Avalanche forecast

South Rockies

Feb 13 – 14, 2012Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    Cornices are large, unsupported and may be a trigger for a large avalanche on the slope below.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Deep and destructive persistent slab avalanches are unlikely, but a large trigger may activate this weakness on a steep, rocky & unsupported area with a shallow snowpack.

Confidence

Fair - Intensity of incoming weather is uncertain on Tuesday

Weather Forecast

Expect to wake up Tuesday morning with 10-15cm of fresh snow in the hills, but flurry activity is expected to taper off throughout the day. A building ridge of high pressure is expected to spread dry conditions Wednesday through Thursday morning before a frontalsystem arrives late Thursday bringing light precipitation. Freezing levels should remain near 1000m and winds should be light and variable throughout the forecast period.

Avalanche Summary

Loose surface snow may be susceptible to sluffing on steep slopes, but not expected to be particularly destructive unless terrain traps are in the runout. Deep persistent slab avalanches remain possible with heavy triggers in shallow rocky snowpack areas on unsupported slopes.

Snowpack Summary

By Tuesday afternoon, up to 15cm of fresh snow could be sitting on the widespread robust surface hoar created during the dry spell at the beginning of the month. This interface will be one to watch as it receives more snow load and/or the slab settles. Below that approximately 20cm of near-surface facets can be found on shady slopes while a sun crust can be found on southerly aspects. A well settled and strong snowpack sits on weak basal facets and depth hoar, which seem to be fairly widespread throughout the region. This deep persistent weakness was recently activated by warm temperatures, but cooler temperatures have once again reduced the sensitivity to triggers. Highly unpredictable glide cracks are also opening up, primarily on slopes with smooth ground cover. These full-depth gaping 'crevasses' could release without warning or act as a significant terrain trap.

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