The Canadian Avalanche Centre has issued a special avalanche warning for the backcountry areas of B.C.'s South Coast.
The warning is in effect from Friday, Dec. 18 through to Dec. 21. Snow from recent storms is resting on a unusually weak layer within the snowpack. This, coupled with warming temperatures, is creating a situation where it will likely be very easy to trigger avalanches large enough to injure a person.
"This being the beginning of the holiday season, many people are eager to hit the backcountry or go outside ski area boundaries," said Karl Klassen, the avalanche centre's public avalanche bulletins manager. "For skiers and snowmobilers on the South Coast, this is not the weekend to ride aggressively in backcountry areas."
The CAC says there is a "considerable" risk of avalanche in alpine and treeline levels throughout the Sea to Sky corridor. There's only a moderate risk below treeline.
The bulletin shows a warning about a wind slab that's impacting slopes with northwest, north, northeast and eastern aspects. There's also a concern about storm snow that's impacting slopes in all directions.
A weather forecast had a "weak storm" passing over the region on Thursday night, bringing drying conditions and cooling temperatures on Saturday before another storm is forecast to hit on Sunday and bring about 10 to 20 centimetres of snow.
Users are advised to stick to simple terrain if they witness any recent avalanches, heavy loading, shooting cracks or any other sign of unstable snow. They're asked to avoid northwest through northeast ridge crests and terrain breaks in alpine and open treeline areas, as well as steep gullies and trigger points such as convexities and thin, rocky areas.
If you come across any "whumpfing," literally the sound of a collapsing snowpack when you cross it, you're asked to avoid large slopes as remote triggering is possible. That means you can trigger an avalanche even from some distance away. It's common to trigger an avalanche from a flat surface or area below the slide itself.
"Generally speaking the snowpack is better, stronger than it was last year," Klassen said in an interview. "We don't have the very deep basal instabilities near the ground that we had last year."
He warned, however, that there's a weak layer that's unusual for the snowpack and the resulting avalanche risk in the backcountry won't go away as quickly as some people might hope.
"Usually when it snows like this, people wait 24, 36 hours before going out," Klassen said. "We're looking at several days before the current conditions settle.
"Normally you need to stay on the lower-angled terrain and simpler terrain and avoid avalanche slopes. I'd avoid avalanche slopes completely for the next few days and then look at our forecasts. This is a situation that will not improve as rapidly as normal in the South Coast."
