Bulletin d’avalanche

Purcells

Mar 18 – 19, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Natural avalanche activity will be driven by solar input on Sunday. Minimize your exposure to steep slopes facing the sun during the hottest part of the day.

Stick to thick snowpack areas where you are less likely to trigger deep weak layers.

Problèmes avalancheux

  • Wind Slabs

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

    Recent snow from earlier in the week has been redistributed by primarily southwest wind into alpine and treeline lee terrain.

  • Persistent Slabs

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

    Numerous weak layers from January and February exist at all elevations on a variety of aspects. On shaded slopes, these layers generally present as surface hoar, and on sun-exposed slopes they present as facets and a crust.

    Be aware these layers can be remotely triggered (from a distance).

  • Deep Persistent Slabs

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

    The base of the snowpack remains very weak. Very large human triggered avalanches are possible at treeline and above. Avoid thin, rocky start zones and shallow areas with variable snowpack where you are most likely to trigger this layer.

Confidence

Moderate

Avalanche Summary

On Friday, a few solar-triggered loose dry avalanches were reported in the region to size 2. A natural size 2.5 windslab, likely triggered by the sun, was observed on a southwest aspect at 2500 m.

Explosives control triggered a deep persistent slab avalanche, size 2.5, on an east aspect at 2350m

If you head out in the backcountry, let us know what you see by submitting a report to the Mountain Information Network.

Snowpack Summary

15-30 cm of wind-affected storm snow falling earlier in the week overlies wind-affected snow in open areas, facetted snow in sheltered areas and a thin sun crust on steep solar slopes. A sun crust is found on the surface of solar slopes at all elevations.

Buried surface hoar can be found 70-90 cm deep in sheltered terrain features. A thin sun crust exists at the same depth on steep south-facing terrain.

The lower snowpack is made up of a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.

Weather Summary

Saturday Night

Clear skies. Treeline temperature -6 °C. Wind light northwest. Freezing levels drop to valley bottom overnight.

Sunday

Sunny. Treeline temperature -1 °C. Wind light southeast. Freezing level rising to 1900m.

Monday

Mix of sun and cloud. Treeline temperature -2 °C. Wind light east. Freezing level 1800m.

Tuesday

Mix of sun and cloud. Treeline temperature -4 °C. Wind light variable. Freezing level 1600m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.
  • Avoid areas with a thin or variable snowpack.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Régions couvertes