Avalanche forecast

Northwest Coastal

Mar 31 – Apr 1, 2017Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Warm, wet, and windy conditions are expected to increase the avalanche danger to HIGH.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    A weak facet/crust layer from late February has produced several large human triggered avalanches the past few days. Triggering this layer is most likely in shallower areas, but a storm slab or cornice fall could act as a trigger.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Forecast new snow and wind are expected to develop or add to existing storm slabs overnight.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Loose wet avalanches may release naturally at lower elevations due to warm daytime temperatures, new snow or rain, and high freezing levels.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Overnight: 10-20 cm of new snow above 600 metres combined with moderate gusty southwest winds. Saturday: 10-15 cm during the day with moderate westerly winds and daytime freezing up to 1100 metres. Sunday: Light west winds with flurries or periods of light snow and freezing levels around 1000 metres. Monday: Broken skies with a chance of clearing in the afternoon.

Avalanche Summary

One natural ice fall and one natural cornice fall size 3.0 were reported from the Bear Pass area on Thursday. Numerous natural storm slabs up to size 2.0 were reported on Wednesday. I suspect that new storm slabs will develop overnight due to the forecast new snow and wind.

Snowpack Summary

Storm slabs continue to develop in the alpine and at treeline. Warm daytime temperatures have created moist snow at treeline and wet snow below treeline. The February 21st persistent weak layer continues to be a concern for triggering large avalanches. This combination of crust and weak facets is now down 100-150 cm, and may be triggered by light additional loads in shallow weak spots adjacent to large terrain features. The snow below treeline may become weak and release as loose wet avalanches or wet slabs in steep unsupported terrain features.

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