what does highest astronomical tide mean
While these datums are based on observations, two others are based on predictions: Highest Astronomical Tide (HAT) is the highest water level predicted and Lowest Astronomical Tide (LAT) is the lowest water level predicted relative to MSL over the NTDE.hile these datums are based on observations, two others are based on predictions: Highest Astronomical Tide (HAT) is the highest water level predicted and Lowest Astronomical Tide (LAT) is the lowest water level predicted relative to MSL over the NTDE.