Bulletin d’avalanche

South Rockies

Jan 6, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

The recent storm snow may take some time to bond, Be aware of weak layers buried near the bottom of the snowpack. Conservative route-selection is suggested.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    With over 50 cm of recent snowfall in the region and mild temperatures, expect slabs to have developed, particularly in lee terrain features. Should they release, they could step down to deeper weak layers.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–3
    A substantial amount of snowfall has loaded a weak layer of sugary faceted snow within the bottom half of the snowpack. Avalanches triggered on this layer will likely scour to the ground, resulting in large avalanches.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY NIGHT: Mainly cloudy, light southwest winds, alpine temperature -6 CSUNDAY: Cloudy with isolated flurries, moderate west winds, alpine temperature -2 C, freezing level 1100 m.MONDAY: Mix of sun and cloud, light to moderate west winds, alpine temperature -10 CTUESDAY: Mix of sun and cloud, light southwest winds, alpine temperature -6 C

Avalanche Summary

A natural avalanche cycle may have occurred in the region with the substantial amount of recent snowfall on Thursday and Friday. Additionally there is a report of an explosives controlled deep persistent slab size 2.5 release on an east aspect at 2100m on Friday.On Wednesday, a naturally-triggered large (size 3) avalanche was observed near Elkford, which likely released on Tuesday. See here. It ran full-path to valley bottom. In the far west of the region, the snowpack has been observed to be weak and touchy, as described here.

Snowpack Summary

Large variability in snow depths still exists in the region, ranging from practically no snow to almost 200 cm. Upwards of 60 cm of snow fell on Thursday and Friday above 1500 m. The snow fell with strong southwest winds. Expect the deepest deposits in the lee of terrain features. This snow will sit on previous hard wind slabs, a scoured and shallow snowpack on exposed ridges, and soft snow in sheltered areas. Below 1500 m, expect to find wet snow that will freeze into a hard crust once temperatures cool.All of this recent snow has loaded a weak snowpack. For average snowpack areas, expect to find weak and sugary faceted grains around 50 to 100 cm deep, which extend to the ground. This weak bottom half of the snowpack has been the culprit for large avalanches in the region over the past few weeks. It will take time for the snowpack to adjust to the added load.

Régions couvertes