Bulletin d’avalanche

Lizard-Flathead

Dec 5 – 6, 2022Avalanche Canada

Voir sur la carte

Archivé · expiré 4 years ago

Danger d’avalanche

Wed

Thu

Alpin

3 · Marqué

Limite forestière

2 · Modéré

Sous la limite

2 · Modéré

Ouvrir la carte complète

Points saillants

Diligently watch for changing conditions throughout the day. As the winds pick up, there's a lot of loose snow available to be transported into fresh, reactive wind slabs.

A weak layer of surface hoar continues to be a concern, particularly around treeline. Uncertainty surrounding this layer is best managed by conservative terrain choices and a cautious approach to risk management.

Problèmes avalancheux

Wind Slabs
N
NE
E
SE
S
SW
W
NW
Alpin
Limite forestière
Sous la limite forestière
Probabilité
Likely
Taille
1–1.5
Increasing wind on Monday is expected to redistribute the recent storm snow into fresh wind slabs in lee areas in the alpine and treeline. Be cautious of wind slabs on all aspects, as recent wind has varied in direction, but expect fresh slabs on North and East-facing terrain to be the most reactive.
It is possible small avalanches in the upper snowpack could trigger deeper weak layers, creating a larger then expected avalanche.
Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Alpin
Limite forestière
Sous la limite forestière
Probabilité
Unlikely - Possible
Taille
1–2.5
Buried layers of surface hoar and facets have been reactive to human triggers in recent days. This layer is widespread throughout the Lizard Flathead. The most reactivity has been observed in shaded areas at treeline, where surface hoar may be preserved, and in wind loaded areas at upper elevations, where a cohesive slab has been formed.
Observations on this layer are currently limited. In times of uncertainty such as this, our best defence is to keep terrain choices conservative and reduce your exposure to avalanche terrain where possible.

Confidence

Moderate

Avalanche Summary

On Sunday, a MIN report from Tunnel Creek reported reactivity in a snowpack test on the Mid-November layer on a south aspect. In this area, the layer presented as facets on a crust. They also observed a large natural avalanche on a west-facing slope at treeline. (Thanks for the report- ESPETERS10)

On Saturday, a small (size 1.5) skier triggered persistent slab avalanche occurred on an east-facing slope at treeline.

Numerous reports of small loose dry avalanches (sluffing) have been reported within the recently fallen low-density surface snow.

We have very few eyes out there. If you do get out please consider reporting in the MIN.

Snowpack Summary

Up to 100 cm of recent storm snow has fallen within the last week. In wind-affected terrain, this new snow has been redistributed into deeper deposits by recent variable winds. In sheltered terrain, cold temperatures will likely maintain low-density, powdery snow.

The middle of the snowpack consists of weak sugary layers of facets and surface hoar. A widespread rain crust remains near the ground at treeline and below treeline.

At treeline, snowpack depths vary from 120-200 cm.

Weather Summary

Sunday night

Mainly cloudy, light snowfall possible with trace accumulation. Southeasterly winds 5-15 km/h at ridgetop. Treeline temperature drops to -14 C.

Monday

Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 15-40 km/h at ridgetop. Treeline temperatures reach a high of -10 C.

Tuesday

Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 5-25 km/h at ridgetop. Treeline temperatures reach a high of -12 C.

Wednesday

Cloudy with snowfall, 1-3 cm of accumulation. Southwesterly wind 15-40 km/h at ridgetop. Treeline temperatures reach a high of -8 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Recent wind has varied in direction so watch for wind slabs on all aspects.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.