Avalanche Forecast

Issued: Jan 18th, 2013 9:36AM

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

ghelgeson, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Freezing level starts at valley bottom, rises to 1000m during the day. Strong ridgetop winds out of the NW. No precip expected.Sunday: Freezing level starts at valley bottom, rises to 1000m during the day. Winds start strong out of the NW, backing down to moderate by dinner time. No precip expected.Monday: Freezing level starts at valley bottom, rises to 1000m during the day. Ridgetop winds mod/strong west. No precip expected.

Avalanche Summary

No new avalanche observations from Thursday. On Wednesday numerous wind slab avalanches to size 2 were reported from NE, E and SE facing slopes along with loose wet avalanches to size 1 were also observed on steep solar aspects.

Snowpack Summary

Recent winds have formed hard slabs, soft slabs and sastrugi in open terrain. We've received reports of hard slabs up to a meter deep in the region. South and West facing slopes have been moistening up during the day with the warm temperatures. Protected areas are growing surface hoar to 10mm. Under the moist snow and wind slabs the January 4th layer can be found down 50 - 150 cm. It consists of small facets, surface hoar (up to 12mm) in sheltered treeline and below treeline areas, and a sun crust on steep solar aspects. When tested, the interface produces the full spectrum of fracture characters from sudden planar to no failure at all. Needless to say it's quite varied. The midpack is well bonded and strong.

Problems

Wind Slabs

Previous extreme winds out of the W/NW left hard slabs, soft slabs, sastrugi and potentially unstable cornices in their wake. Watch for wind slabs behind midslope features like ridges and ribs. Be alert for wind slabs in unusual locations.

Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

Slopes that didn't slide during last week's avalanche cycle are still of concern. Triggering of this layer is most likely in steep unsupported terrain. Triggering may become more likely in the afternoon on sun exposed slopes.

Conditions are greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Valid until: Jan 19th, 2013 2:00PM