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Avalanche Forecast

Archived

Apr 5th, 2022–Apr 6th, 2022

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

Regions

Northwest Coastal.

Recent moderate to strong winds from varied directions have formed wind slabs on a variety of aspects that may remain reactive to human triggers.

Avoid steep or convex slopes where the wind has made the snow stiff or "slabby".

Confidence

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

Weather Forecast

Tuesday night: Partly cloudy with isolated flurries; 0-5 cm / Light west winds / Low of -7 / Freezing level surface.

Wednesday: Increasing cloudiness with flurries in the afternoon; 3-10 cm, and another 15-20 cm overnight / Strong southwest wind / High of -2 / Freezing level 700 m.

Thursday: Snow(above around 800 m), 15-20 cm / Moderate southwest wind / High of 1 / Freezing level 1100 m.

Friday: Mix of sun and cloud / Light west wind / High of 0 / Freezing level 1000 m.

Avalanche Summary

Intense wind loading triggered some very large (up to size 3.5) wind slabs in the Bear Pass area that were reported on Monday morning.

A size 1 storm slab 40 cm deep was skier triggered on a steep roll at treeline on Monday. Warming was reported as the contributing factor that made the slab more sensitive to triggering.

Snowpack Summary

10 cm of new snow adds to the 25-50 cm of recent snow which overlies a hard melt-freeze crust.

Recent moderate to strong winds from varied directions have formed wind slabs on a variety of aspects that may remain reactive to human triggers.

Around 100 cm down, a layer of weak snow (facets or surface hoar) has been occasionally reported in sheltered areas. The distribution of this layer has been reported as isolated and likely not a problem in many areas.

Cornices are very large and exposure to them should be minimized, especially during warm or windy weather.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

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.