Bulletin d’avalanche

Northwest Coastal

Feb 24 – 25, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Wed
Thu
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué

Points saillants

Avalanche danger will rise on Tuesday due to rapidly rising temperatures and the presence of a significant buried persistent weak layer. Stick to low angle terrain that is not exposed to overhead avalanche paths.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Outflow winds have created touchy wind slabs in exposed lee and cross-loaded terrain at all elevations.
  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–5
    Rapidly rising temperatures will likely increase the probability of avalanches releasing on the buried mid February persistent weak layer. The resulting slides could be very large and destructive.
  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3
    A loose wet avalanche could drag you somewhere you don't want to end up, but could also be enough mass to trigger a large slab avalanche.

Confidence

Fair

Weather Forecast

Tuesday: Mainly sunny. A strong alpine temperature inversion is likely between 1500 and 2300 m. Treeline temperatures should be near +5. Temps may remain cooler further inland. Outflow winds should ease off during the day.  Wednesday: A mix of sun and cloud. The freezing level on the coast remains near 2300 m and near surface inland. Winds are light and variable.Thursday: A mix of sun and cloud with a chance of precipitation near the coast. The freezing level on the coast remains near 2000 m and near surface inland. Winds are light and variable.

Avalanche Summary

Numerous natural and skier triggered wind slabs up to size 2 were reported on Sunday in response to the outflow winds. A few large remotely triggered slab avalanches were reported in the Shames backcountry on Saturday. These were primarily from open alpine and treeline terrain and probably released on the February persistent weakness. In addition, a size 2.5 accidentally triggered slab avalanche was reported in the northern part of the region on saturday. This slide released on basal facets in steep rocky alpine terrain.

Snowpack Summary

Strong N-SE outflow winds have resulted in reverse loading and cross loading in exposed terrain at all elevations, and have scoured exposed windward slopes. The prominent mid February persistent weakness (surface hoar, facets, crust and/or wind pressed surfaces) is down 60-100 cm in the north and 120-160 cm in the south. Snowpack tests are now giving moderate to hard "pops or drops" shears on this weakness, and several whumpfs are still being reported. Basal facets and/or depth hoar remain a concern in shallow snowpack areas in the northern part of the region. Cornices are also large and may become weak if northerly winds start to undercut them.

Régions couvertes