Avalanche forecast

Kootenay Boundary

Apr 22 – 23, 2021Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Change is in the air, but even short periods of sunshine combined with high freezing levels can pack a punch. Loose wet avalanches are possible on sun-exposed slopes in the afternoon. 

Steer clear of cornices from above and below.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    Cornices are at their largest at this time of year, and become weaker with warm temperatures and solar radiation.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Wet loose avalanche activity is possible on sun-exposed slopes in the afternoon when the surface crust softens and weakens. These avalanches are generally smaller than wet slabs but they can gather mass as they travel and reach low elevations.  

Confidence

Moderate - The snowpack structure is mostly striaghtforward and not unusually variable. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Overnight Thursday: Clear with a light East wind. Alpine temperatures near -5 and freezing levels 800 m. 

Friday: A mix of sun and cloud. Ridgetop wind light to moderate from the southeast. Alpine temperatures near +2 and freezing levels 2000 m.

Saturday: Precipitation 15-25 mm falling as snow in the alpine and rain below. Ridgetop wind moderate from the southeast. Alpine temperatures near 0 and freezing levels 2000 m.

Sunday: Snow 5-10 cm. Ridgetop wind strong from the southwest. Alpine temperatures near -3 and freezing levels 1700 m. 

 

Avalanche Summary

There have been no recent avalanche reports since last Saturday. 

Last weekend, reports of natural loose wet avalanches size 2-3 on solar aspects continued. Explosive work produced size 2-3.5 wet slab avalanches, failing on crusts in the upper snowpack and gouging to the ground as they ran to near valley bottom.

As the weather pattern changes and the temperatures start to fall, a decline in natural avalanche activity is likely. However, solar slopes and weak cornices remain suspect when the sun is shining. It can really pack a punch this time of year, even for short periods of time. 

Snowpack Summary

The snow surface consists of a melt-freeze crust on all aspects of the mountain top. Only high alpine slopes above 2100 m and due North may still hold some softer, dryer snow. With a limited freeze overnight and rising freezing levels by Thursday afternoon, this crust may break down quickly with mostly wet snow surfaces. There are no layers of concern in the snowpack, which has been melting and settling over the past week. Lower elevations have mostly been isothermal and melting away rapidly.

Large cornices loom along many ridgelines. They are weak and very unpredictable.

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Terrain and Travel

  • Avalanche hazard is expected to to increase througout the day, think carefully about your egress.
  • Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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