Bulletin d’avalanche

Purcells

Mar 24 – 25, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Cloudy areas should see loose wet avalanche problems diminish a bit on Monday. Expect more of the same active loose wet avalanche conditions on any slopes that see strong sun.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1.5–2.5
    A few weak layers still exist within the snowpack. The recent hot weather may have influenced these layers, but time is needed to assess how much they have changed.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5
    If the snow feels slushy, there is potential for triggering a loose wet avalanche. Expect heightened danger on steep slopes that see strong sun or rain. Large loose wet avalanches may start small and move slowly, but they can be highly destructive.

Confidence

Moderate -

Weather Forecast

Sunday night: Mainly cloudy. Light south winds.Monday: Mainly cloudy with isolated flurries bringing a trace of new snow. Light rain below about 1600 metres. Light south winds. Alpine high temperatures around 0 with freezing levels to 2000 metres.Tuesday: Cloudy with scattered flurries bringing a trace to 10 cm of new snow. Light rain below about 1200 metres. Precipitation easing overnight. Light to moderate southwest winds. Alpine high temperatures around -3 with freezing levels to 1600 metres.Wednesday: Mainly cloudy. 24 hour new snow totals of approximately 5-20 cm. Light east winds. Alpine high temperatures around -3 with freezing levels around 1700 metres.

Avalanche Summary

Many wet loose avalanches were observed between last Sunday and Friday. They were large (up to size 3), occurred mostly on southeast to southwest aspects, and at all elevations. Many of these avalanches scoured to basal weaknesses. A notable deep persistent slab avalanche released on Wednesday, likely triggered by a cornice fall. It was 100 cm deep on a northeast aspect at 2900 m.

Snowpack Summary

Forecast trace snowfall will accumulate above a surface of melt-freeze crust in most areas above 1500 metres, with the exception of north aspects above 2000 metres, where it will land on settled and preserved dry snow. Below about 1500 metres, light precipitation as rain will land on variably isothermal (slushy) and crusty surfaces. Any added moisture will promote isothermal conditions where they don't already exist. The mid snowpack is generally consolidated and strong, but exceptions may exist on north aspects above 2000 m, where a gradually strengthening layer of faceted grains buried 40 to 60 cm deep may still be preserved below an overlying slab of old and hard wind-affected snow.The base of the snowpack is composed of weak faceted snow which may coexist with a melt-freeze crust. One very large persistent slab was observed to have failed at this layer during the recent warming event.

Régions couvertes