Avalanche forecast

North Columbia

Apr 21 – 22, 2017Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Cornice failures can trigger large avalanches on sugary facets near the bottom of the snowpack.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Lingering wind slabs may still be reactive in isolated areas below alpine ridgetops.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    Minimize exposure to slopes with large cornices overhead when it is cool and cloudy and completely avoid them if it is warm and/or sunny.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Loose wet avalanches may trigger deeply buried weak layers, resulting in large avalanches.

Confidence

Low - Due to the number of field observations

Weather Forecast

SATURDAY: Mostly cloudy with isolated flurries / Light to moderate southeast wind / Freezing level 2100mSUNDAY: Cloudy with flurries / Light to moderate southwest wind / Freezing level 1900mMONDAY: Cloudy with flurries / Light southwest wind / Freezing level 1800mNOTE: Convective flurries, which are common this time of year, can result in widely varying snowfall amounts. These spring squalls routinely drop 20+ cm of snow in one valley while the adjacent drainage remains dry. For this reason, the distribution of avalanche problems associated with new snow vary greatly within a region.

Avalanche Summary

A significant close call occurred near Mount Sir Sanford on Friday afternoon when a cornice failure triggered a size 3 persistent slab avalanche that involved multiple people. The avalanche occurred on a north aspect at approximately 2800m. Exposure to large overhanging cornices remains a significant concern.

Snowpack Summary

Recent new snow tree line and above has been redistributed by west and south winds. Cornices remain large and continue to become more overhanging. The middle of the snowpack is generally well settled and continues to transition into a spring melt/freeze regime except for high elevation northerly aspects. Expect the entire thickness of the snowpack to be moist or wet at lower elevations. At upper elevations a deep persistent layer consisting of facets sitting on a crust that was buried back in November has been sporadically reactive to heavy loads such as a cornice fall or the weight of a smaller avalanche running.

Regions covered