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Rain Soaks California Region Scarred by Wildfires Mudslides Strike California Region Scarred by Wildfires
(about 1 hour later)
Drenching rain soaked Southern California early Tuesday morning, with mudslides and floods threatening lives and property in a region that faced destruction from wildfires just weeks ago. SAN FRANCISCO — A stretch of Southern California scorched by the worst fire in the state’s history faced a new disaster on Tuesday — mudslides — as heavy rains pelted unstable hillsides denuded by fire.
Rain fell at rates as high as an inch and a half per hour, bringing down power lines and trees and forcing closures along several roads and highways, including a stretch of Highway 101 along the coast south from Santa Barbara, according to the National Weather Service. Triggered by rain that fell at rates as high as an inch an hour, mudslides closed major roads, brought down power lines and threatened lives and property across Ventura County, northwest of Los Angeles.
“We haven’t had this much rain in a while,” said Stuart Seto, a weather specialist with the National Weather Service in Oxnard, southeast of the where the mudslides occurred. The mountains that rise from the Pacific Coast have seen as much as five inches of rain over the past two days, drenching the fire-ravaged hills. “Before the rains started they were already seeing boulder slides, trees sliding. It was already loose,” Mr. Seto said.
In Montecito, the authorities contended with waist-deep mudflows in some areas as they were called in to make multiple rescues, Mike Eliason, spokesman for Santa Barbara County Fire Department, said on Twitter. Some homes were torn off their foundations, according to KEYT News.
Mudslides closed a stretch of Highway 101, the key artery along the coast south from Santa Barbara, and Los Angeles County was also drenched, with muddy water rushing down hillsides.
At least 20,000 people were without power on Tuesday morning, according to Southern California Edison.At least 20,000 people were without power on Tuesday morning, according to Southern California Edison.
Flash floods also threatened parts of Santa Barbara, Ventura and Los Angeles Counties; flooding in and around the area scarred by last month’s Thomas wildfire, the largest on record in California, posed the “greatest threat,” according to the Weather Service. Flash floods also threatened parts of Santa Barbara, Ventura and Los Angeles Counties. But flooding in and around the area scarred by last month’s Thomas wildfire, the largest on record in California, posed the “greatest threat,” according to the Weather Service.
“Residents living in or immediately downstream should take immediate precautions to protect life and property,” it said in a pre-dawn statement. “Quickly move away from the burn area only if it is safe to do so, otherwise shelter in place and move to a second story or the highest location in your home to stay out of the path of fast-moving water and debris flows.”“Residents living in or immediately downstream should take immediate precautions to protect life and property,” it said in a pre-dawn statement. “Quickly move away from the burn area only if it is safe to do so, otherwise shelter in place and move to a second story or the highest location in your home to stay out of the path of fast-moving water and debris flows.”
By 5 a.m., about five inches of rain had fallen north of Ojai, in Ventura County, though totals were lower along the coast and other areas, according to the Weather Service. The worst of the rain had passed by about 7 a.m., though showers and thunderstorms were still possible throughout the day. Jonathan W. Godt, who coordinates the landslide hazards program at the United States Geological Survey, said the area of the Thomas fire was likely to have debris flows for two reasons: the terrain and the nature of the fire, which burned more than 280,000 acres beginning in early December.
In Montecito, the authorities contended with waist-deep mudflows in some areas as they were called in to make multiple rescues, Mike Eliason, spokesman for Santa Barbara County Fire Department, said on Twitter. Some homes were torn off their foundations, according to KEYT News. “That’s some really rugged topography,” Dr. Godt said, with steep slopes and large elevation differences.
At one point early on Tuesday, a rain gauge in the area recorded a quarter-inch of rain falling in as little as five minutes, according to the National Weather Service. The fire, in a mostly chaparral landscape, also burned exceptionally hot, Dr. Godt said. A hot fire changes the physical properties of the soil, making it less absorbent. “It becomes much more erodible,” he said.
As rainwater runs off and flows downhill, it picks up soil and debris and eventually collects in a stream channel. The mix of water and debris, often with a consistency close to wet concrete, can then continue traveling at high speed down the streambed.
“You bring that down at 20 miles per hour and it can do a lot of damage,” Dr. Godt said.
But the rainfall can also make whole slopes give way, he said.
The heaviest rains were north of Ojai, in Ventura County, where a total of seven inches is expected through Wednesday, according to Mr. Seto. The worst of the rain had passed by about 7 a.m., though showers and thunderstorms were still possible throughout the day.
At one point early on Tuesday, a rain gauge in the Montecito area recorded a quarter-inch of rain falling in as little as five minutes, according to the National Weather Service.