The drought-plagued state was slammed with rainstorms Thursday night, with Northern California hit particularly hard. In Southern California, rains started moving in Thursday afternoon. The storm is expected to drop 1 to 3 inches of rain by Friday morning, National Weather Service meteorologist Joe Sirard said. The weather service issued a flash flood watch for the Santa Monica and San Gabriel mountains and foothill communities in the San Fernando, Santa Clarita and San Gabriel valleys.