Avalanche forecast

Lizard-Flathead

Mar 14 – 15, 2017Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

High freezing levels overnight with continued stormy weather will keep avalanche danger elevated.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Cornices are huge and are ripe for triggering with the warm weather. Cornice falls may trigger larger persistent slab avalanches.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Storm slabs are expected to continue to develop due to forecast new snow and wind. Loose wet avalanches may be a problem at lower elevations.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–4
    Storm loading and warming may increase the likelihood of triggering large deep persistent slab avalanches. Concerns include basal facets in alpine terrain and a variety of crust and facet interfaces about a metre deep.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Overnight: Freezing level remaining above 2000 metres, combined with strong southwest winds, and 5-10 mm of precipitation. Wednesday: Freezing level around 2000 metres, combined with moderate-strong southwest winds, and 5-10 mm of precipitation. Thursday: Freezing levels dropping down to at least 1500 metres, moderate southwest winds, and a chance of sunny periods. Friday: Freezing down to valley bottoms, light southwest winds, and mostly sunny with strong solar radiation.

Avalanche Summary

Natural avalanches up to size 2.0 were reported on Tuesday. Observations were limited by poor visibility and travel conditions.

Snowpack Summary

A warm wet storm will form fresh slabs at higher elevations while rain will fall below treeline. Strong winds will load lee features and continue to grow large cornices on alpine ridges. March has delivered regular storms with roughly 80-120 cm of snow sitting above crust and facet interfaces from February. Little is known about the distribution and reactivity of these interfaces. Isolated basal facets still exist in shallow snowpack areas and can produce destructive full-depth avalanches. Possible triggers for these deeper weak layers include cornice falls, rapid warming, or strong solar radiation.

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