In a report published by NOAA, the 2017 nation‐wide average annual frequency of high tide flooding hit an all‐time record.
If high tide flooding in 2018 follows historical patterns, flooding will be most common during the winter (Dec‐Feb) along the West Coast and the northern section of Northeast Atlantic Coast in response to winter storms and more‐predictable monthly highest astronomical tides (predicted tides). Along the Gulf and along much of the Atlantic Coasts, flood patterns are less predictable and occur usually in response to weather effects.
Flooding is, however, most common during the fall (Sep‐Nov) when the mean sea level cycle peaks, and more often during monthly highest predicted tides in some Southeast Atlantic locations. Breaking of annual flood records is to be expected next year and for decades to come as sea levels rise, and likely at an accelerated rate (Sweet et al., 2017b).
When high tide flood frequencies along the entire U.S. coastline are averaged (Figure 3b), the 2017 national average of 6 days . . . is record breaking. Rising ocean levels along the U.S. coastline (Figure 3b, blue line) of about 2 mm/year since 1920 are driving (along with local land subsidence) a rapid increase in U.S. high tide flood frequencies. The U.S. average high tide flood frequency is now 50% greater since 2000 and 100% greater than it was 30 years ago.