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Avalanche Forecast

Archived

Dec 14th, 2020–Dec 15th, 2020

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

Kootenay Boundary.

New snow and strong southwest winds are forming reactive wind slabs in lee terrain features at upper elevations. A shallowly buried crust offers a slick bed surface for avalanches.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Monday night: Partly cloudy, wind increasing to moderate southwest, freezing level valley bottom.

Tuesday: 5-10 cm new snow, strong southwest ridgetop wind, alpine high -8, freezing level 500 m.

Wednesday: Partly cloudy, moderate southwest ridgetop wind, alpine high -6 C, freezing level 700 m.

Thursday: 5-10 cm new snow, moderate southwest ridgetop wind, alpine high -5 C, freezing level 900 m.

Avalanche Summary

Over the last week, avalanche activity has been limited to size 1 skier triggered storm/wind slabs running on the crust. This great MIN from Friday near Nelson includes a photo of an accidental wind slab.

Please submit your observations to the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!

Snowpack Summary

5-10 cm of new snow falls on a layer of surface hoar 5-20 cm above a crust. At upper elevations, strong southwest wind is blowing the new snow into fresh wind slabs amongst previously wind affected surfaces.

The early November crust is sitting about 10-30 cm up from the ground. There is a late November crust in the midpack in some places as well. Uncertainty with these crusts exist due to limited observations, but there haven't been any recent avalanches reported on these layers in this region.

Snowpack depths vary with elevation, treeline averages between 50-100 cm. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs are most reactive during their formation.
  • Keep in mind the crust offers an excellent bed surface for avalanches.

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.