Bulletin d’avalanche

South Coast

Dec 22 – 23, 2014Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Wed
Thu
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

New storm snow with strong winds will quickly increase the hazard on Tuesday.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–3
    The new storm snow is adding to the storm loading from the weekend. In some areas, these storm slabs may be sitting on a hard crust with surface hoar or facets at the interface. Strong SW winds are loading leeward slopes in exposed terrain.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–5
    The increasing load of new storm snow may increase the likelihood of triggering the deeply buried weak layer from early November.

Confidence

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

Weather Forecast

A warm front will bring precipitation and rising freezing levels to the South Coast on Tuesday. The north of the region is expected to see 10-15mm of precipitation whereas the south may see 20-30mm. Freezing levels are expected to reach between 1600 and 1800m and alpine winds should be strong from the SW. On Wednesday, light precipitation is expected to continue (3-6mm) with freezing levels dropping to around 1000m and winds easing to light in the alpine. Christmas day looks to be mostly sunny with freezing levels around 700m and light NW wind in the alpine.

Avalanche Summary

A report from Monday of storm slabs up to size 2 being remote-triggering from flat areas up to 75m away.  This was reported in the NE part of the Coquihalla area.  Slabs were 40-60cm thick and were releasing on the crust/surface hoar layer. On Sunday, natural storm slab activity up to size 2 were reported at treeline and in the alpine.  Natural activity is expected again on Tuesday with additional storm loading.

Snowpack Summary

The new storm slab is typically 40-60 cm thick and sits on the rain crust/surface hoar layer that formed last week. The crust typically extends to around 2200m elevation and the surface hoar that sits above is typically 2-5mm where it exists.  In some areas, the new snow may be well bonded to this layer but in other areas the layer remains highly reactive so some local investigating may be required. Strong forecast winds on Tuesday are expected to quickly form touchy new wind slabs. The November crust is deeply buried near the ground and while triggering this layer is generally unlikely, the likelihood of triggering does increase during the storm with the additional weight of the new snow.

Régions couvertes