Bulletin d’avalanche

South Coast

Jan 7 – 8, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Fri
Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Avalanche conditions are improving quickly but problems still exist.  Use extra caution on steep south facing slopes when the sun is out.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    3–6
    Persistent weak layers down over 1m remain a concern. A smaller avalanche may step down to one of these layers or a heavy trigger like a cornice fall may be able to trigger one of these layers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–5
    Triggering storm slabs in not likely in areas that are capped with a surface crust.  Caution is still required in drier areas or where the crust is breakable.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    If the snow surface is moist or wet, sluffing is expected from steep terrain features. Use extra caution on or below sunny slopes. A wet sluff has the potential to trigger a larger slab avalanche.

Confidence

Fair

Weather Forecast

A strong warm ridge of high pressure is the dominate feature for Thursday. Mostly sunny conditions are expected with alpine winds remaining light. Freezing levels should reach over 3000m with the warmest layer of air sitting around 2000m (+5 deg C or warmer). Conditions are expected to change on Friday. The warm air will break down and freezing levels should fall below 1000m by the end of the day. Alpine winds are expected to be moderate from the SW and it will be mostly cloudy. 2-4mm of light precipitation is expected Friday overnight. Saturday is forecast to be a mix of sun and cloud, and mostly dry. Freezing levels should remain below 1000m and alpine winds should be light.

Avalanche Summary

Explosive testing on Wednesday triggered only isolated pockets of storm snow. A natural cycle was reported on Monday and Tuesday.  Natural avalanches are not expected on Thursday expect possibly loose wet sluffing from steep terrain features.  Ski triggering is unlikely in areas that are capped with a supportive surface crust.

Snowpack Summary

Rain and warm air melted the snow surface at most elevations and cooling Tuesday overnight refroze the surface creating a supportive crust. Reports are suggesting the upper 30-40cm of the recent storm snow is/was moist or wet. Below this is dry storm snow that is less dense creating upside-down conditions but this is expected to settle out quickly with continued warm temperatures. The total storm slab is around 50-70cm thick and sits on a previously variable snow surface that included wind affected surfaces, a freezing rain crust or sun crust, and/or surface hoar or sugary facets in sheltered terrain. The bond between the storm slab and the layer below is reported to be gaining strength but may still be touchy in isolated areas. In the middle and lower snowpack we might find the mid-December surface hoar or crust/facet weak layers. These are now typically buried 1m or more. The old surface hoar layer may be found in sheltered shady areas at and below treeline, while the crust/facet layer is expected to be more widespread but also more variable.

Régions couvertes