Avalanche Forecast

Issued: Mar 25th, 2013 9:30AM

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

pgoddard, Avalanche Canada

Sea To Sky.

Avalanche danger may spike on slopes that are getting warmed by sunshine or warm temperatures. Be alert for changing conditions throughout the day.

Summary

Confidence

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

Weather Forecast

Tuesday: No snow. Partly cloudy. Light S winds. Alpine temperature near -2. Wednesday: Light snow. Light S winds. Alpine temperature near -1. Thursday: Light snow. Light S winds. Alpine temperature near 0.

Avalanche Summary

There was a report of a skier triggered size 2 slab avalanche on Saturday from a rocky south-facing alpine slope, in an area just north of Whistler. A few natural cornice falls triggered thin slabs up to size 2 on the slope below. Solar warming also triggered a few small loose wet avalanches on steep sunny slopes. Skiers triggered small slabs on steep convex rolls on Sunday.

Snowpack Summary

Wind slabs, which recently formed on a widespread basis, have become harder to trigger. On sun-baked and low elevation slopes, a melt-freeze cycle is in play at the snow surface, leaving a crust behind during overnight cooling, which breaks down by day. The upper snowpack structure is highly variable. On sunny aspects (and all aspects at low elevations), a melt-freeze crust is now buried about 30 cm deep, while on high elevation shady aspects, 50-100 cm snow overlies an older melt-freeze crust. Bonding at both of these crust interfaces appears to be improving. Large cornices are looming over some slopes. Mid and lower snowpack layers are well bonded.

Problems

Cornices

Cornices are large and weak. Daytime warming and sunshine could cause cornices to fail, possibly triggering a slab on the slope below.

Give cornices a wide berth when travelling on or below ridges.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 6

Loose Wet

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

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be alert to conditions that change throughout the day.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 26th, 2013 2:00PM