Boletín de aludes

Northwest Coastal

Dec 12, 2017Avalanche Canada
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Archivado · caducó 9 years ago

Peligro de aludes

Wed
Thu
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Lo esencial

Continued warming and precipitation is adding stress to the snowpack and driving the danger rating.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2
    Storm slabs may exist where the recent precipitation fell as snow. Watch for triggering in higher elevation, wind-exposed terrain.

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2
    With continued warming and light precipitation, I would expect loose wet avalanches to occur, especially on steep slopes and terrain features well into the alpine.

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    2–3
    Weak layers buried near the base of the snowpack can't be dismissed while new snow or rain load the surface. I'd limit my exposure to large overhead slopes, especially when the sun makes an appearance on Monday.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Tuesday: Mainly cloudy with light snow in the alpine and rain showers below. Ridgetop winds moderate from the southwest. Alpine temperatures near 1 degree and freezing levels 1700 m.Wednesday: Mainly cloudy with isolated showers. Ridgetop winds light to moderate from the south. Alpine temperatures plus 5 degrees and freezing levels rising to 2200 m.Thursday: Snow amounts 10-20 cm in the alpine and rain below. Freezing levels near 1700 m. Ridgteop winds light with strong gusts from the south.

Avalanche Summary

On Sunday, rain and warmer temperatures initiated numerous natural loose wet and storm slab avalanches up to size 1 throughout the region. On December 7th and 8th a few deep persistent slabs to size 3 out of steep south facing alpine terrain in the Skeena corridor west of Terrace were reported. Basal facets were thought to be the culprit in these events. The Bear Pass area also saw a size 2.5 wet slab avalanche on Saturday. The deep persistent slab is something to keep on your radar, especially with more weather in the forecast.

Snowpack Summary

The past couple of days brought up to 15 mm total precipitation in the Skeena corridor. Given the mild temperatures, I suspect most of that precipitation fell as rain. At alpine elevations snow likely fell and moderate to strong winds are expected to have formed wind slabs in lee terrain. In the Bear Pass area where temperatures were cooler, around 30cm of new snow fell. These accumulations overlie melt freeze crusts and possibly surface hoar.About 70-100cm below the surface you'll likely find a 5-10 cm thick crust which was buried on November 23. Another layer of surface hoar (November 11) continues to be observed down approximately 140 cm in the Bear Pass area, showing some signs of improved bonding. The widespread crust/facet interface that was buried at the end of October can now be found 90-160 cm deep.

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