Bulletin d’avalanche

North Rockies

Mar 9 – 11, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

 A mix of sun, cloud and wind will maintain wind slabs as the main concern. Deeper layers in shallow snowpack areas in eastern parts of the region are still a concern. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2

    The recent winds have created wind slabs across exposed leeward and crossloaded terrain.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3

    The persistent slab problem appears to have been put to rest in deep snowpack areas in the west of the region, but on the eastern slopes (e.g. Kakwa) this is less certain. The most likely triggers are surface avalanches stepping down, cornice fall, or the weight of a machine or a person hitting a thin-spot.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Monday Night: Mainly cloudy with clear periods, moderate west wind, alpine temperature -8 C, freezing level at valley bottom.

Tuesday: Mix of sun and cloud with increasing cloudiness late in the day leading to overnight flurries, moderate to strong west wind, alpine temperature -3 C, freezing level 1200 m.

Wednesday: Mix of sun and cloud, light west and northwest wind, alpine temperature -7 C, freezing level at valley bottom.

Thursday: Mainly cloudy with sunny breaks, moderate to strong west and west wind, alpine temperature -4 C, freezing level 500 m.

Avalanche Summary

We have not received recent reports of avalanche activity.

The warm temperatures last week triggered loose wet avalanches on solar (south through west) aspects. Strong winds triggered wind slabs naturally up to size 2 and explosive controlled avalanche (near Pine Pass) up to size 3. 

Snowpack Summary

Strong south to west winds in exposed areas have scoured some slopes and built windslabs on others. Freezing levels reached treeline last Thursday and Friday. It has cooled since so you will likely find a new snow on the surface or a crust treeline and below.

About a metre of snow covers a weak layer of facets buried mid February. Slightly deeper there is a widespread persistent weak layer from late January/early February that consists of surface hoar. It is most prevalent around treeline elevations, but likely reaches into the alpine and in openings below treeline too. These layers are both significantly shallower in the east of the region.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Avoid freshly wind loaded terrain features.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Régions couvertes