Avalanche Forecast

Issued: Dec 26th, 2012 9:05AM

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 - Timing, track, or intensity of incoming weather is uncertain on Thursday

Weather Forecast

Thursday: Light SW winds. Alpine temp -7. Light snow(around 10 cm). Friday: Moderate SW winds. Alpine temp around -6. Moderate snow.Saturday: Light to moderate SW winds. Freezing level at valley bottom. Very light snow.

Avalanche Summary

A skier triggered a small hard wind slab on a steep north-facing roll near treeline on Tuesday. Natural size 1-2 avalanches were failing in response to outflow wind-loading over the past few days.

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. Some alpine slopes are heavily scoured. 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 has recently given 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

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.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: All elevations.

Likelihood

Possible

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.>Choose the deepest and strongest snowpack areas on your run.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 7

Valid until: Dec 27th, 2012 2:00PM