Avalanche forecast

Purcells

Mar 28 – 31, 2020Avalanche Canada
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Archived · expired 7 years ago

Avalanche danger

Mon
Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

New snow and strong winds will form reactive wind slabs on leeward slopes. This is the final forecast of the season.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Strong winds may form small wind slabs on lee features below ridgetops.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    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

SATURDAY NIGHT: Cloudy with flurries; 3-5 cm, strong southwest winds, alpine low -2 C, freezing level 1500 m.

SUNDAY: Cloudy with flurries; 3-10 cm, moderate to strong southwest winds, alpine high 2 C, freezing level 1800 m.

MONDAY: Snow; 5-15 cm, strong southwest winds, alpine high 0 C, freezing level 1700 m.

TUESDAY: Mix of sun and cloud, light west winds, alpine high -3 C, freezing level 1300 m.

Avalanche Summary

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

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.
  • Be alert to conditions that change with aspect and elevation.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Cornice failure may trigger large avalanches.

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