Avalanche forecast

South Columbia

Feb 23 – 24, 2013Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–6
    Storm loading has added additional stress to a persistent weak layer of surface hoar or a sun crust which now lie up to 100cm below the surface. Triggering this weakness may result in surprisingly large avalanches.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–5
    A storm forecast for late Sunday will add to recent heavy accumulations. Watch for increased reactivity in wind-affected terrain.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Sunday

Weather Forecast

Sunday: Heavy snowfall developing late in the day and continuing overnight / Strong west winds / Freezing level at 900mMonday: Light snowfall / Light northwest winds / Freezing level at 800mTuesday: Mix of sun and cloud / Light southwest winds / Freezing level at 800m

Avalanche Summary

A size 2 slab avalanche occurred on Friday in the north of the region and resulted in a fatality. The avalanche occurred on a northeast aspect at treeline, More details will follow as they are released by the RCMP.

Snowpack Summary

Up to 50cm of new snow and wind have created potent new storm slabs which are likely to be most reactive in wind-exposed terrain. These heavy accumulations add to the 25 to 55cm of snow which overlie the weak surface hoar layer which was buried on February 12th. The additional weight of the new snow and wind affect is expected to add reactivity to this persistent weakness which remains a primary concern for professionals in the region. This interface has also shown reactivity on southerly aspects where a sun crust formed during the period from February 8th-11th. There are older weak layers (surface hoar, crusts on solar aspects, facets) that are now buried down around 60-80 cms and also at about 110 cms. These layers have been unlikely to trigger by skiers, but they may still be sensitive to large loads like avalanches in motion or cornice fall.

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