Avalanche forecast

South Rockies

Dec 17 – 18, 2013Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

This forecast is based on very limited data. If you are out in the mountains, we would like to hear from you at [email protected]

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    Wind slabs have developed recently on a variety of aspects due to shifting winds. Expect to encounter these deep deposits of wind-transported snow below ridge crests and behind terrain features.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–4
    Sugary facets at or near the base of the snowpack are most likely triggered on steep, convex slopes with a thin snowpack. In deeper snowpack areas you may find a stubborn buried surface hoar layer.

Confidence

Poor - Due to the number of field observations

Weather Forecast

A ridge of high pressure will build late-Wednesday, bringing clear and cold conditions for Thursday. On Friday, the next frontal system should reach the region possibly resulting in light precipitation.Wednesday: Light snowfall, freezing levels dropping to valley bottom, light SW winds switching to NE as the ridge builds.Thursday: Clear conditions, freezing levels at valley bottom, light windsFriday: A mix of sun and cloud, light precipitation possible, light winds

Avalanche Summary

On Monday, reports of two wind slab avalanches size 2.5 triggered by explosives south of the Crowsnest Pass and one size 1 wind slab avalanche triggered by a vehicle in the North Flathead area.

Snowpack Summary

Recent incremental snowfall has started to bury the mid-Dec surface hoar and the previously faceted upper snowpack. Snowpack depths at treeline seem to vary from 50 - 110 cm with high variability in wind-exposed areas. Buried surface hoar/facets/crust (late-Nov interface) are down approximately 30-40cm. The base of the snowpack is made up of weak facets and depth hoar. This deep persistent weakness may be stubborn to trigger, especially in deeper snowpack areas, but the sensitivity to triggers likely increases in shallower locations, especially on a steep, convex slopes. In some below treeline areas the snowpack is below threshold and early season hazards like open creeks and stumps remain a concern.

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