Boletín de aludes

Purcells

Mar 26 – 28, 2020Avalanche Canada
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Archivado · caducó 7 years ago

Peligro de aludes

Sat
Sun
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Lo esencial

Small wind slabs below ridgetops are currently the primary concern.

Problemas de aludes

  • Wind Slabs

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

    Recent winds may have formed reactive slabs on lee features below ridgetops.

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–3.5

    Weak faceted snow near the base of the snowpack continues to be a concern. Treat wind-scoured, rocky, shallow terrain as suspect and avoid big alpine slopes that are threatened by cornices overhead. 

Confidence

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

Weather Forecast

THURSDAY NIGHT: Cloudy, light to moderate west winds, alpine low -5 C, freezing level 600 m.

FRIDAY: Cloudy with isolated flurries; 0-3 cm, light to moderate northwest winds, alpine high -1 C, freezing level 1700 m.

SATURDAY: Cloudy with flurries; 0-3 cm, moderate west winds, alpine high 1 C, freezing level 1800 m.

SUNDAY: Cloudy with flurries; 0-3 cm, moderate west winds, alpine high 1 C, freezing level 1800 m.

Avalanche Summary

There are currently very few professional operations reporting in this region and the data stream is very limited.

Over a week ago, there was a report of a skier remotely triggering (from a distance) a large (size 2) deep persistent slab avalanche at 2600 m on a northwest aspect. The avalanche was triggered from a thin spot, released 40-80 cm deep, and ran on depth hoar near the base of the snowpack.

Snowpack Summary

NOTE:We are receiving very limited professional snowpack observations in this region. The snowpack summary below is based on our most recent observations and weather data.

The recent snow sits on a variety of snow surfaces, consisting of sun crusts, hard wind-affected snow, and soft faceted snow. There have also been reports of surface hoar forming on sheltered, shady slopes. See this MIN for a helpful illustration from nearby Glacier National Park. It will be important to track the depth, cohesiveness, and bond of the new snow to these various old snow surfaces across aspects and elevations where you are travelling.

Cornices are large and looming. Surface hoar buried February 22 may be found 50-100 cm deep. Avalanche activity on this layer was last reported March 11th. 

Deeply buried facets lurk near the bottom of the snowpack. This layer has been responsible for sporadic deep persistent slab avalanches, usually triggered from shallow, rocky start zones.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Make observations and assess conditions continually as you travel.
  • Be alert to conditions that change with aspect and elevation.
  • Cornice failure may trigger large avalanches.

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