Avalanche Forecast

Issued: Dec 14th, 2012 8:51AM

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

triley, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Monday

Weather Forecast

Overnight and Saturday: A ridge of High pressure is forecast to remain in the region overnight. The next system should move into the region on Saturday morning bringing 5-10 cms of light snow to all elevations combined with strong Southwest winds.Sunday: Continued light snow at all elevations with moderate Westerly winds at higher elevations.Monday: A strong frontal system is forecast to move in from the coast. Expect strong Southerly winds and moderate precipitation amounts.

Avalanche Summary

Some thin soft slab avalanches up to size 1.5 were reported from explosive control work with large charges (heavy load) near Golden.

Snowpack Summary

Some new surface hoar has been reported overnight. Thin windslabs have developed in the alpine and at treeline in exposed terrain. Some loose snow sluffing may be experienced in steep terrain. Snow pit test results continue to show weak layers of surface hoar that was buried during mid and late November, however we have not seen any activity on these layers recently. The early season rain crust is another layer that continues to show results in tests, but has not been active.

Problems

Wind Slabs

Thin new windslabs have developed in the alpine and at treeline.

Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Stay well to the windward side of corniced ridges.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Buried surface hoar layers continue to give results in snow pit tests. This layer may be triggered from thin weak spots on or adjacent to unsupported terrain features.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Deep Persistent Slabs

Avalanche activity on the deeply buried November rain crust is un-likely without new loading or a rapid rise in temperature. Avalanches that do release on this layer will be large and destructive.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 7

Valid until: Dec 15th, 2012 2:00PM