Bulletin d’avalanche

Northwest Coastal

Mar 24 – 25, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Points saillants

Avoid steep, rocky terrain in the alpine where there is a shallow or highly variable snowpack depth. This will reduce the likelihood of triggering large persistent slab avalanches.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1.5–2.5
    Human triggering of large persistent slab avalanches is most likely in rocky, alpine terrain with a shallow or highly variable snowpack depth.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2
    This problem is more likely at lower elevations where there was a weak or no overnight re-freeze. Sunshine and air temperatures above 0 C can rapidly increase the likelihood of triggering loose wet avalanches.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SUNDAY NIGHT: Clearing / Light, northeasterly winds / Alpine low -2 C / Freezing level 1500 m.MONDAY: Sunny / Light, northeasterly winds / Alpine high 2 C / Freezing level 1500 m.TUESDAY: Sunny with cloudy periods / Light, southwesterly winds / Alpine high 2 C / Freezing level 1500 m.WEDNESDAY: Mix of sun and cloud / Moderate, southeasterly winds / Alpine high 2 C / Freezing level 1600 m.

Avalanche Summary

Natural avalanche activity has tapered off but concern remains for human triggering persistent slab avalanches on a layer of facets that are down 50-100 cm. Explosive control work on Thursday produced several large avalanches, up to size 3, on this layer.

Snowpack Summary

At upper elevations, 50-100 cm of well settled snow overlies weak facets (sugary snow) that were buried around March. 10th. which is currently the primary layer of concern for human triggering persistent slab avalanches.Not much further below the March 10th interface is a second weak layer of facets buried on February 19th. Recent loose wet and slab avalanches have been observed gouging into this faceted snow and entraining additional mass.The prolonged warm spell has transitioned sun exposed slopes in the alpine and all aspects at treeline and below towards becoming isothermal (0 C throughout the snowpack). In these areas that have entered spring conditions, the avalanche hazard will fluctuate greatly depending on the strength of the overnight freeze and how quickly the snowpack is warmed up each day. Check out this guide to managing avalanche hazard during spring conditions HERE.

Régions couvertes