Avalanche Forecast

Issued: Mar 21st, 2012 4:00PM

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

pmarshall, Avalanche Canada

Northwest Coastal.

The avalanche danger is expected to rise during the day if we see prolonged sunny periods.

Summary

Confidence

Fair - Due to variable weather conditions

Weather Forecast

Thursday: Scattered flurries with sunny breaks - 2-5cm. The freezing level should rise to 800m during the day. Winds are moderate from the southeast. Friday and Saturday: A ridge of high pressure builds in giving drier and sunnier conditions. The freezing level bounces from valley bottom overnight to around 1000m during the day. Winds are generally light from the south.

Avalanche Summary

Reports from Tuesday include several skier controlled slab avalanches up to Size 1.5 (15-30cm deep), primarily from wind loaded terrain features. There was also one natural Size 2 avalanche observed on a north aspect with a 50cm crown.

Snowpack Summary

20-40cm of new snow sits on the previous snow surface which included a sun crust on southerly aspects, surface facets or surface hoar in cool shady areas, and pockets of wind slab in exposed terrain. A variety of potential weak layers exist between 60 and 120cm deep. These include surface hoar or facets. There has been no recent activity on these layers but they could wake up with heavy triggers like a large cornice chunk or a snowmobile digging its track in. Cornices in the region are reported to be very large and potentially unstable.

Problems

Wind Slabs

New wind slabs may be triggered in exposed lee and cross-loaded terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Cornices

Cornices are reported to be very large and potentially unstable at this time. A cornice fall could be destructive by itself, and may also act as a trigger on the slope below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 6

Loose Wet

Loose wet avalanches are likely on steep sun exposed slopes if the sun is shining.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Mar 22nd, 2012 9:00AM