Avalanche Forecast

Issued: Apr 20th, 2012 10:41AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Loose Wet, Wind Slabs, Storm Slabs and Cornices.

pgoddard, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Saturday: Warm, dry and mainly sunny in the morning. Freezing level around 2100 m. Light SE winds. A front is due to hit the area late in the day, bringing light to moderate precipitation and increasing SW winds.Sunday: Moderate precipitation. Freezing level rising to 2200 m. Moderate to strong SW winds. Monday: Continued mild temperatures. Light precipitation. Freezing level near 2000 m. Light to moderate SW winds.

Avalanche Summary

Several size 1-2 avalanches were triggered by people and explosives on Friday following overnight snow and wind. These failed on a crust or within recent storm snow layers. Natural avalanches were also triggered by sunshine on solar aspects, and a size 2 natural slab was observed on a NW aspect in Garibaldi Park.

Snowpack Summary

20 cm of new snow has been shifted by the wind into wind slabs on lee slopes. Around 50 cm of snow now overlies a buried crust, which can act as an easy sliding layer. Solar warming de-stabilized new snow above this crust on Friday and this may continue on Saturday before the next front arrives. A deeper crust layer from late March, buried within the upper 2 m of the snowpack, remains a lingering concern, particularly during times of intense upper snowpack warming. Large cornices threaten slopes. Glide slab releases are a possibility, especially in steep rocky terrain.

Problems

Loose Wet

Two processes are likely to cause wet loose or slab avalanches this weekend: first, sun and second, rain. Recent new snow is likely to slide easily on a buried crust when weakened by these warming processes, especially in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 6

Wind Slabs

Touchy wind slabs have developed with recent snow and moderate winds, and more will probably develop with incoming weather. Be alert for these behind ridges and terrain breaks.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Storm Slabs

Recent snow may take some time to settle and bond. Storm slabs may be easy to trigger on a smooth buried crust.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Large cornices are looming. These are a hazard in themselves and could trigger avalanches on the slope below.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Apr 21st, 2012 9:00AM