Bulletin d’avalanche

Purcells

Jan 17 – 18, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    Fresh weak wind slabs are lurking below ridgecrests, behind terrain features, and in cross-loaded gullies. Loose dry snow and storm slabs are also easy to trigger in some locations.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–5
    Most concerning on steep, unsupported slopes, in open glades.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–6
    Susceptible to human triggers particularly from thin spots on slopes with variable snow distribution, heavy impacts, or deep penetration. If triggered, slabs are likely to release across wide areas.

Confidence

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

Weather Forecast

Wednesday: Mainly sunny with a few snowflakes possible. Cold (around -20C). Moderate to strong westerly winds. Freezing level valley floor.Thursday: Light snow possible at times. Remaining cold. Friday: The next frontal system is due to hit the region late in the day, bringing moderate-heavy snow, rising temperatures and gusty winds. Freezing level climbing near 1500m by the evening.

Avalanche Summary

Recent reports indicate loose natural and skier triggered sluffing to size 1.5 in steep terrain. In addition, there have been a few skier triggered soft slabs to size 2. Explosives testing in the southern portion of the region on Friday (size 3.5 on a north aspect at 2700m with 200cm fracture) indicates that avalanches are capable of stepping down to deep basal facets with heavy loads. Cornices have also been failing and could be a heavy trigger for wind and persistent slabs on the slope below.

Snowpack Summary

20-45 cm of low density storm snow has been redistributed by strong, gusty south-westerly winds. Cold temperatures have limited the development of storm slabs, but wind slabs and cornices are likely to build in size and consequence. Below the storm snow are various surfaces including facets, surface hoar in sheltered areas, wind crust, soft slabs and hard slabs. The mid-December surface hoar/facet persistent weakness, now down around 50cm on the eastern side of the range and as deep as 160cm on the western side, is generally producing anywhere from easy (where it's shallow) to hard (where it's deeper) results. Facets and depth hoar exist at the base of the snowpack.

Régions couvertes