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Avalanche Forecast

Archived

Dec 11th, 2023–Dec 12th, 2023

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

Regions

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

Seeking sheltered snow is a good way to avoid wind slabs, but all steep slopes should be approached with caution. A weak layer of surface hoar buried by the storm may still be in play.

Confidence

Moderate

Avalanche Summary

Visibility has been limited but avalanche observations are still coming in. On Saturday and Sunday, many natural and explosives-triggered wind slabs up to size 2.5 were reported in more northern and coastal parts of the region. These occurred on a wide range of aspects, predominantly in the alpine and to a lesser extent at treeline.

We have yet to receive a solid indication of the reactivity of our buried surface hoar layer.

Snowpack Summary

30-60 cm cm of recent storm snow has been redistributed by variable winds, which means wind slabs may be found on all aspects in exposed areas.

In more sheltered areas this recent snow may overlie large, feathery surface hoar at treeline (more likely a crust below treeline). Observations of the surface hoar since its burial on Dec 9 are limited but slabs that form where this layer is preserved could be surprisingly reactive - and destructive if triggered.

The mid snowpack contains several crusts from November that are generally well bonded to the surrounding snowpack. The height of snow at treeline is around 150 cm and tapers rapidly below treeline.

Weather Summary

Monday Night

Mainly clear, Southwest alpine wind 15 to 30 km/h.

Tuesday

Increasing cloud with isolated flurries. South alpine wind 30 to 70 km/h, increasing over the day and overnight. Treeline temperature -3°C with freezing level to 1200 m.

Wednesday

Cloudy with flurries continuing from overnight bringing up to 20 total cm of new snow. Southwest alpine wind 30 to 70 km/h, easing. Treeline temperature -2°C with Freezing level falling to 800 m.

Thursday

Clearing. South alpine wind 40-60 km/h, increasing. Treeline temperature -3°C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be especially cautious as you transition into wind affected terrain.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.