Avalanche forecast

Purcells

Apr 16 – 17, 2013Avalanche Canada
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Archived · expired 13 years ago

Avalanche danger

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

This bulletin was produced using limited data. Significant variations in snowpack structure are likely to exist. If you've been traveling in the backcountry, we'd love to hear from you at [email protected].

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    Wind slabs exist on a variety of aspects at treeline and above. Wind has also formed very large and potentially unstable cornices.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–6
    A weak interface buried in the upper metre of the snowpack can create surprisingly large avalanches. It's been reactive in nearby regions, but there's limited information about its reactivity in the Purcells. Be cautious in alpine terrain.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Thursday

Weather Forecast

Wednesday: Light snow. Light W winds. Freezing level near 1600 m.Thursday: Trace amounts of snow possible. Light W winds. Freezing level near 1800 m.Friday:  Light snow. Light W winds. Freezing level 1900 m.

Avalanche Summary

Explosives triggered several size 2.5-3 slabs on northerly aspects above 2600 m on Monday. The largest failed a metre deep. On Sunday, a naturally triggered size 2.5 slab failed on a buried crust. Numerous small loose dry avalanches were also observed. In neighbouring Glacier National Park, skiers triggered a size 3 slab on a buried crust on an east aspect in the alpine on Monday. The slab above this interface may be reaching tipping point with incremental loading from snow and wind.

Snowpack Summary

Up to 40 cm recent storm snow has been shifted by variable winds into wind slabs at treeline and above.A weak interface down about 60-120 cm consists of a crust on solar aspects, and surface hoar on high-elevation northerly aspects. Cornices in the region are very large and potentially destructive. Periods of warming or solar radiation may increase the reactivity of cornices and storm slabs.

Regions covered