King tides: coastal flooding reported in Florida and California

Tidal flooding along both U.S. coasts pushed seawater into homes, businesses, and streets this week, closing sections of Pacific Coast Highway in Southern California and driving residents in Huntington Beach to place sandbags outside their properties. Some Huntington Beach residents used paddleboards and surfboards to navigate flooded streets.

The flooding began with the full moon earlier this week and forecasters said it could continue into the weekend. King tides arise from the gravitational pull and alignment of the Earth, moon, and sun, and occur several times a year for periods lasting several days.

Forecasters said Wednesday that additional conditions amplified this week's tides. In Florida, strong high pressure to the north combined with low pressure over the Caribbean to generate increased swells, according to Chris Fisher, a National Weather Service meteorologist in Miami. Along the California coast, the ongoing super El Nino warmed the ocean and increased the volume of seawater, while Kelvin waves, a series of warm water pulses that lift sea level, added to the effect, said Roger Gass, a meteorologist with the weather service's Bay Area forecast office in Monterey.

The weather service expected minor flooding through Saturday in low-lying areas along shorelines and tidal waterways in Northern California during peak high tides. Gass said coastal flooding generally occurred within one and a half hours before and after high tides, which were peaking 1.9 feet above normal in Northern California. Tides were also expected to approach record levels in Orange and San Diego counties.

Most of Florida's Atlantic coast remained under flood warnings through early Friday. Street flooding was reported in Charleston and Myrtle Beach, South Carolina, and rip currents were possible as far north as North Carolina's Outer Banks. In Fort Lauderdale, reaching waterfront venues for the boat show required driving through flooded streets next to marinas, hotels, and convention centers.

Fisher said Virginia Key, a barrier island in Miami, recorded its highest king tide and the third-highest water level since records began three decades ago. "The only times we've seen higher was during hurricanes," Fisher said. "It's historical from a king tide perspective."

Fisher also said conditions at the beach would remain rough through the weekend, with a high risk of rip currents and high surf. "It's been a good week to stay out of the water and stay away from the beaches," he said.