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Tropical Cyclone Emma was a weak but unusually large tropical cyclone that affected a substantial portion of Western Australia during the 2005–06 Australian region cyclone season. Forming out of an area of low pressure on 25 February, the precursor to Emma slowly tracked southward. Although classified tropical, the structure of the system represented that of a monsoonal storm. However, low wind shear and well-developed outflow gradually allowed convection to develop near the centre of circulation. As the system approached the Pilbara coastline of Western Australia on 27 February, it intensified into a Category 1 cyclone and attained peak 10-minute sustained winds of 75 km/h (45 mph). After moving inland near Mardie, Emma weakened to a tropical low but became exceedingly large; its cloud cover obscured most of Western Australia. The remnants of the weak storm persisted until 1 March, at which time they dissipated over the Great Australian Bight. Although a weak storm, rainfall from Emma caused flooding in numerous parts of Western Australia. In Karratha, six people required rescue after their cars became stranded in floodwaters. The most significant damage took place along the Murchison River which swelled to roughly in width. Although only one town was threatened by the river, large areas of farmland were inundated by the expanding river, leading to substantial agricultural losses. Despite the extensive flooding, no fatalities were reported as a result of Emma. ==Meteorological history== Tropical Cyclone Emma originated from an area of low pressure that formed to the southeast of Java on 22 February 2006. Over the following few days, a monsoonal trough developed over the Timor Sea, leading to an increased likelihood of tropical cyclone formation from the initial low within several days. On 25 February, the Australian Bureau of Meteorology began monitoring the system as a tropical low. The low tracked slowly towards the south throughout the day and the centre of circulation relocated farther south late on 26 February.〔 By this time, the Bureau of Meteorology anticipated the low to develop into a tropical cyclone and attain winds of 95 km/h (60 mph 10-minute sustained) before moving over land in Western Australia. Early on 27 February, the Joint Typhoon Warning Center (JTWC) classified the system as a tropical depression. During the day, a QuikSCAT pass revealed a broad low-level circulation with the highest winds located around the periphery of the storm, a characteristic of monsoonal systems. Although it was situated within a region of low wind shear and underneath an anticyclone, convective activity was mostly present in the system's large outer bands.〔 Later that day, the Bureau of Meteorology upgraded the system to a Category 1 cyclone on the Australian intensity scale and named it Emma.〔 At this time, Emma was located roughly 305 km (190 mi) north of Onslow, Western Australia.〔 Several hours later, the JTWC classified Emma as Tropical Storm 15S〔 following the development of convection near the centre of circulation.〔 The storm continued to track southward in response to a strong mid to upper-level ridge situated over central Australia. Emma attained its peak wind speed of 75 km/h (45 mph 10-minute sustained) late on 27 February as it neared landfall.〔 However, the JTWC assessed Emma to have been slightly weaker, peaking with winds of 65 km/h (40 mph 1-minute sustained).〔 The storm maintained this intensity through its landfall early on 28 February near Mardie along the Pilbara coastline. Shortly after moving over land, the JTWC declared Emma extratropical and issued their final advisory on the storm.〔〔 The Bureau of Meteorology, however, continued to monitor the cyclone as it rapidly tracked over Western Australia.〔 Over land, the storm became unusually large, with outer bands from the storm covering most of Western Australia. Late on 28 February, the lowest barometric pressure in relation to Emma, 988 mbar (hPa; 29.18 inHg), was recorded. The remnants of Emma persisted through most of 1 March before the system moved over the Great Australian Bight and dissipated.〔 The Australian Bureau of Meteorology uses 10-minute sustained winds, while the Joint Typhoon Warning Center uses one-minute sustained winds. The Bureau of Meteorology's peak intensity for Emma was 75 km/h (45 mph) 10-minute sustained, or 85 km/h (50 mph) one-minute sustained.〔〔 The JTWC's peak intensity for Emma was 65 km/h (40 mph) one-minute sustained, or 55 km/h (35 mph) 10-minute sustained.〔〔 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 Emma (2006)」の詳細全文を読む スポンサード リンク
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