Avalanche alert season begins in High Sierra | SierraSun.com

Avalanche alert season begins in High Sierra

What goes up must come down. Moisture rises from the Pacific Ocean and falls as snow on mountain tops, and often does not stop its descent there.

Throughout the course of a winter season the Lake Tahoe Basin sees thousands of avalanches.

Residents of the Sierra can generally predict when avalanches will occur.

“The avalanche pattern is dependent on the storms,” said Bob Moore of the U.S. Forestry Service. “Ninety-nine percent of avalanches occur after storms when no one is out.”

The Sierra Nevada is in a climate region which is distinct from other mountainous regions of the country.

“The Sierra is a maritime climate,” Moore said. “We are influenced by the Pacific. We are close enough to where we get copious amounts of moisture that come off the Pacific.”

The high amount of moisture in Sierra storms creates thick layers of snow, which are less prone to come down than thinner layers. When avalanches occur in the Sierra they are usually composed of fresh top-layer snow.

The Rocky Mountains experience a continental climate, which is characterized by colder storms which drop considerably less snow per system. There, the avalanche danger is much more unpredictable, since the layers are thinner and more prone to move.

The Sierra has been experiencing somewhat of a continental climate pattern early this season with relatively light snowfall and cold temperatures, but Moore insists it is nothing too unusual.

“It will go away unless we have some unpredictable conditions, but generally it will dissolve by early to midwinter,” Moore said.

With the oncoming winter, those planning on venturing into the back country should be aware of conditions and be able to recognize high-risk avalanche areas.

“The most obvious indicator that there is an avalanche danger is seeing an avalanche running or that an avalanche has just occurred,” said Larry Heywood of Alpine Meadows ski resort. “Ninety percent of avalanches occur on slopes that are 30 to 45 degrees. Wide open slopes that have no trees and are smooth are more likely to trigger.”

“Generally our avalanches occur on the north to northeast facing slopes,” Moore added. “Stay off cornices and pay attention to where you are.”

Those in the Tahoe area who take excursions into the back country know that avalanches are a very real hazard.

“My best friend was the guy who almost died on the face, he is lucky to be alive,” said Greg Dennis, Sports LTD employee and avid back-country skier. “He was actually setting the bombs for the avalanche. It carried him down about 1,000 feet and slammed him into the trees. It is something you take seriously, you don’t joke around with. If there is any hint of instability it is a no go.”

Heywood said that with the proper knowledge, people stand a strong chance of staying out of harm’s way.

“Most people who are caught in avalanches are the trigger themselves,” Heywood said. “There is a Forestry Service warning phone. You can call that for back-country information.”

Dennis recommends that people looking to spend time skiing or riding in the back country take a course on avalanche safety offered at Lake Tahoe Community College.

“Anybody that back-countries and hasn’t taken that should take it,” Dennis said. “Experience is great, but even the most experienced back-country skiers are the ones who get caught in the avalanche. Knowing what to look for and having some training will let you avoid disaster.”

Since avalanches are a very real danger in the Lake Tahoe Basin, persons in the back country should also be equipped with the proper tools and never travel alone.

“Be with someone else who can help you and be wearing an avalanche rescue beacon,” Heywood said. “Everyone should be equipped with probe poles.”

When caught in an avalanche victims can improve their odds of survival by being active.

“Fight for your life actively. If you can ski out of it, ski off to the side. If you are actually caught, use a swimming motion. It may make you more buoyant.”

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