Unusually arid spring weather, topped by the past week of severe temperatures and drastically low humidity, have dried out Southern California's vulnerable hillsides a month earlier than last year, the region's fire prevention specialists said Wednesday.
Normally, the brush fire season does not reach its peak until August or September. But because "fuel moisture" measurements have fallen so quickly, it appears that the danger will remain even when the unseasonable hot weather tapers off.
"The last week and a half of heat has put us into the critical level," said Cathy Taule, fuels management officer for the San Bernardino National Forest.
The problem is shared throughout much of the Western United States, where fire management experts believe drought conditions may portend a summer of forest and range fires of historic proportions. Even before the eruption of fires in California earlier this week, the West had been plagued this fire season by about 1,200 fires that burned nearly 200,000 acres.
"We have the potential for a Tillamook," said a land management official at a federal wildfire center in Boise, Ida., referring to a devastating forest fire that burned 133,000 acres in western Oregon in 1933.
A confluence of variables has speeded up the arrival of the fire season in Southern California:
- Since January, the rainfall that normally keeps plants and brush moist enough to resist major outbreaks in the early summer has been less than half the usual level. Los Angeles received only 5.07 inches instead of its usual 10.43. In three important months--January, March and April--a total of only 2 inches of rain fell, compared to the usual 7.2 inches.
- The current hot streak, caused by a strong and persistent high-level pressure system that has blanketed the region, has further dried rain-starved hillsides with temperatures 20 degrees hotter than usual.
- By effectively stifling the usual flow of Pacific Ocean air, the high-pressure system has slashed midday humidity from a normal 50% to around 15%, further robbing plant growth of its moisture. In normal hot-weather periods, evening humidity allows the growth to recover some of the lost moisture, but that is not occurring now.
- Last year, which was also a bad year for rain, some Southern California hillsides were protected by retaining some of the moisture they enjoyed in 1983, which was a relatively good year for rain. There is no such protection to fall back on this year.
- In recent years, the impact of hot, dry weather on brush has been blunted by the remnants of Pacific Ocean tropical storms, which provide needed humidity. But odds of this happening this year do not look promising. So far this year there have been six such tropical storms, all of which have stayed well south of this area.
"The dryness cycle is running about a month ahead of last year," said Ray Veverka, a forestry assistant with the Los Angeles County Fire Department's vegetation management section.
Shortened Drying Time
"When it gets this hot, it can only take a couple of weeks for fuel to dry out the way it normally would in a month and a half," San Bernardino's Taule added.
Veverka, who monitors fire "fuel" in more than a dozen sections of unincorporated territory, said he based his opinion on visual inspection and lab measurements, which are made by placing fire-prone growth in an oven and determining the ratio of moisture to the weight of the plant itself.
In the rainy season, the fuel moisture reading might be as high as 200%, meaning the weight of the moisture is twice the weight of the plant. Now, the average fuel moisture reading is in the area of 70%, said Paul Downing, a county deputy forester.
Explained Veverka, "If you take something like grease wood, which is one of the major fuels, you figure that 60% fuel moisture is critical. Then the brush will explode when fire is put to it."
Oregon Also Affected
The West's drought covers most of California and much of Oregon. Paradoxically, much of the desert Southwest--Colorado, Utah, New Mexico and Arizona--is wetter than normal. But nearly all of the rest of the region is experiencing at least moderate drought, and the result is a rare combination of simultaneous droughts on the East and West coasts.
The impact is evidenced by the outbreak of fires on "north-facing slopes that are normally cool and moist," said Clyde O'Dell, staff meteorologist at the Boise Interagency Fire Center, which coordinates federal wildfire fighting.
"I'd be surprised if we get out of the summer in Washington and Oregon without major fires," O'Dell said. "California is always a good bet (for fires), but it's a better bet this year."
Effect of Budget Cuts
Jack Wilson, director of the U.S. Bureau of Land Management at the Boise center, said firefighting efforts could well be hampered this year because of federal budget cutbacks that seemed acceptable during the past four, relatively fire-free years.
"We are considerably less capable--by one-third than we were four years ago," he said.
Gordon Rowley, fire management specialist at Angeles National Forest, agreed.
"We've cut forces, and we're dependent upon Northern California, Idaho, Montana, Arizona to bail us out," he said. "With everyone having fires, the national resources we normally move are not there.
"Yesterday," Rowley said, referring to Tuesday's series of blazes throughout Southern California, "if you'd wanted an airplane, you'd have to fight and scratch. You'd have to be losing houses to get aircraft. They wouldn't even talk to you about a helicopter.
"If we are fully manned, with a full complement of forces, and the cities and counties have a full complement, we can usually contain that first fire. But it's the second and third that usually do us in."
Bob Baker reported from Los Angeles and Bill Curry from Boise, Ida.
RAINFALL IN THE REGION These National Weather Service rainfall statistics are for the downtown Los Angeles Civic Center.
Rainfall Normal Percent Month in Inches for Month of Normal January .71 3.69 19.2 February 2.84 2.96 95.3 March 1.29 2.35 54.8 April 0.00 1.17 0.0 May .23 .23 100.0 June 0.00 .03 0.0 Total 5.07 10.43 48.6%