Because the tidal currents are created by the same forces which cause the tides, the currents can be predicted in much the same way as the tides.
Observational data on the currents at a location can be analyzed using the same methods employed to analyze tides, and the results of that analysis can be used to generate predictions of tidal currents.
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.
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.
Most areas of the coast will fall somewhere in between a progressive and standing wave current.
[Example (jpg)] The exact relationship between the times of high and low tides and the maximum current or slack water is unique to each location and cannot be determined from a generic "rule of thumb".
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.