Avalanche Forecast

Issued: Jan 19th, 2013 8:15AM

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

Good

Weather Forecast

Sunday: Inversion. Freezing level at surface. Above freezing layer from 1500m – 2200m. Ridgetop winds Strong NW. Treeline winds moderate NW. No precipMonday: Inversion. Freezing level at surface. Above freezing layer from 1500m – 2200m. Ridgetop winds Strong NW. Treeline winds light W. No precipTuesday: Inversion. Freezing level at surface. Above freezing layer from 1500m – 2200m. Ridgetop winds Strong NW, switching to strong W as ridge flattens in the afternoon. Treeline winds light W switching SW after lunch. No precip

Avalanche Summary

No new natural activity. On Friday a group of skiers triggered a small (size 1.5) hard slab avalanche the failed when the 3rd skier traversed across an east facing slope at 2000m.

Snowpack Summary

Savage winds out of the NW have wreaked havoc on the region. N & W facing slopes are wind pressed or wind-stripped. Slopes lee to these winds were left with wind slabs up to a meter in depth in open areas. Warm temperatures have created moist snow that can be found on almost all aspects up to 2300m. Protected areas are growing surface hoar to 10mm, while many other slopes are sporting a zipper crust due to the warm temps. Under the snow surface lies the January 4th interface, down around 75 cm & obviously much deeper in wind loaded areas. This layer of small/facets/crusts and intermittent surface hoar is producing planar shears in some drainages and no failure at all in others. At the moment it's tough to find soft snow to recreate in. The midpack is well good, nicely 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. Many of these slabs have grown old and tired, but the odd sensitive slab may still be lurking out there.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

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 20th, 2013 2:00PM