Winter rains have started. Temperatures are dropping. Is California’s fire season over?
It depends where you live, experts say.
Much of the northern part of the state, generally from Interstate 80 to Oregon, has seen multiple storms in recent weeks that have soaked dry landscapes and brought snow to the Sierra Nevada. But farther south, little rain has fallen.
“Right now, the risk is really low for Northern California,” said Craig Clements, director of San Jose State State University’s Fire Weather Research Laboratory. “We are getting cold fronts coming through and bringing rain. There’s some snow, which is really helping. We are coming out of fire season. If it stops suddenly and we get warm weather, things could change. But right now it’s looking good.”
Farther south, the threat is far worse, he added.
“Southern California is still dry,” Clements said. “They are going to remain at risk, especially if there is another wind event. The Mountain Fire was a wind-driven fire. The fuels were dry. It just ripped.”
The Mountain Fire began in Ventura County on Nov. 6. A clear reminder of how October and November can often bring some of the most dangerous fires of the year to California — because six months or more have gone by without major rains — it burned 19,904 acres between the cities of Ventura and Simi Valley. Driven by 80 mph winds, it destroyed 234 buildings in the foothills around Camarillo and other communities. On Friday it was 91% contained.
Clements said that as a general rule, once an area receives at least 1 inch of rain after Oct. 1 in California, fire risk diminishes substantially. That’s because moisture levels in the soil, grasses and other plants increase. The weather is also often cooler and more cloudy than during the hottest times of the year. If a fire does start, flames spread more slowly than during extremely dry conditions, allowing firefighters a better chance to get the blaze quickly under under control.
Scott Stephens, a professor of fire science at UC Berkeley, agreed.
“If you get 1 inch of rain and it dries out for 2 weeks, there is fire potential again,” Stephens said. “If you get 1 inch over a longer time period that’s better. You are constantly adding a little bit of moisture so the things that dry out get wet again.”
Since Oct. 1, many areas across Northern California have cleared that 1-inch margin. Crescent City, near the Oregon border, has seen 8.15 inches of precipitation in the past 6 weeks, according to the National Weather Service. Eureka 6.2 inches; Redding 1.92 inches; South Lake Tahoe 1.11 inches; and Santa Rosa 1.61 inches.
But other places, including much of the Bay Area, are below that threshold. San Francisco has had .56 inches since Oct. 1, about the same as Oakland, with .55. San Jose has had less, .34 — all of it in one Veteran’s Day storm on Monday. More rain is forecast for next weekend.
To the south, the rain totals are microscopic. Santa Barbara has received just .01 …read more
Source:: The Mercury News – Entertainment