Bulletin d’avalanche

Purcells

Mar 2 – 3, 2022Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

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

Human triggering of storm slabs should remain on your radar, especially in the southwestern part of the region where we have seen the greatest snowfall amounts. 

Steep wind loaded lee features at upper elevations pose the greatest risk.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2.5

    Human triggering of storm slabs should remain on your radar, especially in the southwestern part of the region where we have seen the greatest snowfall amounts. 

    Even in lower snowfall areas, don't discount the moderate to strong southwest winds, loading lee slopes around ridge crests, as well as cross-loaded features. Investigate the bond of new snow carefully before committing to your line.

Confidence

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

Tuesday night: Light snowfall 0-5 cm, moderate to strong southwest wind, freezing levels dropping to valley bottoms for most of the region with treeline lows of -3.

Wednesday: Light flurries, 0-5 cm, light to moderate southwest wind, treeline high around +2.

Wednesday night into Thursday: 5-10 cm, variable wind, treeline highs around zero.

Friday: Partly cloudy, no new snow, light northeast wind, treeline highs around -3.

Avalanche Summary

On Tuesday a natural avalanche cycle in the size 2 range was observed in the southwest of the region. Also on Tuesday there were some small (size 1) skier-controlled wind and storm slabs reported. On Monday in the northern Purcells there was a skier controlled size 1.5 wind slab on a north-facing cross-loaded feature. There were also some small rider controlled wind and storm slabs reported elsewhere in the region.

Snowpack Summary

Snowfall amounts have varied substantially throughout the region with the southwest side of the Purcells getting the greatest snowfall amounts. Recent storm snow (10-40 cm) overlies a variety of old surfaces such as firm wind-pressed snow, sun crust on solar aspects, surface hoar, and potential cold weak crystals on shaded aspects.

An interface from mid-February is likely now down 40-60 cm. This layer was previously only reactive in wind-loaded terrain where a slab had formed but may become more problematic if covered with a more widespread cohesive slab.

Below that on sheltered north aspects, there is still a surface hoar layer being tracked that was formed in late January. Though there haven't been reports of recent avalanches on this layer in this region, it is still on the radar of many operations.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Investigate the bond of the recent snow before committing to your line.

Régions couvertes