Megastorm: California's Other "Big One"

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California is in the path of a winter rainfall phenomenon that one of these days could swamp the Golden State from the northern redwoods to the southern beaches, a trillion-dollar storm, a deluge more ruinous than a major earthquake, the U.S Geological Survey warned this week.

The agency unveiled the "ARkstorm Scenario," an extensive study by 117 scientists, engineers and other experts of meteorological circumstances that could bring about such a natural disaster and the economic and social consequences that could ensue.

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Just in the last 15 years, since microwave technology aboard satellites produced images of water vapor in the atmosphere, scientists have come to realize that most major winter rainstorms over California, and virtually all flooding episodes, are the result of the unloading of airborne streams of tropical moisture that have come to be called "Atmospheric Rivers." (Hence the name, ARk – Atmospheric Rivers 1,000.) The scenario envisions nearly a month of uninterrupted rainfall over northern and southern California.

"The hypothetical storm depicted here would strike the U.S. West Coast and be similar to the intense California winter storms of 1861 and 1862 that left the central valley of California impassible," the authors said. "The storm is estimated to produce precipitation that in many places exceeds levels only experienced on average once every 500 to 1,000 years."

In addition to property and "business interruption" losses of anywhere from $725 billion to $1 trillion, the team estimated that emergency managers would be faced with the task of evacuating 1.5 million people during the storm and its aftermath. "The numbers that have been presented here are shocking, no doubt about it," observed co-author Laurie Johnson, a private planning specialist who worked on Katrina Hurricane recovery. Such a storm could pose "a fiscal crisis that will cascade through every level of government."

The report was presented at an "ARkstorm Summit," a two-day conference in Sacramento designed to alert government emergency managers and other state and local "lifeline" officials to the potential for such a weather disaster and how flood control and other measures could help alleviate its worst impacts.

VIDEO: A computer model simulates the enormous flow of water vapor from the topics that could result in a catastrophic winter flood in California.  SOURCE; U.S. Geological Survey