A 1,000-Mile-Wide Kelvin Wave Is Closing In on California's Coastline

California is being put on alert for a 1,000-mile-wide wave creeping up the coastline. What makes this wave so dangerous, and why is it happening? This is what you need to know.

Massive Wave Heading to California

Climatologists are warning Californians that a Kelvin wave is on the way. This massive wave could temporarily send water levels up to a foot higher in some areas as it pushes up the coast. A water rise of this magnitude is capable of generating coastal flooding and storm surge, particularly along stretches of coastline that are already susceptible to beach erosion.

Unlike a typical wave that crashes ashore, a Kelvin wave is one giant band of warm water that expands for thousands of miles along the equator. This specific type of wave is yet another byproduct of the strong El Niño phase that is influencing weather across the Pacific and beyond.

NASA's Jet Propulsion Laboratory ocean-circulation researcher Severine Fournier described what happens when the water hits land by detailing that "You can follow them along ... we see the higher sea levels along the equator, and when the wave reaches the coast of South America, it cannot continue to go eastward. So it goes north and south."

The Kelvin wave reached the northern edge of South America in August and has been traveling to the north since. As the wave reaches the West Coast of the U.S., warm water will begin to pool near the coastline. It is this surge of unseasonably warm water that is predicted to trigger the noticeable sea-level rise.

NOAA's Southwest Fisheries Science Center research scientist Nate Mantua explained that, "When the wind stops blowing or weakens, the force that's holding that pile of water in place goes away, so that water surges or sloshes back towards California." High tides naturally send the extra water farther inland, exacerbating beach erosion and raising the threat of coastal flooding capable of damaging homes and businesses.