Urban flooding and poor drainage are expected in areas under the flood watch, including Malibu and the Santa Monica Mountains. Extensive street flooding and potential creek and river overflow may occur. Coastal regions face risks of dangerous rip currents, minor beach erosion, and tidal overflow. Thunderstorms could produce lightning, gusty winds, small hail, and choppy seas, posing risks to marine activities. Residents should remain cautious and avoid flooded areas.