Wednesday, July 29, 2009

Southern California Floods

The Los Angeles Daily News asks if floods could swallow the San Fernando Valley.

It's happened before.

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."


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.

That flood, occurring during 45 days of rain, turned California into an inland sea. It also forced Gov. Leland Stanford to take a rowboat to his inauguration, wiped out a third of taxable land, and virtually bankrupted the state.

And when it does happen again, the culprit will be (wait for it) global warming!

And because of global warming, scientists forecast such a colossal gully-washer born by the "pineapple express" jet stream to happen sooner rather than later.

"With climate change, the West Coast is expected to experience even more extreme winter rainfall than we've seen so far, along with extreme episodes of dry, hot weather in summer," said Marty Ralph of NOAA's Earth System Research Laboratory in Boulder, Colo., a member of the ARk Storm team, in a statement.

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