Avalanche forecast

Northwest Coastal

Mar 15 – 16, 2017Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Freezing levels are expected to drop down to near valley bottoms overnight. Some very low elevation terrain may continue to release as loose wet avalanches.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–4
    The natural storm slab cycle is expected to release persistent slab avalanches. Cornice falls may trigger deeply buried persistent weak layers.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    2–3
    Storm slabs are expected to continue to develop with each pulse of new snow and wind.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Heavy rain on snow may trigger wet slab or loose wet avalanches at lower elevations. This problem may be short lived due to the forecast cooling trend.

Confidence

Moderate - Freezing levels are uncertain on Thursday

Weather Forecast

Overnight: Freezing level dropping down to near valley bottoms, 5-8 cm of new snow, moderate southwest winds. Thursday: Daytime freezing level up to about 500 metres, 10-20 cm of new snow, moderate southwest winds. Friday: Daytime freezing level around 400 metres, 5-8 cm of new snow, light-moderate southwest winds. Saturday: Daytime freezing level around 400 metres, flurries or periods of light snow, moderate southwest winds.

Avalanche Summary

Widespread natural avalanche cycle reported on Tuesday. Natural wet slab avalanches up to size 2.5 and loose wet avalanches up to size 1.5. Reports have been limited due to poor visibility and travel conditions.

Snowpack Summary

Storm slabs continue to develop above 1100 metres. These storm slabs are deep 30-60 cm, with much deeper areas where the wind has transported the snow. Below 1100 metres the snow is moist or wet. The overall results will be widespread touchy storm slabs at higher elevations and unstable wet snow at lower elevations. The storm snow is also stressing a weak interface from February composed of facets, crust, and surface hoar buried over a metre deep. Given the recent activity on this layer before the storm, it should be very reactive during this storm.

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