'Dry lightning' sparks Calif. fires
Phenomenon accompanied by little or no rainfall
SAN FRANCISCO - In less than a day, an electrical storm unleashed nearly 8,000 lightning strikes that set more than 800 wildfires across Northern California - a rare example of "dry lightning" that brought little or no rain but plenty of sparks to the state's parched forests and grasslands.
The weekend storm was unusual not only because it generated so many lightning strikes over a large geographical area, but also because it struck so early in the season and moved in from the Pacific Ocean. Such storms usually do not arrive until late July or August and typically form southeast of California.
"You're looking at a pattern that's climatologically rare. We typically don't see this happen at this time of summer," said John Juskie, a science officer with the National Weather Service in Sacramento. "To see 8,000, that's way up there on the scale."
Thousands of firefighters battled the blazes yesterday from the ground and air. No homes had been destroyed, but voluntary evacuations were in place for residents of at least 25 homes, officials said.
Despite the many lightning strikes that hit the ground on Saturday, the weekend thunderstorm brought little precipitation because the rain evaporated in hot, dry layers of the atmosphere before it hit the ground, Juskie said.
The lightning storm struck California when the state was experiencing one of its driest years on record. Earlier this month, Governor Arnold Schwarzenegger declared a statewide drought and directed agencies to speed up water deliveries to drought-stricken areas. Many communities have adopted strict conservation measures.
From San Francisco to Los Angeles, cities have seen only a tiny fraction of the rainfall they normally receive in a typical year. In the Central Valley, the cities of Sacramento, Modesto, Stockton, and Red Bluff have recorded their driest March-to-May periods since at least the 19th century, according to the weather service.
"A combination of lightning and very dry fuels will spark fires," said Mark Strobin, a weather service meteorologist in Monterey. "It doesn't take much nowadays especially with how dry it is."
Even before the lightning struck, California had already seen an unusually large number of wildfires, although the fire season typically does not start until July and does not peak until late summer or early fall.
"This doesn't bode well for the fire season," said Ken Clark, a meteorologist in Southern California with AccuWeather.com. "We're not even into the meat of the fire season at this point, and the brush is extremely dry. It's not going to get any better, it's going to get worse."
The weekend's lighting storm combined with extremely dry conditions to spark about 840 separate blazes from the Big Sur area of Monterey County to Del Norte County on the Oregon border.
By contrast, 574 lightning-sparked fires blackened about 55,000 acres in Northern California in all of 2007.
One of the state's worst wildfire years occurred in 2001, when more than 2,000 lightning-caused blazes burned 185,000 acres, according to the National Interagency Fire Center.
Areas hit the hardest by the weekend thunderstorm include Mendocino County, where 131 fires have burned more than 13,000 acres; Lake County, where six fires have scorched more than 12,000 acres; and the Shasta-Trinity Forest, where more than 150 fires have burned about 8,000 acres.
Yesterday, fire crews from Nevada and Oregon arrived after Schwarzenegger requested extra help. Smoke from the fires has darkened skies in the San Francisco Bay area and Central Valley, causing public health officials to issue air-quality warnings.
The weather service has said more dry thunderstorms could strike Northern California later this week.
"That's something we have to keep an eye on," said Mark Strobin, a weather service meteorologist in Monterey. The weather pattern "could happen again across Central and Northern California."