Avalanche Forecast

Issued: Dec 4th, 2014 8:04AM

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

pgoddard, Avalanche Canada

South Columbia.

I'd veer away from thin snowpack areas, rocky outcrops and large steep alpine slopes which didn't avalanche last week.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Warm air from the Pacific will push in, bringing warming temperatures but not much precipitation in the short term.Friday: Light snow. Remaining cool. Light to moderate SW winds.Saturday: Light snow. Moderate to strong SW winds. A layer of warm air may form at mountain height, while the valleys remain cool.Sunday: Light snow. Light winds. Temperatures may start to rise towards -2 at treeline.

Avalanche Summary

Explosives testing to the north of the region on Wednesday resulted in isolated soft slabs on a layer of surface hoar and facets at alpine and treeline elevations. Otherwise, no new avalanches have been reported. There is still a chance of triggering avalanches on persistent weak layers formed during November, with high consequences.

Snowpack Summary

Surface: Before Friday, snow surfaces included wind slabs (variable in distribution); surface hoar, which has grown large in sheltered spots; and sun crusts on steep south-facing slopes.Upper-mid pack: Anywhere from 5-30 cm of settling snow sits on a crust which formed in late November. This crust is supportive above about 1800m, but is breaking down at lower elevations. About 1m down, a weak layer of surface hoar and/or facets can be found in some locations. Snowpack tests on this layer are showing improving results, but in some locations "pops and drops" indicate this beast could still be touchy.Lower pack: A thick rain crust from early November is buried over a metre down.

Problems

Persistent Slabs

Weak crystals are buried in the upper metre or so of the snowpack. Deep avalanches on these layers are most likely to be triggered by people from thin snowpack areas, near rocky outcrops, and on steep alpine slopes.

Caution around convexities or areas with a thin or variable snowpack.>Conditions may have improved, but be mindful that deep instabilities are still present.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 5th, 2014 2:00PM