Avalanche Forecast

Issued: Apr 6th, 2012 10:21AM

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

swerner, Avalanche Canada

Northwest Inland.

Summary

Confidence

Good

Weather Forecast

A ridge off high pressure off the coast will bring sunny, dry conditions through the weekend. Saturday: Ridgetop winds will be light from the SE. Alpine temperatures near -1. Freezing levels rising to 1400 m, dropping to valley bottom through the night. Sunday/Monday: Clear, sunny and dry conditions. Freezing levels rising to 1700 m both days. The ridge will start to break down on Monday bringing bands of cloud, and light precipitation through the evening. Solar radiation will be intense through the forecast period.

Avalanche Summary

Reports from Wednesday include some larger wet sluffs from steep rocky sun-exposed terrain. Cornices have also been failing over the past couple of days, some of which triggered wind slab avalanches up to Size 2 on the slope below. Glide cracks are widening at lower elevations.

Snowpack Summary

Moderate winds have blown light amounts of new snow into variable wind slabs in exposed lee and cross-loaded terrain, which are starting to bond. Surface snow on sun-exposed slopes is undergoing a daily melt-freeze cycle. In sheltered areas 15-30cm of new snow sits on the previous surface that includes crusts (found on all aspects below 1000m and on solar aspects higher up), and old wind slabs. Not only will daytime warming and sun-exposure cause surface snow to lose cohesion and cornices to weaken, they will also increase settlement rates and decrease slab stability.

Problems

Loose Wet

Loose wet avalanches are likely on sun exposed slopes during the day. Isolated wet slab avalanches are also possible. Pinwheels, and snowballing are initial indicators of the snowpack deteriorating.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Cornices

Large cornices exist in alpine terrain and they may pop off with warmer temperatures and intense solar radiation. A failure could be destructive by itself, and could also trigger an avalanche on the slope below. Give room above and below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Wind Slabs

Thin wind slabs have formed in exposed lee and cross-loaded features. Watch for triggering in gullies, behind ridge crests and over rolls in terrain. They may feel hollow, and have a drum like sound beneath your feet.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 7th, 2012 9:00AM