SF is bracing for 10 to 30 king tides this winter, as El Ni\u00f1o sends warm water toward the coast in the form of \u201cKelvin waves,\u201d and Governor Newsom declared a state of emergency last month in anticipation of the potentially record-breaking weather.<\/p>\n
As SFist warned in the spring, the coming \u201csuper\u201d El Ni\u00f1o could break records<\/a>, with a strong chance of becoming the strongest El Ni\u00f1o cycle in 140 years. That\u2019s still looking likely, as Governor Gavin Newsom declared a state of emergency in late September, ordering state agencies to prepare for major coastal flooding, as the Chronicle reported<\/a> last month.<\/p>\n San Francisco could see anywhere from 10 to 30 unusually high tides from late November through January, as the Chronicle reported<\/a> Friday.\u00a0The Port of San Francisco’s Waterfront Resilience Program determined that there could be about 30 potential king tides using data from the National Oceanic and Atmospheric Administration, which the California Coastal Commission’s King Tides Project forecasts 10 king tides this year. <\/p>\n As \u201cking tide\u201d is a non-scientific term<\/a>, agencies have different ways of classifying them, but the NOAA says that tides above 1.2 feet could cause minor flooding on the city\u2019s north coast.<\/p>\n Lurie said in a social media video<\/a> Friday that tides are already running about six inches higher than normal in San Francisco. The king tides are expected to peak between November and February, with the highest arriving before between Thanksgiving and Christmas, with a second one peaking around January 21.<\/p>\n KQED explains<\/a> that one reason for the elevated water levels is due to a Kelvin wave, which is a pulse of warm water associated with El Ni\u00f1o that moves through the deeper Pacific Ocean before traveling north and south along the coast. Unlike a tsunami or surface wave, it is a disturbance within the ocean that can temporarily raise coastal sea levels.<\/p>\n Dillon Amaya, a professor at North Carolina State University who studies how climate change affects waters off the US coast, said a first Kelvin wave moved north in May and June. A second is traveling north from the Gulf of California at about 6 mph and could reach the Bay Area by mid-October, while researchers are watching for signs of a third wave around the equator.<\/p>\n \u201cKelvin waves are a symptom of El Ni\u00f1o,\u201d Amaya said, speaking to KQED.<\/p>\n The extra water from a Kelvin wave can reportedly become more consequential when it arrives during an already-high tide or storm, potentially pushing coastal water above levels reached by the tide alone and increasing flooding and erosion.<\/p>\n Sean Vitousek, a research oceanographer with the US Geological Survey, told KQED king tides in late November could rise above 7 feet in San Francisco, putting them \u201con top of the Kelvin wave.\u201d<\/p>\n Previously: Brace Yourselves For What Could Be a Really Nutty El Ni\u00f1o Winter<\/a><\/p>\n