Bulletin d’avalanche

Northwest Coastal

Jan 26, 2017Avalanche Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

A new Pacific storm system will start to brush up against the Northwest coast overnight. Avalanche danger will trend to HIGH by the weekend.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    It may still be possible to trigger avalanches on buried weak layers (Dec 25, Jan 5th, Jan 12th surface hoar) ...or have a smaller avalanche 'step down' and trigger one of these layers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Storm slabs are expected to develop with forecast new snow and wind. Avalanche size and frequency will increase with each pulse of precipitation, increasing winds, and rising freezing levels.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A new Pacific storm system will start to brush up against the Northwest coast overnight. This series of low pressure systems will be deflected to the North by a strong ridge of High pressure over most of the province. Precipitation amounts are expected to be heaviest along the coast and near Kitimat and Stewart. Overnight: 5-10 cm, moderate southwest winds, freezing level 600 metres. Thursday: 10-25 cm with strong southwest winds, freezing level rising to 1000 metres. Friday: 20-40 cm with extreme southwest winds, freezing level rising to 1300 metres. Saturday: 25-50 cm with extreme southwest winds, freezing level rising to 1500 metres.

Avalanche Summary

One report on Wednesday of a skier triggered wind slab size 1.0 on a convex roll at 1500 metres that was about 25cm deep. Expect avalanche size and frequency to increase as the forecast storm moves into the region.

Snowpack Summary

There is 5-10 cm of new snow above the latest buried surface hoar layer from January 23rd that has been found up to size 10 mm at treeline and below. This surface hoar layer may be associated with a crust below 1100 metres. There continues to be several other surface hoar layers of concern from early January and Christmas. Some reports show these persistent weak layers to be rounding and bonding, however we are still getting some reports of sudden planar releases in snowpack tests with hard forces applied. I suspect the forecast heavy precipitation over the next few days will be a good test for these older buried weak layers.

Régions couvertes