Bulletin d’avalanche

Northwest Coastal

Jan 5, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Use caution with your route selection at higher elevations, as wind slabs may linger.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Recent winds were first strong from the southwest and more recently from the east. You may find touchy slabs in lee terrain features at higher elevations.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY NIGHT: Partly cloudy with intermittent snowfall, freezing level below valley bottom.SATURDAY: Cloudy with intermittent snowfall, accumulation trace to 5 cm, light to moderate southwest winds, alpine temperature -6 C, freezing level below valley bottom.SUNDAY: Cloudy with light snowfall, accumulation 5 cm, light northwest winds, alpine temperature -7 C, freezing level below valley bottom.MONDAY: Mostly clear, light to moderate west winds, alpine temperature -9 C, freezing level below valley bottom.

Avalanche Summary

On Thursday, small (size 1) wind slabs were triggered by skiers in wind-loaded terrain features.A natural avalanche cycle occurred during the storm from Monday to Wednesday, with many large to very large avalanches (size 2 to 3.5) propagating widely and running far. For example, see the MIN reports here and here. Some of the avalanches, particularly in the north of the region, stepped down to the deeper weak layers described in the snowpack summary.

Snowpack Summary

The upper snowpack varies substantially with elevation. Above around 1400 m, expect to find lingering wind slabs from Tuesday’s storm, which dropped upwards of 100 cm of snow with strong southwest winds. Below around 1400 m, the storm began with snow and switched to rain and may have switched back to snow again. It is likely that the wet snow has now frozen into a thick and supportive melt-freeze crust.In the northern part of the region, all this snow may overly a couple weak layers of feathery surface hoar buried near the end of December. Expect to find these layers about 50 to 120 cm deep.For most of the region around 150 to 200 cm deep, a weak layer of sugary faceted snow buried on December 8 may still exist. It is likely that this layer was the culprit of a large, remotely-triggered avalanche on December 30 near Terrace, described in a MIN report here. The likelihood of triggering this layer is decreasing, but it could be triggered by humans in shallow snowpack areas.

Régions couvertes