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Category scale unveiled for Atmospheric Rivers

The scale, published Tuesday in the Bulletin of the American Meteorological Society, ranks atmospheric rivers on five levels: Category 1: Weak—primarily beneficial Category 2: Moderate—mostly beneficial, but also somewhat hazardous Category 3: Strong—balance of beneficial and hazardous Category 4: Extreme—mostly hazardous, but also beneficial (if persistent drought) Category 5—Exceptional—primarily hazardous