Avalanche forecast

Purcells

Dec 20 – 21, 2013Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New snow with moderate to strong westerly winds have created dense wind slabs in exposed lee terrain and cross-loaded features. Rider triggering is possible, particularly in steep unsupported terrain.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–6

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Saturday: Mainly cloudy with a chance of flurries and sunny breaks. Little precipitation expected,  freezing level remains at valley bottom and moderate gusty northwest winds continue. Sunday: A mix of sun and cloud. The freezing level is near valley bottom and the upper flow continues to be northwesterly. Monday:  The tail end of a Pacific frontal system will move through the southern part of the Province, bringing light to locally moderate precipitation.

Avalanche Summary

One size 3 accidentally triggered slab avalanche was reported near Golden on Wednesday. This slide was triggered by a skier on a north-northeast aspect in the alpine and likely released on a persistent weakness near the bottom of the snowpack. The initial slide also sympathetically triggered another size 2.5 lower down the slope. Fortunately no one was buried or injured. Several other natural and explosive triggered avalanches (size 1.5-3) have been recently reported . This type of avalanche activity may be a good indication of the potential for large avalanches during periods of loading.

Snowpack Summary

Continued accumulation of low density new snow from the latest systems, accompanied by moderate W-NW ridgetop winds. Expect to find dense wind slabs in exposed lee terrain at and above treeline. A couple of notable persistent weak layers can be found in the top 60 cm. These layers have produced variable results with snowpack tests, but are increasingly concerning as the load above increases and/or a slab develops.  Snowpack depths vary widely across the Purcells from North to South.  If you're in the Golden area check out the latest update on local conditions from Skiing Golden. At the base of the snowpack are weak facets and depth hoar combined with a crust from early October. 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 steep, convex, north-facing slopes. Snow depth is still below threshold in many areas below treeline.

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