Bulletin d’avalanche

Sea To Sky

Jan 31 – Feb 1, 2018Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Fri
Sat
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

New snow and wind will keep the avalanche danger elevated at higher elevations on Thursday.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    New snow and wind on Wednesday night are expected to form new wind slabs in higher elevation lee terrain. This new snow overlies older storm slabs which are gaining strength but may remain sensitive to human triggering in steep, unsupported terrain.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1.5–2.5
    Recent heavy snowfall and high winds have formed fragile new cornices. These monsters may surprise with nasty consequences. Use extra caution around ridge crests.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Wednesday

Weather Forecast

Wednesday Night: 6-10cm of new snow / Moderate to strong southwest winds / Freezing level at 800mThursday: 3-5cm of new snow / Light southwest winds / Freezing level at 900mFriday: 8-10cm of new snow / Light southwest winds / Freezing level at 1200mSaturday: Light flurries / Light and variable winds / Freezing level at 1200m

Avalanche Summary

As recent storms have tapered-off, so has natural avalanche activity. That said, explosives control on Tuesday triggered lingering storm slabs at treeline and above - mostly in the size 1.5-2 range. The exception was a size 3 slab that was explosives-triggered on a southwest facing alpine slope.Looking forward, new snow and wind on Wednesday night is expected to promote a new round of wind slab activity in higher elevation lee terrain.

Snowpack Summary

Monday's continuing storm brought another 30-40 cm of new snow to the surface above about 1600 metres with depths that increase with elevation. At treeline and below light amounts of recent snow now overlie a melt-freeze crust. At higher elevations, extreme southerly winds have scoured the new snow from windward aspects and formed deep deposits and cornices in leeward terrain. Including the new snow, storm snow totals since mid-January have reached about 170 cm. Where they haven't been blown away by the wind, these accumulations sit on a crust from mid-January that shows good signs of bonding to the overlying snow. Other deeper layers in the snowpack include a crust that was buried in early January (now 230-280 cm below the surface) and another crust which was buried in mid-December. Although explosive control work triggered storm slab avalanches that "stepped down" to both of these crusts last week, they are expected to have formed an improved bond with the overlying snow in most areas. With that said, a heavy trigger like a cornice release may still carry the risk of stepping down to deeper layers on isolated features.

Régions couvertes