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Avalanche Forecast

Archived

Jan 4th, 2023–Jan 5th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Coastal, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson, Ningunsaw, Ningunsaw.

Triggering slab avalanches is possible on steep and convex slopes in treeline and alpine terrain.

Confidence

Moderate

Avalanche Summary

No significant avalanche activity was reported on Tuesday.

Triggering large persistent slab avalanches remains a concern. The most recent report of a persistent slab avalanche was on Monday, when two size 2 persistent slabs were triggered on treeline features in northern parts of the region. These avalanches failed on 30 to 50 cm deep facet layers. Similar avalanches were reported in treeline terrain in southern parts of the region last Thursday and Friday.

Snowpack Summary

Recent storm snow continues to settle, with moist snow and crusts possibly forming on some surfaces. Recent strong wind has left wind slabs on lee terrain features, and some cross-loaded features due to outflow winds in coastal inlets. Several persistent weak layers may be found in the top metre of the snowpack, including a surface hoar layer buried on Dec 28 (20 to 40 cm deep) and a facet layer buried on Dec 23 (40 to 80 cm deep). These layers are increasing in strength, but could still be possible to trigger in specific areas. In alpine terrain, triggering one of these layers is most likely on steep rocky slopes where they present as facets, while in treeline terrain, it is most likely triggered on convex rolls in open trees where they present as preserved surface hoar.

Weather Summary

Wednesday night

Partly cloudy, no precipitation, 30 to 50 km/h wind from the southeast, treeline temperatures drop to -8 °C.

Thursday

Mix of sun and cloud, no precipitation, 20 to 40 km/h wind from the southeast, treeline temperatures warm to -4 °C.

Friday

Cloudy with flurries increasing in intensity throughout the day, 5 to 15 cm of snow by the late afternoon, 50 to 70 km/h wind from the south, freezing level climbs to 1500 m around Prince Rupert and Kitimat, but stays below 500 m around Shames and Terrace.

Saturday

Mix of sun and cloud, no precipitation, 30 to 50 km/h wind from the southeast, freezing level drops to 500 m with treeline temperatures around -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Use caution when approaching steep and rocky terrian.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.