Avalanche Forecast

Issued: Mar 17th, 2013 10:52AM

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

pgoddard, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

Sunday night: Light snow. Light W winds. Alpine temperature near -12.Monday: Light snow (5-10 cm). Light W winds, gusting to strong NW. Alpine temperature near -6.Tuesday: No snow. Sunshine. Light SW winds. Alpine temperature near -11.Wednesday: Light snow (10 cm). Light S winds. Alpine temperatures near -4.

Avalanche Summary

Natural avalanche activity, which was widespread during last weekâ€™s storm, began to ease on Saturday. Explosives testing triggered three size 2-3 slabs within the storm snow. A snow cat pushing snow triggered a size 2.5 slab, which ran on a SW aspect just above treeline in the backcountry.

Snowpack Summary

New snow is adding weight above deep and cohesive storm slabs which formed last week. These older storm slabs are slowly gaining strength, but are not yet fully settled. Winds from the south through to north-west have formed wind slabs and cornices in the lee of ridges and ribs. A recent rain-soaking weakened the low elevation snowpack, which is likely to become very strong once refrozen.Weak interfaces deeper in the snowpack have become unlikely to be triggered. A facet/crust layer sits at the base of the snowpack.

Problems

Storm Slabs

New snowfall is adding to existing storm slab problems. Give the snowpack time to find its equilibrium before considering aggressive terrain.

Be wary of slopes that did not previously avalanche - even on low angle terrain.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 6

Wind Slabs

New wind slabs may be encountered behind ridges and ribs.

Avoid freshly wind loaded features.>Travel on ridgetops to avoid wind slabs on slopes below.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Cornices are tender and can trigger slabs on slopes below. Give them a wide berth.

Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

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