Massive Storms Slam California
December 12, 2014
After more than two years of extreme drought, California has been hit by the most powerful storm to cross the state in at least a decade. A weather system known as a “pineapple express” hammered the north and center of the state with hurricane-force winds and up to 10 inches (25 centimeters) of rain yesterday. (A “pineapple express” is characterized by “an atmospheric river”–a strong and persistent flow of atmospheric moisture–that extends from the waters adjacent to the Hawaiian Islands to the Pacific Coast of North America.)
The storm left more than 220,000 people in northern California without electric power today after heavy rains and high winds slammed the region yesterday. For several hours, San Francisco received more than 1 inch (2.5 centimeters) of rain per hour. Some 240 flights were cancelled at the San Francisco airport, and flooding shut down the city’s Bay Area Rapid Transit system in some areas. The San Francisco Bay Ferry company was forced to cancel all ferry trips across the bay due to the foul weather. The National Weather Service in Sacramento yesterday issued a rare blizzard warning for higher elevations in northern California, and wind gusts in the Sierra Nevada mountains topped 140 miles (225 kilometers) per hour.
A Pineapple Express (circled in red)—basically a river in the atmosphere—dumps huge amounts of rain on California in a short time. During this meteorological event, southwest winds bring warm, moist air to the U.S. West Coast. (National Climate Data Center at the National Oceanic and Atmospheric Administration)
The fast-moving storm is currently pounding southern California, leaving some 70,000 people across the region without electric power and triggering rockslides and mud flows. In some areas of the Los Angeles metropolitan area, rain was falling at a rate of 2 inches (5 centimeters) per hour.
Additional World Book articles:
- Climate
- How the Ocean Affects Climate (a special report)
- Weather Terms—Cloudy or Clear? (a special report)
