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Avalanche Forecast

Archived

Feb 20th, 2020–Feb 21st, 2020

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

Regions

Northwest Coastal.

Storm slabs will build through the day Friday as 20-40 cm of new snow falls amid extreme wind. Storm slabs will be especially reactive where freshly wind loaded pockets sit over surface hoar or sun crust.

Confidence

High - We are confident a natural avalanche cycle will begin shortly after the arrival of the incoming weather.

Weather Forecast

Thursday night: 10-30 cm new snow with lightest accumulations around Shames, heaviest near Kitimat. Extreme southwest wind. Freezing level 800 m.

Friday: 10-15 cm new snow. Strong southwest wind. Freezing level 700 m.

Saturday: Partly cloudy with isolated flurries. Moderate southwest to southeast wind. Freezing level 600 m.

Sunday: Partly cloudy. Moderate southeast to southwest wind. Freezing level 500 m.

Avalanche Summary

On Wednesday, fresh wind slab formation was observed, with reported activity limited to a size 2 natural and size 1 skier triggered, in addition to a cornice failure which did not trigger a slab.

Looking forward, a widespread storm slab avalanche cycle is expected with incoming snowfall.

Snowpack Summary

20-40 cm of new snow is forecast to fall by the end of the day Friday. Strong winds are redistributing the new snow in alpine and treeline areas. This new snow, in addition to the 10 cm from Wednesday night, sits on a layer of surface hoar in sheltered areas, and a sun crust on solar aspects.

At treeline and below, a patchy layer of small surface hoar crystals may exist 60-80 cm deep in wind sheltered areas.

A thin layer of facets that formed during the January cold snap is now about 120-170 cm below the surface while an early season crust lingers at the base of the snowpack. These layers produced a few large natural avalanches in early February but have recently been unreactive.

Terrain and Travel

  • Use increased caution at all elevations. Storm snow is forming touchy slabs.
  • The best and safest riding will be on slopes that have soft snow without any slab properties.
  • Choose simple, low-angle, well supported terrain without convexities.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.