Avalanche forecast

Purcells

Mar 26 – 27, 2016Avalanche Canada
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Archived · expired 11 years ago

Avalanche danger

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

A Special Public Avalanche Warning remains in effect for this region over the Easter long weekend. A conservative approach is highly recommended.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–5
    Cornices are an ongoing concern. Cornice falls may trigger deeply buried persistent weak layers.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Sudden planar results in snowpack tests suggest that triggering this layer may result in wide fracture propagations and large avalanches. Avoid convex un-supported terrain features.

Confidence

Moderate

Weather Forecast

SUNDAY: Cloudy with light snow – 2-5 cm. The freezing level is around 1400-1500 m. Winds are light to moderate from the W-SW. MONDAY: Cloudy with a chance of flurries early, then clearing. The freezing level climbs to 1700-1900 m and winds ease to light. TUESDAY: Mainly sunny. The freezing level is around 2000 m and winds are light.

Avalanche Summary

Explosives control on Friday produced a few size 2-2.5 cornice releases, but none of these triggered slabs below. There was one report of a natural cornice fall that did trigger a size 2.5 slab, releasing at or near the ground in spots. Some minor loose dry sluffing was also observed in steep north-facing terrain.

Snowpack Summary

Thin new wind slabs have formed in the alpine and at treeline. Cornices continue to be described as large and fragile, and may fail with additional loading from forecast snow, or from high daytime temperatures. Buried persistent weak layers continue to be a concern for remote triggering in isolated areas where crusts are not strong enough to "bridge" the weakness. The late February surface hoar/crust weak layer is down 40-90 cm. This layer may continue to react to human triggers during periods of strong solar radiation and high daytime temperatures. Loose wet avalanches in motion, or cornice falls may step down to deeply buried weak layers. Conservative terrain without overhead hazard is a good strategy for avoiding the persistent slab problem.

Regions covered