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Avalanche Forecast

Archived

Dec 7th, 2021–Dec 8th, 2021

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.
Below Treeline
Natural avalanches unlikely.

Regions

Kootenay Boundary.

Danger is gradually increasing as snow accumulates above a slippery crust, especially on wind-loaded slopes near ridges.

Confidence

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

Weather Forecast

A cold front will bring gusty winds and 5-20 cm of low density snow on Wednesday. 

TUESDAY NIGHT: Cloudy with some light flurries and 1-5 cm of snow by the morning, moderate wind from the southwest with some gusts to 50 km/h, treeline temperatures around -8 C.

WEDNESDAY: Flurries bring 5-15 cm of low density snow, moderate to strong wind from the west, treeline temperatures around -8 C.

THURSDAY: Mostly cloudy, no precipitation, light wind from the west, treeline temperatures around -10 C.

FRIDAY: Mix of sun and cloud, no significant precipitation, light wind from the southwest with some moderate gusts, treeline temperatures around -10 C.

Avalanche Summary

Recent avalanche activity has been limited to small sluffs (aka loose snow avalanches) running above the shallowly buried crust. Over the weekend there was one explosive triggered storm slab in an open bowl involving a deeper pocket of snow above the crust.

Be on the lookout for this low density snow becoming a more cohesive slab above the crust, especially in wind-affected areas.

Snowpack Summary

Expect more snow to accumulate over the widespread crust on Wednesday. By the end of the day there will likely be 20-40 cm of low density snow above the crust in sheltered areas, while strong wind will likely form wind slabs at upper elevations. The bond of the new snow to the crust is suspect.

The snowpack structure is relatively simple beneath the crust. At upper treeline elevations, the total snow depth is 60-120 cm with a few crusts in the lower snowpack. Below treeline, the snowpack is much thinner and a relatively uniform layer of frozen crusts.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Use ridges or ribs to avoid areas of wind loaded snow.
  • Closely monitor how the new snow is bonding to the crust.
  • Avoid areas where the snow feels stiff and/or slabby.

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.