Avalanche Forecast

Issued: Dec 10th, 2019 8:00AM

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

Parks Canada chris gooliaff, Parks Canada

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Wind slabs and persistent slabs have surprised a number of people recently, especially on S'ly aspects where they overlay a crust. Give steep southern slopes respect!

Summary

Weather Forecast

A mix of sun and cloud today, alpine high of -4*C with light SW winds and fzl rising to 1200m. Wednesday brings light flurries and light SW winds with an alpine high of -7*C. Thursday a cold front passes through the area, delivering 10cm of snow, moderate SW winds, and an alpine high of -5*C.

Snowpack Summary

Moderate S-SW winds have created wind slabs in lee alpine features. 40cm of storm snow (since Dec. 5th) overlies surface hoar in some locations TL and BTL, and is concealing evidence of the recent cycle of natural avalanches. The November 23rd surface hoar/crust/facet layer is buried 80-100+cm and remains reactive in stability tests.

Avalanche Summary

Natural avalanche activity has tapered off, but observations of several human triggered avalanches to sz 2 were made yesterday. A skier kicked off a sz 2 wind slab from a steep, S-facing alpine start zone on Tupper. Another sz 2-2.5 was reported from SE slopes on Ursus Major at around 2500m elevation. Both slabs likely failed on a crust.

Confidence

Problems

Persistent Slabs

An icon showing Persistent Slabs

The November 23rd layer is down 80-100+cm and consists of surface hoar at treeline and below, and a crust on steep solar aspects into the alpine.

  • Evaluate terrain features by digging and testing on adjacent, safe slopes.
  • The storm slab may be more sensitive to human triggering on solar aspects where it sits on a crust

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 3

Wind Slabs

An icon showing Wind Slabs

Recent periods of moderate wind have potentially built wind slabs in immediate lees. Keep an eye out for these as you transition into exposed alpine terrain.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
  • Use caution in lee and cross-loaded areas. Recent wind loading has created new wind slabs.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 11th, 2019 8:00AM