Powerful Storm Bears Down On Los Angeles

LOS ANGELES, CA — The wettest storm to hit Los Angeles in a year is expected to bear down on the Southland Thursday, bringing heavy rainfall, heavy mountain snow and the risk of mudslides in burn areas. It's also expected to help put an end to an epic fire season and help combat the drought emerging in California after an unusually dry year.

The storm, driven by an 'atmospheric river' could dump several inches of rain over the Southland Thursday and Friday, according to the Nationa Weather Service. The local mountains could receive anywhere from one to three feet of snow. On Wednesday, the storm was stalled over Santa Barbara and San Luis Obispo counties, triggering mudslides.

"The front sags southward into Ventura and Los Angeles counties by Thursday afternoon into Friday," according to the National Weather Service. "Heaviest rainfall across the southern counties will occur Thursday night into Friday morning. Several inches of rain are expected with flooding concerns including recent burn areas. Several feet of high elevation mountain snow is also expected, along with moderate to strong winds."

The National Weather Service issued a winter storm warning as the system gathered steam. The weather service initially issued a winter storm watch for the Los Angeles County mountains, excluding the Santa Monica range, from Thursday afternoon through Friday afternoon, but the agency later upgraded it to a winter storm warning. The warning will be in effect from 3 p.m. Thursday to 3 p.m. Friday, with 1 to 3 feet of snow potentially accumulating at elevations above 6,000 feet.

The storm also brings a flash flood watch Thursday afternoon through late Thursday night for the mountains and the Antelope, Santa Clarita and San Gabriel valleys, mainly affecting areas near the Lake, Bobcat and Ranch 2 burn areas. Forecasters said the areas could see rain rates of 0.75 inches per hour, potentially leading to "significant mud and debris flows."

"Residents in or below the recently burned areas are urged to take the steps necessary to protect their property," according to the NWS. "Persons in the watch area should remain alert and follow directions of emergency-preparedness officials. Avoid hiking and camping in canyons and near creeks."

Los Angeles County's emergency management director, Kevin McGowan, urged residents to plan ahead and be prepared to evacuate.

"Our emergency response officials are world-class and will stand ready to defend lives, property and infrastructure if there are emergencies caused by this storm," he said. "But, we need collaboration from the public. It is critical for residents to be aware and prepared so that they can help keep themselves safe."

He urged residents to prepare their family, pets and home in advance of the storm, and have a "go kit" ready, including prescription medications and important documents. He also said residents should park their cars in their driveways facing the street so they can leave quickly.

Winds in mountain areas will blow at 20 to 30 mph, with gusts ranging up to 50 mph. A wind advisory will be in effect for Los Angeles County mountains until 3 p.m. Thursday. Forecasters said the strongest winds are likely in the San Gabriel Peaks and the Grapevine area, making "driving difficult, especially for high-profile vehicles."

According to the NWS, the low-pressure system was gathering strength off the Oregon coast, and will likely remain mostly stationary through Thursday.

"This will create a steady and nearly persistent stream of moist southwest flow, known as an atmospheric river, focused over San Luis Obispo and Santa Barbara counties ... lasting through at least Thursday with two to three days of nearly constant rain," according to the weather service.

Forecasters said Los Angeles County could see 1.5 to 3.5 inches of rain, with 2 to 5 inches possible in the foothills and mountains, although the largest rainfall totals are likely to occur in Ventura County.

Whenever persistent rain is in the forecast, fears are raised about possible mudslides.

"With the potential of this event, the area may approach critical thresholds for mud and debris flows in and around the recent burn areas," according to the NWS.

Los Angeles County health officials have issued a cold weather alert through Thursday for the mountains and Antelope Valley, and through Tuesday for the Santa Monica Mountains and the Santa Clarita Valley.

City News Service and Patch Staffer Paige Austin contributed to this report.