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Tropical Storm Hanna was a moderately strong tropical storm that affected the Gulf Coast and Southeastern regions of the United States. The tenth tropical cyclone and ninth named storm of the 2002 Atlantic hurricane season, Hanna formed through the complex interaction of a surface trough, a tropical wave, and an upper-level low pressure system, a disturbance in the upper atmosphere. Designated a tropical depression at 0000 UTC on September 12, the storm remained disorganized throughout its duration, though it attained tropical storm status and a peak intensity of , with winds of 60 miles per hour (100 km/h). Hanna crossed extreme southeastern Louisiana, and made a second landfall along the Alabama–Mississippi border. Because most of the associated convective activity was east of the center of circulation, Louisiana and Mississippi received minimal damage. However, on Dauphin Island, Alabama, the storm caused coastal flooding which closed roads and forced the evacuation of residents. Florida received high wind gusts, heavy rainfall, and strong surf that resulted in the deaths of three swimmers. 20,000 homes in the state lost electricity. The heavy rainfall progressed into Georgia, where significant flooding occurred. Crop damage was extensive, and about 335 structures were damaged by the flooding. The storm caused a total of about $20 million (2002 USD; $23.96 million 2008 USD) in damage. ==Meteorological history== A broad surface trough extended from the western Atlantic Ocean into the Gulf of Mexico in early September 2002. At the same time, a westward-moving tropical wave entered the gulf on September 10 and spawned a weak low along the trough, with little associated thunderstorm activity. On September 11, an upper-level low over the United States moved into the Gulf and became cut off from the flow, allowing atmospheric convection to develop to the east of the tropical wave. The surface low organized, and convection formed closer to the center of the low. At 0000 UTC on September 12, a Hurricane Hunters aircraft was able to find a well-defined center of circulation; the National Hurricane Center (NHC) thus designated it a tropical depression while it was about south of Pensacola, Florida. After being designated, the cyclone became disorganized, and contained little deep and persistent convection; with dry air infringing on the western edge of the storm, substantial intensification was deemed unlikely. Despite being sheared, the cyclone neared tropical storm status later that day, though it remained a depression due to a partially non-tropical appearance. Initially, the depression meandered towards the northeast due to weak steering currents, and it intensified into a tropical storm at 0600 UTC. As such, it was named Hanna by the National Hurricane Center. Over the next 24 hours, the low-level center rotated around the mid- and upper-level centers, and the entire tropical storm turned southwestward by late September 12.〔 After a jog to the northwest, the low-level center became separated from the convection. Meandering, the storm started to turn northward under the steering currents of a southwesterly flow associated with an approaching mid-level trough. Hanna then strengthened sharply to reach to its peak intensity of 60 miles per hour (100 km/h) at 0000 UTC on September 14.〔 Convection shifted towards the eastern semicircle of the circulation, while the still-exposed center became malformed and elongated. On September 14, the poorly organized cyclone crossed southeastern Louisiana, turned towards the north-northeast and made a second landfall close to the Alabama–Mississippi border at 1500 UTC that day, still at its peak strength. The storm dissipated rapidly as it proceeded inland, and the remnant low pressure area moved into Georgia and South Carolina.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tropical Storm Hanna (2002)」の詳細全文を読む スポンサード リンク
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