Lawinenlagebericht

Purcells

Mar 26 – 27, 2013Avalanche Canada
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Archiviert · abgelaufen 14 years ago

Lawinengefahr

Thu
Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Lawinenprobleme

  • Cornices

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    2–5
    Natural cornice falls are a concern during daytime warming. Cornices may also be triggered easily by traveling near them. Slopes with corniced entrances, or exposed to cornice falls should be avoided with these conditions.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    3–6
    Small solar triggered slides, cornice fall, or thin-spot triggering may overload a persistent weakness buried near 100 cm deep. This could lead to surprisingly large avalanches.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–4
    Wind slabs linger on lee and cross-loaded alpine and treeline slopes, while down-flowing katabatic winds may have created weak wind slabs in unusual places. Expect to see wet loose snow avalanches out of steep rocky sun-exposed slopes.

Confidence

Good

Weather Forecast

The ridge of High pressure is expected to continue to influence the interior ranges for the next few days. As the ridge weakens we may see high cloud reducing the exposure to strong solar radiation. Nights are expected to continue to be clear and cool. Freezing levels in the North should rise during the day to about 1800 metres, and to about 2000 metres in the South.

Avalanche Summary

Reports from Monday are limited to small natural wet loose snow avalanches on steep rocky sun-exposed slopes. However, the potential for large natural cornice releases, or other heavy human triggers, triggering very large slabs remains. A size 3 avalanche taking out the whole basin was triggered by snowmobilers Saturday in Hell Roaring Creek, just south of the region resulting in one fatality. Details are limited at this time; it may be indicative of the persistent slab problem (surface hoar and/or crust buried about 70 - 120 cm) we continue to describe.

Snowpack Summary

Surface faceting and surface hoar growth has been prevalent on shady slopes and at upper elevations, while the surface snow on sun-exposed slopes and at lower elevations has been subject to daily melt-freeze cycles. Cornices are reported to be very large and weakly bonded. Wind and storm slabs are reported to be strengthening, but may continue to be sensitive to human-triggers. The weak layer of buried surface hoar sitting on a crust down around 70-120cm, and has been producing varialbe but sudden results in snowpack tests. This deep persistent weakness remains a concern because of the potential for very large avalanches particularly with heavy triggers such as cornice falls. Old deep persistent weaknesses, including basal depth hoar, are a concern in shallow snowpack areas.

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