Avalanche forecast

South Rockies

Jan 20 – 21, 2012Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–5
    With forecast weather, destructive wind slabs will be easy to trigger on lee and cross-laded slopes.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–6
    A buried surface hoar layer in the top metre of the snowpack continues to be a concern. Although it has become stubborn to trigger, the consequences are high. It's most likely to be triggered from shallow rocky areas on a slope, or by a large load.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–6
    Forecast temperatures, wind and snow will add load and reactivity to a storm slab that has been developing throughout the week.

Confidence

Fair - Intensity of incoming weather is uncertain on Saturday

Weather Forecast

Saturday: 15-20cm of snow (8-12 on the east side) - Strong southwest winds - Freezing level at 900mSunday: Trace amounts of snow - Moderate to strong southwest winds - Freezing level trending from surface to 600m throughout the dayMonday: Light snowfall - Moderate to strong southwest winds - Freezing level at about 800m

Avalanche Summary

Skiers easily triggered size 1 slabs in both the Flathead and South of Crowsnest regions on Thursday. In the Flathead, these were running on a crust/facet/surface hoar combo below the storm snow (about 50-60cm deep). A skier remotely triggered a size 1 slab on a NE aspect at 2300m from 20m away. Expect significant storm and wind slab activity with Friday night/Saturday's forecast weather.

Snowpack Summary

Over the week 40-60cm of snow formed soft slabs over a crust/facet/surface hoar combo. Forecast snowfall, wind and warming on late Friday/Saturday will create a more destructive and reactive storm slab problem.Deeper in the snowpack, a surface hoar layer buried in early December remains a concern, as avalanches triggered on this layer would be destructive. However, information is limited about its current reactivity. From preliminary observations, the rapid storm snow load on Tuesday did not cause any releases on this layer.Facets sandwiched between two firm layers in the top metre of the snowpack are being monitored in the south-east.

Regions covered