Avalanche forecast

Northwest Coastal

Dec 30 – 31, 2015Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Recent winds have been highly variable, and so is the reactivity of recent storm snow. Make observations continually as you travel.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    A few buried surface hoar layers exist in the top 100cm of the snowpack. I would keep these on my radar on steep unsupported slopes, especially at treeline and below.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Up to 40cm of recent storm snow overlies a weak mix of facets and surface hoar. I'd be extra cautious in areas where wind or warming has caused these accumulations to settle into a cohesive slab.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Temperature inversions and solar radiation forecast for the next few days will promote loose wet avalanche activity, especially on steep, sun-exposed slopes.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

The current ridge of high pressure will persist for the foreseeable future bringing mainly clear skies for the forecast period. Ridgetop winds will intensify throughout the day on Thursday, and remain strong and southwesterly until Saturday. An inversion is forecast for all 3 days with above-freezing temperatures expected in the alpine by Thursday afternoon.

Avalanche Summary

Natural avalanche storm slab activity has tapered-off with the current clearing trend. However, human-triggered avalanches will remain a concern for the forecast period, especially at elevations or in parts of the region where recent storm accumulations have settled into a cohesive slab. Solar-induced loose wet avalanches up to size 1.5 have also been reported. The likelihood and size of loose wet avalanches will increase with warmer alpine temperatures expected during the forecast period.

Snowpack Summary

Between 25 and 40cm of recent storm snow overlies a widespread mix of faceted snow and surface hoar. The nature of the snow surface appears to be quite variable. In areas where recent winds were strong, these recent accumulations may exist as a deep, cohesive and reactive slab. In areas where the winds were light, you're more likely to find loose powder. Solar radiation has also come into play, and depending on the time of day, steep solar aspects may be moist or refrozen.Professionals in the region are still keeping an eye on a few other surface hoar layers that developed throughout December which are now buried in the top 100cm. Although these layers may be gaining some strength, they are worth investigating, especially in steep, unsupported terrain at treeline and below.

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