Exceedance Probability Levels and Tidal Datums

Annual exceedance probability levels, displayed in meters or feet, relative to tidal datums and the geodetic North American Vertical Datum (NAVD88), if available. See the Annual Exceedance Probability tab for 95% confidence intervals for each of the exceedance probability levels shown here.

On the left, exceedance probability levels for the mid-year of the National Tidal Datum Epoch (1983-2001) Mean Sea Level (MSL) datum, currently in effect at most stations, are displayed. For stations with rapid sea level rates, such as those in Louisiana, Texas, and Alaska, a 5-year modified epoch MSL datum is used. On the right, projected exceedance probability levels and tidal datums are displayed.The values of the projected levels are based on the linear relative sea level trend and can be displayed for any year between 1992 and 2030. However, options are available that allow for the selection of a future decade and one of the five projection scenarios from the 2022 Interagency Sea Level Report.

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Exceedance Probability Levels and Tidal Datums - Nantucket Island, MA - NOAA Tides & Currents