El Niño Wave to Surge California Shores by Fall

California's coastline is anticipating a rise in sea levels by as much as a foot as early as late September. This rise is attributed to a coastally-trapped Kelvin wave, a slow-moving oceanic phenomenon generated by shifts in equatorial trade winds during El Niño. This wave, traveling at approximately 6 mph, previously raised water levels along Central America and is now heading north.

The arrival of this wave is expected to diminish coastal upwelling, a process that brings cold, deep water to the surface. Consequently, near-shore waters will become warmer, exacerbating existing elevated temperatures already observed in Southern California. Scientists note that while this specific wave won't build on itself, sea levels and temperatures will remain high for weeks before gradually subsiding.

While this surge is unlikely to cause immediate widespread flooding due to typically lower tides in September and October, it serves as a warning for the winter months. California's highest king tides are predicted for Thanksgiving Day and Christmas Day, potentially reaching historic levels even without storms. A combination of these king tides and storm surges could lead to severe coastal flooding and erosion, similar to the impacts seen during the strong El Niño of 2015-16.