LOS ANGELES _ The National Weather Service issued a flood advisory early Thursday in areas recently scarred by devastating wildfires in Los Angeles and Ventura counties as steady rain continued to fall on the region, heightening concerns over possible shallow mudslides and debris flows.
Forecasters said shortly after 5 a.m. that moderate to heavy rain was spreading east across southern Ventura County and heading toward the Hill and Woolsey fires burn areas. The area is expected to see roughly a quarter of an inch of rain per hour. However, just under half an inch an hour is possible.
The soil in burn areas cannot absorb a lot of moisture, so heavy rainfall can lead to fast-moving flows containing mud, debris and even trees and boulders. When rain falls over time, it can be gradually absorbed or dispersed, but when areas see rapid runoff, that's when entire hillsides can come down without warning, sometimes with deadly results.
"Right now, there's heavier rain in the vicinity of the Woolsey fire, but it's moving rather swiftly," said David Sweet, a meteorologist with the National Weather Service. "That's going to limit any potential problems."
Minor rock slides along Decker Canyon, Kanan and Malibu Canyon roads have been reported but did not result in any damage, officials said.
The rain also prompted Pepperdine University to cancel classes at its Malibu campus Thursday. Residents whose homes were spared in the Woolsey fire placed sandbags around their properties in preparation for the storm.
Several neighborhoods in Riverside County burned by the Holy fire, including Amorose, Alberhill, Glen Eden, Grace, Matri, Rice and parts of Glen Ivy, Horsethief, Laguna, McVicker and Withrow were ordered to evacuate late Wednesday.
"People in these zones MUST GO NOW," the county's Emergency Management Department said in an alert Wednesday.
Slick roadways also caused traffic problems across the Southland early Thursday.
A semi-truck veered off the 134 Freeway and crashed into an embankment in Eagle Rock about 2 a.m., according to the California Highway Patrol.
Heavy rains predicted to hit the Big Sur coast closed parts of Highway 1 on Wednesday. The iconic route will remain closed Thursday at its most vulnerable slide points, with a possible reopening Friday morning after the storm has passed, according to Caltrans.
A weather service warning of possible flash floods remains in effect for three counties in Northern California.
Forecasters predicted the second in a series of three storm systems this week could drop more than an inch of rain on the Camp fire burn area in Butte County; the Carr, Delta and Hirz fires burn areas in Shasta County; and the Mendocino Complex fire scar in Lake County.
