Avalanche forecast

Kootenay Boundary

Apr 9 – 10, 2016Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
No rating
Treeline
No rating
Below
No rating
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Highlights

Spring conditions. Avalanche danger is expected to rise during the day with warming and solar radiation. Plan to retreat to cooler north-facing terrain if the snow surface is becoming moist or wet.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Cornices could fail easily during the day when temperatures soar and the sun reappears.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Loose wet activity should continue, particularly on solar aspects during the day.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Ongoing sunny weather and warm temperatures could lead to destructive wet slabs, especially if there is little or no overnight refreeze. 

Confidence

High

Weather Forecast

SUNDAY: Mainly sunny. The freezing level dips to 2000 m overnight but shoots up to 2500 m in the afternoon. Winds are light and variable. MONDAY: Increasing cloud. The freezing level remains near 2600 m and winds are light. TUESDAY: Cloudy with possible showers or flurries. The freezing level around 2400-2500 m. Winds could increase to moderate from the SW.

Avalanche Summary

On Thursday there was a widespread wet loose natural avalanche cycle reported to size 2 on all aspects/elevations. Loose wet activity continued on Friday but most of the activity was small (size 1) and less widespread.

Snowpack Summary

Cornices are large, fragile, and could trigger deep slab avalanches that run to valley bottoms. Monitoring the overnight freeze of the snow surface is very important during the spring. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating and solar radiation will weaken the snowpack much more quickly than it would if there is a well frozen thick crust. This is because the crust must first melt before the sun can weaken the snowpack. Deeply buried weak layers in the mid snowpack and near the ground still have the potential to wake up and become active with a rapid warm up. While unlikely, releases on these deeply buried weak layers would result in very large avalanches. Glide cracks are widespread and best avoided. Low elevation and thin snowpack areas have become isothermal, meaning the snowpack is 0 degrees Celsius throughout. An isothermal snowpack is more prone to full depth wet slab avalanches during the heat of the day.

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