Avalanche forecast

Cariboos

Mar 7 – 8, 2012Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–5
    Lots of snow available for transport, accompanied by strong winds have created wind slabs, even at treeline elevations. Large cornices may act as a potential trigger on slopes below.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–7
    Persistent weaknesses exist in the 150 cm of the snowpack. Surprisingly large avalanches could be triggered naturally by storm snow loading, or by additional weight of a person/sled. Buried persistent weaknesses are tricky to predict.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–6
    New snow and fluctuating temperatures have formed storm slabs. These overlie the mid-February weak interface. Storm slabs that trigger this interface could create surprisingly large avalanches.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Another frontal system tracking inland from the NW Coast will bring unsettled conditions accompanied by light-moderate precipitation. Thursday: Mainly dry conditions with a mix of sun and cloud. Ridgetop winds moderate from the SW. Treeline temperatures near -3. Freezing levels 1500 m. Friday: Snow amounts moderate accumulating 15 cm. Ridgetop winds light-moderate from the SW. Freezing levels 1000 m, falling to valley bottom overnight. Saturday: Light snow amounts. Ridgetop winds L-M from the SW. Freezing levels near 1000 m.

Avalanche Summary

A widespread natural cycle occurred on Monday, operators reported numerous size 2-3.5 natural avalanches, starting in the alpine on all aspects and most elevations.. A minor natural cycle up to size 3 in the Alpine occurred Tuesday. Rider triggered slabs were also reported in the size 1-2 range, failing within storm snow instabilities. I suspect conditions will still remain touchy, and unpredictable. With more forecast snow, wind and warming the avalanche danger will elevate.

Snowpack Summary

The weekend past, 60-100 cm snow has fallen. Strong winds and fluctuating temperatures have created storm slabs and wind slabs on a widespread basis. Persistent weak layers (surface hoar, facets, crusts) buried in February are a concern at all elevations and could be triggered by storm slabs, wind slabs, or the additional load of a sled/skier. Avalanches may be unexpectedly large, and destructive. If the sun shines, watch for snowpack deterioration on solar aspects. Large cornices have formed, and may act as a potential trigger on slopes below. They could step down to the persistent weakness.

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