Bulletin d’avalanche

North Columbia

Feb 6, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

The unusual danger rating is due to a buried weak layer that exists mainly at treeline and below. It is easily triggered by humans and there is the potential for large avalanches at lower elevations. Choose low angled terrain, especially in the trees

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2
    30-80 cm of recent snow has been redistributed by recent winds in many areas, forming wind slabs on all aspects due to shifting wind directions.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1.5–3
    50-100 cm of snow is now sitting on a persistent weak layer of surface hoar and crust that was buried in mid January. This region has been the "hot spot" of activity on this layer, with more reactivity reported here than in neighboring regions.

Confidence

High -

Weather Forecast

TUESDAY NIGHT - Clear with cloudy periods / northwest winds 10-15 km/h / alpine low temperature near -19WEDNESDAY - Mainly sunny / northwest winds 10-15 km/h / alpine high temperature near -16THURSDAY - Mainly cloudy with light flurries, 3-5 cm / southwest winds 10-20 km/h / alpine high temperature near -14FRIDAY - A mix of sun and cloud with scattered flurries / northeast winds, 15-25 km/h / alpine high temperature near -16

Avalanche Summary

Natural avalanche activity began to slow down on Sunday, but a persistent weak layer that was buried in mid January continues to be reactive to human triggers. This layer is sensitive enough for humans to trigger avalanches remotely (from a distance). Human triggered avalanches up to size 2.5 were reported on both Sunday and Monday. This layer is the most reactive at treeline and below treeline.This MIN report from Monday does a great job of illustrating the sensitivity of this weak layer.Widespread avalanche activity was reported on Friday and Saturday. Numerous natural and explosives triggered avalanches to size 3.5, and human triggered avalanches to size 2 were reported. Many of these avalanches were triggered remotely (from a distance) and failed on the mid January layer.Human triggered avalanches failing on the mid January persistent weak layer have been reported almost daily for the past two weeks in the North Columbia region.

Snowpack Summary

30-80 cm of recent new snow sits on surface hoar (feathery crystals), facets (sugary snow), wind slabs and a crust on sun-exposed slopes. In many areas, recent winds have redistributed the new snow, forming wind slabs on all aspects due to shifting wind directions.The most notable feature in the snowpack at this time is a persistent weak layer that was buried in mid January, which is now buried 50-100 cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer is the most prominent at treeline and below, and continues to be produce avalanches.

Régions couvertes