Avalanche forecast

Banff Yoho Kootenay

Mar 12 – 13, 2013Parks Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

We expect a natural avalanche cycle to start Wednesday and last for the next 48 hours. SH

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    Strong to extreme W winds will be developing wind slabs on lee aspects and will be sensitive to human triggering.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    1–2
    At higher elevations, expect all gully features and exposed terrain to slough with the increased winds and new snow.  Steep terrain below treeline may slough far and fast.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–3
    New storm slabs will be sitting on a variety of surfaces, from colder powder snow or sun crust at higher elevations depending on aspect, to rain crust 1800m and below. 

Weather Forecast

West winds up to 110km and 30+cm of snow is forecast Wednesday at higher elevations, with highest amounts along and West of the divide  Freezing levels are expected to rise to 1900-2000m over the next 24hrs and remain there until Friday.  We could see some rain in areas such as Field and Kootenay as freezing levels rise.

Snowpack Summary

A field trip to Kootenay found a well settled 2m snowpack at 2000m with the only compression results in the top 15cm of loose storm snow.  10cm supportive rain crust to 1800m in that area.  This is a stark contrast to thinner snow pack areas which have storm slabs and wind slabs 30-40cm thick sitting over a mainly facetted snowpack.

Avalanche Summary

Ski cutting produced small but far running sloughs in steeper terrain today within the top 15-20cm of snow.  The sloughs ran for approx. 200m.  No other avalanches reported or observed.

Confidence

Forecast snowfall amounts are uncertain on Wednesday

Regions covered