Avalanche Forecast

Issued: Feb 3rd, 2012 11:32AM

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

jlammers, Avalanche Canada

South Columbia.

This is the first significant warm spell of the season and the snowpack is revealing its secrets, especially in alpine locations. Make conservative terrain choices as destructive avalanches are a real possibility.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Expect clear skies and light southerly winds for the entire forecast period. An inversion is also meant to dominate the region with alpine temperatures sitting at about 1.0'.

Avalanche Summary

Numerous natural cornice falls were reported, some of which triggered slabs on the slope below. Wet sluffing was also observed on sun-exposed slopes.

Snowpack Summary

Storm slabs up to 60cms thick have formed . They seem to be settling out quickly, but still show isolated sensitivity to rider triggers; particularly on steeper slopes and convex rolls. Wind slabs have formed on North through East slopes in the alpine and at treeline. Buried below seems to be a fairly settled mid-pack, with a couple of lingering layers. most notably the January 13th surface hoar/facet layer . Recent snowpack field tests have shown generally moderate results, including resistant planar shears. This layer is getting stronger; but it may become reactive with a larger load or warming. The average snowpack depth at 1700m is 2-3 m.Sun-exposed slopes as well as weak and large cornices are a concern with the current warming pattern.

Problems

Cornices

Large and unsupported cornices have formed and have become weak with warm alpine temperatures. Failing cornices are destructive by themselves and have the potential to trigger large avalanches on the slope below.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

3 - 6

Deep Persistent Slabs

Deep persistent layers are re-awakening with recent warm temperatures. They are most likely to be triggered on solar aspects or by larger triggers such as cornice fall or an airborne sled.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 7

Storm Slabs

Storm slabs may be susceptive to rider triggers. You're most likely to trigger a storm slab in steep and/or unsupported/convex terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Wind Slabs

Although they are strengthening, wind slabs may still be sensitive to rider triggers. They're most likely to be found on N-E aspects, and below ridgecrests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Feb 4th, 2012 3:00AM