Avalanche Forecast

Issued: Apr 2nd, 2015 8:27AM

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

ccampbell, Avalanche Canada

Sea To Sky.

Deep persistent weaknesses are still producing avalanches. Big alpine features cannot be trusted.

Summary

Confidence

Good

Weather Forecast

5-10 cm of snow is expected on Friday and another 5-10 cm by Saturday morning, before things start to dry out with a mix of sun and cloud on Sunday. Daytime high freezing levels are expected to hover around 1500 m for the forecast period. Moderate southwesterly alpine winds are expected on Friday then light but gusty southwesterlies for the weekend.

Avalanche Summary

Reports from Wednesday include explosive triggered storm slab avalanches up to Size 2, and one Size 3 persistent slab release on the mid-March persistent weakness.

Snowpack Summary

Up to 25 cm of low density storm snow is sitting on a thin breakable crust that caps 30-40 cm of recent moist snow on rain crust buried last Saturday. Reports suggest this 5 cm thick solid rain crust exists up to at least 2200m. Strong southwest winds have shifted these new accumulations into touchy wind slabs in exposed terrain. A facet/crust persistent weakness buried mid-March is down approximately 70-130 cm and is still producing hard but sudden results in snowpack tests. This remains the chief concern amongst avalanche professionals in the region due to it's potential for very large avalanches.

Problems

Persistent Slabs

A cautious approach is still required because, although it would likely take just the right trigger in just the right spot, avalanches failing at this interface may not be survivable.

Be aware of the potential for large, deep avalanches due to the presence of a buried crust/facet layer.>Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Storm Slabs

Recent storm accumulations have been shifted into deeper deposits by strong southwest winds. Watch for increased reactivity in high elevation lee terrain.

Be alert to conditions that change with elevation.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 3rd, 2015 2:00PM