Powerful waves lash California coast as storm threatens more damage

Powerful waves battered communities along Southern California’s coast, turning a storm-driven surf event into a damaging emergency. The effects reached homes, public infrastructure, and city streets. The danger mattered because Tropical Storm Rachel was still approaching, with more wind, rain, flooding, and coastal damage possible through the weekend.

Long Beach saw significant sections of its boardwalk crumble under pounding waves. Several homes suffered serious structural damage, while water cascaded through streets. The morning high tide made it easier for waves and seawater to reach farther inland. Malibu and Long Beach also faced continued flooding risks.

Rachel was expected to make a rare West Coast landfall near the California–Mexico border early Sunday. The National Weather Service warned that damaging seawater flooding could continue, with the risk expected to peak around Sunday morning. Officials had distributed sandbags in vulnerable communities.

High tide makes wave-driven flooding more dangerous because the ocean is already higher before storm waves arrive. Waves then need less additional height to overtop beaches, seawalls, and coastal structures. This allows seawater to push farther inland and increases pressure on roads, homes, and public infrastructure.

The article reports that powerful surf hit Southern California while the morning tide was high. In Long Beach, waves pounded the coast so severely that parts of the boardwalk crumbled and homes sustained serious structural damage. Water also cascaded through streets. The National Weather Service warned that Long Beach and Malibu remained vulnerable.

Morning high tides of more than 7 feet, or 2.1 meters, were expected throughout the weekend. Those tides combined with Rachel’s waves, possible heavy rain, and a coastal surge of water. The overlap created a larger flood threat than the storm or tide would have produced alone.

The main hazards combined several different scales. Tropical Storm Rachel had maximum sustained winds near 45 miles per hour, or 75 kilometers per hour, with stronger gusts. Morning high tides were expected to exceed 7 feet, or 2.1 meters. A separate Kelvin wave could raise sea levels by up to 1 foot, or 30 centimeters.

The coastal trapped wave was also enormous, reaching up to 18 miles, or 30 kilometers, in width. It was a slow-moving surge of water along the U.S. West Coast. By lifting the sea beneath already powerful surf, it increased the amount of seawater available to flood coastal communities.

These measurements describe overlapping hazards rather than one single wave. Strong winds and heavy rain could add damage after Rachel’s expected landfall near the California–Mexico border early Sunday. Flooding risk was expected to peak around Sunday morning.

El Niño occurs roughly every two to seven years when surface temperatures rise in the central and eastern Pacific Ocean. This warming changes wind patterns and rainfall around the world. It matters for storms because the altered atmosphere can create conditions that support stronger weather systems.

In the Pacific, El Niño weakens vertical wind shear. Wind shear is the difference in wind speed or direction between levels of the atmosphere. When that disruptive difference weakens, storm systems can organize and grow stronger. The article links this pattern to an unusually active Pacific hurricane season.

El Niño can also influence rainfall. Human-caused climate change can make its effects worse because a warmer atmosphere holds more moisture. That added moisture can produce more intense rain. Scientists gave this El Niño an 83% chance of reaching strong to very strong levels into winter.

A tropical storm watch is unusual in California because the state rarely faces a tropical storm threat. Rachel’s approach was exceptional enough for officials to issue a watch across all of San Diego County. The county borders Mexico and was near the storm’s expected landfall area.

The article states that this was only the second time a tropical storm watch had ever been issued in California. The alert reflected the possibility of strong winds, heavy rain, coastal flooding, and further damage. It did not describe the watch as a routine seasonal measure.

Rachel had weakened from a hurricane to a tropical storm, but the reduced strength did not remove the danger. The National Weather Service still warned of coastal hazards, with flooding risk expected to peak around Sunday morning. The system was forecast to make a rare West Coast landfall near the California–Mexico border early Sunday.

A Kelvin wave, also called a coastal trapped wave, is a large, slow-moving surge of water traveling along the U.S. West Coast. It matters because it raises the sea’s baseline level before or during storm conditions. Waves and tides then act on a higher ocean surface, increasing the chance of flooding.

The article describes the surge as up to 18 miles, or 30 kilometers, wide. It can raise sea levels by up to 1 foot, or 30 centimeters. That extra water does not need to become a breaking wave to cause problems. It adds to the water already pushed toward shore by surf and high tides.

Along with Rachel and morning tides above 7 feet, the Kelvin wave aggravated threats to coastal communities. Long Beach and Malibu faced damaging seawater flooding. The combined conditions made the West Coast situation especially dangerous.

Flood and storm damage grew because several physical factors acted at once. Warm central and eastern Pacific water helped create an unusually active season. El Niño also weakened vertical wind shear, allowing Pacific storm systems to grow stronger. Climate change added moisture to the atmosphere, increasing the potential intensity of rainfall.

Near the coast, high tides raised the ocean before waves arrived. A Kelvin wave added up to 1 foot to sea levels, increasing the water available for flooding. Rachel brought powerful surf, possible strong winds, and heavy rain. Together, these forces pushed more water toward homes, streets, boardwalks, and other coastal structures.

The result was visible damage in Long Beach and flooding concerns in Malibu and other communities. Morning tides above 7 feet were expected over the weekend, while Rachel’s hazards were expected to peak around Sunday morning. The article describes the combined situation as dangerous for the West Coast.