Avalanche Forecast

Issued: Mar 25th, 2013 9:51AM

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

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Good

Weather Forecast

The ridge of High pressure is expected to continue to influence the interior ranges for the next few days. As the ridge weakens we may see high cloud reducing the exposure to strong solar radiation. Nights are expected to continue to be clear and cool. Freezing levels in the North should rise during the day to about 1800 metres, and to about 2000 metres in the South. Some light precipitation may start to move in from the coast on Thursday afternoon.

Avalanche Summary

Cornice falls continue to be reported on a daily basis. Some cornice falls are releasing slab avalanches in the track or on the fan.

Snowpack Summary

Cornices are reported to be very large and weakly bonded. Natural cornice falls are a concern during daytime warming. Cornices may also be triggered easily by travelling near them. Slopes with corniced entrances, or exposed to cornice falls should be avoided with these conditions. Dry windslabs may be found on Northwest thru Northeast aspects at higher elevations. These wind slabs are reported to be improving their bond to the old surface, but may continue to be triggered by skiers and riders. Loose moist or wet snow may fall naturally out of very steep terrain on sun exposed slopes. Small loose snow avalanches may trigger the recent storm snow slab where it is moist from solar heating and sitting on a planar sliding surface like an old sun or rain crust. The weak layer of buried surface hoar from March 10th is down more than a metre in most places, and is giving variable results in snow profile tests. The lower snowpack consists of well bonded layers that are well settled and strong.

Problems

Cornices

An icon showing Cornices
Cornices are large and weak and may fall off naturally. Some of these cornice failures may be the size of a van or a bus.
Do not travel on slopes that are exposed to cornices overhead.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Likely

Expected Size

2 - 6

Storm Slabs

An icon showing Storm Slabs
The recent storm has left a storm slab on Southerly aspects that may be triggered by strong solar radiation or loose snow in motion. Wind slabs at higher elevations remain dry on shaded aspects and terrain features.
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Large loads like cornice fall may trigger the deeply buried March 10th surface hoar layer.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Mar 26th, 2013 2:00PM