Avalanche forecast

North Columbia

Apr 20 – 21, 2017Avalanche Canada
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Avalanche danger

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

Sunshine and rising freezing levels will elevate the potential for cornice failures resulting in large avalanches on Friday.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Convective flurries and moderate southwesterly winds may create wind slabs in lee features below ridgetops.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    The likelihood of cornices triggering increases with intense sunshine and/or during the warmest parts of the day.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Loose wet avalanches may trigger deeply buried weak layers, resulting in large avalanches.

Confidence

Low - Due to the number of field observations

Weather Forecast

FRIDAY: Mix of sun and cloud / Light northwest wind / Freezing level 2100mSATURDAY: Cloudy with sunny periods and isolated flurries / Light southeast wind / Freezing level 2000mSUNDAY: Cloudy with flurries / Light southwest wind / Freezing level 1900mNOTE: 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

Several natural and skier triggered wind/storm slab avalanches to size 3 on northerly aspects in the alpine were reported on Wednesday in areas that had received 20+ cm of recent snow. Additionally, numerous natural and skier triggered loose wet avalanches up to size 1.5 were reported on solar aspects. 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 i.e. a cornice fall or the weight of a smaller avalanche running. Cornices remain large and continue to become more overhanging.

Regions covered