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Avalanche Forecast

Archived

Feb 21st, 2022–Feb 22nd, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
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

Northwest Coastal.

Large, human-triggered wind slab avalanches have been reported in recent days. The most likely place to trigger an avalanche is in the alpine, on unsupported or convex terrain where the slope rolls away from you. Don't get surprised!

Confidence

High -

Weather Forecast

Monday night: Clear, strong outflow winds, low of -16.

Tuesday: Increasing cloud, wind easing to light northwest, alpine high of -8.

Wednesday: Mostly cloudy with flurries up to 5 cm, moderate northwest wind, alpine high of -6.

Wednesday: Sunny, light northwest wind, alpine high of -4.

Avalanche Summary

On Sunday, natural size 2.5 wind slab avalanches were reported east of Kitimat.

On Saturday, several skiers were surprised by a handful of separate incidents of accidentally and remotely triggered size 2-2.5 (large) storm slabs, including the one reported in this MIN. These avalanches slid on the thick crust beneath the most recent storm snow. At least one was on a previously skied slope. Near Shames, storm slab activity included a few natural size 1s on solar aspects and skier triggered size 1.5s on convex slopes.

 

Snowpack Summary

In the alpine, 30-50 cm of recent, wind-affected snow appears to be bonding poorly to the underlying crust. Below 1300 m, formerly moist snow is refreezing in the cold temperatures.

The 10-30 cm thick rain crust beneath the recent snow effectively caps the underlying snowpack, making human triggering of avalanches on deeper weak layers very unlikely.

Terrain and Travel

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Wind slabs may be poorly bonded to the underlying crust.

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.