Bulletin d’avalanche

South Coast Inland

Mar 24 – 25, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Saturday will bring the end of the storm as well as a chance solar exposure. Wind slabs are already primed for human triggering, but a touch of sun may make them especially reactive.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Light new snow amounts combined with moderate to strong southeast to southwest winds have been building wind slabs in the lee of exposed terrain features. A chance of sun exposure may make these slabs especially reactive on Saturday.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Recent warm and windy weather has been promoting cornice growth. While they are a hazard in themselves, the danger increases with wind slabs sitting beneath them. The chance of solar exposure may promote natural cornice falls on Saturday.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–4
    In northern parts of the region, heavy triggers such as a cornice fall or a wind slab avalanche could potentially step down to weak layers buried about 1 m deep.

Avalanche Summary

Reports from Thursday showed both natural and skier triggered storm and wind slabs releasing from Size 1-2 in the north of the region. Wind slabs were noted releasing above the melt freeze crust that was buried on March 22. In northern parts of the region, the deeper February weak layers continue to present a low probability / high consequence avalanche danger scenario.

Confidence

Moderate -

Weather Forecast

Friday night: Flurries bringing 5-10 cm of new snow. Strong southwest winds.Saturday: Mainly cloudy with continuing isolated flurries and a trace of new snow. Moderate southwest winds. Freezing level to 1300 metres with alpine temperatures around -5.Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Light southeast winds. Freezing level to 1300 metres with alpine temperatures around -5.Monday: Cloudy with isolated flurries and a trace of new snow. Light to moderate southwest winds. Freezing level to 1700 metres with alpine temperatures around -1.

Snowpack Summary

Steady light snowfalls over the week have deposited 20-30 cm of heavily wind affected new snow at upper elevations. Periodic rises in freezing levels to 2000 metres or higher over the same time period have been setting up a series of crust layers (March 20, 22, 23) within the upper snowpack at lower elevations and on solar aspects. A more widespread thick rain crust (March 15) exists up to 2100m and is now buried approximately 45-70cm below the surface. In the north of the region, the February weak layers are 100-140 cm deep and include a buried surface hoar layer that recently produced a few persistent slab avalanches and a crust/facet layer that appears to be gaining strength. In the southern parts of the region, the mid and lower snowpack are generally well settled and strong.

Régions couvertes