The release area at the top of the avalanche path.
The start zone is the portion of the avalanche path where an avalanche releases. Start zones are located at the top of an avalanche path and are characterized by terrain steeper than about 30 degrees that lack dense forest cover.
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The start zone is the upper part of an avalanche path where the avalanche initially releases from. Credit: Crested Butte Avalanche Center
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Start zones are generally steeper than about 30 degrees, lacking dense tree cover. This photo shows slope angles of an avalanche that caught a group of skiers. Credit: Utah Avalanche Center.