National Climate Report - May 2018
2017 State of U.S. High Tide Flooding and a 2018 Outlook
This month's State of the Climate report includes an annual update of the state of coastal high tide flooding. This type of flooding occurs when water levels measured at NOAA tide gauges exceed heights based on national flooding thresholds released in February by NOAA’s Center for Operational Oceanographic Products and Services.
As relative sea level increases, it no longer takes a strong storm or a hurricane to cause coastal high tide flooding. High tide flooding causes frequent road closures, overwhelmed storm drains, and compromised infrastructure.
Such coastal flooding is increasing in frequency, depth and extent in many areas of the U.S. due to ongoing increases in local relative sea level. For example, the report finds that the Southeast Atlantic coast is currently experiencing the fastest rate of increase in annual high tide flood days, with more than a 150 percent increase since 2000 predicted in 2018 at most locations.
- During the 2017 meteorological year (May 2017-April 2018), the U.S. average number of high tide flooding days was the highest measured at 98 NOAA tide gauges. More than a quarter of the coastal locations tied or broke their individual records for high tide flood days.
- Water reached a flooding threshold at NOAA tide gauges a record-breaking number of times in the Northeast and Gulf of Mexico due to a combination of active nor’easter and hurricane seasons combined with sea level rise to make these events more impactful.
- The top five cities that saw the highest number of flood days across the U.S. and broke records include Boston, MA; Atlantic City, NJ; Sandy Hook, NJ; Sabine Pass, TX; and Galveston, TX. These cities faced the brunt of an active nor’easter and hurricane seasons and sea level rise, which has made these and other less extreme events more impactful.
- The projected increase in high tide flooding in 2018 may be as much as 60 percent higher across U.S. coastlines as compared to typical flooding about 20 years ago and 100% higher than 30 years ago. This is due to long-term sea level rise trends and, in part, by El Nino conditions that may develop later this year.
Find the complete coastal flooding report here:
Citing the complete report: Sweet, W.V., D. Marcy, G. Dusek, J. J. Marra, M. Pendleton, 2018: 2017 State of U.S. High Tide Flooding with a 2018 Outlook. Supplement to State of the Climate: National Overview for May 2018, published online June 2018, retrieved on [date] from https://www.ncdc.noaa.gov/monitoring-content/sotc/national/2018/may/2017_State_of_US_High_Tide_Flooding.pdf