Los Angeles County will be under a flash flood watch through Monday evening due to a rare summer storm that brought rain to the region.
The watch affects the Los Angeles. County Mountains, excluding the Santa Monica Range; the San Gabriel Valley; and the Antelope Valley. Areas likely to be impacted included Lancaster, El Monte, East Los Angeles, Topatopa Peak, Reyes Peak, West Covina, Alhambra, Falling Springs, Pasadena, Pomona, Palmdale and Whittier.
Scattered showers and thunderstorms -- some capable of producing heavy downpours, with rainfall rates up to an inch per hour -- are possible. Locations most susceptible to flash flooding include those in and below recent burn areas, including the Bobcat, Dam, Ranch2, and Lake burn areas. Shallow mud and debris flows capable of producing localized damage are possible in and below these burn areas.
A flash flood watch means that conditions may develop that lead to flash flooding. The NWS advised residents of affected areas to remain alert and follow directions of emergency preparedness officials.
To the east, the low pressure system drifting in from Arizona prompted a flash flood warning for parts of eastern Riverside County. The warning will be in place through 6:45 p.m. for Riverside County desert areas, including Chiriaco Summit, Box Canyon Road and the North Shore area near the Salton Sea.