Avalanche Forecast

Issued: Apr 3rd, 2015 9:36AM

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

bcorrigan, Avalanche Canada

Northwest Coastal.

A weak layer of surface hoar and facets has created touchy avalanche conditions in parts of the region. If you have field observations, please consider sharing them through the Mountain Information Network

Summary

Confidence

Good - Forecast snowfall amounts are uncertain

Weather Forecast

5-10cm of snow is expected throughout the day Friday with another 5 cm each day on Saturday and Sunday. Daytime high freezing levels are expected to hover around 1300 m for Friday and Saturday and a bit higher on Sunday. Alpine winds are expected to belight throughout the weekend.

Avalanche Summary

There have been several explosive-controlled wind slab avalanches up to Size 2.5 running on facets buried March 25th. On Thursday, a remotely triggered Size 2.5 avalanche released above two skiers catching both of them and burying one, who was successfully recovered. This avalanche failed on the same March 25th weakness, where it was buried surface hoar on a northeast aspect at 1450 m.

Snowpack Summary

50-70 cm of recent settled storm snow is bonding poorly to a variety of old snow surfaces including surface hoar and facets buried on March 25th. This weakness is very touchy with a high propensity for propagating fractures, especially where buried surface hoar exists. The problem seems more touchy in the northern part of the region, but has been reported throughout the northwest coastal area. Weaknesses have also been found within the recent storm snow with snowpack tests producing moderate sudden results down approximately 30 and 40 cm. The early March facet/crust persistent weakness is now down around a metre and appears unreactive with snowpack tests.

Problems

Persistent Slabs

With recent storm loading, the March 25th surface hoar/facets combo is now buried 50 to 70 cm from the surface and requires careful consideration.

Dig down to find and test weak layers before committing to a line.>Be aware of the potential for large avalanches due to the presence of buried surface hoar.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Storm Slabs

Recent storms have left us with soft storm slabs, great skiing in some places, potentially dangerous in others. Take the time to examine the possible consequences to your choice of riding terrain.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be alert to conditions that change with aspect and elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 4th, 2015 2:00PM