Avalanche Forecast

Issued: Mar 24th, 2013 9:05AM

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

pmarshall, Avalanche Canada

South Coast.

Summary

Confidence

Good

Weather Forecast

Synopsis: A ridge of high pressure over the interior of BC will maintain generally dry conditions over the next few days. A series of weak low pressure systems will brush the coast resulting in cloudy periods and possible precipitation, primarily closer to the coast. Accumulations will be very light. Sunny breaks are also likely. Temperatures are expected to gradually warm over the next few days. Daytime freezing levels could jump up to 1800 m by Wednesday. Winds are generally light and variable throughout the period.

Avalanche Summary

Several rider triggered wind slabs, up to size 1.5, were reported throughout the region on steep lee features on Friday and Saturday. There were also a couple large cornice failures, some of which pulled out slabs on the slope below. Loose wet avalanches up to size 1.5 were observed on steep sun-exposed slopes on Saturday.

Snowpack Summary

The snowpack is variable across the region. Recent storm snow has been redistributed by mainly SW winds into wind slabs over various crust layers in the upper snowpack. In some areas, a melt-freeze crust down about 35 cm has a questionable bond with the snow above. Surface hoar, buried down about 50-70 cm, gave hard, sudden (pops) results in recent snowpack tests. Triggering this layer has become less likely, but still remains possible with a heavy load or from a thin-spot trigger point. Cornices are large and unstable in some areas. Warm temperatures may weaken them further.

Problems

Loose Wet

Daytime warming and solar radiation will likely cause loose wet avalanches on steep south aspects. There is also potential to trigger slabs in steep rocky or sparsely treed south-facing terrain.

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

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

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 - 5

Persistent Slabs

Avalanches failing on a crust and/or surface hoar layer buried about 50-70 cm down are becoming less likely, but could be triggered with a heavy load (cornice), or from a thin or convex-shaped part of a slope.

Avoid convexities or areas with a thin or variable snowpack.>Do not travel on slopes that are exposed to cornices overhead.>Plan escape routes and identify safe zones before committing to your line.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Mar 25th, 2013 2:00PM