Bulletin d’avalanche

South Coast Inland

Mar 3, 2018Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Keep a close eye on the effects of the strong late-winter sun on Saturday, even brief periods of direct sun could initiate natural avalanche activity.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Strong wind and snowfall this week formed wind slabs that are becoming less sensitive to triggering. Scattered cloud cover and light northerly wind should limit the effect of the sun, but even brief solar periods could initiate natural avalanches.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    Large cornices have formed along ridgelines. Cornices are inherently unstable, unpredictable, and demand respect, especially if the sun is shining.

Confidence

Low - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

We are moving into a high and dry period for the foreseeable future. Northwest flow across the province will allow a couple of shortwave troughs to ripple along the upper flow giving a mix of sun and cloud. At this time, precipitation amounts will be insignificant.SATURDAY: Scattered cloud cover, freezing level rising to around 800 m, light north/northeast wind, trace of precipitation possible.SUNDAY: Scattered cloud cover, freezing level rising to around 1000 m, light west/southwest wind, no precipitation expected.MONDAY: Broken cloud cover, freezing level rising to around 800 m, light west/southwest wind, no precipitation expected.

Avalanche Summary

On Thursday wind loaded features produced natural avalanches to size 2.5. Several natural wind slab avalanches to size 2 were observed on steep north facing alpine terrain. Control work produced avalanches to size 2 in steep unsupported terrain.On Wednesday a natural size 1 wind slab was reported from an east facing feature at 1950 m. Isolated soft wind slabs were also being observed on steep convexities.Several small wind slab avalanches 15 to 25 cm in depth were susceptible to ski cutting Tuesday on north, northeast and east facing features between 1800 and 2000 m.

Snowpack Summary

The region picked up 10 to 40 cm of storm snow this week accompanied by wind mainly out of the southeast, south and southwest. As the storm exited the region Thursday winds shifted to the east/northeast. This new storm snow rests on top of old wind slabs that are becoming more stubborn and somewhat resistent to human triggering. The February 23 weak layer is now down 30 to 70 cm below the surface. This interface consists of wind hardened snow, facets, a sun crust on solar aspects and surface hoar that is present at and below treeline. Compression tests preformed Thursday continue to show planar results at this interface. The mid and lower snowpack are well settled and strong.Variable winds in the past month have created cornices on many alpine ridgelines. They will become touchier as they grow in size, as temperatures rise, and as the strong late-winter sun shines down upon them on clear days.

Régions couvertes