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Severe Cyclonic Storm Onil (India Meteorological Department designation: ARB 03; Joint Typhoon Warning Center designation: 03A) was the first tropical cyclone to be named in the northern Indian Ocean. Forming out of an area of convection several hundred kilometres southwest of India on October 1, 2004, Cyclone Onil quickly attained its peak intensity on October 2 with winds of 100 km/h (65 mph) and a barometric pressure of 990 mbar (hPa; 29.23 inHg). However, dry air quickly entered the system, causing it to rapidly weaken to a depression just off the coast of Gujarat, India. Over the following several days, the system took a slow, erratic track towards the south-southeast. After turning northeastward, the system made landfall near Porbandar on October 10 and dissipated shortly thereafter. Throughout southeastern Pakistan and northwestern India, thousands of residents were evacuated prior to the cyclone's arrival. In these areas, the storm produced moderate to heavy rainfall, peaking at in Thatta, Sindh, Pakistan. These rains led to flash flooding in several areas. Nine people died in several incidents related to the storm in Karachi. The drainage system of Hyderabad sustained significant damage, leading to several protests and demonstrations by city residents. Offshore, 300 fishermen are believed to have gone missing during the storm; no reports have confirmed their whereabouts since they disappeared. ==Meteorological history== Severe Cyclonic Storm Onil was first identified as an area of convection early on September 30, 2004 situated roughly 465 km (290 mi) southwest of Mumbai, India. Satellite imagery depicted a poorly organized system with deep convection partially surrounding a low-level circulation. Situated over warm water and within an area of moderate wind shear,〔 the Joint Typhoon Warning Center (JTWC) assessed the system's chances of developing into a tropical cyclone as "fair". Within several hours of being identified, the Indian Meteorological Department (IMD) began monitoring the system as Depression ARB 03. Despite a decrease in convection later on September 30,〔 the IMD upgraded the cyclone to a deep depression, stating that three-minute sustained winds had reached 55 km/h (35 mph).〔 Early the next day, organization substantially improved,〔 prompting the JTWC to issue a Tropical Cyclone Formation Alert.〔 Around 0900 UTC on October 1, the IMD upgraded the deep depression to Cyclonic Storm Onil.〔 Upon being named, the storm became the first tropical cyclone on record to be named in the northern Indian Ocean. The WMO/ESCAP Panel agreed in May 2004 that in September, tropical cyclones in the Northern Indian Ocean attaining gale-force winds would be given names. Later on October 1, the JTWC issued their first advisory on the storm, classifying it as Tropical Cyclone 03A.〔 Tracking towards the northeast, Onil intensified as convection consolidated around the center of circulation.〔 Roughly 24 hours after being named, the system attained its peak intensity as a severe cyclonic storm with winds of 100 km/h (65 mph) and a barometric pressure of 990 mbar (hPa; 29.23 inHg) according to the IMD with.〔 Upon reaching this strength, the system featured a pinhole eye surrounded by deep convection. Additionally, Dvorak technique intensity estimates reached 3.5, indicating a high-end tropical storm. However, the JTWC stated maximum winds to be 65 km/h (40 mph), a low-end tropical storm.〔 As the storm neared the Indian coastline, dry air quickly entered the circulation, causing most of the convection associated with Onil to dissipate.〔 Located within 100 km (65 mi) of land, the JTWC downgraded the system to a tropical depression and the IMD downgraded Onil to a deep depression.〔〔 On October 3, the center of Onil skimmed the coastline of northwestern India; however, the center did not cross land.〔 Around this time, the upper-level circulation detached from the low-level circulation, further weakening the storm.〔 Early on October 4, the JTWC stated that the system had degenerated into a non-convective remnant low pressure system. After executing a counter-clockwise loop, the depression slowly tracked south-southeastward, away from land. By October 7, the system was reclassified as a tropical depression by the JTWC as it stalled several hundred kilometres southwest of Gujarat, India. The system maintained a relatively low intensity for the following several days before making landfall near Porbandar with winds of 45 km/h (30 mph).〔 Within hours of moving inland, Onil dissipated early on October 10.〔 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「Cyclone Onil」の詳細全文を読む スポンサード リンク
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