Dangerous Fire Season Is Forecast

This year’s fire season could be just as bad as last year’s, experts say. And last year’s was the worst in history.

They say a number of factors are coming together -- a prolonged drought, tree-killing pests and a century of shortsighted firefighting strategies -- to turn the forests of brush and timber surrounding the Southland’s cities into vast piles of kindling. The situation, they say, could continue for years.

Cities are contributing to the problem, expanding ever farther into the foothills and forests, increasing the likelihood that fires will start and increasing the numbers of homes and lives that are threatened, fire officials say.

Because of changes in forest vegetation brought about by the drought and 100 years of fire suppression, the fires that start now tend to burn hotter and expand faster than the blazes of the early 1900s. In some cases, they burn so hot and so fast that nothing can be done to halt their advance.

Normally, fires slow at night as winds abate, temperatures drop and relative humidity rises.

“But one night last month, at the Crown fire near Acton, 6,000 to 7,000 acres burned in three hours,” said Jody Noiron, supervisor of the Angeles National Forest. “The winds, the fuel, there was nothing to stop it.”

“Some of those big fires, with all that intense heat, they sort of create their own weather,” said John R. Todd, an assistant chief for the Los Angeles County Fire Department. “Huge clouds of smoke create downdrafts that blow the fire in all directions. You’ve got to back off. You just try to protect structures and get people out safely.”

Todd said this year’s fire season looks a lot like last year’s, “only this year, the fires started a lot earlier.”

Forest fires in Southern California last year killed 26 people, burned more than 738,000 acres and destroyed more than 3,600 homes and other buildings. Most occurred in October, at the end of the fire season.

By the end of July last year, 1,373 acres had burned in the Angeles National Forest. By the end of July this year, more than 10 times as much, 17,091 acres, had burned. Part of the San Bernardino National Forest has been closed because of the danger.

William Patzert, an oceanographic meteorologist at the Jet Propulsion Laboratory in Pasadena, said the drought began more than six years ago, when downtown Los Angeles got only 9 inches of rain, compared with a normal season’s total of about 15 inches. The 2001-02 season was the driest in history, with less than 4 1/2 inches. And in the season that ended in June, only about 9 inches fell. Over the last six years, the average has been less than 75% of normal.

The National Oceanographic and Atmospheric Administration says the drought now extends across all of California and parts of 12 other Western states.

Under the Palmer Drought Severity Index, a tool for evaluating prolonged periods of abnormally dry or wet weather, all of California but the northwest coast is considered to be in an extreme drought, the highest Palmer rating. Along the northwest coast, the drought is rated as severe.

The dry cycle, Patzert said, could last an additional 10 years, or more.

Studying records that stretch back more than a century, he has concluded that there are cyclical phenomena in the Pacific Ocean that seem to have enormous influence over Southern California’s weather. One is the now familiar El Nino/La Nina cycle. During El Ninos, Southern California sometimes gets more rain than usual. During La Ninas, it’s almost always drier.

But those phenomena seldom last more than a year or two, and the current drought is headed into its seventh year.

“Clearly, there are other forces at work,” Patzert said.

These other forces, he said, apparently include a much longer cyclical phenomenon, caused by surface water temperatures, known as the Pacific Decadal Oscillation. He said this oscillation may trigger weather phases in Los Angeles and the Southwest that last as long as 20 years. Right now, he said, we’re in the middle of a dry phase.

Richard Minnich, a professor of earth sciences at UC Riverside, isn’t so sure about what causes those phases or how long they last. He thinks the El Nino/La Nina cycle and sheer random chance are more important factors in the drought than the Pacific Decadal Oscillation.

He also thinks that when it comes to wildfires, the condition of the vegetation is at least as important as the weather itself.

Current measurements show that the moisture content of the chaparral draping the lower slopes of Southern California’s mountains is extraordinarily low.

“Things are just extremely dry, extremely ready to burn,” said Rick Vogt, a Riverside County fire captain.

Under a formula used by firefighting agencies, the weight of a plant’s moisture is compared with the weight of the plant’s dry, woody fibers. The ratio is expressed in percentages -- 100% would mean the moisture in a plant equaled the weight of the fibers. Because plants are like sponges, they can absorb a lot more than their dry weight, so figures well over 100% are possible.

Over the course of a year, brush moisture in the Angeles National Forest typically ranges from a high of about 175% in the late spring to a low of about 63% in late October. Anything under 80% is considered dangerously dry.

“This year, it was down to 63% by the end of July,” Noiron said.

Although the drought has a lot to do with the dry brush, Minnich said, other factors are at work. He said a century of trying to put out every wildfire that burns, often with considerable success, has left vast chunks of forest that are over-timbered and choked with brush.

In Southern California’s mountain ecosystem, he said, conifer forests should be relatively sparse -- about 40 trees per acre -- a density that would be maintained if fires were allowed to burn unchecked over the years. At 40 trees per acre, moisture and nutrients are sufficient to keep trees healthy, able to survive the stresses of fire and the predations of destructive pests like bark beetles.

Today, because of fire suppression, there are about 150 to 200 trees per acre in Southern California mountain resort areas, such as Lake Arrowhead and Wrightwood. Lacking adequate water and nutrients, the clumping trees weaken and die, Minnich said.

More than a million trees have died in Riverside, San Bernardino and San Diego counties, and with bark beetles now moving into Los Angeles County near Wrightwood, trees are starting to die there too.

Fire suppression has had similar effects on brush, Minnich said, allowing huge acreages of chaparral to grow unusually large and lush and exacerbating the effects of drought.

“Plants are like faucets, taking moisture out of the soil and putting it in the air,” he said. “The more foliage, the more you desiccate the ground.”

“We’ve taken the natural fire out of the equation, and that’s left us with thicker, denser brush,” Noiron said. “By now, the whole San Gabriel Mountain front is like that, from La Canada Flintridge to Glendora.”

Experts say the big stands of unnaturally dense brush and timber call for new tactics, a shift away from the century-old philosophy of attempting to snuff out every fire that starts. Where safe, they say, fires are now being allowed to burn and some fires are being deliberately set, creating patchworks of sparsely vegetated land that will deny fuel to subsequent blazes.

It will take time, they say, but eventually, the vast stands of choked brush and timber will be thinned. To that end, about 10,000 acres of the 690,000-acre Angeles National Forest have been manicured under a $90-million federal grant.

“If we can keep it up, it should help a lot,” Noiron said.

Another problem, fire officials said, is the steady expansion of homes into the foothills. Encroaching communities mean more people in fire-prone areas, and people start fires, either accidentally or, in far fewer cases, deliberately. More than 90% of the fires in the Angeles National Forest are human-caused, fire officials said. In addition, more residents in dangerous areas mean more resources must be committed to saving lives and property.

“People who live far away are subsidizing, with tax dollars, the people who live in hazardous areas,” said Todd, the assistant Los Angeles County fire chief.

Noiron and Todd said that despite the state’s financial trouble, their funding is intact, their staffing is full and their equipment is state of the art.

Helicopters carry television cameras to provide fire commanders with live images of what’s happening on the ground. Bulldozers are equipped with global positioning system transmitter/receivers to pinpoint the location of fire breaks. Computers provide up-to-date maps.

“We’re as ready as we can humanly be,” Noiron said.

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Times staff writer Janet Wilson contributed to this report.