Bollettino valanghe

Purcells

Jan 12 – 13, 2012Avalanche Canada
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Archiviato · scaduto 15 years ago

Pericolo valanghe

Sat
Sun
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Apri la mappa completa

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    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

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    3–5
    Most concerning on steep, unsupported slopes, in open glades glades.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    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

Friday: Cloudy but dry, with freezing levels in valley bottoms and moderate to strong westerly winds. Saturday: 5-15cm of accumulation expected with freezing levels remaining in valley bottoms, and strong southwesterly winds. Sunday: Unsettled conditions with light snowfall, light to moderate southwesterly winds, and freezing levels in valley bottoms.

Avalanche Summary

Recent reports include numerous fresh natural wind slab avalanches up to Size 2.5 on southeast through northeast facing alpine slopes suspected to have occured 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.

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.

Regioni coperte