Bulletin d’avalanche

North Columbia

Mar 13 – 14, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

35-50 cm new snow and strong south wind have formed reactive storm slabs at all elevations.

Make conservative terrain choice and use small low consequence slopes to test the bond of the new snow.

Problèmes avalancheux

  • Storm Slabs

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

    35-50 cm new snow and strong south wind have formed reactive storm slabs at all elevations.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–1.5

    Expect natural wet loose avalanches on steep sunny aspects when the sun comes out.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    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

An explosive triggered size 2.5 deep persistent slab on an east aspect in the alpine was reported north of Keystone Standard Basin on Sunday.

Additionally, a couple size 1 rider triggered wind slabs on north and west aspects at treeline were reported.

Snowpack Summary

35-50 cm of new snow, strong south winds, and rising freezing levels have formed reactive storm slabs at all elevations.

The storm slabs overlie a variety of surfaces, which include surface hoar (3-10 mm) on shady slopes at all elevations, wind affected surfaces at treeline and above, and sun crust on sunny aspects.

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

Monday Night

Snow; 5-15 cm / 30 km/h southwest ridgetop wind / Low temperature at treeline around -10 C / Freezing level valley bottom

Tuesday

Mix of sun and cloud / 20 km/h southwest ridgetop wind / High temperature at treeline around -9 C / Freezing level 1100 m

Wednesday

Mix of sun and cloud with isolated flurries; 0-3 cm / 20 km/h west ridgetop wind / High temperature at treeline around -8 C / Freezing level 1300 m

Thursday

Sunny / 10 km/h south ridgetop wind / High temperature at treeline around -5 C / Freezing level 1500 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • Use small low consequence slopes to test the bond of the new snow.
  • Avoid exposure to slopes that have cornices overhead.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Régions couvertes