Avalanche Canada ahanna, Avalanche Canada

Northwest Coastal Avalanche Forecast

Jan 13th, 2020 4:00PM

If you're braving the cold on Tuesday, be on alert for wind slabs in lee features at all elevations and loose dry sluffing in steep, sheltered terrain.

Summary

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Monday night: Clear. Light to moderate northeast winds. Alpine temperatures around -25 C.

Tuesday: Sunny. Strong valley outflows with light to moderate alpine wind from the northeast. Alpine temperatures around -23.

Wednesday: Sunny. Strong valley outflows with strong alpine wind from the southeast. Alpine temperatures around -25.

Thursday: Increasing cloud. Moderate southeast winds. Alpine temperatures around -20.

Avalanche Summary

A natural windslab cycle, size 2-3 was observed Sunday and Monday morning amid reverse loading by strong outflow winds. In an isolated incident, a crown depth of 2 m was observed on a southeast aspect in the alpine. It is suspected to have stepped down to deep persistent layers from mid December. 

Sheltered areas may continue to react to human triggers as dry loose sluffs, under the cold forecast temperatures.

Snowpack Summary

Extensive wind effect observed at all elevations. Scoured northeast to southeast aspects, loaded lees, with lots of snow sublimating into the air. Not much snow remains for wind transport by the forecast continued outflow. Snow in protected areas is unconsolidated and well preserved by the cold temperatures.

The surface snow may cover a layer of surface hoar at lower elevations in sheltered areas, or a thin sun crust on steeper south-facing slopes. The mid to lower snowpack is generally well consolidated. Layers of note include a crust 1 m deep, found below 1400 m and a couple of layers of surface hoar 1.5 m deep. The recent storm cycle was a good test of these layers, with no reports of avalanches stepping down to them.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Keep your guard up at lower elevations. Wind slab formation has been extensive.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

Valid until: Jan 14th, 2020 5:00PM