Avalanche Canada pgoddard, Avalanche Canada

Sea to Sky Avalanche Forecast

Apr 22nd, 2012 4:00PM

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

Summary

Confidence

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

Weather Forecast

Monday: Light rain, with snowfall possible only at very high elevations. Freezing level around 2600 m. Light to moderate south-easterly to south-westerly 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. On Saturday, similar activity continued.

Snowpack Summary

20 cm of snow which fell on Thursday night was shifted into wind slabs on slopes lee to the south or south-west. Around 50 cm of snow now overlies a buried crust, which has been acting as an easy sliding layer. Solar warming de-stabilized new snow above this crust on Friday and Saturday. Warm temperatures through Saturday night didn't allow the snow surface to refreeze. This pattern is likely to continue for the next few days, which could lead to a weak, wet snowpack at all elevations. A deeper crust layer from late March, buried within the upper 2 m of the snowpack, remains a lingering concern for big avalanches, particularly during times of intense or prolonged snowpack warming. Large cornices threaten slopes. Glide slab releases are a possibility, especially in steep rocky terrain.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 3
Wind slabs have developed with recent snow and moderate winds, and more may develop with incoming weather. Be alert for these behind ridges and terrain breaks.

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Cornices

An icon showing Cornices

Likelihood

Possible

Expected Size

1 - 5
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.

Loose Wet

An icon showing Loose Wet

Likelihood

Very Likely - Likely

Expected Size

1 - 6
Wet loose or slab avalanches may slide easily on a buried crust, particularly while rainfall or mild temperatures continue. These can gather mass, push you around and become surprisingly large.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Apr 23rd, 2012 9:00AM