Avalanche Forecast

Issued: Feb 16th, 2013 8:31AM

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

ghelgeson, Avalanche Canada

Northwest Inland.

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

Sunday: Freezing Level: 500m, Wind: Mod SW, No significant precip.Monday: Freezing Level: 500m, rising to 750m Wind: Mod S, No significant precip.Tuesday: Freezing Level: 500m, Wind: Light W, No significant precip.

Avalanche Summary

No recent avalanche observations have been reported.

Snowpack Summary

Depending on the location, light to moderate amounts of new snow have been shifted into wind slabs and overlie older wind slabs that formed earlier in the week. Below treeline, light rain has saturated the surface. In general, between 30-60cm of storm snow sits over a variety of old surfaces which include facets, crusts and isolated pockets of surface hoar (sheltered treeline and below treeline). There is very limited information about the nature of this interface, with the only results suggesting reactivity in sheltered, shady treeline and below treeline slopes (preserved surface hoar). I would stress the importance of digging down to find and test weak layers.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

Problems

Wind Slabs

New snow has combined with strong to extreme winds creating fresh and potentially deep wind slabs. Due to the nature of the winds, watch for loading lower on the slope and in other unusual locations.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>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

Likely

Expected Size

1 - 4

Persistent Slabs

Buried beneath the new snow sits a surface hoar/crust/facet weakness. This may be sensitive to rider triggers in steeper sheltered terrain or over convex rolls, especially at treeline and below treeline elevations.

Dig down to find and test weak layers before committing to a line.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 17th, 2013 2:00PM