Avalanche forecast

Purcells

Apr 9 – 10, 2013Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche danger will vary from place to place depending on local snowfall amounts and freezing levels. The heaviest precipitation is expected in the west.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–5
    New snow and wind will create new storm slabs at high elevations, which may overload a weakness buried in the upper snowpack, creating large avalanches.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Loose wet avalanches and glide slabs may fail naturally in response to rainfall at low elevations.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Tuesday night/ Wednesday: 10-30 cm snow. Strong to extreme W winds. Freezing level around 1500 m overnight, rising to near 2000 m in the south (~1700 m in the north). Thursday: Light snow. Moderate to strong NW winds. Freezing level around 1600 m. Friday: Light snow. Light S winds. Freezing level around 1500 m.

Avalanche Summary

An avalanche cycle of slabs up to size 3 occurred during last weekend’s storm. Many of these events were on NE-NW aspects above about 2400 m. Several size 2 skier-remote triggered slabs were also reported on Sunday. These failed on surface hoar buried below the storm snow. They occurred on W-NE aspects above 2500 m. Little activity was reported on Monday.

Snowpack Summary

Up to 50 cm recent storm snow is sitting on a variable interface, consisting of a crust, moist snow, surface hoar or facets. The surface hoar or facet interface is mainly found on high-elevation northerly aspects. It has recently been very touchy, with remote skier-triggering occurring. Forecast precipitation will add to this storm slab problem and create new wind slabs at high elevations, and weaken the snowpack with rain at low elevations. Large cornices are likely to increase in size and become more prone to failure during Wednesday’s storm.

Regions covered