Bulletin d’avalanche

Northwest Inland

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

Danger d’avalanche

Wed
Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible

Points saillants

Continue to assess for wind slabs in steep terrain.

Problèmes avalancheux

  • Wind Slabs

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

    Wind slabs may be found at higher elevations, particularly in steep terrain adjacent to ridgelines. The wind has shifted directions, meaning slabs may be found on all aspects.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–3.5

    Weak, sugary faceted grains exist near the base of the snowpack. Riders are most likely to trigger this layer in steep, rocky slopes where the snowpack is inherently thin. The likelihood of avalanche activity on this layer will increase during periods of rapid change to the snowpack, such as heavy snowfall, rain, extensive warming, or large loads like a cornice fall.

Confidence

Moderate

Avalanche Summary

Riders observed evidence of naturally triggered wind slab avalanches from the past few days, mostly occurring on north aspects in the alpine.

Snowpack Summary

Around 10 cm of snow overlies large (10 mm) surface hoar crystals in terrain sheltered from the wind. Wind affected snow is predominant on all aspects in wind-exposed terrain due to variable wind directions. A hard melt-freeze crust is likely found on sun-exposed slopes.

Several hard crusts with associated weak facets and/or weak layers of surface hoar can be found in the top 150 cm of the snowpack. These layers haven't produced recent avalanche activity or alarming snowpack test results but they remain on our radar.

The lower snowpack consists of weak basal facets, which may become active with any rapid change to the snowpack, such as rapid loading (e.g., heavy snowfall, cornice fall) or prolonged and extensive warming. Avoiding thin and rocky slopes is still recommended.

Weather Summary

Monday Night

Cloudy with snowfall, accumulation 2 to 5 cm, 20 km/h southwest wind, treeline temperature -12 °C.

Tuesday

Mix of sun and cloud with isolated flurries, accumulation 1 to 3 cm, 20 to 30 km/h south wind, treeline temperature -11 °C.

Wednesday

Cloudy with snowfall then clearing, accumulation 2 to 5 cm, 40 to 50 km/h southwest wind, treeline temperature -10 °C.

Thursday

Cloudy with snowfall, accumulation 2 to 5 cm, 30 to 40 km/h south wind, treeline temperature -5 °C, freezing level 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Carefully evaluate steep lines for wind slabs.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Conditions may have improved, but be mindful that deep instabilities are still present.

Régions couvertes