Bollettino valanghe

Northwest Coastal

Jan 21 – 22, 2017Avalanche Canada
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Archiviato · scaduto 10 years ago

Pericolo valanghe

Sun
Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole

In sintesi

Although conditions have improved, professionals and experienced riders are still making conservative terrain choices because of the potential for large persistent slab avalanches.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–3
    It may still be possible to trigger avalanches on buried weak layers (Dec 25, Dec 30, Jan 5th, Jan 12th surface hoar) ... or have a smaller avalanche 'step down' and trigger deeper instabilities.
  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3
    Recent storm snow has settled into slabs that will be most reactive at higher elevations and on wind-loaded features.

Confidence

High - Due to the number and quality of field observations

Weather Forecast

SUNDAY: Sunny with cloudy periods, light southeast winds, alpine temperatures around -5.MONDAY: Mix of sun and cloud, light west winds, alpine temperatures around -5.TUESDAY: Cloudy with scattered flurries along the coast, moderate southwest winds, freezing level rising to 500 m with alpine temperatures around -3.

Avalanche Summary

Evidence of widespread natural activity during last week's storm has been reported throughout the region. In the southern part of the region, size 2 to 3 avalanches released in the storm snow as well as on deeper surface hoar layers (likely the January 5th). Avalanches will become less likely at lower elevations as the wet snow freezes, however triggering storm and persistent slabs will remain possible at higher elevations.

Snowpack Summary

A warm wet storm delivered 40-60 cm of heavy snow in the south of the region, with freezing levels reaching 1200 m. Expect to find storm slabs at higher elevations, particularly on wind-loaded northeast slopes. At lower elevations, moist snow is freezing into a hard crust. At this point there is some uncertainty as to how deeper persistent weak layers are responding to the recent loading and warming. Several weak surface hoar and facet interfaces were reactive during the storm, but have shown signs gaining strength since. This includes the January 5th layer about 50 cm deep and the December 25th layer up to a metre deep. These are not typical conditions for this coastal region, and it will take more time to gain confidence about the distribution and likelihood of triggering these deeply buried weak layers.

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