Avalanche Forecast

Issued: Jan 19th, 2013 9:43AM

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

slemieux, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday night and Sunday: Ridge of high pressure continues to dominate for the whole period. No precipitation, mild temperatures, scattered clouds and valley clouds and strong Westerly winds in the alpine tapering off slightly on Sunday.Monday: Similar conditions with warmer temperatures and freezing level rising to 1200 m. Tuesday: Dry conditions persist, light SW winds and freezing level around 1000 m.

Avalanche Summary

A couple natural avalanches up to size 3 were observed in Roger’s Pass area as well as a remote skier triggered slab avalanche size 1.5 on a windloaded feature at top of treeline in the same area. Another natural slab avalanche size 1.5 was reported which would have run on a steep NE facing slope.

Snowpack Summary

A trace to 3 cm of new snow fell with Strong NW-SW winds. Recent and past strong NW-SW winds have left wind slabs in many areas, even at treeline. These are gaining strength with mild temperatures and as the amount of snow available for transport diminishes. Around 40-60 cm settled storm snow sits above surface hoar, a sun crust (on steep S to SW -facing slopes) and facets. Results on the surface hoar layer vary from sudden planar to resistant planar in the moderate to hard range. It appears to be more reactive in the Northern part of the region, especially in the 1900 to 1500 m. range. The distribution of these weaknesses is patchy, but where they exist, it may still be possible to trigger a large avalanche with the weight of a person or snowmobile. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is generally considered inactive.

Problems

Wind Slabs

Solar radiation and warm temperatures could weaken some steep wind loaded slopes. Triggering a windslab could potentially step down to a deeper instability.

Pay attention to overhead hazards like cornices.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Triggering persistent slabs is becoming less likely, but a cautious approach to steep south-facing slopes and sheltered terrain below treeline is still advised.

Dig down to find and test weak layers before committing to a line.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Valid until: Jan 20th, 2013 2:00PM