Avalanche forecast

Northwest Coastal

Nov 26 – 27, 2015Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
No rating
Treeline
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Below
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Highlights

The snowpack is extremely variable depending on aspect and elevation and does not adjust well to rapid change. Watch for rising alpine temperatures to well above zero. Check out the Mountain Information Network. Give info, get info!

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Stiff wind slabs likely exist on opposite slopes due to northerly outflow winds. Destructive wind slabs from last weekends storm may still be rider triggered, watch for wide propagations, especially in the lee of ridgecrests.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Increasing and strengthening warm air aloft (above 1000 m) may deteriorate snow surfaces initiating loose wet avalanches. Smaller avalanches could dig down to deeper layers, especially at higher elevations, initiating larger slab avalanches.

Weather Forecast

The above freezing layer will exist over the Northern regions through the forecast period. Temperatures could rise as high as 8 degrees above 1200 m and stay below zero with the outflow winds in the valleys. Patchy valley cloud may accompany the strengthening inversion as moisture becomes trapped. Ridgetop winds will generally be light and from the southwest.

Avalanche Summary

Numerous natural loose avalanches from steep solar aspects were observed on Thursday. Surface snow may start to deteriorate especially on solar aspects with the warming. Watch for obvious clues of instability like natural avalanches, snow balling and moist/ wet snow. Reports also indicate that there has been some for glide crack activity, you don't want to be skiing anywhere near those things when they release. They can be very large and destructive.

Snowpack Summary

The snowpack is extremely variable depending on aspect and elevation, with new wind slabs developing on reverse loaded southerly slopes and widespread surface crusts on all aspects at lower elevations. In the alpine, last weekends storm produced stiff wind slabs on northerly aspects, especially in the northern parts of the region. The snowpack doesn't adjust well to rapid change, so it may take several days to adjust and settle with the warm temperatures at higher elevations. Snow surfaces are becoming wet during the daytime and the average height of snow at 2000 m is near 150 cm. Due to limited observations, I have very little confidence in what that underlying structure may be, although I suspect faceting, crusts and possible surface hoar. One report mentions a series of crusts and faceted interfaces exist and are showing hard/ resistant results in snowpack tests, however; the fracture character is sudden and planar. If I were traveling in the mountains, I'd maintain an investigative approach and dig down to test for weak layers before committing to a slope.

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