Bulletin d’avalanche

South Rockies

Jan 12, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Wind is a critical factor and changing winds may build fresh and reactive wind slabs.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Recently formed wind slabs may still be reactive to human triggering. Changing wind directions may build  wind slabs on all aspects.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    Where stiffer snow overlies weak, sugary snow, there is the potential to trigger large, destructive avalanches.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Arctic air continues to be entrenched in the South Rockies. The pattern will start to shift Thursday to a zonal flow, allowing Pacific frontal systems to make way into the region early next week. Little change is expected  for the weekend.Thursday/ Friday/ Saturday: Mix of sun and cloud with a strong alpine inversion bringing temperatures near -15 and valley bottoms -20.  Ridgetop winds light-moderate from the West.

Avalanche Summary

On Tuesday, ski cutting produced numerous size 1-1.5 loose dry avalanches from steeper terrain features. Switching winds on Thursday may build new and reactive wind slabs. Variability in the winds has been the name of the game and wind slabs may be found on all aspects at upper elevations. Persistent slab avalanches also remain an ongoing concern, creating a low probably, high consequence problem for the region. Extra caution is recommended in shallow snowpack areas.

Snowpack Summary

15-20 cm of recent snow has buried variable old snow surfaces which consists of heavily wind scoured surfaces or old wind slabs in exposed terrain, surface hoar in sheltered terrain, and/or widespread faceted old snow. Recent moderate winds from a variety of directions is expected to have redistributed some of this new snow on leeward slopes. The mid pack appears to be quite variable throughout the region and the structure is dependant on snow depth. In deeper snowpack areas, the snowpack appears to be well settled and right side up with isolated concerns for the mid-December weak layer. In shallow snowpack areas and lower elevations, the snowpack is heavily faceted and there are concerns for the mid-December weak facet layer as well as weak basal facets. Due to inconsistencies in snowpack structure throughout the region, its a good idea to dig down and test weak layers in your local riding area.

Régions couvertes