Boletín de aludes

Kootenay Boundary

Feb 28, 2019Avalanche Canada
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Archivado · caducó 8 years ago

Peligro de aludes

Fri
Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Lo esencial

Reactive wind slabs formed in response to the recent wind event Tuesday and Wednesday. Southerly aspects will likely be more reactive to human triggers especially at treeline and above. Old, buried wind slabs still linger on on aspects and elevation

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    1–2
    Northeast winds have formed fresh and reactive wind slabs on southerly slopes and terrain features. Old, buried wind slabs also linger on a variety of aspects.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5
    It remains possible to trigger an avalanche on one of the surface hoar or crust layers buried 30 to 80 cm deep. These layers are most prominent around treeline elevations.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

WEDNESDAY OVERNIGHT: Light snowfall amounts 2-5 cm with light to moderate East wind. THURSDAY: New snow 5-10 cm by the end of the day. Ridgetop winds strong from the southwest and alpine temperatures near -8. FRIDAY: Cloudy with sunny periods and isolated flurries. Ridgetop winds light from the northeast and alpine temperatures near -9. SATURDAY: Mix of sun and cloud. Ridgetop winds moderate from the East. Alpine temperatures near -16.

Avalanche Summary

On Tuesday, a skier triggered a persistent slab avalanche on an E-SE aspect between 1680-1770 m. This is believed to have failed on the early February surface hoar/ crust interface that exists 40-60 cm down. This avalanche was 100 m wide and ran 300 m in length. Wind slabs were also reactive to human triggers up to size 2 and explosive controlled wind slab avalanches were reported up to size 2.5 failing on southerly aspects 1900-2100 m. Last Sunday, a large (size 2.5) persistent slab was triggered by a skier in the Evening Ridge area. It occurred on a southeast aspect at about 2000 metres and featured a crown fracture around 50 cm deep and 350 metres wide. A weak layer from early February is suspected as the failure plane.

Snowpack Summary

Reactive wind slabs have formed on southerly slopes in response to the recent wind event. This MIN report reflects the Kootenay Pass area well. The storm last weekend brought 15-25 cm of low density snow that now covers variable old wind slabs at higher elevations and sun crusts on south-facing slopes. A weak layer of surface hoar crystals and a crust that was buried on February 7th is now 30-50 cm deep. This layer has been reactive, and has produced avalanches as large as size 3. Two other surface hoar layers are buried 50 to 80 cm deep the snowpack (referred to as the February 1st and mid-January layers) and continues to be reactive to human triggers. The mid-pack is complex and requires diligence and patience. The lower snowpack is considered generally strong.

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