Experts planning for a flood of Noah's Ark proportions

First come the wildfires.

Then the extended cloudbursts.

Then the furies of mud, rock and debris that roar out of the San Gabriel foothills.

And in the floods' wake, every few decades, rage death and destruction across Southern California.

"The debris flows, reported as mudslides, pick up speed like a water-born avalanche coming down off the mountains - moving at 40 miles per hour picking up boulders like minivans and sweeping into the city," said Lucy Jones, chief scientist for the Multi-Hazards Demonstration Project at the U.S. Geological Survey in Pasadena.

"In (1934 and) 1978, it happened in La Crescenta ... and it'll happen again."

California may be caught in the throes of a years-long drought, but Jones and other crisis experts are now planning for a flood of Noah's Ark proportions.

Worried about the long-term effects of climate change, the USGS and the National Oceanic Atmospheric Administration are co-creating a scenario for a cataclysmic flood across the Golden State.

Last year, a USGS-led team of 300 scientists created a detailed scenario for a 7.8-magnitude earthquake in Southern California, followed by a "ShakeOut" drill of 5.4 million residents, a disaster preparedness record.

Many of the same scientists are now fashioning a hypothetical ARk Storm scenario similar to the mother of all known California floods - the Great Flood of 1861-62.

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