Bulletin d’avalanche

Northwest Coastal

Nov 26 – 27, 2012Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the forecaster's blog for further details on interpreting early season bulletins.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–4
    Recent strong winds have created deep wind slabs on a variety of aspects, which may be sensitive to triggering on steep convex shaped slopes.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–5
    A crust near the base of the snowpack remains a concern. It may be difficult to trigger an avalanche on this layer, but if you do the consequences could be very serious.

Confidence

Poor - Due to limited field observations

Weather Forecast

Synopsis: A ridge of high pressure over southern BC should maintain dry conditions on Tuesday; however, expect thickening cloud as a frontal system approaches the region from the west. The system should give moderate precipitation on Wednesday and Thursday. Tuesday: Increasing cloud with flurries possible late in the day. Freezing level at around 500 m. Winds light from the southwest. Wednesday: Periods of snow – 10-20 cm. Freezing level steady at around 300 m. Thursday:  Periods of snow or flurries – 5-10 cm. Freezing level at the surface.

Avalanche Summary

A few small natural slab avalanches were reported in the Shames backcountry on Sunday. These were generally 20 cm deep, failing within the recent storm snow. Some larger avalanches (up to size 2.5) were also observed in surrounding areas. Slope testing on several small steep slopes on Sunday afternoon produced no results. Human triggered avalanches remain possible on Tuesday, particularly in exposed wind loaded terrain. The potential for natural avalanches may increase again on Wednesday with more snow and stronger winds forecast.

Snowpack Summary

60-80 cm of storm snow fell in the past few days, accompanied by shifting south to northwest winds. Weaknesses may exist within or under the storm snow. Expect deep wind slabs in exposed lee terrain and in cross-loaded gullies or terrain features. A recent profile at 1200m in the Shames area showed a thin layer of facets sitting on a crust 35cm off the ground. A snowpack test produced easy results on this layer, but the resistant fracture didn't propagate across the entire column. Total snowpack depth are probably around 150 cm in most treeline areas and deeper but more variable in the alpine. The snowpack below treeline may still be below threshold depth for avalanches in some areas. Check out the Skeena/ Babine discussion forum for more information from the area.

Régions couvertes