Bulletin d’avalanche

Sea To Sky

Feb 8 – 9, 2016Avalanche Canada
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Archivé · expiré 11 years ago

Danger d’avalanche

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

Continued warming and solar radiation will drive the Avalanche Danger on Tuesday. Avalanches will become more frequent and destructive throughout the day.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–4
    Cornices are huge and will become weakened by forecast warming and solar radiation. They can be destructive by themselves, and may also become the trigger for a large slab avalanche on the slope below. Use extra caution around ridge crests.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    Although recently formed storm slabs have gained significant strength, they may remain sensitive to rider triggering in high elevation lee terrain.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–4
    Rising freezing levels and solar radiation on Tuesday will spark ongoing loose wet avalanche activity on sun-exposed slopes. Loose wet avalanches may also step down to deeper, more destructive layers.

Weather Forecast

On Tuesday expect mainly clear skies, and freezing levels at about 3500m. On Wednesday the region should see increased cloud and freezing levels dropping to about 2200m. Moist snowfall (5-10cm) is forecast for Wednesday night and Thursday. Ridgetop winds should remain mainly moderate from the southwest for the forecast period.

Confidence

High

Avalanche Summary

On Monday, warming and solar radiation triggered widespread loose wet avalanche activity in steeper, sun-exposed terrain. Large cornice collapses were also observed. Of note, warming also triggered a size 3.5 avalanche on the south face of Mt Currie. Similar action is expected on Tuesday. Warming will also increase the likelihood of triggering wet slabs and deep and destructive persistent slabs.

Snowpack Summary

Rising freezing levels and solar radiation will leave most surfaces moist or wet on Tuesday. This warming will also continue to have a significant destabilizing effect on the snowpack. On Friday between 60 and 100cm of new snow fell. Strong to extreme southwest winds shifted these accumulations into deep and dense storm slabs. Cornices were already large before the storm, and new growth is expected to be fragile. About 70-100cm below the surface, you likely find a rain crust which formed on January 28th. This crust is widespread and exists up to about 2050m. Where it still exists, the mid-January surface hoar layer may be found between 130 and 200 cm below the surface. The combination of ongoing heavy storm loading and warm temperatures has flushed out this weak layer in most areas. That said, warming and solar radiation forecast for the next few days may be what it takes to wake up this deep and destructive persistent weak layer.

Régions couvertes