NOAA’s 2023 High Tide Flooding Outlook documents high-tide flooding events from May 2022 to April 2023 at 98 NOAA tide gauges along the US coast. It highlights that coastal communities in eight locations along the East and West Coasts experienced record high-tide flooding during the past year – a trend that is expected to continue in 2024. For many communities, the expected strengthening of El Niño will bring even more high-tide flood days.
High-tide flooding is becoming increasingly common due to continued sea level rise, driven in part by climate change. It occurs when tides reach anywhere between 0.30-0.61m above the daily average high tide, depending on location. As sea level rise continues, it no longer takes severe weather to cause disruptive flooding along the coast.
NOAA predicts that from May 2023 to April 2024 the US will experience between four and nine high-tide flood days – an increase from last year’s prediction of three to seven days and about three times as many as typically occurred in 2000.
This year, the expected strengthening of El Niño could further amplify high-tide flooding frequencies along the East and West Coasts. Communities on the Mid-Atlantic and Gulf Coasts are expected to experience the most high-tide flooding, as El Niño conditions will compound the effects of sea level rise in some areas.
NOAA continues to advance its ability to predict high-tide flooding. This year, to help coastal communities better understand when and where high-tide flooding may occur, NOAA has released a new Monthly High Tide Flooding Outlook. It provides the likelihood of high-tide flooding for each day in the calendar year, up to a year in advance, at NOAA tide gauge locations around the country.
The Monthly High Tide Flooding Outlook does not account for real-time conditions or weather forecasts, but it does provide critical situational awareness about windows of time that have higher flooding risks. As potential flood days grow near, the monthly outlook can be paired with weather forecasts to understand if an upcoming storm event might compound impacts from already elevated water levels.
“The new monthly outlook represents a leap forward in NOAA’s ability to predict high-tide flooding at a subseasonal scale,” said Nicole LeBoeuf, director of NOAA’s National Ocean Service. “Armed with more precise and timely data, coastal communities can make informed decisions about flooding risks, and take action to mitigate impacts by closing roads, performing maintenance on storm drain systems and protecting vulnerable infrastructure.”
By 2050 the US is expected to experience an average of 45 to 85 high-tide flooding days per year. Long-term projections are based on the ranges of expected relative sea level rise of about 0.3m, on average, across the US by 2050.
For more about high-tide flooding, click here.