Virtually all of Southern California was under flash flood advisories and watches, including the Los Angeles area, where between 5 and 10 inches (12.7 to 25.4 centimeters) of rain had fallen and more was expected, according to the National Weather Service. At the downtown measuring station, 6.7 inches of rain had fallen by Monday afternoon, nearly half the yearly average of 14.25 inches. It was already the third-wettest two-day period since 1877, the service said.