White death

Slide into oblivion
Avalanches unveiled
Rotten snow
Avalanche forecasting
Staying safe
Anatomy of a snowflake

A chute like this is a sure sign of avalanche. If you have to travel here, stay in the trees!

Courtesy Westwide Avalanche Network.


High marking snowmobiler gets a surprise.

Sequence of photos by Jeff Halligan, Snow Ranger, Payette National Forest. Courtesy Westwide Avalanche Network.

A nightmare out there
How can you stay clear when a mountain of snow has sliding on its mind?

A lane of snow with scattered limbs is surrounded by trees; the hill slopes steeply toward the rear. Let's start with the basics: To have an avalanche, you need snow and you need slopes -- generally between 30 degrees and 45 degrees. (You can buy an inclinometer to tell you the exact slope.)

Duh. Like, what else?

Suddenly, we go from the obvious to the sublime -- the judgment realm. Here are some signs of avalanche, in no particular order.

    Recent avalanches in the area.

    Avalanche tracks -- chutes where sliding snow has removed the trees.

    Warnings from avalanche centers

    A whoomping! sound from the snow, indicating a small- - or large -- failure.

The "key thing about avalanche safety is that people just miss some obvious clues," says forecaster Karl Birkeland. "You see recent avalanche activity, you know the snow is unstable. It sounds really dumb, but how many times do we go past places with avalanches to investigate avalanche fatalities? It's crazy!"

Sequence of photos by Jeff Halligan, Snow Ranger, Payette National Forest. But it's not just nincompoops who die under the snow. Alex Lowe, a mountaineer who was called the best in the world, was killed in 1999 in a giant avalanche in Tibet, where he was planning to ski down Shisha Pangma, an 8,000 meter peak!

Finally, a note for snowmobilers: It's dangerous up there! In the past few years, the machines have been getting faster, leading to a competition called "highmarking," where the winner reaches the highest point on a snowfield.

Through such progress, getting avalanched on a noisy sled has joined falling through the ice as a deadly hazard of the gasoline-powered sport: Forty percent of 1998-'99 avalanche deaths in the United States were snowmo riders. Snow physicist Colbeck says word is gradually getting out to snowmobile riders: "When enough of your friends die, you learn that it's not much fun."

Taking portraits of individual snowflakes sounds a lot more fun than getting crushed by billions of flakes...

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