Bulletin d’avalanche

Kootenay Boundary

Mar 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
2 · Modéré
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Points saillants

A storm slab problem is developing. Pay attention to reactivity at the new snow interface and expect danger to increase as you transition into wind exposed terrain.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    At upper elevations where the recent rain crust is not as thick and strong, there is a lingering potential to trigger deeper buried weak layers. A smaller storm slab release could be the perfect trigger.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Light snowfall and moderate southwest winds have been forming touchy storm slabs. This problem will be more pronounced in wind affected areas. Storm slabs have been reported being especially reactive over a crust currently buried about 10 cm deep

Confidence

Moderate -

Weather Forecast

Friday night: Flurries bringing approximately 5 cm of new snow. Moderate southwest winds.Saturday: Cloudy with sunny periods and scattered flurries bringing a trace to 5 cm of new snow. Light to moderate southwest winds. Freezing level to 1500 metres with alpine temperatures around -4.Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Light southeast winds. Freezing level to 1600 metres with alpine temperatures around -3.Monday: Cloudy with flurries bringing approximately 5 cm of new snow. Light southwest winds. Freezing level to 1700 metres with alpine temperatures around -2.

Avalanche Summary

Reports from Thursday showed explosives control south of Nelson producing storm slab releases up to Size 1.5 with crown depths of 10-15 cm.Reports from Wednesday showed our recent snow accumulations triggering naturally as loose moist sluffs from Size 1-2 below treeline. The recent snow also reacted to ski cutting and small cornice releases at higher elevations, producing Size 1 results. Looking forward, similar activity can be expected on Saturday as light new snow amounts accumulate and are redistributed into wind slabs in wind affected terrain. Meanwhile, the lingering possibility of persistent slab reactivity continues to demand a more cautious approach to terrain selection in the alpine.

Snowpack Summary

Roughly 20-30 cm of snow from the past few days lies over a widespread rain crust that exists at all elevations. Periodic high freezing levels and solar exposure have formed a series of thin crusts in this upper snowpack at lower elevations and on solar aspects. Moist or wet snow exists below the widespread rain crust. 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 may still be present at upper elevations and may still be reactive and become a concern as surface crusts break down with daytime warming.

Régions couvertes