Updated

A planetary-scale oceanic 'Kelvin wave' is approaching Southern California and is expected to reach the San Francisco Bay Area by early October as it moves toward Alaska. The phenomenon could raise sea levels by up to a foot along the coast, driven by a very strong El Niño trapping warm water against North America's western shoreline. California communities are rushing to prepare for potential storm surge and flooding impacts, with scientists warning the El Niño-supercharged wave increases risks in the coming months.