Avalanche Forecast

Issued: Jan 17th, 2013 10:35AM

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

Kootenay Boundary.

Summary

Confidence

Good

Weather Forecast

Friday: Extreme W ridgetop winds at ridgetop. No precip. Potential above freezing temperatures in the alpine.Saturday: Strong NW winds at ridgetop. No precip. Potential above freezing temperatures in the alpine.Sunday: Moderate NW winds at ridgetop. No precip. Potential above freezing temperatures in the alpine.

Avalanche Summary

Numerous wind slab avalanches to size 2 were reported from NE, E and SE facing slopes Wednesday. 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 recieved 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. Under the moist snow and windslabs 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. Test pits are still showing resistant planar shears at this interface, but it hasn't been reactive to human triggering for days now.The midpack is well bonded and strong.

Problems

Wind Slabs

Strong to extreme winds out of the W/NW have 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.

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

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 18th, 2013 2:00PM