Weeks of cold temperatures coupled with fresh snow has made for potentially hazardous sledding conditions in the Columbia region near Sicamous and Revelstoke.
“Any time we receive a significant amount of snow, 20 centimetres plus, avalanche danger starts to increase,” said Mark Bender, a senior public avalanche forecaster with Avalanche Canada.
Bender added the avalanche danger caused by the falling snow is compounded by a buried weak layer in the snow pack which has been identified as the cause of several snowmobiler and skier-triggered avalanches in recent weeks. He said weak layers are often caused by dew freezing on the surface of the snow pack during periods of clear, cold weather like the one that persisted for most of early February.
“It creates a situation much like a house of cards essentially. There are v-shaped crystals which form on the surface of the snow pack and then when snow falls on top of those, eventually the weight of the snow sitting on top of it overcomes the strength of those crystals and then releases in avalanches,” Bender said.
He said avalanche danger generally remains stable when the weather is clear and cold and then increases with new snowfall.
Bender expects the weak layer to be problematic for backcountry users regardless of how much new snow falls on top of it. He said other factors such as wind also affect the degree of avalanche danger.
Avalanche Canada posts daily avalanche danger forecasts for 20 mountainous areas in B.C. and western Alberta. Usually avalanche danger is most serious in the alpine but Bender said in the North Columbia, an area north of the stretch of Highway 1 which runs between Kamloops and Rogers Pass, the danger is elevated at and below the tree line.
In the South Columbia area, spanning Salmon Arm, Enderby, Armstrong and the vast swath of mountains between Highways 1 and 6, avalanche danger is moderate at all elevations. Bender said with more snowfall the hazard is likely to increase.
Gord Bushell, general manager of the Eagle Valley Snowmobile Club, said danger from snow conditions can be minimized by making good choices on the mountain.
“It’s a really big concern for all of us, and everybody really has to watch out on those slopes. You basically have choices –you can make a choice to stay in the meadows and play in the deep snow and have just as much fun as climbing steep chutes and avalanche-prone areas,” he said.
The cold itself can also pose a hazard up in the mountain. Bushell said wise decisions are especially important when the temperature as low as it is. If back country users become stranded he said they must be prepared to survive until they can be rescued.
“Right now the temperatures are down here are -12, but up top they could be -25 overnight,” Bushell said.
“Your chances of surviving in -6 or -12 are a lot better than -25, so you have to make wise choices when you’re up there during the day.”
It is advised backcountry users check the daily forecast for their preferred area at www.avalanche.ca before setting out for a day in the mountains. Avalanche danger ratings are also posted at the trailheads of each area the Eagle Valley Snowmobile Club manages.