Avalanche Forecast

Issued: Dec 20th, 2019 5:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada MBender, Avalanche Canada

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Recent snow and wind has promoted wind slab development at upper elevations.

Summary

Confidence

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

Weather Forecast

Friday Night: Cloudy with scattered flurries. Alpine temperature -5 C. South wind 20-40 km/hr.

Saturday: Cloudy with sunny periods. Alpine temperature -7 C. Southwest wind 15-20 km/hr.

Sunday: Mix of sun and cloud. Alpine temperature -7 C. Southwest wind 10-20 km/hr.

Monday: Cloudy with isolated flurries. Alpine temperature -8 C. south wind 20-30 km/hr. 

Avalanche Summary

There have been no recent reports of avalanche activity.

Between Tuesday and Wednesday, and further east of the Northwest Inland region, a natural wind slab avalanche cycle to size 2.5 in alpine and treeline areas was triggered by intense wind loading.

Snowpack Summary

15-30 cm of snow fell in the region early this week. Strong south-southwesterly winds have since developed reactive wind slabs, especially around ridge features and into the alpine. 

Reports suggest there are 2 buried layers of surface hoar in the upper snowpack - one down 15-25 cm below the new snow, and another down 25-40. Where wind has scoured the snowpack, a crust from November is at or near the surface. In leeward terrain, a this crust is 40-60 cm deep, and may include surface hoar in sheltered openings up to treeline.

Older crusts can be found deeper in the snowpack and are generally breaking down. In areas with a relatively thin snowpack, the base of the snowpack likely consists of weak faceted grains.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

Wind Slabs

An icon showing Wind Slabs

Recent new snow has been redistributed by wind blowing from a variety of directions.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 21st, 2019 5:00PM

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