Bulletin d’avalanche

South Coast

Dec 31, 2014 – Jan 1, 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
1 · Faible
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Points saillants

This is not your typical South Coast snowpack. Potentially touchy recently buried surface hoar means you need to exercise discipline with your terrain choices.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–4
    Outflow winds left the biggest wind slabs on south facing features, but slabs of varying thickness/hardness will be found on all wind exposed slopes. Some are resting on the late Dec surface hoar which may keep them sensitive to human triggering.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    3–5
    Continued warm alpine temps may reactivate a layer of small facets, mixed forms and in some places surface hoar that overlies a rain crust down 10 to 120 cm. Surface avalanches in motion may also step down to this interface.

Confidence

Poor - Wind speed and direction is uncertain on Friday

Weather Forecast

Synopsis: Warm air riding up and over the arctic air has created an above freezing layer at upper elevations that should stick around through Thursday evening. Looks like we swing back into the storm track Saturday night with a few successive systems that will likely keep things warm and wet through early next week.Thursday: Freezing Level: Valley Bottom, Above Freezing Layer 1300m to 2800m; Precipitation: Nil; Wind: Treeline: Light, NW | Ridgetop: Light, N/NW.Friday: Freezing Level: 300m; Precipitation: Trace; Wind: Treeline: Moderate, W | Ridgetop: Strong, W.Saturday: Freezing Level: Valley Bottom; Precipitation: Trace; Wind: Treeline: Light, SW | Ridgetop: Moderate, W.

Avalanche Summary

No new avalanche activity to report from Tuesday, but on Monday numerous wind slab avalanches ran naturally and were triggered by skiers/vehicles to size 2.5 on SE through SW facing features between 2000 and 2200m.A member of a very experienced ski touring party was caught and carried by an avalanche on an alpine feature near Tenquille lake Monday. Aspect/bed surface unknown at this time.

Snowpack Summary

Strong outflow winds on Dec. 28 left due north slopes mostly wind pressed, some are even scoured down to the mid Dec crust. Hard wind slabs up to a meter deep can be found on south facing alpine features and some degree of cross loading exists on everything but the most wind sheltered terrain.Three primary layers of concern: Late Dec SH (Surface Hoar): Previously covered by 5 to 15cm and present on all aspects/elevations, distribution post wind event is certainly different, but for the time being I would presume that every slope has it until proven otherwise.Mid-Dec SH: Down 60 to 80 cm, it is becoming harder to trigger, but snowpack tests are still showing that it has potential for wide propagation. It appears to be most reactive in sheltered treeline locations.Early Dec Crust: Down 40 to 100cm and reported to be on all aspects/elevations. In some places its just a crust, other spots feature mixed forms, small grained facets and even the above mentioned surface hoar on top of the crust. My gut says that surface avalanches in motion could step down to this crust. The mid pack below this crust contains several old crust layers, but they seem to have gone dormant for the time being.

Régions couvertes