Avalanche forecast

South Rockies

Dec 26 – 27, 2013Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Recent strong winds have redistributed loose surface snow into pockets of wind slab at many elevations. Wind slabs may be gaining strength, but triggering is still possible in unsupported terrain.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    A skier-triggered size 2 avalanche in the Harvey Pass area indicates persistent weaknesses buried at the end of November have become active. The variable nature of this instability requires an investigative approach for safe mountain travel.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Friday: Light flurries / Moderate southwest winds with extreme gusts / Freezing level at 1300mSaturday: Mix of sun and cloud / Light winds / Freezing level at 900mSunday: Overcast skies / Light winds / Freezing level at valley bottom

Avalanche Summary

On Christmas Eve a backcountry skier triggered a size 2 slab avalanche on an alpine slope in the Harvey Pass area. The slab was reportedly 70cm deep and 150m wide and was thought to have slid on the late-November crust/facet interface. There were no reported injuries with the avalanche.

Snowpack Summary

There appears to be a lot of snowpack variability across the region. Snowpack depths at treeline seem to vary from 60 - 130 cm with high variability in wind-exposed areas. Mostly modest amounts of low density snow have fallen over the last week and have likely been shifted into small wind slabs in exposed areas. Located just below the surface is a layer of weak faceted crystals which formed during the cold snap at the beginning of December. At this point, there does not seem to be enough of an overlying slab to create a widespread problem. In the mid pack is the late-November/early-December interface which is made up of surface hoar, a crust, and/or facets. This layer is typically down 30-70cm and has reached the tipping point for rider triggering in a few areas including the Harvey Pass area. Check out this video of a recent snowpack test on this layer.

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