Avalanche Forecast

Issued: Jan 5th, 2012 9:17AM

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

ccampbell, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Good - -1

Weather Forecast

Friday and Saturday: Generally dry, with freezing levels near valley bottoms and light winds. Light snowfall expected overnight Saturday into Sunday accompanied by moderate to strong westerly winds.

Avalanche Summary

Recent activity on the mid-December surface hoar includes a snowcat remotely triggering a 70cm deep Size 2 slab avalanche from 10m away on a log-haul landing in a cutblock. Recent storm snow overlying a crust is also highly reactive to human triggers with slope-cuts producing numerous loose snow and 10-30cm thick slab avalanches up to Size 1.5.

Snowpack Summary

New snow and gusty winds are keeping wind slabs and cornices fresh and weak, and in some places buried old wind slabs are a concern. A lightly buried thin crust extends into treeline elevations. Compression tests have been producing easy to moderate sudden results on the mid-December surface hoar, down 30-80cm, and propagation tests, whumpfing, and remote triggering suggest that avalanches associated with this persistent slab have a high propensity to propagate over large areas. Other weaknesses within the slab create the potential for step-down avalanches. Basal facets and depth hoar remain a concern in shallow rocky areas.

Problems

Persistent Slabs

Persistent weaknesses remain susceptible to human-triggers, including remote triggering.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

Fresh wind slabs are lurking below ridge crests, behind terrain features, and in cross-loaded gullies. New cornices are also weak.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 6th, 2012 8:00AM