Bulletin d’avalanche

South Columbia

Mar 18 – 19, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    New snow and wind over the weekend created new wind slabs. Watch for loading on a variety of aspects due to variable wind directions. Recent winds also formed large cornices which may be large and destructive.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–6
    About 1m of snow overlies surface hoar or a sun crust buried on March 10th. Although triggering has become less likely, avalanches on this layer could be surprisingly large and destructive. Watch for increased reactivity with forecast sun on Tuesday.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Forecast sun on Tuesday may pack enough punch to trigger loose wet avalanches on sun-exposed slopes. Reactivity may be higher do to the presence of a crust which currently underlies loose dry snow.

Weather Forecast

Tuesday: Mix of sun and cloud / Light to moderate southwest winds / Freezing level at 1200mWednesday: Moderate to heavy snowfall /  Strong to extreme southwest winds / Freezing level at 1500mThursday: Light snowfall / Light to moderate west winds / Freezing level at 900m

Confidence

Fair - Forecast snowfall amounts are uncertain on Wednesday

Avalanche Summary

A widespread slab avalanche avalanche cycle to size 2 took place on Sunday. The activity occurred in response to new snow and variable winds at all elevations. One notable occurrence was a size 3 slab avalanche which took place in the southeast corner of the region. The avalanche occurred on an east-northeast aspect at 2500m and was likely triggered by rapid loading from strong northwest winds. Observations were limited, but its size may suggest that a persistent weakness was the failure plane.

Snowpack Summary

Light to locally heavy amounts of new snow fell over the weekend and have have been distributed by northerly winds into deeper windslabs in lee terrain. These recent accumulations overlie a thick rain crust which is reported to extend up to 2000m. About 1m below the surface is a layer surface hoar or a sun crust buried on March 10th. Avalanche activity has become less likely at this interface; however, isolated natural activity and remote triggering is still occurring in some areas. At lower elevations where last week's heavy rain saturated the snowpack, subsequent cooling has formed crusts and has dramatically strengthened the snow.Weaknesses deeper in the snowpack have become unlikely to trigger.Widespread cornice development has also taken place, and cornices are reported to be very large and weak.

Régions couvertes