Updated

Scientists are raising concerns about a slow-moving, planetary-scale ocean phenomenon known as a Kelvin wave heading toward California, which could raise sea levels along the coast by up to a foot. The wave is linked to an unusually strong, developing El Niño that is trapping warm water along the coast and could supercharge the threat of storm surges and flooding in the coming months. No landfall impacts have occurred yet, but researchers say the phenomenon adds to a broader pattern of El Niño-fueled extreme weather seen this year, including active hurricane seasons in the Pacific and Atlantic.