Avalanche forecast

South Coast

Dec 11 – 12, 2021Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
4 · High
Below
2 · Moderate
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Highlights

Heavy snowfall and strong wind are creating very dangerous avalanche conditions. Having the skills to recognize and avoid avalanche terrain will be critical to managing your risk on Saturday. Stick to simple, low-angle slopes with no overhead hazard. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–3

    Significant and rapid accumulations of snow accompanied with strong southwest winds are building a widespread reactive storm slab problem. The additional snow and strong wind forecast for Saturday could make this problem even more touchy, particularly in wind-exposed areas. Storm slab avalanches will likely be large and run far on the underlying crust. Stick to simple, low-angle slopes with no overhead hazard. 

Confidence

Moderate - We are confident a natural avalanche cycle will begin shortly after the arrival of the incoming weather.

Weather Forecast

A fast-moving storm plows through overnight and hammers the region with snow and wind.

Friday night: Cloudy, 30-60 cm of snow above 1100 m, strong southwest wind, treeline temperatures rising to near 0 C, freezing level reaching 1100 m and dropping to 600 m by morning.

Saturday: Cloudy, 5-15 cm of snow above 600 m, strong southwest wind, treeline temperatures near -3 C.

Sunday: Cloudy, 15-25 cm of snow above 600 m, moderate southwest wind, treeline temperatures near -5 C. 

Monday: Increasing cloud, 10-20 cm of snow above 700 m, winds becoming southeast and increasing to moderate, treeline temperatures near -3 C.

Avalanche Summary

We expect that natural and human triggered avalanches will release large and run far during the storm.

Snowpack Summary

A potent storm with strong wind is forecast to bring 40-70 cm of new snow to the mountains by the end of Saturday. This will create a widespread, reactive storm slab problem that will be particularly pronounced where the snow is drifted by southwest winds. The snowpack will need time to adjust to this rapid, hefty new load. Closely monitor how the new snow is bonding to the old surface as the cold snow is not expected to bond well to the hard crust. 

Storm accumulations are covering a variety of old snow surfaces. These include: two distinct crust layers that formed in early December, wind-affected surfaces at upper elevations, and soft snow preserved in sheltered areas up high. Below the early December crust layers, the snowpack is generally well-settled. With this storm event, a greater number of areas at treeline elevations may meet the threshold for avalanches.

Terrain and Travel

  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Avoid the runout zones of avalanche paths. Avalanches could run full path.
  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
  • Expect slab conditions to change drastically as you move into wind exposed terrain.
  • Don't let the desire for deep powder pull you into high consequence terrain.

Regions covered