be triggered on steep features where snowpack depths are variable.The lower snowpack has a weak structure composed primarily of sugary faceted snow around a crust near the ground. Should a shallower avalanche be triggered, it is likely that it would step down and scour to the ground.

Regions covered