Bulletin d’avalanche

Northwest Coastal

Mar 15, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

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

Weak disturbances with little new snow and wind suggest little change to conditions and danger ratings. Watch for warming forecast later this weekend!

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    A weak layer buried around 60 cm below the surface sits only a little below the recent storm snow and has recently been reactive.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1.5–2.5
    Storm snow concern is greatest in colder areas in the north. Forecast winds focus concerns to wind loaded features.Previous weaknesses in the upper snowpack (30 - 40 cm of sugary facets) were activate during the storm; see Persistent Slabs below.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

THURSDAY NIGHT: 5-10 cm of additional snow. South winds 30-50 km/h. Freezing level around 500 m.FRIDAY: More snow, around 10 cm. Freezing level around 900 m. Moderate southerly winds.SATURDAY: Moderate snow, around 10 to 15 cm most of it arriving early as the weather dries out during the day. Freezing level around 1100 m. Light southerly winds.SUNDAY: Continued warming with freezing level reaching around 1900 m.

Avalanche Summary

Recent avalanches can be divided into two classes -- light triggers and large triggers. For light triggers there are reports of wind slabs up to size 2.5 on northerly aspects in northern areas . Throughout the region there were reports of a solar triggered cycle up to size 2 on solar aspects. Closer to Terrace there was a report of small soft slab triggered by a skier, a wind slab cycle up to size 1.5 (due to some strong southerly winds), and some loose dry avalanches, possibly as large as size 2. Most recent avalanche activity was a result of larger triggers, namely explosives. Explosive tests and control resulted in mostly size 2 avalanches but some inland areas in the east side of the region avalanches up to size 3.5 were triggered.

Snowpack Summary

Continued snowfall is adding to the 40-60 cm of previous storm snow. The recent snow is settling but is covering a wide variety of old snow surfaces: crusts on solar aspects, facets up high, and surface hoar in sheltered locations. Not much further below this storm snow interface is a second weak layer buried on February 19 made up of weak facets and surface hoar crystals. Recent avalanche activity was more or less equally split between these two layers.The lower snowpack is generally strong.

Régions couvertes