Bulletin d’avalanche

South Coast

Apr 18 – 19, 2021Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

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

Start (and finish) your day early to avoid exposure to sun-exposed avalanche terrain. Steer clear of cornices overhead and plan your egress route carefully.

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–3

    Cornices are at their largest at this time of year, and become weaker with warm temperatures and solar radiation.

  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    2–3

    The likelihood of wet slab avalanches increases during prolonged periods of warm temperatures, as the heat penetrates deeper into the snowpack. In the neighboring Seat to sky Region several very large wet slab avalanches have been observed in the last couple days. These avalanches are dense, destructive and can run far, reaching otherwise snow-free valley bottoms.

    Wet loose avalanche activity can also be expected on sun exposed slopes and below treeline. These avalanches are generally smaller than wet slabs but they can gather mass as they travel and reach low elevations.

Confidence

Moderate - Confidence is due to a stable weather pattern; little change is expected for several days. Uncertainty is due to the limited number of field observations.

Weather Forecast

Sunday night - Clear / light to moderate northerly wind / alpine low temperature near +5 / freezing level dropping to 2500 m

Monday - Sunny / light wind / alpine high temperature near +3 / freezing level 2500 m

Tuesday - Sunny / light wind / alpine high temperature near +3 / freezing level 2500 m

Wednesday - Sunny / light wind / alpine high temperature near +5 / freezing level 2700 m

Avalanche Summary

There have been a few reports of wet loose avalanches and cornice failures in recent days.

In neighboring Sea to Sky region, multiple wet slab avalanches were observed over the weekend near Whistler, size 2-4. Many of these involved the full depth of the snowpack, running to valley bottom. We suspect similar activity to have occurred in the South Coast region as well.

Snowpack Summary

High overnight freezing levels mean that the snow surface remains moist or wet. In places where the surface forms a crust overnight, it should quickly soften during they day with sunshine and warm temperatures. The highest elevation north aspects may still hold soft snow or wind slabs.

Cornices are large and looming along ridgelines. Sun and warm temperatures will increase the chances of cornice failures, especially when temperatures remain above zero overnight.

Terrain and Travel

  • Avalanche hazard is expected to to increase througout the day, think carefully about your egress.
  • Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Keep in mind that wet avalanches can be destructive due to their high density.
  • Avoid lingering or regrouping in runout zones.

Régions couvertes