Boletín de aludes

Kootenay Boundary

Apr 4 – 5, 2012Avalanche Canada
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Archivado · caducó 14 years ago

Peligro de aludes

Fri
Sat
Alta montaña
4 · Fuerte
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely - Very Likely
    Tamaño
    2–6
    The increased wind and new snow have formed windslabs in lee zones at ridgecrest. A small windslab event could step down to the deep, persistent weakness.

  • Cornices

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    2–7
    Cornices continue to grow. There is potential for triggering deep persistent slabs on underlying slopes.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–6
    The new snow may create an additional load on top of the recent 70-100 cm of snow that is sitting above a mixture of melt-freeze crusts and wind affected surfaces. The storm slab may be moist or wet below treeline.

Confidence

Fair - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

The storm on Wednesday was a little bit slower and a little further west than originally forecast. Heavy precipitation is forecast for Wednesday evening and overnight into Thursday morning, bringing about 20 mm of precipitation. The wind is forecast to be about 70km/Hr out of the south-southeast tonight at ridgetops. As the freezing level drops tonight, the precipitation could become up to about 30 cm of snow at higher elevations. The storm is expected to move east into Alberta by Thursday noon. A ridge of high pressure is expected to move into the region by Friday bringing clear skies and light winds with freezing levels rising to about 1400 metres during the day.

Avalanche Summary

The region has been very active with avalanches the past 4 days. Natural, explosive and human triggered avalanches have been reported up to size 2.5. Reports come from all aspects, with a bias to north facing slopes. At lower elevations (where the surface is moist) these are running as loose events and at higher elevations the new snow is propagating as a slab. Remote triggering has also been observed. The new storm snow is expected to develop windslabs that may be easily triggered. The recent storm slab may become active with the additional load from the new storm.

Snowpack Summary

New snow combined with moderate southwest winds started to fall Wednesday morning. Up to 100cm of new snow has fallen since March 26. Shears within the upper storm snow are tightening with the persistent warm temperatures, although a reactive layer down 40-50cm remains. The March 26 interface is a melt freeze a crust on all aspects except true north treeline and alpine, where small surface hoar (5mm) is present in sheltered places. The bond at this interface is gaining strength, with lingering concerns on true south aspects where the crust is thickest and where the surface hoar lurks. At lower elevations, the consistent high freezing levels have kept the new snow heavy and moist. The deep, persistent early February surface hoar lingers in the snowpack giving sudden results in testing. Concern remains with heavy triggers (cornice), step down avalanches and rapid loading from intense precipitation, strong winds or sun.

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