Avalanche forecast

South Rockies

Apr 16 – 17, 2012Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
No rating
Treeline
No rating
Below
No rating
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Highlights

Daily bulletins with danger ratings are finished for the season for this region. General advice can be found in the Avalanche Problems section and on the Forecast Details tab below. Additional information can be found in the Forecaster Blog.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–7
    Strong solar radiation or persistent warm temperatures may trigger deeply buried weak layers.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Moist or wet loose snow avalanches may release during periods of daytime warming or if periods of rain showers persist. Loose snow avalanches may trigger deeper weak layers.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Large triggers like cornices or loose snow avalanches may propagate slides on the buried weak layer from March 27th. The likelihood may increase if there is no overnight freeze.

Weather Forecast

Avalanche Summary

Spring conditions exist in the region. Avalanches are most likely to occur in response to solar radiation, warm temperatures, and periods of rain. Particularly dangerous conditions may develop during prolonged periods of warming, heavy rain, or on days with no overnight freeze. Under these conditions, surface avalanches may step down and trigger deeper wet slab avalanches. Prolonged warming may also weaken large and destructive cornices, which are a danger in themselves or could act as a heavy trigger on the slope below. Typically, avalanche activity ramps up during the day and is at a peak during the afternoon. If it's raining or there was no overnight freeze, avalanche activity can happen at any time.

Snowpack Summary

As we transition into spring the surface layers have a great deal of influence on the snowpack. When there is a solid re-frozen surface crust, travel is fast and easy, and the snowpack is held together by the surface cap. Any deeper persistent weak layers are unlikely to fail until the surface cap breaks down from daytime heating. During warm conditions, melt water is able to percolate within the snowpack and cause deeper weak layers to fail. If it cools off and snows, new snow may not bond well to the hard spring crusts, and isolated storm and wind slabs can easily develop.

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