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Avalanche Forecast

Archived

Dec 4th, 2021–Dec 5th, 2021

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.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

South Columbia.

Isolated wind slabs may lurk around ridges and steep alpine features. Be mindful that travel may be the most hazardous part of your day.

Confidence

Moderate - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

SATURDAY NIGHT: Mostly cloudy with light flurries, clearing into morning. West-northwest wind, 25-35 km/hr. Alpine low temperature -14 C. Freezing level valley bottom. 

SUNDAY: Partly cloudy with sunny breaks. Decreasing northwest-west wind, 15-30 km/hr. Alpine high temperature -7 C. Freezing level valley bottom. 

MONDAY: Partly cloudy with sunny breaks. Light and variable wind 10-15 km/hr. Alpine high temperature -9 C. Freezing level valley bottom. 

TUESDAY: Sunny with increasing cloud cover. Southwest wind 10-15 km/hr. Alpine high temperature -8 C. Freezing level valley bottom. 

Avalanche Summary

A natural cornice failure was reported on Friday, Dec 3. The small cornice did not trigger the slope below.

On Thursday, Dec 2, explosives triggered size 1-2 avalanches above 1800 m, with the larger (size 2) avalanches reported above 2000 m and included cornice failures triggering slopes below.

On Wednesday, Dec 1, explosives triggered size 1 loose wet and storm slab avalanches near Revelstoke.

The recent series of atmospheric rivers onslaught brought heavy precipitation, strong winds, and warm weather. Widespread and very large natural avalanche cycles were observed (up to size 3) following each wave of storms, with avalanches frequently running full path to valley bottom. No new natural avalanches have been reported since Dec 1. Hard frozen debris will likely be found in the runout of most avalanche paths.

Snowpack Summary

Up to 20 cm loose snow covers a crust in protected areas and depressions at treeline and above. Wind has redistributed snow and exposed the crust in any open terrain.

Below the Dec 1 surface crust, the snowpack is generally well-consolidated with a few early season crusts. The mid-November crust is found down 70-150 cm with faceting below the crust; this feature disappears above 1900 m.

Snowpack depths range from 120-250+ cm at treeline and above. Below 1600m the snowpack decreases rapidly.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.