Bollettino valanghe

Northwest Coastal

Dec 3 – 4, 2012Avalanche Canada
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Archiviato · scaduto 14 years ago

Pericolo valanghe

Wed
Thu
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–6
    Basal facet/crust weaknesses are 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 and destructive.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely - Very Likely
    Dimensione
    1–5
    New storm and wind slabs have formed; especially on lee slopes and behind ridges. Natural activity is likely with continued loading, and rider triggers are very likely.

Confidence

Poor - Due to limited field observations

Weather Forecast

A broad upper trough remains just offshore while a cooler, unstable onshore westerly flow has strengthened.  A multitude of systems will bring light –moderate precipitation, and strong SW winds. The region returns to normal seasonal temperatures, as the arctic air retreats.Tuesday: Freezing levels near 500 m, snow amounts 15-25 cm, ridgetop winds SW 50-70 km/hr, alpine temps -7.Wednesday: Freezing levels near 500 m, snow amounts 2-5 cm, ridgetop winds W 30 km/hr, alpin temps -9.Thursday: Freezing levels at the surface, snow amounts 5-10 cm, ridgetop winds SW 20 km/hr, alpine temps -11.

Avalanche Summary

On Sunday in the Shames area, a fairly large (no size was listed) natural avalanche had was seen on a North aspect initiating from the alpine just below the ridgeline. A couple skier triggered size 1.5 slab avalanches were reported from the same group skiing down from the Dome. The slab initiated as the second skier made a turn over a convex slope. The slab was 20-40 cm deep, 20-30 m wide and ran approx. 50 m down slope. For more information and observations from the area, please check out the Regional Forum Posts.

Snowpack Summary

Recent observations suggest that the alpine is fairly wind hammered from the steady, moderate SE winds. Hard slabs, storm, and wind slab instabilities exist at treeline and in the alpine. Recent test results done in the upper storm snow show an easy (RP) shear down 20-25 cm and a hard (RP) down 80 cm. The mid-pack is gaining strength and is well settled.Digging down deeper is the early November facet/crust layer. This crust sits near the base of the snowpack, and tests done in the Bear Pass area around 1100 m have shown this layer to be unreactive. Testing done in the Shames area on this interface have also shown no results, with moist snow below.Total snowpack depth is around 150-180 cm at treeline, and deeper but more variable in the alpine. The snowpack at below treeline elevations is near 100 cm deep, and reported to be strong.

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