Avalanche Forecast

Issued: Mar 21st, 2013 10:41AM

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

pgoddard, Avalanche Canada

Sea To Sky.

Avalanche danger may spike on slopes receiving direct sun. Avoid travelling on or underneath sun-baked terrain.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Friday: Trace amounts of snow possible. Becoming increasingly sunny. Light N winds. Alpine temperature near -7.Saturday: No snow. Light winds. Sun and cloud. Alpine temperature near -6.Sunday: No snow. Light winds. Sunny. Alpine temperature near -7.

Avalanche Summary

Intense wind-loading triggered several wind slabs, mainly on north aspects at alpine and treeline elevations, on Wednesday. Skiers also triggered size 1-2 storm/wind slabs.

Snowpack Summary

Recent snowfall was redistributed by very strong SE to SW wind, leaving wind slabs 30 cm to 1 m deep on many lee terrain features. These were initially reactive to the weight of a person but gained some strength by Thursday. Subsequent NW winds may have caused some reverse loading - so keep an eye out for wind slabs on all aspects. A couple of weak layers are buried in the upper metre of the snowpack. These comprise faceted snow, surface hoar and/or a crust, with variable distribution. The current snow structure varies with only a subtle change in elevation, aspect, wind or sun exposure. Mid and lower snowpack layers are well bonded.

Problems

Wind Slabs

It may be possible to trigger slabs in steep terrain or on convex shaped slopes. Variable winds may have left slabs on many slopes.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Cornices

Cornices are reported to be very large and may fail with solar warming. They are a danger in themselves and could also trigger a slab avalanche on the slope below.

Avoid steep slopes below cornices.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

3 - 6

Loose Wet

Direct sun may trigger loose snow avalanches on steep sunny slopes.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Pay attention to overhead hazards.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Mar 22nd, 2013 2:00PM