Avalanche forecast

South Coast

Mar 22 – 23, 2015Avalanche Canada
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Avalanche danger

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

Touchy conditions exist in the North of the region with the potential for large and destructive avalanches.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Wind and snow forecast for Monday may form touchy new wind slabs in high elevation lee terrain. Watch for triggering in the lee of ridge crest and terrain breaks.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–4
    Easy snowpack test results and large natural avalanches indicate that a recently buried crust/facet layer deserves our respect. Touchy conditions are expected to persist for the foreseeable future, especially in the north of the region.

Confidence

Fair - Due to the number of field observations on Sunday

Weather Forecast

Scattered convective snowfall (up to 10cm) is expected on Monday as a cold front moves across the region. By late Tuesday a short-lived ridge will bring clearing. On Wednesday a more organized warm and wet frontal system will bring rain to most elevations. Ridgetop winds are expected to be moderate from the southwest with Monday's snowfall, otherwise remaining light. Freezing levels should hover around 1500m on Monday and Tuesday, and then climb to about 2500m with Wednesday's system.

Avalanche Summary

Over the past week, there have been a number of avalanches to size 2.5 occurring on the March 11 persistent weak layer. Some avalanches have occurred naturally, or remotely from distances of up to 100m. Hot spots for avalanche activity seem to include the Duffey Lake area, the Birkenhead drainage, the Hurley and the South Chilcotins. Snow and wind on Monday will likely add a round of wind slab activity to the mix. But it will also add load to the March layer, potentially adding to its reactivity and destructive potential.

Snowpack Summary

New wind slabs have formed in response to recent wind, snowfall and warm temperatures. At lower elevations, rain has saturated the snowpack. Cornices may also be fragile. A touchy crust/facet persistent weak layer, buried up to 60 cm down, has been reactive producing easy test results at upper treeline and alpine elevations, especially in the north of the region (see avalanche summary). Avalanche problems associated with this layer may linger for a while with the potential for surprisingly large and destructive avalanches. Below this, the snowpack is reported to be generally well-settled and strong.

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