Bulletin d’avalanche

Kootenay Boundary

Mar 17 – 18, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

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

Saturday's storm has all of the the ingredients for large avalanches. Travel in avalanche terrain is not recommended.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–4
    The storm will also create the potential for very large avalanches on buried persistent weak layers. Smaller avalanches or cornices are likely triggers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–3
    Heavy amounts of new snow and warming will form very touchy storms slabs and widespread natural activity. Extreme winds and cornices will add to the danger.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Rain at lower elevations will likely produce wet snow avalanches in steep terrain, including forested areas.

Confidence

High -

Weather Forecast

FRIDAY NIGHT: Storm begins with 10-20 cm, strong southwest winds, and freezing level around 1500 m.SATURDAY: Storm continues with another 15-30 cm (and possibly more around Kootenay Pass), strong to extreme southwest winds, freezing level climbing up to 2000 m.SUNDAY: Clearing skies following the storm as alpine temperatures drop to around -8 C, light west winds.MONDAY: Sunny with cloudy periods, alpine temperatures around -5 C, light winds.

Avalanche Summary

Reports continue to come in about a widespread natural avalanche cycle that occurred during last week's rain event. Avalanches were reported on all aspects and elevations, many up to size 3 and over 100 cm deep. A few large cornice failures occurred as well. Several avalanches in the Bonningtons were reported to step down to the late-February interface, and similar step downs likely occurred in other areas as well. Avalanches at lower elevations entrained significant amounts of wet snow. Activity tapered off on Thursday, but the snowpack has not yet had to time to adjust to the heavy loading and warming.On Saturday, heavy precipitation and warming will result in another round of large natural avalanches with the potential to step down to deep weak layers.

Snowpack Summary

A juicy storm will start as snow on Friday night and switch to rain in the morning to form very touchy storm slabs at high elevations and unstable wet snow at lower elevations. Extreme southwest winds will have a dramatic effect on all exposed terrain and likely form touchy cornices. The storm is burying a rain crust that exists up to about 2200 m. Several deeper weak layers were tested during last week's storm including the late-February facet / surface hoar interface (70-120 cm deep), the mid-February crust (90-130 cm deep), and basal facets in shallow snowpack areas. These layers may remain reactive with additional loading and warming.

Régions couvertes