Photo: DogoraSun / iStock / Getty Images
LOS ANGELES (CNS) - The first substantial rain storm of the fall drenched much of the Southland overnight and past daybreak Tuesday, making for a treacherous morning rush hour and prompting evacuation orders and warnings near recent burn areas due to the threat of flooding and mud and debris flows.
By mid-morning Tuesday, some areas had received as much as three inches of rain, most notably in Southland foothills and mountains. National Weather Service forecasters said the storm was moving slower than originally anticipated, meaning "it may take well into the afternoon to exit L.A. County to the east."
Driving on area freeways Tuesday morning was treacherous, with numerous spin-outs and collisions reported. The northbound Golden State (5) Freeway in the Sun Valley area flooded, leaving only one lane open. A stretch of the Antelope Valley (14) Freeway in Newhall was also flooded.
As the system advanced through the area, the NWS issued a series of severe storm and flood warnings, primarily affecting communities near the Palisades Fire burn zone, where some evacuation orders and warnings were in effect.
About 120 homes in the Pacific Palisades area were under mandatory evacuation orders, according to the Los Angeles Fire Department.
Within the Palisades Fire burn area, 114 of the homes under mandatory evacuation were in the Mandeville Canyon area, five were in the Hearst area and one in the Sunset area, LAFD spokeswoman Margaret Stewart said.
All were deemed to be at higher risk from possible debris flows and Los Angeles police began knocking on doors of those homes Monday night, she said.
The storm was expected to produce between three-quarters of an inch to 1.5 inches of rain across most areas, with 2 to 4 inches possible on south- facing mountain slopes, according to the National Weather Service. Forecasters said as much as 5 inches could potentially fall in the San Gabriel Mountains.
"All areas will see rain. Some areas will see short bursts of heavy rain, although it remains difficult to predict exactly where," according to the NWS. "South-facing slopes and foothills have the highest chance of seeing those heavy bursts, but they can happen anywhere."
As of Tuesday morning, peak rainfall rates were ranging from a half- inch to an inch per hour, "which is more than enough to create flooding and debris flows" in recent burn areas, forcasters said.
Hail and gusty winds were also potential threats, with waterspouts or a weak tornado possible, the agency added. A wind advisory will be in effect until 2 p.m. Tuesday in the San Gabriel Mountains, where isolated gusts of up to 50 mph are possible.
"The peak of the storm remains focused ... through Tuesday afternoon," according to the NWS. "... Rain rate forecasts will likely be increased, especially for any south- and southwest-facing slopes. Nearly every high-resolution model is showing streaks of heavy rain moving through the region, and while not every area will see them, these narrow bands could happen anywhere. Several of the projections are now showing the rain the organizing and intensifying as it swings into LA County, which is concerning for the recent burn scars -- especially the Eaton and Bridge scars."
In advance of the rain, evacuation warnings were posted for most recent burn scar areas, including the Palisades and Eaton fires, along with the Hurst Fire in Sylmar and the Sunset Fire in the Hollywood Hills. Residents were urged to prepare to evacuate due to the possibility of flooding and debris flows.
Malibu officials announced evacuation warnings and shelter-in-place advisories for residents of a number areas.
The warnings include Rambla Pacifico, Carbon Beach West / Malibu Beach, Sweetwater Canyon, Sweetwater Mesa, Serra Retreat. Malibu Creek, Cross Creek, Malibu Colony, the Civic Center, Malibu Knolls, Malibu Road, Malibu Country Estates, Puerco Canyon, Las Flores Mesa, Big Rock, Big Rock Beach, Tuna Canyon (south), Las Tunas Beach and Topanga Beach Drive.
The shelter-in-place will be in effect until at least Wednesday evening for the Franklin Fire burn scar near Pepperdine University due to the risk of flash floods and mud and debris flows, according to the city.
"While this may be a short-duration storm, even a burst of intense rain can quickly create dangerous conditions in burn areas," Los Angeles County Public Works Director Mark Pestrella said in a statement. "Our crews are ready, and we urge residents to make personal safety their top priority. Avoid driving on mountain roads or in burn areas, if at all possible, and keep trash cans and vehicles off streets to allow storm runoff to travel freely."
Los Angeles Mayor Karen Bass said city crews were gearing up for the storm and possibility of mud and debris flows.
"The city has bolstered the hillsides and vulnerable areas from potential debris flows in recent burn scar areas -- these resources remain in place," Bass said in a statement. "Today, we have strategically deployed resources for the Palisades and across the city, including strike teams, rescue teams and helicopters. Be cautious on the roads, pick up free sandbags if needed and sign up for emergency alerts at NotifyLA.org. To all Angelenos: stay safe, stay informed and follow official evacuation guidance."
In Orange County, mandatory evacuation orders took effect at 10 a.m. for Trabuco Creek including the RC Airport, fire station, campground/park and school; Bell Canyon including Starr Ranch; and Hot Springs Canyon including Lazy-W Ranch. Evacuation warnings were in place for Long Canyon and Modjeska Canyon.
All those areas are in the area of the Airport Fire burn scar.
OC Animal Care at 1630 Victory Road in Tustin was accepting dogs, cats and other small pets for people under evacuation orders. A large animal shelter was established at the Orange County Fair Grounds, 88 Fair Drive in Costa Mesa.
O'Neill Regional Park was also closed due to the storm.
The NWS advised residents across the region to take precautions, remain indoors as much as possible and avoid parking vehicles near tall trees that could be uprooted.
"Avoid the roads as much as possible, and if you have to drive, allow extra time as traffic will be increased due to slippery roads, low visibility, and localized flooding," forecasters said. "If you are near a burn scar, there is a risk of significant debris flows. Heed the advice of local officials, and expect at the very least mud and debris on some roads."
A flood watch went into effect Monday night, to last through Tuesday evening, in recent burn areas in Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, with forecasters saying the storm has the potential to trigger "hazardous and damaging flooding and debris flows."
Although the storm had slowed significantly, forecaster said the area will see clearing skies once the system passes, with "mostly clear skies" possible by Tuesday evening.
Wednesday will be sunny and dry, with temperatures rising about 5 to 10 degrees, forecasters said.