Avalanche Forecast

Issued: Feb 6th, 2012 9:57AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Good - -1

Weather Forecast

A ridge of high pressure will continue to keep the region dry, and sunny through Tuesday. Ridgetop winds are light from the SE. Freezing levels near 1100m dropping to valley bottom overnight. The pattern will start to change on Wednesday afternoon. Light snow amounts are expected with freezing levels near 1200m. Alpine temperatures could drop to -9, and treeline temps may hover near -6. Light snow amounts may spread across the region on Thursday with freezing levels possibly reaching 1500m.

Avalanche Summary

One notable size 2 skier triggered avalanche occurred outside the ski area boundary near Whitewater. This was on a North aspect @1985m. The crown depth was reportedly 40-60cms, 50 wide and running 150m down slope. 2 skiers were involved, and sustained no injuries. Other observations from around the region includes small surface sluffing from steep North facing aspects.

Snowpack Summary

Temperatures dropped below freezing again Sunday night, and persisted through the day at higher elevations. Crusts have been forming due to the melt and freeze cycle for the past few days. There is still dry snow on northerly aspects at higher elevations. Sun crusts have developed on steep solar aspects. Pin-wheeling and other signs of moist snow have been observed on solar aspects at and above treeline At treeline and below treeline surface faceting and surface hoar growth (up to 15mm) are forming; especially on shady aspects in sheltered locations. This may become future layers of concern once buried. Steep planar slopes with shallow snowpacks are the most suspect. The recent storm snow layer is about 30-50 cm thick and is quite variable across the region. There are a couple of thin crusts buried below the storm snow that have been producing moderate to hard shears in tests. Some areas are still getting sudden planar shears on the mid-December surface hoar layer.

Problems

Cornices

An icon showing Cornices
Forecast warm temperatures and strong solar radiation may weaken large fresh cornice growth. Cornice falls are a large load that may trigger deeply buried weak layers and cause large avalanches on the slopes below.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 6

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
A couple of recent avalanches have released deep in the snowpack. Some may have stepped down from avalanches released due to warming on southerly aspects. Some others on north aspects may have failed on the deep weak layer with light triggers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Feb 8th, 2012 8:00AM