Wetter Winter May Lie Ahead, but Drought’s Impact to Linger

The National Oceanic and Atmospheric Administration predicted Tuesday that Southern California could be in store for higher-than-average rainfall in the next few months, but experts agreed that any extra precipitation would be insufficient to reverse the effects of a six-year drought.

With another major storm barreling into the region late Tuesday, Los Angeles had already broken a 115-year record for rainfall in October. This storm, and two earlier ones, came from the Gulf of Alaska that meteorologists said had produced the kind of heavy rain extremely rare for October, which is more known in the Southland for hot Santa Ana winds.

UC Berkeley’s Central Sierra Snow Lab had measured 48 inches of snow on the ground at Soda Springs by Tuesday afternoon, the most in an October since the lab began keeping records in 1945.

The big question, forecasters said, is whether the unusually large amount of early-season rain will be followed in January and February by a more familiar weather pattern: El Nino. That phenomenon, which involves a warming of tropical waters in the Pacific Ocean, has been the cause of heavy rains in California in the past.

Computer models and other forecasting tools show a mild El Nino kicking up early in the new year, said Ed O’Lenic, a meteorologist with the National Oceanic and Atmospheric Administration, which oversees the National Weather Service.

But other forecasters are more skeptical.

“October could be a preview of coming attractions, but it definitely won’t be an El Nino winter,” said Bill Patzert, an oceanographer who studies weather for the Jet Propulsion Laboratory in Pasadena.

Patzert described the wet October as “absolutely unusual, a 100-year event” but said it could not be viewed as a precursor of El Nino conditions. The systems are unrelated, he said. El Nino storms generally come from warm southern Pacific waters, while this month’s storms have come from cold, northern waters.

Even if an El Nino developed and caused a wet winter, it would do little to help the region escape the impact of a prolonged drought, forecasters said.

Over the last six years, the average rainfall in Southern California has been less than 75% of normal, according to researchers. In the season that ended in June, only about 9 inches fell. The normal annual rainfall for Los Angeles is about 15 inches.

“In dry areas, any amount of rain is helpful, and it does tend to put a dent in the kind of long-term drought you’ve had,” said meteorologist O’Lenic, who is based in Maryland. “But it won’t erase it, because you’ve had such a long-standing deficit.”

Moreover, most of Southern California’s water comes, not from rain that falls here, but from snow in the Sierra Nevada and in the Colorado River watershed.

The mild El Nino conditions predicted by the weather service would not be strong enough to appreciably boost Sierra snowpacks, said Adan Ortega, vice president of external affairs for the Metropolitan Water District. El Nino storms generally bring heavy rain to Southern California, but they don’t always deliver heavy snow to the Sierra.

Even with strong rains across the Southwest, providing snow to the Rocky Mountains and water to the Colorado, Ortega said, it could take as many as 10 years to refill reservoirs, such as Lake Mead, along the river.

“Up to a decade -- that is how much damage this Southwest drought has done,” he said.

Today’s storm could drop 1 to 4 inches of rain on the Los Angeles Basin, said Bonnie Bartling of the National Weather Service. Up to 7 inches could fall in the foothills, raising new fears of flooding in areas burned by wildfires a year ago and over the summer.

Fire officials were hoping for gentle, steady rain, saying that downpours could cause the already saturated hillsides to give way, causing mudslides and flash floods.

By 11:30 p.m., up to 2.79 ,inches of rain had fallen in the mountains near Mt. Wilson and up to 1 1/2 inches in the San Fernando Valley. The heaviest rain was falling in a line from La Canada Flintridge through downtown Los Angeles toward Long Beach.

The California Highway Patrol said 111 collisions occurred in the county between 4:30 and 9:30 p.m., compared to 70 on a typical dry day.

In Santa Clarita, more than 400 residents of a mobile home park were stranded for the second time in two weeks when runoff from a burned area flooded the only access road. And in Silver Lake, three trees fell into electrical lines, blacking out an unknown number of homes.

Rescuers in El Monte pulled someone unharmed from the San Gabriel River. And in San Bernardino, the body of a man who apparently was swept away last week by a storm was found by crews cleaning debris in the Lytle Creek wash area.

The initial storm earlier this month was the first in the region in 180 days, and it did much to alleviate fears that Southern California was ripe for the type of catastrophic wildfires that destroyed more than 3,000 homes last year.

The U.S. Forest Service reopened large swaths of the Cleveland, San Bernardino and Angeles national forests that had been closed because of the fire danger.

The cool, wet conditions have also allowed fire crews to begin burning piles of dead trees killed by bark beetles.

“Before, the fuel moistures and the relative humidity were so low [that] the potential for conflagration” was too great to reopen the closed areas, said Jim Wilkins, a spokesman for the forest service.

Wilkins said further rain, particularly the steady, mild kind, could reinvigorate trees that were stressed by a lack of water and could thus create continued buffers against huge wildfires. But too much rain might spur rapid growth of vegetation that could easily catch fire a year from now if Southern California experienced another hot and dry summer, he said.

No one is sure why October was so wet. There were no long-term forecasts predicting the storms, O’Lenic said.

The National Oceanic and Atmospheric Administration found evidence that a mild El Nino would arrive in Southern California by January. That, along with a “large pattern of wetness worldwide,” provides a higher-than-average chance of a wetter winter, O’Lenic said.

“These rains will probably not change much” in terms of the drought, he said. “They could have a small impact, because the major driving force will be the weaker El Nino.”

JPL’s Patzert agreed that satellite data had shown El Nino conditions building in the Pacific. But he believes the conditions have lessened significantly in recent weeks.

There has been disagreement worldwide about the prospects for an El Nino.

Federal officials have said doubters don’t realize that their forecast suggests El Nino might come later in the winter than it normally does, a possibility that has spurred some of the conflicting predictions.

Patzert isn’t sold.

“The guys back East say it’s a mild El Nino, and I say it’s puny if that -- and so we’re a little adrift here,” he said. “They’re saying El Nino is going to be resurrected like Lazarus, and I’m saying this El Nino at this particular point is six feet under.”

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Times staff writer Sandra Murillo contributed to this report.