The American River Watershed is particularly receptive to this phenomena arising often from La Nina conditions, and the potentially disastrous flooding which can result from it.
One hopes public leadership eventually realize the only solid protection against the continued dice roll we face—being satisfied with a 100-200 year level of protection when a 500 year level is called for—is the Auburn Dam.
La Niña's back – so brace for possible deluge
By Matt Weiser - Bee Staff Writer
Published 12:00 am PDT Thursday, October 18, 2007
Most people know El Niño as the weather monster that brings record rain, floods and highway-closing snowdrifts to California.
But the weather phenomenon's nasty little sister, La Niña, has been the bigger troublemaker in the Sacramento area. And she's visiting again this winter.
Forecasters say La Niña will bring a greater chance of heavy rain in Northern California through February.
In past La Niña years, California got weeks of flooding, bracketed by odd periods of utterly dry weather.
La Niña is the opposite of El Niño because it is triggered by a cooling of waters in the equatorial Pacific Ocean. It usually shifts the jet stream farther north, bringing drought to Southern California and extra-wet conditions in the Pacific Northwest.
For areas in between – like Sacramento – the impact is less predictable and sometimes unwelcome.
This winter's La Niña should be mild to moderate, according to the National Weather Service. But there are signs of it strengthening.
"It definitely seems to be getting stronger," said Bill Patzert, climatologist at NASA's Jet Propulsion Laboratory and often a contrarian in such predictions. "Right now, I'm saying the dice are loaded."
The historical record for the Sacramento River shows that some of the biggest floods – and craziest mixes of rain and dry stretches – came in La Niña years.
"It's kind of an interesting paradox about La Niña," said Kelly Redmond, deputy director at the National Weather Service's Western Region Climate Center in Reno. "A case in point was the 1996-97 floods. We had a flood at the start of January, then another in the third week of January. Then we had one of the driest periods in history for the next four months."
There were epic floods in 1950, 1955, 1965, 1986 and 1997 – all La Niña years, or years with borderline La Niña conditions.
