California’s deadly wildfires could come to an end in the coming days when a weekend storm douses historically dry terrain, but the storm will come with the potential for a different problem: flash floods.
Flood watch alerts have been issued in the same Los Angeles areas that were burned by the blazes that began burning this month amid hurricane-force winds after a more than seven-month stretch without rain, a record for parts of Southern California.
The 24-hour flood watch alerts cover the still-active Palisades Fire, which has burned 23,448 acres and is 77 percent contained, and Eaton Fire, which has burned 14,021 acres and is 95 percent contained, starting at 4 p.m. Sunday.
The National Weather Service said the possibility of mudslides inspired the watches, which indicate conditions for flooding are favorable but not imminent. Federal forecasters said the probability of significant flooding and debris flow is 10% to 20%.
“While damaging debris flows are not the most likely outcome, there is still a lot of uncertainty with this storm,” the weather service office in Oxnard said Friday. “The threat is high enough to prepare for the worst-case scenario.”
The burn scar created by September’s Bridge Fire in the Angeles National Forest above the San Gabriel Valley and the area of Hughes Fire in the forest northwest of L.A., which started earlier this week and has burned 10,396 acres and was 56% contained Friday, were also under the scheduled flood watches.
Los Angeles County as well as cities such as Los Angeles, Pasadena, and Baldwin Park are offering sandbags to residents who want to prepare for the possibility of mudflows.
Rain could start falling in Los Angeles County on Saturday afternoon and get heavier Sunday, when “moderate to locally heavy rain and small hail or graupel” were possible, according to a weather service forecast discussion.
A quarter-inch of rain could fall in urban Los Angeles, while up to an inch was possible in San Diego, forecasters said. Sunday could be the rainiest day, they said.
Expected snow in Southern California mountains and their communities, including Wrightwood, Big Bear City, Big Bear Lake, Crestline, Running Springs, and Lake Arrowhead, has inspired winter storm warnings for the San Gabriel and San Bernardino ranges. The 48-hour warnings are set to start at 4 p.m. Sunday.
As much as 18 inches of snow could accumulate above the 6,000-foot elevation level, with as much as 6 inches possible above 4,000 feet from Saturday afternoon through Monday afternoon, the weather service said.
The vital 5 freeway, which runs between the U.S. borders with Mexico and Canada, could get a “dusting” of snow that could amount to 1 to 2 inches in the area of Lebec along its Grapevine, the weather service office in Oxnard said in a forecast discussion. Travel disruption was possible, the office said.
Even the mountains of urban Los Angeles and San Diego counties could see snow accumulation of 14 inches and 8 inches, respectively. The forecast comes as the Border 2 fire in San Diego County had burned 6,273 acres since Thursday, with 10% containment Friday evening.
The weather service office in San Diego said on Jan. 10 only .14 inches of rain had fallen since the start of the water year Oct. 1, representing the driest winter so far since 1860, when officials started recording weather data.
Southern California temperatures over the weekend are expected to drop 10 to 15 degrees, forecasters said.
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