Bulletin d’avalanche

Northwest Coastal

Jan 5 – 6, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Wed
Thu
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué
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Points saillants

Storm conditions will keep the hazard elevated in the south of the region for the next couple days. Stick to simple, mellow terrain and give the storm snow a few days to stabilize.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–6
    There are a couple buried persistent weak layers in the upper and mid snowpack, primarily in northern areas like Bear Pass and Ninginsaw Pass. The weight of the new snow may increase the likelihood of triggering one of these layers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    2–5
    Heavy snowfall and strong winds have built storm slabs in the south of the region. In the northern areas that received less snowfall, wind slabs are the primary concerns.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The next storm pulse hits the NW on Monday night. Southern parts of the region may see 30-40mm of precipitation whereas the north is around 10-20mm. Alpine wind is expected to be strong from the SW and treeline temperatures are expected to be around -10C. There will be a bit of a break during the day on Tuesday before the next storm pulse hits on Tuesday night. Another 10-20mm is possible for the south and 5-10mm for the north. On Wednesday, a temperature inversion is expected to form and a layer of above-zero air may sit in the alpine. Light precipitation is possible and winds are expected to be moderate from the SW. Thursday looks to be the warmest with freezing levels reaching up to 2500m. The inversion should keep the valleys cooler. Dry conditions are expected on Thursday with light winds.

Avalanche Summary

On Sunday, several natural avalanches were reported. These were primarily wind slabs on W through N aspects and were up to size 3 avalanches. Natural storm and wind slab avalanches are expected to continue on Tuesday and Wednesday as storm conditions continue.

Snowpack Summary

Conditions are highly variable throughout the region. Southern sections near Terrace received around 30 cm of new snow while Bear Pass and Ninginsaw didn't see any new snow on Saturday night. Strong winds are one common theme in all areas though. Ridge winds were cranking from the SE stripping windward slopes bare and probably forming hard or dense wind slabs in lee and cross-loaded areas. A buried surface hoar layer, down 25-35 cm, may be more prevalent in northern sections like Bear Pass and Ninginsaw Pass. The mid December crust can be found down around 40 to 80 cm and is sandwiched with facets and surface hoar. The November crust, down 70 to 175 cm, is gaining strength but is still reactive in some test profiles. The deeper snowpack weaknesses could 'wake up' with heavy loading from new snow and wind.

Régions couvertes