Bulletin d’avalanche

Sea To Sky

Mar 14 – 15, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

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

On Wednesday, touchy storm slabs are expected in the high alpine. Extra caution is also required on all sun exposed slopes if the sun comes out in full force.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–4
    A weak layer down around 1 metre is creating a low probability/high consequence scenario. It may still be possible to directly trigger this layer in isolated areas or a small avalanche or cornice fall could step down to it.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    In the high alpine, recent storm snow is expected to be touchy on Wednesday, especially in wind loaded terrain. Extra caution is also needed around cornices right now.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    If the sun comes out in full force, expect sluffing from steep sun exposed slopes. Cornices will also become weak with prolonged sun exposure.

Confidence

Moderate -

Weather Forecast

Wednesday is expected to be mainly dry with a chance of sunny breaks and moderate alpine wind from the southwest. Freezing levels are forecast to drop to around 1000 m Tuesday overnight and reach around 1500 m in the afternoon. The next pulse of precipitation is expected to arrive Wednesday overnight or Thursday morning and 20-30 mm is currently forecast between Thursday morning and Friday morning. Alpine wind is expected to be moderate from the southwest on Thursday with freezing levels around 1000 m. Friday is currently forecast to be mainly dry with the next storm system arriving Friday overnight or Saturday morning.

Avalanche Summary

On Monday, natural storm slab avalanches up to size 1.5 were observed west of Bralone. In the Whistler area, explosives were triggering storm slabs up to size 2 and a skier triggered a size 1.5 storm slab on a north aspect at 2100 m elevation. Most of this storm slab activity had slab thickness of 20-30 cm but one was 80 cm thick in a wind loaded pocket. A natural cornice release was also reported on a northeast aspect at 2300 m. On Sunday, two explosives triggered size 2 storm slab avalanches were reported. One of these featured a 60 cm crown fracture and is suspected to have stepped down to a deeper weak layer, quite possibly the mid-February interface.On Wednesday, stability is generally expected to improve as temperatures drop. However, if the sun comes out, it can quickly destabilize the snowpack on sun exposed slopes. In the high alpine, the recent storm snow is expected to remain touchy, especially in wind loaded terrain.

Snowpack Summary

On Tuesday, freezing levels reached at least 2200 m and rain was reported to at least 2000 m. As temperatures drop on Wednesday, a new surface crust is expected to be widespread. The mid-February crust/facet layer is now typically down 80-120 cm. In wind loaded terrain, it may as deep as 200 cm. With 5-20 cm of faceted, sugary snow above it, this mid-February crust layer continues to produce easy, sudden results in snowpack tests and remains an ongoing concern. Below the crust layer, the mid and lower snowpack are well settled and strong.

Régions couvertes