Total water level (TWL) at the shoreline is the combination of tides, surge, and wave runup. The Total Water Level and Coastal Change Forecast viewer shows animated estimates of the elevation where the ocean will meet the coast for the next 6.5 days. TWL predictions show daily changes due to high and low tides as well as expected changes caused to storms and natural astronomical alignments (when the Moon is new or full while its orbit is close to Earth).

TWL forecasts show local dune features such as the elevation of the base and/or crest of a sand dune to illustrate the probability of coastal erosion events such as dune erosion, overwash, and inundation/flooding. TWL forecasts in the viewer show when these erosional events could occur. In some locations, the elevation of coastal features may correspond to rocky cliffs, rip-rap, or infrastructure which do not erode or change like sandy beaches.

This operational model combines NOAA wave and water level predictions and a USGS wave runup model with beach slope observations to provide regional weather offices with detailed forecasts of total water levels. The USGS compares these total water levels to the protective dunes along sandy coastlines to forecast the probability of coastal change.