Bulletin d’avalanche

South Rockies

Mar 8 – 9, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–5
    Recent SW and NW winds have set up touchy wind slabs in lee terrain in exposed areas.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–6
    A prominent persistent weak layer from the middle of February exists in some areas, and is most prevalent in the Flathead range. If triggered, this layer has the potential to produce large and dangerous avalanches.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–4
    New snow has generally bonded well to existing snow surfaces. However, places to watch are steep rolls and unsupported, convex slopes.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Another dry day is expected for Friday. Freezing level is expected to remain high at around 2300 m and strong southwesterly winds are anticipated. For Saturday, flurries or light rain is expected, with only minimal accumulation. Winds should be moderate southwesterly and freezing levels should drop to around 1800 m. On Sunday, further light snow/rain is expected with continued southwesterly winds and freezing levels around 1700 m.

Avalanche Summary

On Wednesday, a size 2 avalanche was reported from around 2300m in the South York Creek area on an east aspect. Limited amounts of sluffing from solar activity was also noted. On Tuesday a snowmobiler was buried in an avalanche below treeline in the Flathead: more details are here: https://avalanche.ca/Forums/forums/t/5550.aspx

Snowpack Summary

20 to 50 cm of recent storm snow has been reported from different parts of this region. Winds from the SW and the NW have set up wind slabs in lee areas in exposed terrain. Warm temperatures have moistened the snow surface in many locations; where this has happened, expect an overnight freeze to set up a surface crust. The mid February surface hoar layer is now down between 40 & 100cm and is more prevalent in the west and south of the region, particularly in the Flathead. Recent snowpack tests as well as a rider-triggered avalanche on this weak layer indicate that it still has the potential to be triggered in many areas and if it is triggered, a large avalanche could result. Lingering concern remains for basal facets, particularly in shallower snowpack areas with steep, rocky start zones. Cornices are becoming well developed in response to recent winds and are likely starting to droop with the warm temperatures.

Régions couvertes