Bulletin d’avalanche

Lizard-Flathead

Jan 31, 2018Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Continual reports of large destructive avalanches in this region highlight the importance of sticking to simple low-angled terrain and avoiding overhead hazards like cornices.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2.5
    New snow and has formed storm slabs, while winds are building fragile cornices and loading lee slopes. Storm slabs have shown the potential for wide propagations and running long distances.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–4
    Several deeply buried weak layers are producing large destructive avalanches. Cornices have been a common trigger, so be sure to avoid exposure to overhead hazards.

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

WEDNESDAY: Isolated flurries with trace accumulations / light to moderate west wind / alpine temperatures around -8 C.THURSDAY: Isolated flurries with trace accumulations / light to moderate west wind / alpine temperatures around -8 C.FRIDAY: Isolated flurries with accumulations of 5-10 cm / moderate west wind / alpine temperatures around -5 C.

Avalanche Summary

Large storm slab and deep persistent slab avalanches continue to be reported every day.On Tuesday, numerous large avalanches (size 2-3.5) were triggered naturally as well as with explosives. Many of the natural avalanches were triggered by cornices falling and releasing slabs on the December and November layers, producing 150-250 cm thick crowns. See the avalanche photos in this Mountain Information Network report.Similar activity over the past few weeks highlights the sustained dangerous conditions in this region.

Snowpack Summary

The most recent snowfall was accompanied with strong gusty winds, leaving touchy slabs in the alpine and large fragile cornices. Warm temperatures on Monday left moist snow and crusts up to 1700 m.About 60-80 cm of settled storm snow now covers a layer of surface hoar on sheltered aspects (especially prominent from 1400-1900 m) and sun crust on solar aspects, that was buried mid-January. Beneath the mid-January interface lie a number of very concerning buried weak layers. A layer of surface hoar from early-January is buried 90-110 cm below the surface. A weak layer buried mid-December (predominantly surface hoar and/or a sun crust) is around 120-160 cm below the surface at treeline and below treeline elevations. A rain crust with sugary facets buried late-November is near the bottom of the snowpack and is now up to 200-250 cm below the surface. All of these layers remain active and have produced recent large, destructive avalanches.

Régions couvertes