Bulletin d’avalanche

Lizard-Flathead

Jan 30 – 31, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

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

The new snow formed reactive storm slabs at all elevations. The slabs are particularly reactive where they overlie surface hoar. Moderate southwest wind will build fresh wind slabs at higher elevations throughout the day.

Problèmes avalancheux

  • Storm Slabs

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

    20-35 cm of recent storm snow has formed reactive storm slabs in the alpine and at treeline elevations. With relatively warm temperatures the new snow might become more bonded and become reactive particularly where it overlies surface hoar below treeline and in sheltered areas at treeline elevations.

    The new snow might be redistributed throughout the day by moderate southwest wind and form fresh wind slabs on lee terrain features at higher elevations. 

    Loose dry avalanches might run longer than expected. 

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

FRIDAY NIGHT: Cloudy with clear periods, up to 5 cm new snow, light to moderate southwest wind, treeline temperature -7 C.

SATURDAY: Cloudy, 5 cm new snow, moderate southwest wind, treeline temperature -6 C.

SUNDAY: Cloudy, 10 cm new snow, moderate southwest wind, treeline temperature -4 C.

MONDAY: Cloudy, 15-20 cm new snow, moderate southerly wind, treeline temperature -2 C.

Avalanche Summary

A skier triggered size 2 slab avalanche was reported on Friday (see this valuable MIN post). Several slab avalanches up to size 2 released naturally and were triggered by explosives on Thursday. Other parties reported signs of instability as whumpfing and shooting cracks. Loose dry avalanches (sluffs) in steep alpine and treeline features were observed in the last few days. 

Snowpack Summary

20-30 cm recent snow buried surface hoar and other old surfaces. In the alpine, the new snow sits on top of layers of hard wind slab, scoured areas, sastrugi and isolated pockets of soft snow. A hard crust underneath the new snow is found up to 1800 m.    

A solid mid-pack sits above a deeply buried crust and facet layers near the bottom of the snowpack (150-200 cm deep), which are currently unreactive. 

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Be carefull with sluffing in steep terrain, especially above cliffs and terrain traps.

Régions couvertes