Avalanche forecast

Cariboos

Mar 26 – 27, 2012Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Variable wind slabs found in the alpine and at treeline. These exist on lee aspects, and terrain features. Cracking and/or whumphing felt below you is a good indicator of unstable, wind effected snow.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Large cornices exist and are becoming more likely to fail, especially when temperatures fluctuate. A cornice fall could trigger a very large avalanche on the slope below.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    4–8
    A weak interface down 1-2 m remains concerning. While avalanches on this layer have become less frequent, those that do release are very large and destructive.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

A series of systems will be crossing the Southern part of the province through the forecast period. Most of the punch will be in the South, but the Cariboo's will see light- moderate precipitation amounts, and a dominating SW flow with above normal temperatures. Tuesday: Snow amounts 2-5 cm. Ridgetop winds light from the South. Treeline temps near 2 degrees. Freezing levels 1700 m. Wednesday: Snow amounts 5-10 cm. Ridgetop winds moderate from the SW. Freezing levels 1200-1400 m overnight, rising to 1600 m during the afternoons. Thursday: Light-moderate snow amounts. Ridgetop winds mod-strong from the SW. Freezing levels 900 m.

Avalanche Summary

On Monday a size 2.5 natural cornice fall triggered the slope below. This was at 2400 m, on a North aspect. On Sunday, a size 3 natural, solar induced slab avalanche was reported from the Miledge Creek area. This ran in steep, unsupported terrain. No other observations reported. On Saturday three, size 3 natural avalanches were observed in steep, rocky, unsupported terrain. They occurred between 2000-2800m on north to east aspects and are suspected to have run on the February persistent weak layer.

Snowpack Summary

Recently formed wind slabs exist in the alpine and at treeline. Solar radiation has led to moist surfaces on sun exposed slopes with good crust recovery developing at night. Cornices have grown large and have become unstable; they may act as a large trigger on slopes below. A consolidated slab overlies a persistent weak layer that was buried in early February. Now 1-2 m below the surface, these weaknesses include surface hoar, facets or crusts. Concern still exists about the potential for deep and destructive releases at this interface. This may be a low probability, high consequence problem.

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