Roads flooded, water pushed into homes and businesses, and tide gauges that have been recording for more than a century logged numbers they had never seen before. That was the California coast between Oct. 24 and 30, and NOAA has now explained what made it happen.
The NOAA National Ocean Service released its analysis this week, which found that four stations, San Diego, La Jolla, Los Angeles, and Santa Barbara, set all-time water level records, with San Diego topping out at 2.80 feet above its average highest tide on Oct. 27. Closer to home, Monterey logged its seventh highest reading ever and Port San Luis its fourth.
Three forces lined up at once. A perigean spring tide, when a full moon sits closest to Earth, pushed tides higher than normal. El Niño added Kelvin waves, slow pulses of warm water that cross the Pacific and can lift West Coast sea level by six to 12 inches for weeks. The marine heat wave off California piled on, since warm water takes up more room than cold…