Heavy rain drenched the Southland Thursday, raising fears of flooding, flash-flooding, mudslides, debris flows and furious winds.

The National Weather Service issued a flash flood watch for the Woolsey, Hill, and South burn areas Thursday morning through early afternoon. It also issued a flash flood watch for the San Gabriel and Santa Monica mountains and adjacent foothills, including the Stone burn area Thursday morning through early afternoon, as well as areas not damaged by fire.

“A very moist air mass associated with an atmospheric river will bring periods of rain to Southwest California through tonight,” warned an NWS statement. “The heaviest rainfall is expected to occur this morning into early this afternoon. Peak rainfall rates during this period are expected to range between a half inch to an inch per hour, with the highest rates focused across south- and southwest-facing slopes of the Santa Monicas and San Gabriels.

“Shallow mud and debris flows will be likely in the first-year burn areas, with the potential for more significant and damaging debris flows. In addition, roadway flooding is likely, especially in low lying areas, along with rock and mudslides on canyon roads and below steep terrain.”

The weather service said that peak rain rates of three-quarters of an inch to an inch per hour are possible across the Los Angeles county mountains, with the highest rates focused across the San Gabriels.” There will likely be an extended period of heavy rain across the San Gabriel mountains and adjacent foothills. Rainfall totals between 3 and 5 inches are possible in these area between 3 a.m. and 1 p.m. Thursday.

“There will be the potential for flash-flooding as well as significant risk for mudslide/rockslides activity due to the extended period of heavy rain expected Thursday morning through early Thursday afternoon, especially in the San Gabriel mountains and adjacent foothills,” wrote the NWS. “Flash flooding and debris flows will be a particular threat in and below the recently burned areas.”

Flash flooding is also possible in the Santa Monica Mountains, the Santa Clarita and San Fernando valleys, the L.A. County coast, beach cities, Hollywood and several communities in Ventura County, according to the NWS, which added that “Mudslides and rockslides will be likely across canyon roadways and Highway 1, bringing an increased threat of road closures.”

The highest rates are expected in the Santa Monica Mountains. Storm totals are expected to range between an inch-and-a-half and 3 inches.

People residing in or below the recently burned areas are urged to take the steps necessary to protect their property. Persons in the watch area should remain alert and follow directions of emergency preparedness officials.”

A flash flood warning was also issued for coastal and inland Orange County. Live Oak Canyon Road was closed down near Trabuco Oaks Drive in the Trabuco Canyon area, and Pacific Coast Highway was closed south of Warner Avenue in Huntington Beach.

Strong winds are also an aspect of Thursday’s storm. A high wind warning denoting an expectation of 58-mile-per-hour wind or gusts will be in force until 3 p.m. in the San Gabriel Mountains, where south winds of 20-35 mph are expected Thursday morning, gusting at 60 mph. The wind will lighten in the afternoon.

“Winds this strong may down trees and power lines, causing property damage or power outages,” the NWS warned. “Cross winds can make driving difficult, especially for drivers of high profile vehicles and vehicles towing trailers. This includes Interstate 5 and Highway 14 in Los Angeles County.

A wind advisory will be in force until 7 p.m. in the Antelope Valley, where winds of 20-35 mph will increase later Thursday morning and persist through early this evening.

The NWS forecast rain Thursday and highs of 49 degrees on Mount Wilson; 59 in Saugus; 60 in Burbank; 61 in Avalon, Pasadena and San Gabriel; 62 in Woodland Hills; and 63 in Downtown L.A., Long Beach and at LAX.

Showers were forecast in Orange County along with highs of 51 on Santiago Peak; 55 on Ortega Highway at 2600 feet; 58 in Fremont Canyon; 59 in Trabuco Canyon; 60 in Mission Viejo and Yorba Linda; 61 in Anaheim, Newport Beach, Laguna Beach, and San Clemente; and 62 in Fullerton.

More precipitation is expected in L.A. and Orange County Friday and again Sunday.

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