Avalanche forecast

Northwest Inland

Jan 15 – 16, 2013Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Snowfall amounts are highly uncertain for the forecast period. Danger ratings are based on forecast models which call for higher accumulations.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Strong westerly winds are forecast to create new windslabs on lee terrain. With higher than normal wind values, watch for loading lower on the slope and in other unsuspecting locations.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    New snow will add additional load to buried weak layers. Watch for triggering in steeper, unsupported terrain.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–5
    A deeply buried facet/crust weakness exists near the base of the snowpack. This layer could be triggered by large loads such as a cornice collapse or from a thin-spot trigger point.

Confidence

Poor - Forecast snowfall amounts are uncertain for the entire period

Weather Forecast

Overnight and Wednesday: Light to moderate snowfall / Strong to extreme west winds / Freezing level climbing to 1000mThursday: Heavy snowfall / Strong to extreme west winds / Freezing level at 800mFriday: Light snowfall / Moderate west winds / Freezing level at 700m

Avalanche Summary

On Monday a size 2 windslab avalanche was skier-triggered in a chute above Crater Lake. The crown was about 30m wide with a maximum height of 80cm.

Snowpack Summary

A surface hoar layer that was buried at the end of December is now down 60-80 cm, and has become reactive in some areas with recent warming. There are also signs of recent intense northwest winds in the alpine and at treeline leaving scoured areas and hard windslabs on lee side of ridges and terrain breaks.  A strong mid-pack overlies a weak base layer of facets/depth hoar and the remnants of a crust.

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