Avalanche Forecast

Issued: Apr 11th, 2012 4:00PM

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

pgoddard, Avalanche Canada

Sea To Sky.

Summary

Confidence

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

Weather Forecast

Thursday: A mix and of cloud, sun and light precipitation. Freezing level around 1600 m. Light southerly winds.Friday: Light precipitation, dissipating. Light winds. Freezing level around 1500 m. Saturday: Clearing skies. Light south-westerly winds. Freezing level rising to around 2000 m.

Avalanche Summary

On Tuesday, several size 1-2 loose moist avalanches were triggered by solar warming or by people. On Sunday, a natural and human-triggered wind slab cycle occurred on north-west and west aspects following overnight winds. A size 3 natural slab is suspected to have stepped down to the March crust on Monday. It failed on a sun-exposed south-west aspect at 2300 m. There has also been some cornice fall.

Snowpack Summary

A melt-freeze crust exists on solar aspects and at low elevations. In some areas, limited overnight cooling has kept surface snow from re-freezing, leaving it loose and cohesionless. Areas of wind slab formed with recent southerly or easterly winds. Pockets of snow can be found on high north aspects, now buried underneath wind slabs in some areas. A predominately crusty weak interface from late March, now down 50-190 cm, has become less likely to trigger, but remains a lingering concern.

Problems

Wind Slabs

Wind slabs exist below ridges in some areas. These could be triggered by the weight of a person.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Warm temperatures may continue to weaken surface snow, especially at low elevations. Avoid traveling above terrain traps or under any slopes which have glide cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Persistent Slabs

Persistent slab avalanches have become less likely, but remain possible, especially with a large trigger like cornice fall.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 7

Valid until: Apr 12th, 2012 9:00AM