Bulletin d’avalanche

Northwest Inland

Feb 19 – 20, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Mon
Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible

Points saillants

Benign weather this week. Watch for isolated wind slabs and shallow snowpack areas where triggering a deep persistent slab avalanche remains possible.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2
    Watch for wind slabs on lee and cross-loaded terrain.
  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–4
    A weakness at the bottom of the snowpack is lingering and may be triggered in shallow snowpack areas or by the weight of smaller avalanches.

Avalanche Summary

On Saturday, numerous small natural wind slabs (size 1-1.5) were reported on northwest aspects around treeline. Small loose dry avalanches running above the rain crust were reported in steep terrain. Watch for isolated pockets where thicker wind slabs could produce larger avalanches. Also keep in mind that a basal weakness continues to drive a low probability/high consequence avalanche problem for the region. Very large avalanches remain possible, especially in shallow snowpack areas.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY: Isolated flurries with trace accumulations, light south winds, alpine temperatures around -8 C.TUESDAY: Cloudy with sunny periods, light northwest winds, alpine temperatures around -10 C.MONDAY: Mix of sun and cloud, light northwest winds, alpine temperatures around -12 C.

Snowpack Summary

Clear cold weather and shifting winds have created a variety of surface conditions including isolated wind slabs, pockets of soft snow (5-10 cm deep), sun crusts, and surface hoar. A supportive rain crust exists below 1000 m. A layer of surface hoar that was buried on February 10th may exist 30-60 cm below the surface, but there's a fair bit of uncertainty regarding the reactivity and distribution of this layer. A stiff mid pack sits above weak sugary snow near the ground. Although possibly dormant, this basal weakness has the potential to produce very large destructive avalanches.

Régions couvertes