Avalanche Canada ldreier, Avalanche Canada

Sea to Sky Avalanche Forecast

Jan 12th, 2020 4:00PM

Changing direction in wind to northerly will form new slabs in the alpine and around treeline. If below treeline elevations are affected by outflow wind overnight or during the day on Monday, consider the avalanche danger on all elevations bands Considerable.

Summary

Confidence

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

Weather Forecast

SUNDAY NIGHT: Mostly clear, moderate northerly wind, alpine temperature -17 C, freezing level below valley bottom.

MONDAY: Mostly sunny, moderate northerly wind, alpine temperature -18 C, freezing level below valley bottom.

TUESDAY: Mix of sun and cloud with isolated flurries, light to moderate southwest wind, alpine temperature -20 C, freezing level below valley bottom.

WEDNESDAY: Mostly sunny, light variable wind, alpine temperature -22 C, freezing level below valley bottom.

Avalanche Summary

On Saturday, several large (up to size 2.5) slab avalanches were triggered with explosives. A few small (size 1.5) slab avalanches were triggered by skiers. Two natural avalanches of size 3 and 3.5 were reported. 

On Friday, a large (size 2) machine triggered avalanche was reported. It released on a deeper weak layer in the snowpack. Several small (size 1) avalanches released naturally or were triggered by skiers within the new storm snow.

On Thursday, several explosive triggered and a few natural avalanches up to size 3 were reported. 

Snowpack Summary

Strong to extreme southerly wind has formed wind slab in lee terrain features in the alpine and around treeline. In sheltered areas the snow surface stayed soft. 

Previous storms have loaded a weak layer of feathery surface hoar buried around 100 to 180 cm in some areas of the region. In parts of the region near the bottom of the snowpack around 150 to 250 cm deep, sugary faceted grains and a hard melt-freeze crust exist from mid-November. This is is an indicative snowpack setup for large and destructive avalanches. The likelihood of human-triggered avalanches decreases as the layer gets deeper but the consequence of triggering it would be severe.

Terrain and Travel

  • Choose low-angled, sheltered terrain where new snow hasn't been wind-affected.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.

Valid until: Jan 13th, 2020 5:00PM