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Avalanche Forecast

Archived

Dec 29th, 2022–Dec 30th, 2022

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.

Use extra caution at treeline where persistent weak layers have been most reactive. Be aware that wind slabs could step down to deeper layers.

Confidence

Moderate

Avalanche Summary

On Wednesday one size 1.5 avalanche was remotely triggered by a snowcat. This avalanche was at treeline on a northeast aspect and failed on the facets formed during last weeks cold period. In the north of the region explosives triggered several small wind slab avalanches.

Snowpack Summary

New wind slabs exist in exposed terrain at treeline and above on all aspects. A new crust exists on the surface below 1000m.

30 to 50cm of recent storm snow overlies a variety of surfaces formed during the previous cold snap. In the alpine these surfaces are generally facets, old wind slab and Surface hoar. At treeline it is more likely to find surface hoar at this interface in sheltered terrain.

A layer of surface hoar and facets from early December can be found down 50cm in shallower snowpacks and over 80cm in deeper areas. recently this layer has not been reactive but still produces sudden results in snowpack tests.

The mid November crust is buried down over a meter in most places and is unreactive. The mid and lower snowpack is generally well settled.

Weather Summary

Thursday Night

Cloudy with light flurries bringing around 5cm of new snow. Light southerly winds and a low of -5 at 1500m.

Friday

Cloudy with flurries bringing trace amounts of new snow. Light variable winds in the alpine and moderate northerly at valley bottom. High of -3 at 1500m.

Saturday

Cloudy with light flurries bringing trace amounts of new snow. Light southwest winds and a high of -4 at 1500m.

Sunday

Cloudy with no new snow expected. Light to moderate south winds and a high of -3 at 1500m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Use ridges or ribs to avoid areas of wind loaded snow.

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.