Boletín de aludes

Northwest Coastal

Nov 29 – 30, 2012Avalanche Canada
Ver en el mapa
Archivado · caducó 14 years ago

Peligro de aludes

Sat
Sun
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
Abrir el mapa completo

Lo esencial

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    2–6
    Basal facet/crust weaknesses are often prone to remote triggering and step down avalanches, and typical trigger points include thin rocky areas. They may be difficult to trigger, but deep persistent slab avalanches are often very large.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely - Very Likely
    Tamaño
    1–4
    New storm slabs will build and hide old wind slabs. Reverse loading may occur and form new wind slabs on opposite slopes, which may surprise you. Natural activity is possible with continued loading, and rider triggers are likely.

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Cool arctic air remains embedded in Northern Regions bringing light snow amounts and moderate SE winds. Strong outflow winds will persist through Friday, easing off Saturday. The arctic air will keep cold surface temperatures through the weekend with no inversions. Friday: FLVL’s surface, snow amounts near 5 cm, ridgetop winds SE 30 km/hr with strong valley outflows, alpine temps -12.Saturday: FLVL’s surface, snow 5-8 cm, ridgetop winds SE 20km/hr, alpine temps -9.Sunday: FLVL’s surface, snow amounts 5-10 cm, ridgetop winds SE 25 km/hr, alpine temps -11.

Avalanche Summary

No recent avalanche activity has been reported.The most recent reports came in on Wednesday with a notable event that occurred earlier in the week, during a period of colder temps where natural icefall induced avalanches occurred size 2.5-3.0. On Tuesday a flight through the Bear Pass area saw numerous old (previous 3 days) large natural avalanches. These were size 2-3, 50-80 cm deep, in the immediate lee around 1600-2000 m. Last Monday around the Shames area a size 3.0 avalanche was observed on a north-northeast aspect at 1500m, which may have been a thick wind slab or possibly released on a facets near the ground.Natural avalanche activity will likely pickup again with more snow and wind in the forecast. Rider triggered avalanches are likely, particularly in exposed wind loaded terrain.

Snowpack Summary

New storm slabs and wind slabs instabilities will be developing through the forecast period and continue to load a couple of weaknesses that exist lower in the snowpack. The first weak layer (from the top down) lies an old storm snow weakness from the past week. This has been found down around 60-80 cm. I suspect the cooling trend that existed in the earlier part of the week may have helped stabilize that interface. If it's still reactive, the current new snow load may act as a trigger, and larger avalanches could occur. The second weakness sits near the base of the snowpack. A recent profile at 1200m in the Shames area showed a thin layer of facets sitting on a crust 35cm off the ground. An Extended Column Test produced easy results on this layer, but the resistant fracture did not propagate across the entire column. Total snowpack depth is probably around 150cm in most treeline areas and deeper but more variable in the alpine. The snowpack below treeline may still be below threshold depth for avalanches in some areas. Check out the Skeena/ Babine discussion forum for more information from the area.

Regiones cubiertas