Bulletin d’avalanche

South Coast

Mar 8 – 9, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré

Points saillants

Sunny skies and rising temperatures may initiate wet loose avalanches on lower elevation and/or sun-exposed slopes. Steer clear of cornices and wind-drifted areas as they have the potential to produce large avalanches. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–3

    Strong south winds have had ample snow to drift into reactive wind slabs on lee features at upper elevations. Watch for cracking, changes in snow stiffness, and the pattern of wind-drifting in the terrain where you are traveling. Triggering large wind slabs on specific features remains likely on Monday. 

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1.5–2.5

    Cornices have seen substantial growth since the last storm, and they may release naturally with the impact of solar radiation. Cornice falls can act as triggers on slopes below. 

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2

    Wet loose avalanches may release naturally on low elevation or steep sun-exposed slopes. A wet snow surface, pinwheeling or loose wet point releases out of the rocks are good indicators that it is time to back off. 

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Dry conditions for the next few days

Sunday night: Mainly cloudy, 5-10 cm of snow, light south winds, freezing level near 600 m. 

Monday: Mainly sunny, light southeast winds, freezing level rising to 1300 m by end of day and dropping to 1000 m overnight.

Tuesday: Mix of sun and cloud, light southeast winds, freezing level rising to 1300 m and dropping to 500 m overnight.

Wednesday: Mainly sunny, light to moderate northwest winds, freezing level rising to 1200 m. 

Avalanche Summary

Recent snow and cornices may become unstable due to warming from sun and rising temperatures. Cornices could reach their breaking point, like this MIN from Sky Pilot last week.

Snowpack Summary

Since Friday, the mountains in the south coast region have seen anywhere from 20-60 cm of snow that fell on a mix of previous surfaces, including a warm crust, wet snow, wind-pressed snow, and settled cold snow. This new layer has been accompanied by moderate to strong strong south winds, forming wind slabs on leeward slopes at upper elevations that may be likely to trigger. Massive cornices exist on ridgelines, which can act as triggers on slopes below. 

Below the recent snow, the snowpack consists of a series of rain crusts and settled snow that is well-bonded. 

Terrain and Travel

  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Cornice failure may trigger large avalanches.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.

Régions couvertes