Avalanche forecast

Northwest Coastal

Apr 19 – 20, 2012Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    New wind slabs may develop at treeline and above with forecast snow and wind. Watch for these behind ridges and terrain breaks. Sluffing, and loose snow avalanche activity may occur from steeper slopes on all aspects.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Loose wet avalanches are most likely during periods of warming from rainfall or sunshine. These can push you around, entrain mass and become surprisingly large.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–7
    Warm temperatures or rain may continue to weaken the snowpack, leading to full-depth releases. Avoid traveling on or underneath any slopes which sport glide cracks. Glide cracks have been releasing all week, initiating large-very large avalanches.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

An approaching Pacific low will mix up the recent weather pattern starting Thursday evening. Overnight Thursday: Snow amounts 10-15 cm. Ridgetop winds moderate gusting strong from the SE. Freezing levels 1000 m. Friday: Snow amounts 10-20 cm. Ridgetop winds moderate-strong from the SW. Freezing levels 1200 m by the afternoon. Saturday/Sunday: A ridge will persist on Saturday bringing dry conditions and sunshine. Sunday will see dry and mild conditions with increasing high cloud. Freezing levels through the weekend will hover around 1500 m.

Avalanche Summary

Reports od natural glide activity continued through the Skeena corridor. Loose wet avalanches up to size 1.5 continue on steep solar aspects. Explosive testing done within concerning glide slabs produced 2 size 1-2 releases. On Tuesday a large explosive control mission reported 10 size 2-2.5, and 1 size 3 avalanches. Slopes targeted were E-SE, 1500 m and below.

Snowpack Summary

Forecast new snow and wind may build wind slabs on lee slopes, and behind terrain features. Recent spring-like conditions exist through the region. Melt and frozen surfaces continue on all aspects. Slopes that start to become wet, and slushy should be avoided because loose wet avalanches may occur. Lately, a lack of consistent overnight freezing has left the snowpack weak and unconsolidated, even isothermal below 1100 m, although some re-freezing has been reported in some areas. Glide cracks have opened up and pose the threat of large, full-depth releases, especially on steep rocky terrain features at low elevations. Large cornices loom, and ice cliffs pose a threat from above. For more information on Spring Conditions and ways to mitigate risk, please visit the new Forecasters Blog Post.

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