Bulletin d’avalanche

North Columbia

Mar 11 – 12, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

Sat
Sun
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible

Points saillants

Wind slabs may remain reactive to human triggers in isolated locations below alpine ridgetops. Sheltered, north facing terrain at upper elevations is likely to provide the best riding, but minimize exposure to slopes with large cornices overhead.

Problèmes avalancheux

  • Wind Slabs

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

    Lingering wind slabs may remain reactive to human triggers on steep, convex slopes below ridgetops. 

    Minimize exposure to cornices overhead when the sun is out.

Avalanche Summary

On Tuesday, a small cornice failure triggering a size 2.5 windslab on a east aspect in the alpine was reported. Additionally, several naturally triggered small wet loose avalanches were reported on steep, rocky, sun exposed slopes.

On Saturday, at least three large to very large (size 2.5 to 3) wet slab avalanches were observed at low elevation (1100-1400 m) on south aspect slopes, triggered in response to warm temperatures and strong sun.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

  

WEDNESDAY NIGHT: Few clouds / Light, northwest ridgetop wind / alpine low temperature -14 / Freezing level valley bottom.

THURSDAY: Sunny / Light, northwest ridgetop wind / alpine high temperature -5 / Freezing level 1300 m.

FRIDAY: Mix of sun and cloud / Light, west ridgetop wind / alpine high temperature -1 / Freezing level 1600 m.

SATURDAY: Sunny / Moderate, southwest ridgetop wind / alpine high temperature 3 / Freezing level rapidly rising to 2500 m.

Snowpack Summary

Up to 25 cm dry soft snow can be found on shaded aspects above around 1500 m. On south-facing slopes and at lower elevations expect crusty snow in the morning and soft, moist snow in the afternoon. Winds have slackened off as of late, but recent wind slabs and cornices still pose a hazard close to steep ridgelines.

The lower snowpack has strengthened over the past week as previous persistent weak layers have become unreactive. The main layers that we had been tracking were a layer of facets that was buried in mid-February (60-100 cm deep) and a layer of surface hoar and/or a crust that was buried in late January (80-120 cm deep).

Terrain and Travel

  • Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Caution around slopes that are exposed to cornices overhead.

Régions couvertes