California is preparing for a powerful winter storm system that is expected to bring significant rainfall, strong winds, and snow across the state. An atmospheric river is set to unleash a deluge, particularly impacting Southern California, including Los Angeles and Pasadena, which may face flash flooding and mudslide risks due to saturated ground conditions from previous storms. The approaching storm has raised concerns of flooding, especially in fire-scarred areas. Traffic in Los Angeles has worsened due to the weather, with the city anticipating the strongest storm of the season. Residents are advised to prepare for severe weather conditions, as agencies issue warnings and extend closures on hazardous roadways.