Avalanche forecast

Purcells

Mar 27 – 28, 2016Avalanche Canada
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Avalanche danger

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

Warming and sunshine will drive avalanche danger this week. Plan to start your day early and to avoid large sun-drenched slopes during the heat of the day.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–6
    Natural cornice falls are likely during periods of strong solar radiation and warm daytime temperatures. Cornice falls may trigger deeply buried persistent weak layers.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    A buried persistent weakness, around 50-90 cm deep, could reactivate with strong spring sunshine and climbing temperatures this week.

Confidence

High

Weather Forecast

MONDAY: Cloudy with a chance of flurries early, then sunny breaks. The freezing level climbs to 1600-1800 m and winds are moderate from the N-NE. TUESDAY: Mainly sunny. The freezing level is around 2000 m and winds are light to moderate from the North. WEDNESDAY: Mainly sunny. The freezing level spikes above 2200 m. Ridge winds are generally light to moderate from the North.

Avalanche Summary

No new slab avalanches were reported on Saturday. 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 places.

Snowpack Summary

Thin new wind slabs have formed in exposed lee terrain in the alpine and at treeline. On solar aspects you might find a dusting of new snow on top of a melt-freeze crust. 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 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. Cornices continue to be described as large and fragile, and may fail with forecast warming and strong sunshine this week.

Regions covered