Topics / ENVIRONMENT : Avalanche Potential Not Just a Snow Job

This is the time of year that U.S. Forest Service ranger George Duffy looks at the behavior of snow.

He digs into snowpacks to check the layering. He whacks off a column of snow to see how easily it shears. He examines snow crystals under a magnifying glass to check for strength.

Duffy and other rangers are watching for avalanche dangers in the Angeles National Forest, especially in the danger times between storms. So far, rangers say the chances of major slides are minimal, and they are not aware of any snow avalanches in the forest’s main areas. But they are watching steep slopes in the Mt. Baldy area and other popular spots, ready to post warning signs if treacherous conditions exist.

“It’s not just a pile of white stuff on the ground,” Duffy warned. “It’s always getting stronger or weaker.”

Often, Duffy said, people forget the dangers when they see the soft, pretty snow. In fact, every year in the forest there are two or three snow-related fatalities and about 100 injuries in incidents including falls and slides, Duffy said. Two skiers died in an avalanche on the back side of Mt. Baldy in 1992.

Problem snow includes soft powder atop an old, hard layer; in that case, an avalanche can be triggered by the weight of the new snow itself or by a skier or sledder who puts extra weight on the snow pack “and away it goes,” said Tom Spencer, the forest’s district recreation officer. “Sometimes, it’s just hanging there by a hair trigger, waiting to go.”

Snow visitors should avoid steep slopes, especially in areas with no plant growth to secure the snowpack in place. Danger signs include small balls of snow rolling down a slope, an indication that the snow is unstable, Duffy said. Also, he said, your boot should make a clean indentation in the snow. If powder falls into your footprint, that’s a sign of loose snow.

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Sudden weather changes are also potentially hazardous, Duffy warned. For instance, someone could sled safely all morning and then take a lunch break during a subtle weather change in which the sun drops over a ridge and casts a shadow over the slope.

“As soon as it’s in shadow, bingo, it’s going to start breaking up,” he said.

People should not assume that rangers will post warning signs at all dangerous spots within the 694,000-acre forest, he said. And they should keep their jackets zipped and hats and mittens on as insulation in case of an avalanche.

“We’re not discouraging people from coming to the snow after a snowfall,” Duffy said. “The thing you have to do is stay away from steep, open slopes.”