Bulletin d’avalanche

Yukon

Dec 11 – 12, 2021Avalanche Canada
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Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
Sans niveau
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Points saillants

Weak, sugary crystals exist at the base of the snowpack. Try to stay where the snow is deep and manage overhead hazard diligently. New snow is likely to form relatively short-lived wind slabs.

Problèmes avalancheux

  • Wind Slabs

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

    There is a lot of new snow available for wind transport and by Saturday morning, new wind slabs will have formed in exposed, upper treeline areas and in the alpine. The wind was particularly strong in inland areas around Paddy Peak and Powder Valley. Keep in mind that the wind is forecast to change from south to north during the day on Saturday so remain aware of where snow is being distributed as you travel through the terrain. 

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    Although this layer is becoming more deeply buried and somewhat harder to trigger, if triggered, it would likely result in a large avalanche. You are more likely to trigger this layer in areas where the snowpack is shallow so avoid fat to thin transitions and stick to places where the snowpack is deep. Remote triggering is possible so be aware of your overhead exposure. 

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

FRIDAY NIGHT: mostly cloudy skies, 2-4cm of snow, wind moderate tapering to light from the southwest, temperature -10 C at highway elevation. 

SATURDAY: mostly cloudy in the morning with periods of clearing in the afternoon, no significant precipitation, light wind from the south in the morning changing to moderate wind from the north in the afternoon, -12 C in the morning decreasing to -15 C in the afternoon

SUNDAY: Partly cloudy skies, no precipitation, moderate wind from the north, temperature -21 C. 

MONDAY: Partly cloudy skies, no precipitation, moderate wind from the north, temperature -23 C 

Avalanche Summary

Explosive control earlier in the month produced many large avalanches that failed on the weak sugary crystals at the bottom of the snowpack. These avalanches ran full path.

On December 1, a size 2.5 avalanche was remotely triggered by a recreational group on Log Cabin. This avalanche likely failed on the weak, sugary snow at the bottom of the snowpack.

On Saturday, the most likely avalanche activity will be in wind-affected areas on exposed treeline features and high alpine features. 

Snowpack Summary

Up to 50cm of recent fresh powder snow will be redistributed by moderate south and then north winds over the weekend. Snow quality will be best in sheltered treeline and sheltered, low angled alpine features. The middle snowpack is supportive to travel but snow depth still varies greatly with aspect and elevation. In most places, the entire snowpack sits on top of a layer of weak, sugary snow at the base of the snowpack. This deeply buried layer will likely become weaker over time with cold temperatures starting on Sunday. This is our main layer of concern and, if triggered, could result in large avalanches. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be alert to conditions that change with elevation and wind exposure.
  • Approach lee and cross-loaded slopes with caution.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Be aware of the potential for large avalanches due to the presence of a deep persistent slab.

Régions couvertes