Lawinenlagebericht

Purcells

Jan 13 – 14, 2012Avalanche Canada
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Archiviert · abgelaufen 15 years ago

Lawinengefahr

Sun
Mon
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–3
    Weak wind slabs are lurking below ridgecrests, behind terrain features and in cross-loaded gullies.
  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    3–5
    Most concerning on steep, unsupported slopes, in open glades glades.
  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    3–6
    Susceptible to human triggers particularly from heavy impacts or in areas with thin snowpack. If triggered, slabs are likely to release across very wide areas producing highly destructive avalanches.

Confidence

Fair - -1

Weather Forecast

SATURDAY: Light amounts of snow with temperatures cooling to -15. Winds moderate to strong from the west.SUNDAY: Light amounts of snow leading to clearer and colder conditions in the afternoon. Winds light from the north.MONDAY: Cold and clear as arctic air descends from the north. Light northerly winds

Avalanche Summary

Last few days reports include numerous fresh natural wind slab avalanches up to Size 2.5 on southeast through northeast facing alpine slopes suspected to have occurred during a wind-loading event on Tuesday. Cornices have also been failing and could be a heavy trigger for wind and persistent slabs on the slope below. Bugaboos. Xh dropping cornices and mushrooms triggering deep instabilities to grnd in isolated features to sz 2.5

Snowpack Summary

Recent light amounts dry snow has maintained the snow supply for fresh wind slab development and cornice growth.Surface condition in wind-exposed areas is highly variable with scoured areas, sastrugi, and pockets of fresh hard and soft wind slabs. Cold temperatures are promoting surface faceting, and a new batch of surface hoar is probably growing in sheltered areas.The mid-December surface hoar/facet persistent weakness, down 40cm on the eastern side of the range and as deep as 150cm on the western side, is generally producing anywhere from easy results where it's shallow to hard results where it's deeper. But all tests consistently 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.

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