Unstable storm snow complicates matters in West Kootenay backcountry
By Nelson Daily Editor
By Timothy Schafer, The Nelson Daily
With new snow bonding poorly to old surfaces and further snow, warmer temperatures and strong winds due to arrive this week, the recipe for unstable storm snow conditions are brewing in the West Kootenay backcountry.
As a result, the danger of an avalanche in the West Kootenay backcountry has crept back up to considerable for Thursday and Friday — after remaining at moderate last week — according to the Canadian Avalanche Centre.
Due to rapid loading from heavy amounts of new snow and high winds, the avalanche danger has spiraled upwards in alpine areas, said CAC’s Penny Goddard. At the tree line and below the tree line, the avalanche risk also is increasing, both areas hitting considerable risk by Thursday.
More light snow is expected Thursday, around five centimetres, falling. Temperatures are dropping below freezing in the valley bottom, but winds are diminishing to light or moderate from the southwest.
Avalanche activity was triggered naturally and by people and explosives on Monday. Slabs up to size three failed at the base of the storm snow and were particularly reactive in cross-loaded gullies. Skiers triggered several avalanches in the size one to two range, which ran fast and far in steep ground.
During periods of high danger, Goddard said, backcountry skiers are asked to avoid exposure to avalanche terrain unless professional level safety systems are in place.
Areas of concern are:
• Wind slabs on steep, unsupported terrain;
• Any steep terrain loaded with new snow, especially if there is a terrain trap (like a cliff, flat bench or trees) below; and
• Slopes threatened by cornices.
A patchy layer of surface hoar (mostly small crystals) exists buried down around 30 cm. On southerly aspects, this layer is also associated with a sun crust.
At the tree line there is a crust buried around 50 cm. from a brief rain event on Feb. 14.
editor@thenelsondaily.com
