Avalanche forecast

South Columbia

Apr 2 – 3, 2016Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A Special Public Avalanche Warning remains in effect Sunday. The freezing level remains quite high (2600 m) which will keep danger ratings elevated.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–5
    Continued high freezing levels and warm temperatures are expected on Sunday, which means that natural cornice failure remains a serious problem. Large cornice fall may trigger buried weak layers resulting in very large avalanches.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Continued warm weather may add enough heat to the snowpack to wake-up deeply buried persistent weak layers resulting in very large and destructive avalanches which have the potential to run full path.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Forecast high freezing levels may break down surface crusts early and result in loose wet avalanches from steep solar aspects. Wet slab avalanches are possible if loose snow propagates on a buried crust.

Confidence

Moderate - Freezing levels are uncertain on Monday

Weather Forecast

Temperatures are expected to remain warm Sunday before beginning to cool Monday as a weak Pacific front injects cooler and cloudier marine air into the region. SUNDAY: Freezing level starting near 2300 m, climbing to 2600 m, light southwest wind, no significant precipitation expected, increasing cloud cover throughout the day. MONDAY: Freezing level beginning near 2500 m, lowering throughout the day to around 1700 m by sunset, light to moderate southwest winds, 5 to 15 mm of precipitation expected, overcast skies. TUESDAY: Freezing level beginning near 1500 m rising to around 1900 m, overcast skies, light to moderate wind generally out of the west, convective snow/rain flurries/showers possible. For more detailed mountain weather information visit avalanche.ca/weather

Avalanche Summary

Lot's of activity to report from Friday. Loose wet avalanches ran on southeast, south, southwest and west facing features to size 3 between 1200 m and 2900 m. One small skier triggered wet slab was reported on a north facing alpine feature. Glide crack failure to size 3 was reported. Not surprisingly, cornice failure was also an issue. On Thursday, strong solar radiation resulted in numerous loose wet avalanches up to size 3.0 on various aspects. Some wet slab activity was also reported from southerly aspects, and one persistent slab avalanche size 2.5 on a south aspect in the alpine that was 100-150 cm deep.

Snowpack Summary

New surface crusts have formed at all elevations on solar aspects, and on all but high alpine shaded aspects. Some areas have reported a new layer of surface hoar growing in high sheltered alpine locations above 2300 metres. Approximately 40-50 cm of settled storm snow sits on a melt-freeze crust buried on Mar. 22. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60-110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. Cornices continue to be described as large and fragile. Expect loose wet avalanches and natural cornice failure with continued warming Sunday. Forecast warming may also trigger very large slab avalanches on one of the buried crusts or associated weak layers.

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