LOS ANGELES (CNS) - A storm system that could unleash mud and debris flows over slopes denuded by wildfires will hit the Southland today and Thursday, the National Weather Service said.
The rain is likely to reach the Southland around noon and last through 5 p.m., said meteorologist Keily Delerme at the NWS station in Oxnard, and a flash flood watch will be in force from tonight through Thursday evening in Orange County, according to the NWS in San Diego.
“A Pacific storm system will draw a large amount of moisture across southwestern California on Thursday. This will set the stage for widespread moderate to locally heavy rainfall along and west of the mountains and into the high deserts. Heaviest amounts will be on the coastal mountain slopes with very high snow levels. The warmer conditions at high elevations will also melt much of the snowpack, adding to runoff and potential flooding problems,” said a statement issued by the NWS in San Diego.
In the San Gabriel Mountains, a wind advisory will be in effect until 3 p.m. Thursday. NWS forecasters said southeast winds of 20-30 mph would buffet the mountains today, gusting to 45 mph, then increase to 20 to 35 mph with 55 mph gusts from Thursday morning through mid-afternoon.
“Winds this strong may down trees and power lines, causing property damage or power outages. Cross winds can make driving difficult, especially for drivers of high profile vehicles and vehicles towing trailers,” the NWS warned in a statement. “When driving, use extra caution. Be prepared for sudden gusty cross winds.”
Delerme said the storm system could produce 1-2 inches of rain along the coast, 2-3 inches along coastal slopes and 3-4 inches in the mountains. She said there's a chance of mud and debris flows if the rain begins coming down at a rate of a quarter-inch per hour with the Woolsey Fire zone in L.A. and Orange County being the most vulnerable.
The system, which originated in the Central Pacific, will combine with a colder system out of the Gulf of Alaska Friday and Saturday, generating heavy rain through Saturday, forecasters said. High surf and heavy winds are also expected.
NWS meteorologist Curt Kaplan noted that this winter's rain in the Southland is considerably more extensive than in 2018. He said that since Oct. 1, 2018, Downtown L.A had received 13.29 inches of rain compared to the previous year's 1.89 inches and the normal, which is 8.54 inches.
The NWS forecast rain in L.A. County today and highs of 48 degrees on Mount Wilson; 53 in Lancaster; 54 in Palmdale; 55 in Saugus; 57 in Burbank; 58 in Pasadena and San Gabriel; 59 in Avalon and Woodland Hills; and 61 in Downtown L.A, Long Beach and at LAX.
Rain is also forecast in Orange County, along with highs of 47 on Santiago Peak; 54 on Ortega Highway at 2600 feet; 57 in Fremont Canyon; 58 in Trabuco Canyon and Yorba Linda; 60 in Newport Beach Laguna Beach, San Clemente, Fullerton Anaheim and Mission Viejo; and 61 in Irvine.
The NwS forecast rain Thursday in L.A. and Orange Counties, showers on Friday and again on Sunday.