Bulletin d’avalanche

Northwest Inland

Apr 10 – 11, 2021Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

Mon
Tue
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible

Points saillants

Recent snow and strong winds from shifting directions which have formed fresh wind slabs on a variety of aspects at treeline and above. Watch for newly formed and reactive wind slabs as you transition into wind affected terrain and avoid slopes with large cornices overhead.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    5-20 cm. of recent snow has been accompanied by periods of strong winds from shifting directions which have formed fresh wind slabs on a variety of aspects at treeline and above. 

    Wind slabs up to 50 cm. thick have recently been reported on lee and cross loaded slopes in the alpine. 

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    Cornices are large and looming along many ridgelines and have likely grown with the recent wind. 

    Strong solar radiation and warming are common triggers for cornice failures which could trigger large avalanches.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–1.5

    Small wet loose avalanches may start to run naturally on steep solar aspects when the sun comes out.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

  

SATURDAY NIGHT: Clearing skies / Moderate, northwest ridgetop wind / alpine low temperature -13 / Freezing level valley bottom.

SUNDAY: Sunny / Moderate, northwest ridgetop wind / alpine high temperature -3 / Freezing level 800 m.

MONDAY: Sunny / Light, south ridgetop wind / alpine high temperature 0 / Freezing level 1500 m.

TUESDAY: Sunny / Moderate, west ridgetop wind / alpine high temperature 4 / Freezing level rapidly rising to 2000 m.

Avalanche Summary

A few explosive triggered wind slabs up to size 2.5 were reported in this region on Friday.

Snowpack Summary

5-20 cm. of recent snow has been accompanied by periods of strong winds from shifting directions which have formed fresh wind slabs on a variety of aspects at treeline and above. Wind slabs up to 50 cm. thick have recently been reported on lee and cross loaded slopes. 

The recent snow has covered a variety of snow surfaces, including wind affected snow, crusts on solar aspects and at lower elevations, and soft snow on sheltered slopes at upper elevations.

 Cornices are large, looming, and capable of triggering large avalanches when they fail.

The lower snowpack is reported as well settled and strong in most areas. However, weak facets exist at the base of the snowpack in the more shallow snowpack zones across the region. Where it exists, this layer has the potential to be triggered on steep, rocky slopes with a shallow or thin to thick snowpack; especially with large loads such as a cornice fall.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Avoid lee and cross-loaded terrain.
  • Avoid exposure to slopes that have cornices overhead.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Régions couvertes