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Avalanche Forecast

Archived

Dec 6th, 2021–Dec 7th, 2021

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

North Columbia.

Avalanche danger will gradually increase in wind-affected terrain this week. 

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

MONDAY NIGHT: Clear skies, no precipitation, light wind from the west, treeline temperatures around -15 C.

TUESDAY: Increasing cloud with some light flurries in the afternoon, no significant precipitation, moderate wind from the southwest, treeline temperatures warming to -12 C.

WEDNESDAY: 10-25 cm of low density snow, light to moderate wind from the west, treeline temperatures around -12 C.

THURSDAY: Mostly cloudy skies, no precipitation, light wind from the west, treeline temperatures around -12 C.

Avalanche Summary

Avalanche activity over the weekend was limited to a few small dry loose avalanches and one larger wind slab. This avalanche was naturally triggered on a wind-loaded alpine slope northwest of Revelstoke.

Last Thursday and Friday, there were a few very large deep persistent slab avalanches in the northern edge of the region near Blue River and Kinbasket Lake. These avalanches occurred in steep rocky north-facing terrain and failed on a deeply buried crust layer. One of the avalanches was triggered by a cornice collapse.

There is still visible evidence of a widespread avalanche cycle from the Dec 1st atmospheric river.

Snowpack Summary

10-30 cm of low density snow covers a supportive crust which has been found as high as 2400 m. Winds have exposed the crust in open areas and built wind slabs in leeward terrain. Loose snow persists in protected areas and depressions. 

The snowpack is generally well-consolidated below the surface crust. The mid-November crust is found down 70-150 cm with some faceting below the crust. This feature disappears above 1900 m and does not appear to be problematic at this point.

Snowpack depths range from 100-250 cm at treeline and above. The snowpack decreases rapidly below 1600 m.

For an in depth look into the recent weather, current snowpack and our thoughts for the future visit the Forecasters' Blog.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Use caution when approaching steep and rocky terrian.
  • Wind slabs may be poorly bonded to the underlying crust.

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.