Bulletin d’avalanche

South Rockies

Jan 5, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Sun
Mon
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Buried weak layers will take some time to strengthen with all the recent snowfall. Best to avoid alpine avalanche terrain and overhead exposure.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–2
    With over 50 cm of recent snowfall in the region and mild temperatures, expect touchy 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
    Likely - Very 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

FRIDAY NIGHT: Mostly cloudy, freezing level 1000 m.SATURDAY: Mostly clear, light southwest wind, alpine temperature -5 C, freezing level 1000 m.SUNDAY: Cloudy with light snowfall, accumulation 5 cm, light to moderate southwest winds, alpine temperature -5 C, freezing level 1300 m.MONDAY: Mostly cloudy, light to moderate west winds, alpine temperature -10 C, freezing level below valley bottom.

Avalanche Summary

A natural avalanche cycle may have occurred in the region with the substantial amount of recent snowfall. It may take a bit of time for us to obtain observations and determine the extent of what the storm did in the region.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. New snow is loading this weak and touchy snowpack and increasing the likelihood of avalanche activity.

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