Bulletin d’avalanche

Purcells

Mar 16 – 17, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

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

Points saillants

Spring-like diurnal conditions exist and the rating reflects the highest hazard level anticipated during the day. Pay attention to steep south facing slopes as they heat up in the afternoon and possibly destabilize. Give looming cornices a wide berth from above and below. 

Problèmes avalancheux

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    Where cornices exist they pose a threat both from the potential to collapse under your feet (or machine) and from the potential to send large chunks of snow far down a slope. If anything can trigger the more stubborn persistent weak layers it's a large falling cornice. They are most likely to fail during the heat of the day.

  • Loose Wet

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

    Slopes that face the sun will become unstable as they warm during the day.

Confidence

High - Confidence is due to a stable weather pattern; little change is expected for several days.

Weather Forecast

A ridge of high pressure will remain anchored over the Interior until Thursday bringing warmer temperatures and sunny skies. 

The typical spring-like diurnal weather pattern will hold afternoon alpine temperatures near -2 and freezing levels around 1500-2000 m. Overnight periods will see the freezing levels drop back to the valley bottom.

An approaching Pacific frontal system will move onto the coast Wednesday bringing unsettled weather and new snow to the Interior regions by Friday and through the weekend. 

Avalanche Summary

There have been no recent avalanche reports from this region. Sunshine and daytime warming may initiate loose wet avalanches on steep solar slopes and weaken cornices. 

Snowpack Summary

Dry snow can be found on shaded aspects at upper elevations. On solar aspects and at lower elevations expect crusty snow in the morning and soft, moist snow in the afternoon. Lingering wind slabs and large cornices may still pose a hazard close to alpine ridgelines.

A persistent weak layer of facets 40-60 cm deep that was buried in mid-February was reactive in the north of the region earlier this month but since the first week of March, only a couple of avalanches have been reported on this layer resulting from large triggers such as cornice fall. There are several other weak layers deeper in the snowpack composed of old surface hoar, facets and/or crusts, all of which have been recently unreactive.

Terrain and Travel

  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • Avoid exposure to slopes that have cornices overhead.

Régions couvertes