Tides and waves of varying scales this week mean low-lying parts of the Bay Area could flood by more than a foot and a half, according to the National Weather Service.
Along San Pablo Bay, San Francisco Bay, and the Pacific Coast, forecasters expect high tides, swells from post-tropical cyclone Rachel, a deep-ocean wave or Kelvin wave caused by El Niño, larger surface waves, and already above-average sea levels due to thermal expansion to bring floods.
El Niño is marked by warming in the Pacific Ocean’s surface layer, and Kelvin waves are the delivery system for warm water associated with El Niño. As tropical trade winds slow or reverse, ocean water slowly sloshes east, eventually smacking into South America and moving north and south. That deep ocean wave, moving under the ocean’s cold and warm layers, travels about 6 miles per hour and can cause up to a foot of temporary inundation for weeks or months…