Bulletin d’avalanche

North Rockies

Jan 10 – 12, 2021Avalanche Canada
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Archivé · expiré 6 years ago

Danger d’avalanche

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

While the snowpack is slowly gaining strength in many locations, Pine Pass remains weaker than other locales. Wherever you go, watch for potentially deep wind slabs in exposed terrain and stay away from cornices. The best & safest riding will be found out of the wind.

Problèmes avalancheux

  • Wind Slabs

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

    West/southwest wind has been the theme for the last few days and it looks like plenty more is in store Sunday/Monday. The existing wind slabs are getting harder to trigger as they age but human triggering remains possible, especially in extreme terrain. There isn't too much snow left to form into fresh slabs but the riding in wind effected country isn't great. Seek out wind sheltered features where you can avoid wind slabs and have a great day.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3

    A persistent weak layer exists throughout the region 80 to 90 cm below the surface. In most places it looks like the overlying snow is gaining strength and human triggering is trending towards unlikely. However, areas around the Pine Pass seem to remain problematic and there has been some recent large avalanche activity on this interface.  

Confidence

Moderate - Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

Warming temperatures and quite a bit of west/southwest wind are in store.

SATURDAY NIGHT: Freezing level at valley bottom, strong southwest wind, trace of snow possible. 

SUNDAY: Broken cloud cover at dawn with clear skies by lunch, freezing level beginning at valley bottom steadily climbing throughout the day to about 1400 m by sunset, strong southwest wind, trace of snow possible. 

MONDAY: Scattered cloud cover, freezing level starting at valley bottom rising to about 1500 m during the day, strong to extreme southwest wind, trace of snow possible.

TUESDAY: Broken cloud cover, freezing level starting at valley bottom rising to about 1800 m during the day, strong to extreme southwest wind, 5 to 10 cm of snow at upper elevations with rain in the valleys.

Avalanche Summary

Several size 1 to size 2.5 natural avalanches were observed on north, northeast and east facing slopes in the alpine around the Bullmoose area near Tumbler Ridge Friday, more details in this MIN report.  

Our field team found some recent avalanche activity in the Pine Pass on Thursday in the Bijoux area, more details here. Recent wind slabs to size 1.5 were reported from the Kakwa Saturday.

Snowpack Summary

The last storm was pretty warm, and you're likely to find a crust on or just below the surface up to about 1200 m.

80 to 90 cm of snow rests above a weak layer buried in early December which has created a persistent slab avalanche problem and a low probability/high consequence scenario. Depending on location, the buried weak layer is composed of surface hoar and/or a crust/facet combination.

This interface remains active and problematic at Pine Pass, but elsewhere it's gaining strength. It's presence is spotty in the McGregors and Tumbler Ridge, recent testing on this interface near Tumbler did not produce any results. This problem has not been found at Renshaw, but has been found in the surrounding areas near McBride. There is very little information coming out of the Kakwa right now, but preliminary information suggests it may not be a player there, at least not yet.

Total snow depths are 150-300 cm around Pine Pass & the McGregors. Near McBride there is 150 to 200 cm, around Tumbler 50 to 200 cm can be found. 

Terrain and Travel

  • Expect slab conditions to change drastically as you move into wind exposed terrain.
  • Be aware of highly variable recent wind loading patterns.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.

Régions couvertes