Bulletin d’avalanche

Lizard-Flathead

Jan 16, 2018Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Wed
Thu
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Avalanche conditions are still very dangerous! It's hard to have any confidence traveling in the backcountry with such a complex snowpack and sustained warming.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Variable winds have redistributed loose snow into wind slabs around ridge crests and exposed terrain features. A small wind slab release may provide enough stress to trigger a deeper persistent weak layer.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–4
    Large avalanches are being triggered on a number of buried weak layers, even in fairly dense trees and shallow slope angles, including remotely triggered slides. These layers are touchy and can produce very large, destructive avalanches that run far.

Confidence

-

Weather Forecast

TUESDAY: Increasing cloud throughout the day, moderate southwest winds, mild inversion with alpine temperatures hovering around 0 C.WEDNESDAY: Light flurries in the afternoon, strong southwest winds, alpine temperatures around - 2 C.THURSDAY: 5-10 cm of new snow, strong southwest winds, alpine temperatures around -5 C.

Avalanche Summary

On Monday, a few solar triggered avalanches (up to size 2.5) were reported in steep terrain. A small wind slab (size 1.5) was also reported on a northeast alpine feature. On the weekend, explosive testing produced several large persistent slab avalanches on deep weak layers, including a size 3.5 persistent slab that failed on the November crust. This avalanche ran nearly 800 m and exceeded the path's historic runout distance. Very significant avalanche activity occurred in the region last week, and the potential for more large avalanches remains.

Snowpack Summary

Warm alpine temperatures are rapidly settling recent storm snow as well as forming moist snow on solar aspects. More importantly, warming is stressing deeper layers in the snowpack. The early January surface hoar layer is roughly 60 cm below the surface and the unstable weak layer from mid-December (predominantly surface hoar and/or a sun crust) is found roughly 100 cm below the surface at treeline and below treeline elevations. Below, a rain crust that developed late-November with associated sugary facets is also being stressed. Snowpack test results show sudden fracture characters and high propagation potential for all of these buried layers, indicating that they can be triggered and could propagate into large, destructive avalanches.

Régions couvertes