Boletín de aludes

South Columbia

Dec 11 – 12, 2021Avalanche Canada
Ver en el mapa
Archivado · caducó 5 years ago

Peligro de aludes

Mon
Tue
Alta montaña
4 · Fuerte
Límite del bosque
4 · Fuerte
Bajo el límite
3 · Notable
Abrir el mapa completo

Lo esencial

New snow and wind are forming touchy slabs. A weak layer in the upper snowpack means slab avalanches can be larger than expected. Having the skills to recognize and avoid avalanche terrain will be critical to managing your risk on Saturday. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3

    50-80 cm of snow from the previous week now sits over a weak layer on a thick crust. This weak layer is most pronounced at mid-elevations at this time. Natural and human triggered slab avalanches were observed on this layer in the days prior to the current storm, so with the additional snow load this weekend we are expecting this layer to be reactive and produce large avalanches.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    1–2

    New snow and wind are forming fresh, reactive slabs.

Confidence

High - We are confident about the likelihood of avalanche activity, what is less certain are their possible size. A small change in the upper snowpack could dramatically change avalanche conditions.

Weather Forecast

Friday night: 5-10 cm of new snow. Strong southwest wind. Freezing level climbing to 800 m.

Saturday: 5-10 cm of new snow. Strong southwest wind. Treeline temperatures around -5 C. Freezing level 1300 m.

Sunday: 10-20 cm of new snow. Moderate southwest wind. Treeline temperatures around -8 C. Freezing level 500 m.

Monday: 5-10 cm of new snow. Light southeast wind. Treeline temperatures around -7 C. Freezing level 500 m.

Avalanche Summary

Reports from Wednesday and Thursday indicate increasing slab reactivity prior to burial by the current storm. There were several reports of natural size 2 avalanches in alpine terrain as well as several human triggered size 1 wind slabs around treeline. The most reactive slabs were on convex wind-affected slopes. Most avalanches were in the top 20-30 cm of snow.

Avalanche activity is expected to be large and widespread on Saturday.

Snowpack Summary

10-20 cm of new snow falls amid strong wind over 20-40 cm of settling snow from the past week. Beneath this recent snow lies a variety of suspect layers. The most prominent and widespread is a crust that formed during last week's atmospheric river. This crust extends into the alpine (as high as 2400 m), and there is potential for a poor bond to snow sitting above it. There is also a thin breakable crust closer to the surface. We are uncertain about how reactive the recent snow will be as it settles over the upcoming days. The snowpack structure is relatively simple beneath the crust, with treeline snow depths around 100-200 cm.

Terrain and Travel

  • Use increased caution at all elevations. Storm snow is forming touchy slabs.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
  • Travel in alpine terrain is not recommended.
  • The trees are not the safe-haven they normally are at this time. Terrain at treeline is primed for human triggered avalanches.

Regiones cubiertas