Avalanche Forecast

Issued: Apr 8th, 2013 10:13AM

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

pgoddard, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Tuesday: Light snow. Light NW winds. Alpine temperature near -6. Wednesday: 10-20 cm snow. Strong SW winds. Alpine temperature near -4.Thursday: Light snow. Light SW winds. Alpine temperature near -5.

Avalanche Summary

An avalanche cycle of slabs up to size 3 occurred during the weekendâ€™s storm. Many of these events were on NE-NW (wind-loaded) aspects above about 2400 m. Several size 2 skier-remote triggered slabs were also reported on Sunday. These failed on surface hoar buried below the storm snow. They occurred on W-NE aspects above 2500 m.

Snowpack Summary

Recent storm snow (up to 40 cm) is sitting on a variable interface, consisting of a crust or moist snow; or a recently formed layer of surface hoar or facets, which is mainly found on high-elevation W through NE aspects. In some locations the surface hoar/facet interface is touchy, with skier triggering likely. Winds have shifted storm snow into reactive slabs lee to south-easterly to south-westerly winds. Below treeline, the snow is in a spring melt-freeze regime, melting by day and freezing by night. Cornices are very large and loom as potential triggers for avalanches.

Problems

Storm Slabs

In some areas, new snow is bonding poorly to a weak interface buried below. Skiers have been triggering slabs remotely, from up to 60 m away.

Choose well supported terrain without convexities.>Remote triggering is a concern, watch out for adjacent slopes.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Wind Slabs

Wind slabs are a problem on high elevation lee slopes. The large cornices that loom over many slopes have the potential to fail and trigger avalanches.

Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Loose Wet

Watch for loose wet avalanches and glide slabs, which may fail naturally in response to rainfall at low elevations.

Avoid travelling on slopes which are becoming wet due to rain, warm temperatures, or sun.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Apr 9th, 2013 2:00PM