Boletín de aludes

Northwest Coastal

Feb 14 – 15, 2022Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

Wed
Thu
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Lo esencial

New snow and shifting winds from southwest to northwest may form small reactive wind slabs on lee features at treeline and above.

Small wet loose avalanches may run long distances in steep terrain.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    New snow and shifting winds from southwest to northwest may form small reactive wind slabs on lee features at Treeline and above.

    Larger wind slabs may exist in the north of the region at upper elevations where the intense rain on Wednesday fell as snow.

    Cornices overhead are a primary concern during sunny, warm, or windy conditions. Cornice failures may trigger very large persistent slab avalanches that would otherwise be difficult to trigger.

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    1–1.5

    New snow forecast for Sunday night will lose cohesion when it is heated by the sun. Small wet loose avalanches may run long distances in steep terrain.

Confidence

High -

Weather Forecast

SUNDAY NIGHT: Cloudy with flurries; 5-10 cm / Light, west wind / Low of -3 / Freezing level 500 m.

MONDAY: Mix of sun and cloud / Strong, northwest wind / High of 0 / Freezing level 1000 m.

TUESDAY: Cloudy with isolated flurries; 0-3 cm / Strong, northwest wind / High of -2 / Freezing level 700 m.

WEDNESDAY: Cloudy with flurries; 3-5 cm / Strong, northwest wind / High of 2 / Freezing level 1100 m.

Avalanche Summary

Numerous naturally triggered size 2-3 storm slab avalanches were reported west of Ningunsaw Provincial Park on Saturday. They were releasing at the rain/snow line between 1200-1500 m on all aspects.

Explosive triggered cornice failures released several very large (size 3) persistent slab avalanches that likely failed on a crust buried in early February. They occurred northeast of Terrace on Friday. This is a good reminder that large loads, such as cornices or smaller avalanches in motion, can trigger deeply buried weak layers that would be difficult to human trigger.

 

Snowpack Summary

5-10 cm of wind-pressed snow overlies a thick (10-15 cm) rain crust that extends to mountain tops. This crust has created challenging travel conditions and a "slide-for-life" hazard on steep slopes.

Small wind slabs may be found on lee features in the alpine. 

The weak layers in the snowpack (such as the crust or surface hoar layers down around 100 cm) are unlikely to human trigger in areas where a hard surface crust is present. If the surface crust is warmed up and breaks down, triggering persistent slab avalanches becomes more likely.

However, cornices overhead are a primary concern during sunny, warm, or windy conditions. Cornice failures may trigger very large persistent slab avalanches that would otherwise be difficult to human trigger.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Loose avalanches may start small but they can grow and push you into dangerous terrain.
  • Avoid exposure to slopes that have cornices overhead.
  • Cornice failure may trigger large avalanches.

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