Los Angeles area braces for 3 days of rain, bringing possible flooding and storms
The first of two storms arrives in parts of the Southland on Wednesday, bringing scattered showers before the second storm arrives with more steady rain.
The National Weather Service issued a flood watch that will be in effect across Los Angeles County beginning at 10 p.m. Tuesday and continuing until Thursday night. In Orange County, the flood watch will be in effect from 10 p.m. Tuesday through Friday afternoon for coastal and inland areas and the Santa Ana Mountains and foothills.
The Los Angeles area could receive 2 to 4 inches of rain during the "atmospheric river" event accompanying the second storm system, with 4 to 8 inches possible on south-facing foothill areas and coastal slopes. Rainfall rates of 0.3 to 0.6 inches per hour are expected in some areas, but if thunderstorms develop, some areas could see rain falling at a rate of 1 inch per hour.
"Extensive roadway flooding, especially in low-lying areas, and flooding of creeks and streams are possible," according to the National Weather Service.
There will be the risk for flash flooding and debris flows in recent burn scars, especially the South Fire burn scar in Ventura County.
There will also be strong potential for rock and mudslide activity, especially on canyon and mountain roadways. Flooding and rock/mudslide activity may lead to significant travel delays and road closures. Increased flow in rivers and streams will bring an increased threat for swiftwater rescues.
Los Angeles County Lifeguards warned people to exercise caution if they visit the beach.
"Ocean conditions will also have a bit more activity with waves in the head to overhead range," lifeguards warned on social media.
"Plenty of varying factors these next few days, so make sure to stay tuned, and if you decide to come to the beach make it a point to check in with a lifeguard tower prior to entering the water."
County health officials issued their standard warning for people to avoid entering the ocean water in the days following rain, noting that runoff can carry bacteria and debris into the ocean, raising the risk of illness.
Orange County will likely start seeing heavy rain late Wednesday night into Thursday.
The first of the back-to-back storm systems brought cloud cover and some light rainfall to the Los Angeles area on Monday afternoon and into the overnight hours Tuesday morning. NWS forecasters said periods of "generally light showers" will continue through Tuesday afternoon.
"A stronger storm will bring several hours of steady moderate to heavy rain and gusty winds Wednesday and Thursday, with threats for flooding and thunderstorms," forecasters said.
Conditions are expected to dry out on Friday, although gusting northwest winds are expected to linger into Saturday.
Snow levels are expected to remain above 7,000 feet, with forecasters saying snow impacts from the storm will be "minimal."
Los Angeles County officials said various agencies were coordinating to ensure public safety while also hoping to capture as much stormwater as possible for future use.
"L.A. County owns a world class system of water conservation and flood protection. This system is prepared to capture and conserve valuable stormwater while protecting communities," county Public Works Director Mark Pestrella said in a statement. "Our system is primed to capture as much stormwater as possible in our efforts to increase the region's overall local water supply by 600,000-acre feet by 2045."
County officials urged residents to heed instructions from emergency responders and alert notifications; drive cautiously and slow down in wet conditions; and avoid trying to cross flooded roadways.
Daytime temperatures will remain in the 60s in the region for much of the week. Overnight lows will generally be in the upper 40s and lower 50s throughout the Southland, but will dip into the 30s in some parts of the mountains and high desert.