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However, because the relationship between tides and tidal currents is unique to each location, tide predictions and tidal current predictions are generated separately.
The question of "Perigean Spring Tides" has been one that our office has been required to answer on numerous occasions over the years.
The largest difference occurs in certain areas of the Alaska coast where the range of the tide was increased by approximately 6 inches.
But considering that these areas have an average tidal range of more than 30 feet, the increase is but a small percentage of the whole (less than a 2% increase). Woods' book examines the occurrences of coastal flooding though history.
Caution should be exercised when using tide predictions from other websites.
Some obtain their tide predictions from our office; others obtain their predictions from sources that may or may not be accurate or up to date.
The vertical rise and fall of the tides, created by the gravitational force of the Moon and Sun acting on the oceans water, also creates a horizontal motion of the water in the bays, harbors and estuaries. In general, as the tides rise there will be a current flowing from the oceans into the bays, harbors and estuaries; this is termed a "flood current".Some examples would be: Progressive currents are most common at the oceanic entrance to many bays and harbor.Standing wave conditions are most common at the head (most inland point) of larger bays and harbors.These are called "spring tides." Three or four times a year, the occurrence of a new or full moon will coincide with the "perigee" of the moon, which Mr. The difference between the "perigean spring tides" and the normal tidal ranges for all areas of the coast is small.In most cases the difference is only a couple of inches.