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Avalanche Forecast

Archived

Apr 1st, 2023–Apr 2nd, 2023

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

Regions

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

Watch for cornices and new wind slabs if travelling into alpine terrain.

Confidence

Moderate

Avalanche Summary

We've seen a decline in avalanche activity over the past week, with most observers only seeing small (size 1) wet loose avalanches triggered by warm and sunny weather. Several large (size 2) cornice falls have been observed, most of which have not triggered slabs on the slopes below. However, there are a few exceptions where cornices did trigger large avalanches, including two avalanches north of Stewart on Tuesday (100 to 250 cm thick slabs) and one avalanche north of Terrace on Thursday (30 cm thick slab). This suggests that the snowpack is generally strong, but it could be possible for heavy triggers like a collapsing cornice to trigger a large avalanche.

Snowpack Summary

New snow amounts range from 5 to 20 cm, with deeper deposits in lee terrain. In most areas this snow has covered moist or crusty snow layers, except shaded terrain above roughly 1500 m where the snow has remained dry over the past week. The lower snowpack is strong and bonded.

Weather Summary

Friday night

Cloudy, light flurries with 1 to 5 cm of snow (and some localized accumulations of 10 cm along the immediate coast), 30 km/h southwest wind, treeline temperatures around -5 °C with freezing level dropping to valley bottom.

Saturday

Cloudy with sunny breaks in the afternoon, isolated flurries with 2 to 5 cm of snow, 20 km/h southwest wind, treeline temperatures around -5 °C with freezing level up to 800 m.

Monday

Sunny, no precipitation, 10 km/h northwest wind, treeline temperatures around -3 °C.

Tuesday

Mix of sun and cloud, isolated flurries with trace amounts of snow, 20 km/h northwest wind, treeline temperatures around -3 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Carefully evaluate steep lines for wind slabs.
  • Caution around slopes that are exposed to cornices overhead.

Problems

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.