Tidal surges

A storm surge is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low pressure weather systems (such as tropical cyclones and strong extratropical cyclones), the severity of which is affected by the shallowness and orientation of the water body relative to storm path, and the timing of tides. Most casualties during tropical cyclones occur as the result of storm surges.

The two main meteorological factors contributing to a storm surge are a long fetch of winds spiraling inward toward the storm, and a low-pressure-induced dome of water drawn up under and trailing the storm's center.

The deadliest storm surge on record was the 1970 Bhola cyclone, which killed up to 500,000 people in the area of the Bay of Bengal. The low-lying coast of the Bay of Bengal is particularly vulnerable to surges caused by tropical cyclones. The deadliest storm surge in the twenty-first century was caused by the Cyclone Nargis, which killed more than 138,000 people in Myanmar in May 2008. The next deadliest in this century was caused by the Typhoon Haiyan (Yolanda), which killed more than 6,000 people in the central Philippines in 2013 and resulted in economic losses estimated at $14 billion (USD).

The Galveston Hurricane of 1900, a Category 4 hurricane that struck Galveston, Texas, drove a devastating surge ashore; between 6,000 and 12,000 lives were lost, making it the deadliest natural disaster ever to strike the United States.

The highest storm tide noted in historical accounts was produced by the 1899 Cyclone Mahina, estimated at almost 44 ft (13 metres) at Bathurst Bay, Australia, but research published in 2000 saw the majority of this was likely wave run-up, due to the steep coastal topography. In the United States, one of the greatest recorded storm surges was generated by 2005's Hurricane Katrina, which produced a maximum storm surge of more than 25 ft (8 metres) in the communities of Waveland (41.5 ft), Bay St. Louis (38 ft), Diamondhead (30 ft) and Pass Christian (35 ft) in Mississippi. Another record storm surge occurred in this same area from Hurricane Camille in August 1969, with the highest storm tide of record noted from a high water mark as 24.6 ft (7.5 m), also found in Pass Christian (the back side of St. Louis Bay got up to 35 ft). A high storm surge occurred in New York City from Hurricane Sandy in October 2012, with a high tide of 14 ft (4.2 m).

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Wikipedia