Avalanche forecast

South Coast

Apr 6 – 7, 2014Avalanche Canada
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Avalanche danger

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

What's going to happen to the snowpack if it warms up significantly on Monday/Tuesday? Read a discussion here...

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New snow with strong SW winds has set up storm and wind slab problems on steep lee terrain features. Watch for sensitive storm slabs lee of both ridge crest and mid slope features like ribs/rock outcroppings. Cornices may become weak with warming.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    With warmer temperatures, limited overnight re-freeze and rain forecast, loose wet avalanches are likely. A good indicator of weak snow is wet or moist surface snow, snowballing, and natural avalanches.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–7
    Three buried weak layers exist in the snowpack. Deep releases have become rare, but I would be concerned about an increased likelihood of a large destructive event during a period of intense warming.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

By Tuesday the cold front will reach the south coast bringing light-moderate precipitation, cloudy skies and rising freezing levels. Precipitation will be less on the Duffy.Monday: A mix of rain and snow up to 10 mm. Freezing levels rising to 2300 m. Alpine temperatures near 5.0 degrees. Ridgetop winds moderate from the SW, gusting strong. Freezing levels will slowly start to drop overnight to 1800 m. Tuesday: Periods of rain 15-25 mm. Alpine temperatures near 5.0 and freezing levels rising to 2100 m with no re-freeze overnight. Ridgetop winds remain strong from the SW.Wednesday: A mix of sun and cloud. Light precipitation. Alpine temperatures near -3.0 and freezing levels dropping to 1200 m. Ridgetop winds moderate from the SW.

Avalanche Summary

Small loose dry avalanches were seen from steep rocky terrain features. Loose wet avalanches were also seen on solar aspects. I suspect natural activity will continue with the warmer temperatures and rain through Monday/Tuesday. Smaller surface avalanches may trigger deeper weak layers, especially in thinner snowpack areas.

Snowpack Summary

Up to 20 cm of new snow sits above a mix of surface hoar, facets and melt freeze crusts. The new snow seems to have a poor bond to old surfaces and isolated wind slabs likely exist. Warmer temperatures and rising freezing levels will likely weaken the snow surfaces and become moist or wet.Recent warm temperatures have helped to settle and strengthen the upper snowpack and snowpack tests have been producing hard resistant planar shears on the late March crust down 30-50 cm.The persistent weak layers from early March and early February continue to be a concern. The March melt-freeze crust/surface hoar is reported to be down 60 - 100cm. The February crust/facet/surface hoar layer is now deeply buried down 150 - 250cm. These layers are mostly inactive at this time, but could re-awaken with extended warming, solar influence and precipitation through the forecast period.

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