Avalanche forecast

South Rockies

Apr 15 – 16, 2021Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

 

As freezing levels rise, the likelihood for large cornice failures and wet loose avalanches will increase. Start early and plan to be off large slopes before the heat of the day.

Check out the latest Forecaster's Blog for more information on managing current conditions.

Avalanche problems

  • Wind Slabs

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

    Watch for pockets of unstable snow in steep alpine terrain.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    Strong solar radiation and warming will likely trigger the large cornices that hang over ridgelines. Cornice falls could trigger large avalanches on the slopes below.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2.5

    Expect natural wet loose avalanches to occur on solar aspects when the sun comes out.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

  

THURSDAY NIGHT: Clear / Moderate, northeast ridgetop wind / alpine low temperature -4 / Freezing level 2100 m.

FRIDAY: Sunny / Light, northeast ridgetop wind / alpine high temperature 8 / Freezing level 2700 m.

SATURDAY: Sunny / Light, northwest ridgetop wind / alpine high temperature 11 / Freezing level 2900 m.

SUNDAY: Cloudy with flurries; 5-10 cm. / Moderate, northeast ridgetop wind / alpine high temperature 0 / Freezing level dropping to 1700 m.

Avalanche Summary

Prolonged warming may increase the sensitivity of deeply buried layers, although there is a fair bit of uncertainty about how likely this is in the South Rockies region. There have been some notable slab avalanches reported to the north of the region recently including a skier triggered avalanche in Kananaskis Country on Saturday (see reports here and here) as well as cornice triggered deep persistent slab avalanche in Kootenay National Park on Tuesday (see photo here). These avalanches provide a good reminder of why it's good to be extra cautious during the heat of the day this time of year.

Snowpack Summary

Lingering wind slabs may still be reactive in isolated locations on steep northerly aspects in the alpine. All other terrain is undergoing a melt-freeze cycle with successive days of warm sunny weather. 

Strong solar radiation and warming will likely trigger the large cornices that hang over ridgelines. Cornice falls could trigger large avalanches on the slopes below.

The snowpack is overall strong and settled in most areas, however, sustained warming can increase the likelihood of large avalanches failing on deeply buried weak layers.This is most likely to occur on steep, rocky alpine slopes with a shallow or thin to thick snowpack.

The snow line is slowly creeping up the mountains, making some access areas snow-free. 

Terrain and Travel

  • Extra caution is needed around cornices under the current conditions.
  • Avoid exposure to slopes that have cornices overhead.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • Carefully evaluate steep lines for wind slabs.

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