Bulletin d’avalanche

Northwest Inland

Mar 6, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Mon
Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

A few days of cool benign weather. Concerns include wind slabs at higher elevations and the ongoing potential to trigger deep persistent slabs in shallow snowpack areas.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    Gusty southwest winds at upper elevations have formed fresh wind slabs on leeward slopes and behind terrain features. Loose dry avalanches may be easily triggered below treeline or in areas sheltered from the wind.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    A lingering weakness at the bottom of the snowpack may remain sensitive to human triggering, especially in shallow snowpack areas. Smaller avalanches in motion also have the potential to step down and trigger deep persistent slabs.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

We're looking at isolated flurries and cool temperatures throughout the forecast period. MONDAY: Cloudy with scattered flurries and up to 5 cm of new snow, 20-40 km/h south winds, alpine temperatures around -14 C. TUESDAY: Isolated flurries with up to 5cm of new snow, 20-40 km/h south winds, alpine temperatures around -14 C. WEDNESDAY: Light flurries, 20-30 km/h south winds, alpine temperatures around -18 C.

Avalanche Summary

On Saturday, skiers were able to remote-trigger a storm slab (Size 1.5) on a north aspect at 1800m in the northern part of the region. On Friday, several size 1-2 natural wind slabs were reported in both the Telkwas and Sinclair areas on north and east aspects. The avalanches likely occurred during the storm on Thursday. A few small size 1 slab and loose dry avalanches running on a crust were skier triggered in steep low elevation terrain.Isolated wind slabs may still be found in alpine locations on leeward slopes behind terrain features.

Snowpack Summary

We've had up to 6cm of snow Saturday overnight into Sunday, bringing recent storm snow totals to 15-45 cm. In some areas wind effect at higher elevations resulted in wind slabs on east and north aspects. The new snow buried a variety of old snow surfaces including stiff wind slabs, facets, crusts and surface hoar. The new snow may have a poor bond to these interfaces, especially in places where the slab is stiffer and more cohesive due to winds. At treeline, the average snowpack depths are 120-190 cm and a well consolidated mid-pack of approximately up to 100 cm sits above weak basal facets (sugary snow) near the ground. Recent snowpack testing has shown sudden easy results down 25 cm on a surface hoar layer and sudden hard results down 100 cm within the faceted snow. The deeper basal weakness remain a concern, especially in thin rocky start zones and shallow snowpack locations.

Régions couvertes