<P> Tidal data for coastal areas is published by the national hydrographic service of the country concerned . Tidal data is based on astronomical phenomena and is predictable . Storm force winds blowing from a steady direction for a prolonged time interval combined with low barometric pressure can increase the tidal range, particularly in narrow bays . Such weather - related effects on the tide, which can cause ranges in excess of predicted values and can cause localized flooding, are not calculable in advance . </P> <P> The typical tidal range in the open ocean is about 0.6 metres (2 feet). Closer to the coast, this range is much greater . Coastal tidal ranges vary globally and can differ anywhere from near zero to over 11 metres (38 feet). The exact range depends on the volume of water adjacent to the coast, and the geography of the basin the water sits in . Larger bodies of water have higher ranges, and the geography can act as a funnel amplifying or dispersing the tide . The world's largest tidal range of 16.3 metres (53.5 feet) occurs in Bay of Fundy, Canada, and the United Kingdom regularly experiences tidal ranges up to 15 metres between England and Wales in the Severn Estuary . The top 50 locations with the largest tidal ranges worldwide are listed by the National Oceanic and Atmospheric Administration of the United States . </P> <P> Some of the smallest tidal ranges occur in the Mediterranean, Baltic, and Caribbean Seas . A point within a tidal system where the tidal range is almost zero is called an amphidromic point . </P> <P> The tidal range has been classified as: </P>

Why is it important to know the average tidal range for an area