Shallow and weak.
That’s how Tyson Rettie, a forecaster with Avalanche Canada, describes the snowpack in the Northern Rockies this season.
For sledders, that means taking more care as rocks and stumps are barely buried. “The snow that would generally cover those things is just not there,” says Rettie, who says that a couple weeks back, 15 machines had to get towed out of the Renshaw riding area near McBride after getting damaged.
He says a lot of people think that less snow means less danger of avalanches, but that’s not always the case. “When you have a shallower snowpack combined with cold temperatures, it means the snow grains don’t want to bond well together. That means that we have a few problematic weak layers that have developed within the snowpack that are very low down. And those weak layers are going to linger longer and produce avalanches for longer periods of time.”
These weak layers developed in late November, which means they are quite close to the bottom of the snowpack. Add to that a crust that formed shortly after Christmas, overtop of a layer of unconsolidated, sugary facet crystals, and he says that testing “continues to produce some fairly alarming test results.”
He says people are heading out into the mountains, and will be fooled, as there’s not a lot of natural avalanche activities currently. “They’re probably going to ride fairly steep terrain features. Take more risks. And nothing might happen. However, they could go to ride something they’ve been playing on all day, and just happen to pick the wrong slope or the wrong place on the wrong slope. And something that was very similar to the terrain they’ve been riding all day just gives way. While the snow isn’t deep, if it does avalanche, it could be nearly the entire snowpack that runs downhill. There’s a misconception among some people that a shallow snowpack is a safer snowpack. Because if there’s less snow, the avalanches will be smaller. But that’s actually not the case. A shallower snowpack is generally a weaker snowpack.”
He says there’s a possibility that the snowpack could heal. Warm weather can cause the sugar snow to melt slightly and consolidate. As well, deeper snow can create a degree of insulation from that weak layer, though it can come back to haunt riders in the spring.
Finally more snow can trigger natural avalanches, triggering those weak layers.
“If we started seeing ongoing precipitation and the snowpack built back up to what would be a seasonal average or ideally beyond seasonal average, as storms are taking place, that could result in natural avalanche activity. In the long term, a deeper snowpack would be healthier. Sometimes you get layers like this and they do heal up over time, although other times they linger through the entirety of the season.”
A lot of avalanche professionals have been comparing this season to the one in 2003. “If you look back at avalanche fatality statistics from 2003, there were 29 people who died in avalanches that year,” he says. “That was the year, for instance, when seven students from a high school in Alberta died in an avalanche in Rogers pass. The setup we’re seeing is similar to that. We’re asking people to make conservative decisions. Make conservative terrain choices story, and really consider the consequences of what if the slope does avalanche.”
And any new weather patterns can change the avalanche danger quickly.
Before heading out, always check the Avalanche Canada website, at www.avalanche.ca where you’ll find the most up to date information to help inform your backcountry choices.
Trent is the publisher of Tumbler RidgeLines.
