Avalanche Forecast

Issued: Apr 17th, 2013 10:54AM

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

swerner, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Two approaching frontal systems will bring warm, wet and windy weather through the forecast period. Thursday: Overcast. Light-moderate precipitation amounts. Ridgetop winds light-moderate from the NW. Freezing levels rising to 1800 m. Friday: Overcast. Moderate precipitation amounts. Ridgetop winds moderate from the West. Freezing levels 1700 m. Saturday: Overcast. Light precipitation amounts. Ridgetop winds moderate to strong from the NW. Freezing levels falling to valley bottom.

Avalanche Summary

On Tuesday, a cornice fall triggered a size 2 avalanche in steep terrain burying old skier tracks. This occurred from a NE aspect at 2500 m.

Snowpack Summary

New snow and wind may build new wind slabs, burying older wind slab problems found at treeline and above. Cornices are very large and remain a concern. In some locations a surface hoar interface exists buried within the upper metre of the snowpack. This is mostly found on northerly aspects at upper elevations. It may be slowly gaining some strength, but I’d remain suspicious of these slopes. On other aspects, recent storm snow overlies a crust. This crust interface has recently become reactive in regions further south and may become reactive in your area with additional load.

Problems

Wind Slabs

New snow and strong winds will likely build new wind slabs on lee slopes. Buried wind slabs exist on a variety of aspects at treeline and above. Large, looming cornices exist on ridgelines and pose a threat to slopes below.

Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

A weak interface is buried about a metre down. A surface avalanche stepping down, cornice fall, or the weight of a person from a thin-spot trigger point could trigger it.

Be aware of thin areas that may propagate to deeper instabilites.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Apr 18th, 2013 2:00PM