Avalanche Canada ccampbell, Avalanche Canada

Sea to Sky Avalanche Forecast

Apr 3rd, 2012 10:14AM

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

Summary

Confidence

Good

Weather Forecast

Unsettled conditions in the wake of Tuesday's storm system are expected to produce cloudy conditions and isolated light flurries with a few centimetres each day for the forecast period. The freezing level is expected to drop to and remain around 800 m, and the winds should remain light and variable.

Avalanche Summary

Reports from Monday include numerous soft wind slab avalanches up to size 1.5 occurring naturally as well as with direct and remote human triggers. Sustained heavy loading from snow wind and rain on Tuesday likely resulted in continued natural avalanche activity particularly on lee slopes.

Snowpack Summary

As of Tuesday morning heavy snowfall has already deposited up to 50cm, which is being redistributed by strong southwesterly winds into thick wind slabs. These wind and storm slabs are poorly bonded and continued snowfall and wind is adding additional load. A predominately crusty weak interface from late March, now down 50-150cm, remains a potential failure layer for large slab avalanches, especially with heavy triggers such as cornice falls and step-down avalanches. Cornices are also huge and weak.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 5
Generally lurking below ridgecrests, behind terrain features, and in gullies. Thick fresh wind slabs are highly sensitive to human triggers and cornice falls.

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Storm Slabs

An icon showing Storm Slabs

Likelihood

Possible

Expected Size

1 - 6
Storm slabs could be sensitive to human triggers and have the potential to step-down to deeper weaknesses buried last week resulting in highly destructive avalanches.

Aspects:

All aspects.

Elevations:

All elevations.

Cornices

An icon showing Cornices

Likelihood

Possible

Expected Size

1 - 6
Cornices are very large and probably unstable. Not only are they a hazard in themselves, but can also act as a heavy trigger for very large avalanches on the slope below.

Aspects:

North, North East, East, South East.

Elevations:

Alpine.

Valid until: Apr 4th, 2012 9:00AM