Avalanche Forecast

Issued: Mar 8th, 2012 8:53AM

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

Avalanche Canada ccampbell, Avalanche Canada

Summary

Confidence

Good

Weather Forecast

Friday: Precipitation is expected to taper off to scattered light showers under an unstable airmass, however strong southwesterly winds are expected to continue. Freezing levels are expected to hover around 500-700 m. Saturday and Sunday: A fairly weak system is expected to arrive on the north coast on Saturday bringing light precipitation to the area. This system will be through by Sunday but isolated flurries will likely prevail under a very unstable airmass. Strong southerly winds and freezing level around 500-1000m are expected for both days.

Avalanche Summary

Observations from Wednesday are limited, but reports suggest that fresh wind slabs are touchy with a few small skier-triggered 10-40cm thick slabs on wind-exposed rolls treeline and below.

Snowpack Summary

Intense wind-loading was observed at all elevations on Wednesday with snow surfaces either getting scoured or packed into hard wind slabs. Warm temperatures and sun-exposure have moistened the surface snow on all aspects below around 1000m and some areas as high as 1600m. Recent snowpack tests on a northeast aspect at 1480m gave several resistant planar shears the recent storm snow and two hard resistant planar shears down 37cm and 70cm where the total snowpack depth was 5m. The mid February interface, down around 60cm, is variable and generally consists of a strong melt freeze crust below 1000m. Above that elevation, expect to find buried facets, and/or surface hoar (in more sheltered areas), and/or a sun crust on southern aspects. The surface hoar is not widespread but is responsible for much of the larger avalanches that occurred earlier this week. This layer should be on your radar, as it may be susceptible to rider triggers.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent intense winds have deposited fresh wind slabs, generally below ridgecrests, behind terrain features and in gullies. Cornices are large and weak and could trigger large wind slabs below.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
The persistent weak layer continues to be buried by a few cm each day. Avalanches on this layer have not been reported for a few days, but we feel that it could still be easily triggered by skiers and riders.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Mar 9th, 2012 8:00AM