Avalanche forecast

Purcells

Jan 11 – 12, 2012Avalanche Canada
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Archived · expired 15 years ago

Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Weak wind slabs are lurking below ridgecrests, behind terrain features and in cross-loaded gullies. Hard drum-like wind slabs often have the potential to release well above the trigger point.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–5
    Most concerning on steep, unsupported slopes, in open glades glades.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Susceptible to human triggers particularly from thin slab spots on variable slopes, heavy impacts, or deep penetration, such as sled tracks trenching. Slabs are likely to release across entire bowls producing highly destructive avalanches.

Confidence

Good - -1

Weather Forecast

Thursday: Dry and clear, with freezing levels near valley bottoms and moderate northwesterly winds. Friday: Increasing cloud in the afternoon with freezing levels briefly rising as high as 1500m. Saturday: Light flurries possible with freezing levels around 900m.

Avalanche Summary

A skier was killed in a Size 3 avalanche in the Dogtooth range near Golden on Friday. The 4th skier on the slope triggered the slide. On Saturday a skier triggered another Size 3 persistent slab avalanche in the Quartz Creek alpine, the crown averaged 100cm in depth & the avalanche was reported to have run full path. The group had been skiing in the area all day without result until the avalanche happened. Avalanche activity on Sunday was confined to operational explosive use & produced avalanches to Size 2 on high elevation NE facing slopes.

Snowpack Summary

Warm temperatures and light to moderate precipitation settled the 40-60cm of recent storm snow and created upside down slabs and/or thin surface crust on Monday. Since then, light amounts dry snow is maintaining the snow supply for wind slab development, but cold temperatures are likely starting to improve storm slab stability. Touchy mid-December surface hoar is down anywhere from 40cm on the eastern side of the range to 150cm on the west side is recently produced easy snowpack test results that show a high propensity to propagate fractures. Check out this YouTube video posted by the Panorama ski patrol of an ECTP2 down around 40cm on surface hoar: https://www.youtube.com/watch?v=1_NQns2Nuh0. Basal facets remain a concern for human triggering in shallow snowpack alpine areas. When these persistent weaknesses are combined with weak wind slabs, thin trigger points, and other weaknesses within and under the recent storm snow, the result is a highly variable snowpack with the potential for deep slab avalanches, especially from heavy, thin spot, and/or step-down triggers.

Regions covered