<P> Before it became a hurricane, Isaac produced flooding rain across much of the Lesser and Greater Antilles . Particularly hard hit was the island of Haiti, where 24 people lost their lives . Overflowing rivers led to significant structural damage and many roadways were washed away, preventing aid to the affected area . Gusty winds and rainfall were reported in Cuba, but damage was limited to a few buildings . In Florida, Isaac produced several inches of rain, leading to flooding . Strong winds knocked out power to thousands, and waves along the coast caused minor beach erosion . The most severe effects of the storm, however, occurred in Louisiana after the storm was upgraded to hurricane intensity . </P> <P> Tropical storm - force sustained winds, with gusts well over hurricane strength, knocked out power to hundreds of thousands, and heavy rain led to flooding . Many dams along the coast were briefly over-topped, though they did not break completely and were later pumped to prevent failure . Gusts near hurricane intensity and heavy rain also led to widespread power outages in the neighboring state of Mississippi, and parts of Alabama recorded nearly 1 ft (0.3 m) of rain . As an extratropical cyclone, Isaac produced torrential rains across Arkansas, flooding numerous streets and homes, and damaging many crops across the region . Strong winds felled downed lines and trees . Overall, Isaac caused $3.11 billion (2012 USD) in damage and led to 41 fatalities . Despite the damage, the name was not retired . </P> <P> A tropical wave crossed the west coast of Africa between August 15 and August 16 . Later that day and early on August 17, the system began developing more convection, while located just west of Sierra Leone . As a result, the National Hurricane Center (NHC) began monitoring the system in the Tropical Weather Outlooks (TWOs). Thereafter, further organization briefly halted, though by early on August 18, associated convection became more concentrated . On the following day, the wave reached a "high" probability of tropical cyclogenesis . Between early on August 19 and early on August 21, minimal structural improvement occurred, despite increases in development probability . By August 21, the system developed enough organization for the NHC to initiate advisories on Tropical Depression Nine; at the time, the depression was about 715 mi (1150 km) east of the Leeward Islands, moving west to the south of a large ridge . Conditions were generally favorable for further intensification, except for northeasterly wind shear . </P> <P> Late on August 21, a Hurricane Hunters mission observed flight - level winds of 51 mph (84 km / h), and on this basis the NHC upgraded the depression to Tropical Storm Isaac . Despite its intensification, the storm was disorganized with its center north of the deepest convection . The circulation became elongated early on August 22, and the storm absorbed drier air in its northeast quadrant . Later that day, the low pressure area passed just south of Guadeloupe and into the Caribbean Sea . Dry air continued to hinder convection, although Isaac gradually became better organized . By late on August 24, the Hurricane Hunters observed a well - defined circulation; by that time, however, the strongest convection was moving over Hispaniola . An eye feature developed early on August 25, and Isaac attained winds of 70 mph (110 km / h) before crossing the southwest peninsula of Haiti . </P>

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