Bulletin d’avalanche

South Coast Inland

Mar 6, 2018Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Wed
Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Cornices and surface snow could become weak when hit by direct sunlight.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5
    Recent storm snow may still be reactive on steep wind-loaded features, particularly on south-facing slopes where it sits above a buried sun crust.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1–2.5
    Continued snowfall and strong wind from around the clock has formed large cornices on many ridgelines. Cornices are inherently unstable, unpredictable, and demand respect, especially when the sun is out.

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

TUESDAY: Clouds clearing in the morning and then sunny in the afternoon, light west wind, freezing level rising to around 1000 m.WEDNESDAY: Sunny, light to moderate southwest wind, freezing level rising to around 1300 m.THURSDAY: Flurries increasing throughout the day with up to 5 cm of snow by the afternoon, moderate southwest wind, freezing level rising to around 1200 m.

Avalanche Summary

On Sunday, a large natural avalanche (size 2) was observed on a sparsely treed north-facing slope at 2000 m in the northern part of the region.On Saturday, one natural size 2 slab was observed on a south aspect at 1900 m in the Duffey area and another smaller slab was reported on a steep wind-loaded feature in the Coquihalla area. Wet loose avalanches were observed in steep south-facing terrain throughout the region.On Friday, wind slabs were sensitive to skier triggering to size 2 on north and northeast facing slopes around 2000 m. These slabs were 10 to 25 m wide with crowns averaging 40 cm in depth.

Snowpack Summary

A thin sun crust has formed on solar aspects and the surface is wind affected in most exposed terrain. Southern parts of the region, such as the Coquihalla, received up to 100 cm of snow last week while northern regions received closer to 40 cm.The mid-February weak layers are now 80 to 120 cm deep in the southern part of the region and about 40 cm deep in northern parts of the region. These interfaces consists of wind hardened snow, facets, a sun crust on solar aspects, and surface hoar that is present at and below treeline. Some of these layers have been reactive in snowpack tests, but no recent avalanche activity has been reported on these layers. 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