Seattle – A string of warm‑water pulses known as Kelvin waves is set to push the West Coast shoreline higher this month, potentially adding six to twelve inches to the already elevated sea level. The surge, which can travel up to six miles per hour, is expected to move northward from California through Oregon and into Washington, lasting through February.
What a Kelvin wave is
Kelvin waves are not tsunamis. Think of them as a bulge of water that sloshes along the ocean floor, similar to water moving in a bathtub during an earthquake. The bulge can be 12 to 20 miles wide and about 200 meters deep. These waves are a regular feature of El Niño events, and this year’s “super” El Niño may amplify their impact.
How the wave raises sea levels
Michael Jacox, a research oceanographer with NOAA’s Fisheries Ecosystem Science Division, explains that the wave does not flood on its own; it simply raises the baseline. “If you start with sea levels that are six inches higher than normal, when you have really high tides, big storms or storm surges, the water levels are now six inches higher,” he said. The higher baseline means any storm surge or spring tide will sit on top of an already elevated water line, increasing the chance of coastal flooding and beach erosion.
Potential impacts on coastal communities
Coastal towns from San Clemente, California, to the Oregon and Washington coasts are already dealing with rising seas and erosion. “People are on edge,” said Dillon Amaya, an assistant professor at North Carolina State University. “They think about more flooding happening, more beach erosion.” Sean Vitousek, a U.S. Geological Survey oceanographer, warns that the combination of higher sea levels, larger North Pacific swells, and strong spring tides could cause “exceptional erosion” along the West Coast. Past strong El Niños in 1982‑83, 1997‑98 and 2015‑16 produced the worst recorded beach loss in the region.
State and local responses
Orange County officials are already placing emergency sand on vulnerable beaches, and Deputy Chief of Staff Alyssa Napuri noted that forecasts show water levels could rise six to twelve inches. California Governor Gavin Newsom has declared a state of emergency to accelerate protective measures and resource staging. In Washington, the Department of Natural Resources is coordinating with the state Emergency Management Division, though no special preparations have been ordered yet.
What residents can do
Experts advise residents near the coast to monitor local tide forecasts, secure property where possible, and stay informed about any evacuation orders. While the Kelvin wave itself will not cause a disaster, its contribution to higher baseline water levels means that any concurrent storm could have amplified effects.
As the wave continues its northward trek, scientists will keep tracking sea‑level changes and issuing updates. The situation underscores the broader challenges posed by climate variability and the need for resilient coastal planning.
Original reporting: KTBS 3 (Shreveport) — read the source article.
