Downpours Ride In on a Jet Stream

More rain has fallen in Los Angeles over the last three months -- 15.68 inches -- than normally falls in an entire year, making this the wettest start to a rainy season since 1966.

Now, forecasters expect a storm coming from the north and drawing moisture from warmer southern waters to dump up to 15 inches of rain in the mountains and up to 5 inches in Los Angeles beginning today and continuing through the weekend.

The storms point to a larger weather phenomenon across the West, with California, Arizona, New Mexico and southern Nevada receiving more rain than normal while Washington, Oregon, Idaho, Montana and Wyoming are getting less than normal.

So as Southern Californians built beach berms, filled and cleared clogged storm drains Thursday in anticipation of the new storm, residents of Seattle and Portland were dealing with drier-than-normal conditions.

The lack of rain is being felt at Washington ski resorts, which have laid off workers because of a lack of snow.

“I keep watching the weather, and the jet streams are kicking all these arctic fronts down your way,” said Tom Stebbins, a marketing coordinator for the Ski Washington trade group. “You’re the ones getting the snow in the mountains.”

Forecasters admit being puzzled by exactly what was causing the abnormally heavy rains here.

Kelly Redmond, a climatologist for the Western Regional Climate Center in Reno, is among those who believe that El Nino conditions have contributed to some of the wetness.

El Nino is a weather phenomenon marked by warmer-than-normal sea surface temperatures off the west coast of South America. In the past, El Ninos have been responsible for higher-than-normal amounts of rain in the Southland.

The recent storms and the one expected today have moved along a single jet stream from the north and have traveled farther to the south than usual, picking up moisture from the central Pacific. As with an El Nino, tropical moisture is being pulled into Southern California.

But the current rains also differ from an El Nino in significant ways. During a classic such phenomenon, the west-east jet stream splits. One arm moves directly across the North Pacific and through Washington, Idaho and the northern Midwest. The other arm flows across the central Pacific, picking up tropical moisture that is deposited in Southern California. No such split has yet occurred this season.

El Nino is one of several long-term weather cycles currently under study, and how these cycles interact is still not clearly understood, Redmond said.

“I think El Nino has been a contributing factor, but it hasn’t been the only game in town,” he said of this season’s precipitation.

William Patzert, a meteorologist for the Jet Propulsion Laboratory in Pasadena, said he doubted that an El Nino was having any effect on the weather here. He placed responsibility for the wet season on the polar jet stream from the Gulf of Alaska.

“The last couple of years we’ve been having all kinds of El Ninos that don’t exist. I call them fictional El Ninos,” Patzert said

This season’s rain has eased Southern California’s drought conditions, although many major reservoirs and lakes such as Lake Mead remain below normal levels. It would take several years of above-normal rain to end the West’s six-year drought.

The rains have also created brisk business for auto-repair shops fixing fender-benders and roofers working on leaky and collapsed roofs.

“Wow! We have 12 lines and they’re all lit up throughout the course of the day,” said Nicole Barrett of Advanced Roofing Solutions in Lakewood. “A couple of days ago we had to schedule over 100 appointments from the South Bay to the Valley. We had over 300 calls, and we had to turn people away.”

Officials are most concerned about possible damage along coastal hills that have already received the most rain, as well as parts of the San Bernardino Mountains where the warm storm system could melt snow, increasing the threat of flash floods and mudslides in areas burned in fall 2003.

Despite the drenchings Southern California has received, Patzert noted that much of the runoff washes out to the ocean.

“We’re not set up to capture water in the Southland,” he said. “When you get this much rain this quickly, it’s like trying to fill a bucket with someone aiming a fire hose at you.”

One thing the sustained rain will probably do is significantly lessen the danger of wildfires that have plagued California and other Western states during the drought years.

“In the past years, four states had the biggest fires in history, and in every one of those instances, they were very deep in drought,” Redmond said. This season’s precipitation “is going to help the forests quite a bit.”

But the prospect of another weekend of rain has many Southern Californians on edge.

In Topanga Canyon, Virgil Mirano stacked sandbags near a fence on his creek-side property to shore up the foundation of his house. Mirano said he was worried that the remains of 40 eucalyptus trees cut from a nearby park could cause problems.

“If there’s a very heavy rain, it will motivate the debris to create a temporary dam, which could break loose and overflow the banks,” said Mirano, who was also busy clearing debris from the creek.

Frank Kelly, another Topanga Canyon resident, said he didn’t think the already saturated ground could absorb much more water, making the risk of flooding greater.

“There’s no more dry ground to soak it up,” he said.

But Kelly doubted that this weekend’s rainfall would be as bad as some storms he’s lived through in the canyon. During a deluge more than 30 years ago, he recalled, cars and entire houses were swept up by raging waters and carried to the ocean.

In areas of San Bernardino County scarred by the 2003 wildfires, the U.S. Department of Agriculture’s Natural Resources Conservation Service has built several erosion-control structures.

The work has included a $500,000 temporary concrete channel that runs down Devore’s Greenwood Avenue, a street that was evacuated last week and has been the site of heavy flows of rocks, mud and trees in the last year.

In Ventura County, bulldozers and other equipment will be on standby to remove debris from the Ventura River, channels and drains. The goal is to avoid blockages that could cause flooding.

Along the coast, the storm is expected to bring pounding surf.

In Seal Beach, city officials spent Thursday contacting residents in low-lying areas prone to flooding, urging them to move vehicles from garages to higher ground.

At the Capistrano Shores mobile home park in San Clemente, where heavy surf and high tides ripped apart units during a 1998 El Nino storm, manager Tony Louch posted warning signs and knocked on doors telling residents to take precautions.

Climatologist Redmond said that if the past was any indication, the next month and a half should see more precipitation.

“Normally, the heart of winter in California is still to come,” he said. “My expectation is that we’ll probably see more precipitation events, especially in the next 30, 40 days or so.”

But he said history had also shown that the weather could do a complete about-face.

“In the last decade or so, we’ve had several years that started out like gangbusters and ended up on the dry side,” Redmond said. “We could be sitting pretty on top of the hill, then have all that taken away from us by some kind of warming event, and that’s not out of the question by any stretch.”

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Rainier than usual

Cities around California are registering more rain than normal this season, which runs from July 1 to June 30. Here’s a look at totals so far, compared with the 1997-98 El Nino year totals:

Rainfall totals (in inches)

*--* Total through Normal through City Thursday Jan. 6 ‘97-’98 total Eureka 19.51 17.09 58.56 Redding 19.14 12.58 65.61 L.A. Downtown 15.68 4.32 31.01 San Francisco 12.25 7.48 47.22 L.A. Airport 11.89 4.19 27.78 San Diego 11.00 3.52 17.78 Sacramento 10.87 6.64 32.25 Long Beach 10.83 4.12 22.67 Santa Maria 8.23 4.34 32.98 Fresno 7.16 3.73 20.36 Bakersfield 3.57 2.06 14.66

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Source: National Weather Service

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Times staff writers Eric Malnic, Lance Pugmire, Sara Lin, Catherine Saillant, Gregory W. Griggs and David Reyes contributed to this report.