Avalanche Forecast

Issued: Apr 16th, 2013 10:10AM

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

pgoddard, Avalanche Canada

South Columbia.

Northern parts of the region may have similar conditions to the North Columbia and Glacier National Park regions. Check these bulletins to get the complete picture.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Wednesday: Light snow. Moderate SW winds. Freezing level near 1500 m. Thursday: Light snow. Light to moderate SW winds. Freezing level near 1800 m. Friday: Moderate to heavy snow. Light SW winds. Freezing level near 1800 m.

Avalanche Summary

On Sunday, a naturally triggered size 2.5 slab failed on a buried crust. Numerous small loose dry avalanches were also observed. In neighbouring Glacier National Park, skiers triggered a size 3 slab on a buried crust on an east aspect in the alpine on Monday. The slab above this interface may be reaching tipping point with incremental loading from snow and wind.

Snowpack Summary

Up to 40 cm recent storm snow has been shifted into variable wind slabs at treeline and above. In some areas, easterly winds have led to wind slabs on different slopes than you might usually expect. Cornices are very large and potentially destructive.A weak interface down about 60-120 cm consists of a crust on solar aspects, and surface hoar on high-elevation northerly aspects. Recent very large avalanches in neighbouring regions to the north failed on this interface. The slab above this interface may be reaching tipping point with incremental loading from snow and wind. Periods of warming or solar radiation may increase the reactivity of cornices and storm slabs.Â

Problems

Wind Slabs

Wind slabs exist on a variety of aspects at treeline and above. Wind has also formed very large and potentially unstable cornices.

Be cautious as you transition into wind affected terrain.>Travel on ridgetops to avoid wind slabs on slopes below.>Avoid steep slopes below cornices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

A weak interface buried down about 60-120 cm has been creating surprisingly large avalanches in neighbouring regions. Incremental loading by snow and wind may have brought the slab above this layer closer to its tipping point.

Choose well supported terrain without convexities.>Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 6

Valid until: Apr 17th, 2013 2:00PM