Thunderstorms peppered the Santa Monica Mountains and Hollywood Hills with rain today, part of a day-long surge of subtropical weather that is being pumped into the Southland today.
At 10 a.m., National Weather Service radar showed a thunderstorm moving north from Malibu and Point Mugu, over the Santa Monica Mountains, and into the Thousand Oaks area. Isolated thunderstorms had popped up over the Hollywood Hills, and near Long Beach, and the NWS said the storms were moving north at about 10 miles per hour.
A larger, more-intense storm was centered over Big Bear Lake.
The NWS said a pair of weather systems responsible for strange weather were not moving anywhere, guaranteeing a second day of scattered storms that at times seemed more apropos of Arizona or Florida.
A low pressure system centered off the Baja California coast near Ensenada was spinning significant subtropical moisture into the Southland, the NWS Oxnard office said. Coupled with high pressure over the Four Corners, warm, moist and unstable air was moving up from Sonora into the Southland.
"The moist and unstable air mass will bring a threat of showers and thunderstorms to much of Southern California at times through Sunday,'' the NWS said in a midmorning Special Weather Statement.
A flash flood watch was issued today for the San Gabriel Mountains and the Antelope Valley, where forecasters said the topography would assist the evolution of the moisture into thunderheads.
Intense rainfall and flash flooding is possible, due to slow-moving thunderstorms. Debris flows are also possible in recently burned areas.
A flash flood watch for the Los Angeles-area mountains, excluding the Santa Monica range, will stay in effect through this evening, according to the NWS.
The NWS warned hikers against venturing into narrow canyons that can be inundated with flood waters. In desert areas, runoff from distant storms can flood normally dry washes suddenly.