Storm Tide

Storm tide is the total observed water level during a storm, the sum of the storm surge and the astronomical tide above the tidal datum. It is distinct from storm surge, which is only the meteorological residual from wind setup and the inverse-barometer rise. The same surge produces a far higher storm tide if it lands on a spring high water than on a neap low, so coastal flood forecasting predicts surge and adds it to the harmonic tide. Wave run-up and setup sit on top of the storm tide to give the total still-plus-dynamic level that defenses must withstand, and it is the quantity behind return-period flood statistics.