Bulletin d’avalanche

Lizard-Flathead

Dec 19 – 20, 2022Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

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

New snow continues to put more load on weak buried layers.

Don't be enticed by fresh lines as there is potential for 'step down' and the creation of large avalanches.

Problèmes avalancheux

  • Persistent Slabs

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

    Two persistent weak layers can be found in the top meter of the snowpack. The first is a surface hoar/crust layer from early December and the second is a surface hoar, facet or crust layer from mid November. The most recent activity on these layers has been in the northern part of the forecast region. These layers are most concerning on sheltered treeline features where surface hoar is most likely to be preserved.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–1.5

    Build up of recent storm snow may produce slab properties on weak layers creating primed conditions for avalanche activity.

    Sluff management is important to keep in mind as a build up could trigger weaker layers further in the snow pack.

Confidence

Moderate

Avalanche Summary

As of this writing, no new avalanches were reported in the last 24 hours. With the accumulation of storm snow, expect this to change.

On Friday large avalanches were triggered using explosives on north-facing treeline features.

On Thursday Several size 2 natural avalanches were observed in treeline terrain in the Elkford area. These avalanches likely occurred earlier in the week and failed on the mid-November surface hoar layer which is down around 40 cm in this area.

Persistent slab avalanche activity has continued to taper off but these layers will likely remain triggerable in specific terrain features.

Snowpack Summary

Around 30 cm of recent low-density snow overlies a thin sun crust on steep solar slopes and surface hoar and facets in sheltered terrain. Moderate westerly winds will more than likely redistribute this snow and formed wind slabs

A well-settled upper snowpack may overlie a spotty layer of surface hoar and a thin sun crust formed in early December, now buried 40 to 60 cm deep. The mid-November layer consisting of facets and surface hoar is now buried around 80 cm deep. However, both these layers can be found much shallower in the northern part of this forecast region. At the bottom of the snowpack, a thick crust sits on the ground.

At treeline, snowpack depths vary from 100 to 200 cm.

Weather Summary

Sunday Night

Cloudy, 5 to 10 cm accumulation, 25 km/h west wind, -25 C at 1500 m.

Monday

Cloudy with sunny periods, trace accumulation, 15 to 25 km/h northwest winds, alpine temperature of -25 C.

Tuesday

Cloudy with sunny breaks, up to 4 cm accumulation, 20 km/h east wind, temperature -25 C at 1500 m.

Wednesday

Mix of sun and cloud, trace accumulation, 20 to 25 km/h northeast winds, alpine temperature of -25 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Closely monitor how the new snow is bonding to the old surface.
  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • In times of uncertainty conservative terrain choices are our best defense.
  • Avoid open slopes and convex rolls at and below treeline where weak layers may be preserved.
  • The new snow may require another day to settle and stabilize.

Régions couvertes