Bulletin d’avalanche

Purcells

Jan 10 – 11, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Sun
Mon
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué

Points saillants

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–5
    Two persistent weak layers exist in the upper meter of the snowpack. Intense loading from snow and wind could overload these weakness, potentially creating very large avalanches. 
  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–5
    Some areas could see 50 cm of new snow by the end of the weekend. Winds are also expected to be very strong from the W-SW. Expect deep and touchy wind slabs in exposed lee terrain.
  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–6
    This layer could become reactive again this weekend. This problem could be triggered by intense loading from snow and wind, or a smaller avalanche could step down and create a very deep and large avalanche.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Saturday: Moderate to locally heavy snow – around 10-15 cm by morning and another 15-20 cm on Saturday. Winds are strong from the S-SW. The freezing level may jump to around 1500 m briefly before dropping slightly on Saturday.Sunday: Mainly cloudy with periods of light snow. The freezing level should be near valley bottom and winds are strong from the W-NW. Monday: Cloudy with flurries. The freezing level should jump to around 1400 m and winds remain strong and gusty from the W-NW.

Avalanche Summary

There have been a few different close calls with large avalanches in the north of this region in the last three weeks. Check out the incident database for more details. Reports from the last 4 days indicate several natural cornice triggered avalanches running to size 3 on east and southeast aspects at treeline and above.

Snowpack Summary

Up to 20 cm of new snow sits on a variety of snow surfaces ranging from stiff wind slab, a soft layer of facetted snow and/or surface hoar. These sit on top of old wind slabs and a couple of persistent weak layers that exist in the upper meter of the relatively thin snowpack. The mid December surface hoar is buried around 30-90 cm. The early December facet/crust combo is buried down 50-150 cm. Both interfaces give variable results with snowpack tests, but professional operators are treating them with caution.A bigger concern, especially in the Northern part of the region is a layer of weak sugary depth hoar crystals at the base of the snowpack that lie above a crust from early October. Several large avalanches in the last two weeks have been attributed to failures at this layer. Wide propagations on relatively gentle terrain have been noted, as well as a tendency for seemingly disconnected slopes to become connected by one large avalanche.

Régions couvertes