Bulletin d’avalanche

Northwest Coastal

Dec 26 – 27, 2013Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Sat
Sun
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–7
    Primarily a concern in northern sections. A number of buried persistent weaknesses exist in the mid-snowpack and a crust/facet layer lurks near the base of the snowpack. Triggering is possible in shallow snowpack areas. 

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–4
    Heavy snow and strong winds have created touchy storm slabs everywhere, with wind slabs on north through east facing aspects at higher elevations. Rider triggering remains likely.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Friday: Heavier precipitation should ease off by morning, then cloudy with flurries (5-10 cm). The freezing level lowers to around 800 m. Winds are light to moderate from the W-NW. Saturday: Cloudy with flurries or periods of snow 5-10 cm. The freezing level is near 500 m and winds are light to moderate from the southwest. Sunday: Periods of snow 10-20 cm. The freezing level should climb to 1500 m.

Avalanche Summary

It is likely that a natural avalanche cycle is ongoing Thursday morning with continued heavy precipitation, mild temperatures and strong winds. On Wednesday, several natural and explosive controlled avalanches up to size 2 were reported, but observations were limited. Natural avalanche activity should taper off on Friday as temperatures cool slightly and precipitation eases off; however, rider triggering remains likely.

Snowpack Summary

The stormy weather pattern continues with another 15-30 cm accumulating by Thursday morning (and more expected through the day). Temperatures have been mild with rain up to treeline in parts of the region. Winds have also been strong from the W-SW resulting in continued wind slab formation in exposed lee terrain. The December 22nd surface hoar layer is now over 100cm deep in southern sections and around 50 cm further north. This layer may have been flushed out in many areas, but remains a concern on slopes that have not released or where less snow has accumulated. The mid pack features several persistent weak layers but these have likely gained strength at this point. In the north of the region a basal facet and crust combo lingers near the ground and is most prevalent on NW - E facing aspects at the upper TL and alpine elevations.

Régions couvertes