Avalanche Forecast

Issued: Feb 2nd, 2012 9:29AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Good - -1

Weather Forecast

A strong ridge of high pressure will persist through the forecast period bringing dry conditions, sunny skies, and warmer temperatures. On Friday/Saturday freezing levels may rise to 1000m in the afternoon, then drop to valley bottom at night. Ridgetop winds may generally be light from the South. Maximum alpine temperatures near -1. Sunday brings alpine sun, developing valley cloud and inversions.

Avalanche Summary

Very little natural slab avalanche activity to report. Reports indicated natural sluffing from steep rocky terrain features size 1-2. Several reports of rider triggered avalanches occurred on various aspects @ elevations of 1400-2100m. This tell me the storm slabs are still reactive to lighter loads. Also to note, cornice failures have been occurring naturally producing size 2. Explosive cornice control done Wednesday produced a size 2.5 on the slope below. I suspect cornice fall may increase under forecast alpine sun, possibly creating large slab avalanches on the slopes below.

Snowpack Summary

Storm slabs up to 60cms thick have formed. They seem to be settling out quick, but still slow sensitivity to rider triggers; especially on steeper slopes and convex rolls. Wind slabs have formed on North through East slopes in the alpine and at treeline. Buried below seems to be a fairly settled mid-pack, with a couple lingering layers.We continue to monitor the January 13th surface hoar/facet layer, and the January 28th interface. Recent snowpack field tests have shown generally moderate results, including resistant planar shears. These layers are getting stronger; but they may become reactive with the forecast warming. The average snowpack depth at 1700m is 2-3 m.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs may look smooth, feel stiff, and have a hollow sound under foot. They're most likely to be found on N-E aspects, and below ridgecrests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Storm Slabs

An icon showing Storm Slabs
Storm slabs may be susceptive to rider triggers. You're most likely to trigger a storm slab in steep and/or unsupported/convex terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Cornices

An icon showing Cornices
Large cornices have formed. They may become weak with rising freezing levels. You should give them a wide berth whether traveling near them or far below them. Failing cornices have the potential to trigger large avalanches on the slope below.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Feb 3rd, 2012 3:00AM