Snow pack will get worse before it gets better 

Warming trend will trigger more slides, but may help in long run

The word from the Canadian Avalanche Centre (CAC) is that avalanche conditions will actually get worse in the South Coast before they get better, but don’t write off the entire season just yet.

“What’s happening now is we’re in an extended warming period, and in the short term it’s going to cause more pain in the snowpack,” said Ilya Storm, an avalanche forecaster for the CAC in Revelstoke. “It’s going to increase the avalanche hazard.”

Storm explained that ice and hard snow form strong bonds, “but as you warm up the snow loses strength,” he said. “You can do things with snow or cold ice that you can’t do with a lake. As the snow warms, it causes the snow to creep, glide and deform more, and there’s more stress on these deep, weak layers we’ve been talking about.”

After a prolonged freezing period in December, the entire province was hit with storms of really dry, light, and powdery snow. Heavier snow followed, compressing that lower layer but not bonding with it. As a result, there is nothing to anchor all the recent snow to the slopes.

The upside is that the warming will trigger many natural avalanches, and could cause the weak layer to bond.

“We have a couple of ideas how it will play out, and in the long term the warming may — and I emphasize ‘may’ — help us,” said Storm. “It will help the snow to settle, and when it turns cold again it will strengthen. That could — and again I emphasize ‘could’ — help us in the long term.

“That’s the big question, and we won’t know the answer until we see how everything plays out, and whether it’s enough to help the deep weak layers.”

The other thing that could help stabilize slopes, “is 40 days and 40 nights of snow,” Storm adds. “A whole bunch of snow, followed by another cycle or two of big, amazing avalanches, should squish all this weak stuff together… until it’s one big coastal snowpack again.”

Storm says the current type of “upside down” snowpack is more common in the Rockies than the coast and interior of the province.

Rain could help, he said, by triggering natural avalanches quickly, but otherwise could create more problems by creating a crust layer that could be as dangerous as the dust layer, says Storm. Last winter, 2007-08, the instability that lasted most of the season was the result of rain earlier in the year.

“Rain on the mountain top is not like hitting the restart button,” he said. “It’s a double edged sword, on one side it could be good and possibly help the snowpack, on the other it could make things worse.”


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