Bulletin d’avalanche

North Rockies

Apr 5 – 6, 2022Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré

Points saillants

 Warm temperature and sunshine will increase the likelihood of avalanche activity, especially on steep slopes that are baking in the sun. 

 A conservative approach to terrain is a great way to ease into your day while assessing along the way. 

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–3

    Springtime cornices are large and unpredictable. The sunshine can pack a punch and lead to cornice failures. Give them a wide berth when travelling at ridge crest and avoid overhead exposure.

  • Storm Slabs

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

    Up to 25 cm of new storm snow has accumulated throughout the region building fresh storm slabs. The slabs will be most reactive where they overlie a crust and when the sun comes out.

    Moderate to strong southwest wind has redistributed the new snow forming wind slabs in lee terrain features in the alpine and at treeline. 

  • Loose Wet

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

    Sun and warm temperatures will weaken the snow surface on sun-exposed slopes, creating wet avalanches. Watch for wet and heavy snow and be aware of overhead exposure to big sunny slopes. 

    Wet loose avalanches could trigger deeper wet slabs. 

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Wednesday: A mix of sun and cloud with strong solar input and light ridgetop wind light from the southwest. Freezing level 1400 m and alpine temperatures near -6 C. 

Thursday: WARM. Freezing levels rise to 2500 m by the afternoon. Alpine temperatures +3C and ridgetop wind moderate from the southwest. No overnight refreeze.

Friday: Cloudy and warm with up to 10 cm of new snow. Freezing levels remain near 2500 m with alpine temperatures near +3C. Freezing levels should drop to 1400 m by Saturday with alpine temperatures near -10 C

Avalanche Summary

No recent reports since last weekend. 

Avalanche activity will likely increase when the sun comes out, especially on southerly slopes. Be aware of overhead hazards like failing cornices and big avalanche paths that are facing the sunshine. 

On Sunday, a small natural wind slab avalanche was observed on a north aspect in the alpine. A rider triggered a small slab avalanche on the same slope. Both avalanches likely occurred on Saturday.

On Saturday, many natural dry loose avalanches were reported in steep terrain, as well as a large cornice failure that released a slab on the slope below. 

Snowpack Summary

10 to 25 cm of new storm snow blankets upper elevations with the greater snowfall amounts being in the Renshaw. Strong west to southwest wind will be redistributing the new storm snow in exposed high elevation terrain forming touchy wind slabs and developing large cornices. The upper 60 cm of the snowpack consists of multiple crusts. The surface snow consists of a thin crust up to 1800 m that is supportive below 1400 m. 

30-60 cm of snow sits on the thick melt-freeze crust from late March. This crust can be found up to 1900 m on all aspects. 

Wednesdays' sun and warming will likely create moist/ wet surface snow on all aspects up to 1500 m and to the mountain top on southerly slopes. 

Terrain and Travel

  • Watch for changing conditions today, storm slabs may become increasingly reactive.
  • Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
  • Cornices become weak with daytime heating or solar exposure.
  • Adjust your travel plans accordingly to the changing conditions of elevation and time of day.

Régions couvertes