Bulletin d’avalanche

North Columbia

Mar 21 – 22, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

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

Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.

Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

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 northerly aspects in the alpine.

  • Loose Wet

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

    Strong solar radiation will increase the likelihood of wet loose avalanches on sunny aspects in the alpine.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2.5–4

    A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth, but large triggers such as cornice failures or smaller avalanches in motion have the potential to produce very large avalanches with surprisingly wide propagation. Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.

Confidence

High

Avalanche Summary

Numerous naturally triggered wet loose avalanches up to size 3 (very large) were reported on steep sunny aspects in the alpine on Monday.

A helicopter landing on a ridge triggered a size 2 wind slab on the steep slope below. It was a northerly aspect in the alpine.

A couple rider triggered size 1 wind slab avalanches were also reported on northerly aspects in the alpine.

Snowpack Summary

Expect to find a melt-freeze crust on the surface of all aspects at treeline and below and on sunny aspects in the alpine. Solar radiation will break down the crust on sunny slopes throughout the day.

Lingering wind slabs may remain reactive to human triggers on northerly aspects in the alpine.

30-50 cm down there is a sun crust on sunny aspects and surface hoar (3-10 mm) on isolated shady and sheltered slopes.

The mid-snowpack is generally strong but the lower snowpack is a different story..

The November facets are still prominent at the base of the snowpack. They are showing signs of improving but this layer remains a significant concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.

Weather Summary

Tuesday Night

Clear skies / 10 km/h northeast ridgetop wind / Temperature at treeline around -8 C / Freezing level valley bottom

Wednesday

Sunny / 10 km/h southwest ridgetop wind / Temperature at treeline around 0 C / Freezing level 2000 m

Thursday

Mix of sun and cloud / 10 km/h southwest ridgetop wind / Temperature at treeline around -3 C / Freezing level 1700 m

Friday

Mostly cloudy with isolated flurries; 0-5 cm / 10 km/h west ridgetop wind / Temperature at treeline around -8 C / Freezing level 1300 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Cornice failure may trigger large avalanches.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Régions couvertes