Avalanche Forecast

Issued: Dec 24th, 2012 8:17AM

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

pgoddard, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair

Weather Forecast

Tuesday: Moderate SE winds. Alpine temp -14. No precipitation.Wednesday: Light SE winds. Alpine temp -8. No precipitation.Thursday: Light S winds. Alpine temp -8. Light to moderate snow.

Avalanche Summary

On Saturday, several natural size 1-2 loose dry and thin slab avalanches failed in steep isolated terrain features wind-loaded by outflow (down-valley) winds. Explosives triggered size 2-3 slabs which failed near the ground in facets. Near Bear Pass, natural ice fall triggered size 2.5 and 3 loose snow avalanches, entraining old storm snow. No avalanches were reported on Sunday.

Snowpack Summary

Wind slabs and cornices have developed on a fairly widespread basis and may be found on many slopes due to variable wind directions. Surface faceting is likely to continue while the weather remains cold. A layer of surface hoar buried in the upper metre of the pack has been observed in the Shames backcountry. The mid-pack is generally well settled. Near the base of the snowpack, a crust/facet layer continues to give hard, sudden results in snowpack tests. This weakness is unlikely to be triggered by a single person, but it remains possible with a very heavy load (e.g. cornice fall) or from a thin-spot trigger point.

Problems

Wind Slabs

New wind slabs have formed in response to down-valley winds. These could be triggered by the weight of a person or snowmobile.

Be cautious as you transition into wind affected terrain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

A deeply buried weakness may be triggered from thin, rocky snowpack areas or with a large trigger.

Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 7

Valid until: Dec 25th, 2012 2:00PM