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Severe Tropical Cyclone Lua affected a sparsely populated region of Western Australia during mid-March 2012. Originating in a broad low pressure area that formed northwest of Australia by 8 March, the storm was plagued by inhibiting wind shear for the duration of its formative stages. However, it gradually organized, and received the name Lua on 13 March. The cyclone meandered for the first several days of its existence, caught between weak and competing steering currents. After the cyclone drifted northwestward, a building ridge of high pressure to the north drove Lua southeastward toward the Pilbara region. Ultimately intensifying into a borderline Category 4 severe tropical cyclone with maximum sustained 10-minute winds of 165 km/h (105 mph), Lua made landfall near the remote community of Pardoo, about 150 km (95 mi) east of Port Hedland. It steadily weakened as it progressed south over interior Western Australia, diminishing below tropical cyclone status on 18 March. The threat of the impending cyclone halted local industries such as oil production and iron ore mining and exporting. The Port of Port Hedland, a highly important iron ore shipping terminal, was forced to close for about 52 hours, contributing to inflated iron ore prices and delayed shipments. Multiple companies suspended work at oil fields and mines throughout the region, cutting national oil production by 25% and iron ore exports by 4.7% versus the previous month. Overall, Lua is attributed to $217 million (2012 AUD; $230 million 2012 USD) in lost revenue. Lua produced strong winds and widespread rainfall on land, but damage was limited by the lack of population in the storm's path. The Pardoo Roadhouse bore the brunt of the storm, and damage was reported at several other cattle stations and homesteads; at these sites, the storm damaged the exteriors of various structures and brought down swaths of trees. Central Western Australia endured several days of record-breaking rainfall and cool weather. The Government of Western Australia provided disaster relief funds to the hardest-hit areas, and ''Lua'' was later retired from the list of tropical cyclone names. ==Meteorological history== Cyclone Lua originated in a broad area of disturbed weather that was spawned by a deep trough of low pressure and enhanced by a Madden–Julian oscillation pulse.〔 The precursor to Lua was first identified through satellite imagery by 8 March 2012, while situated about to the north-northwest of Learmonth.〔 Analysis of the disturbance revealed a diffuse low-level center of circulation loosely bounded by sporadic, but multiplying, convection. On 9 March, the Bureau of Meteorology's (BoM) Tropical Cyclone Warning Center (TCWC) in Perth recognized the developing system and remarked on the potential for tropical cyclone formation over the following several days. The low pressure area meandered for several days, making some progress toward the east, and gradually consolidated. By 12 March, the system had developed persistent deep convection over the eastern half of its core and organized banding features elsewhere. Moderate vertical wind shear initially hampered intensification, though the BoM designated the system Tropical Low ''16U''; at the time, it was centered roughly northwest of Karratha, Western Australia. At 2300 UTC on 12 March, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert. With increasingly favorable environmental conditions—including warm ocean waters and dwindling wind shear—the low organized significantly between 12 and 13 March, and at 0600 UTC on the 13th, TCWC Perth upgraded the low to Tropical Cyclone ''Lua''. Simultaneously, the JTWC issued its first tropical cyclone warning on ''17S''. Contrary to real-time operations, the official BoM "best track" database does not list the storm as having attained Category 1 tropical cyclone intensity until 0000 UTC on 14 March.〔 At the time of its designation, Lua was nearly stationary in terms of forward movement, caught in the equilibrium between a blocking ridge to the southwest and increasing monsoonal winds from the northwest.〔 The ridge began to drive Lua north-northwestward at up to , before the storm resumed its slow pace on 14 March. The storm remained relatively disorganized, its strengthening limited by moderate wind shear and dry air entering its center. Consequently, a large void of thunderstorm activity created a "horseshoe pattern". Nonetheless, Lua proved resilient, and good outflow helped compensate for the adverse shear. The southwesterly steering currents weakened, causing the storm to begin its anticipated curve toward the east and east-southeast. According to the JTWC, the storm completed a small loop as a result of competing steering factors. At the same time, the upper levels of the atmosphere became far more conducive to the cyclone's intensification, and the storm's banding pattern tightened. With a building ridge to its north, Lua accelerated east-southeastward on 15 March, and with wind shear oscillating but generally decreasing, the storm became a Category 3 severe tropical cyclone at 1800 UTC.〔 Continuing to intensify, Lua began to exhibit an ill-defined eye on visible satellite imagery on 16 March. The storm was expansive, producing storm-force winds in a circular area across. Still, the deepest convection and most favorable outflow was focused away from the eastern semicircle due to persistent light easterly wind shear. The storm's structure improved throughout the day and into the night, and at 2000 UTC on 16 March, the storm attained its peak 10-minute maximum sustained winds of 165 km/h (105 mph), classifying it as a low-end Category 4 severe tropical cyclone.〔(【引用サイトリンク】publisher=Bureau of Meteorology )〕 Early on 17 March, the storm turned due south toward the Pilbara coast, and the JTWC reported that Lua's peak strength was marked by 1-minute sustained winds of 175 km/h (110 mph), at 0600 UTC. At its deepest, the storm possessed a central barometric pressure of . Lua made landfall near Pardoo, about 150 km (95 mi) east-northeast of Port Hedland, at 0700 UTC while still at peak intensity.〔 The cyclone steadily weakened as it progressed southward, tracking directly over the Yarrie mine before passing about halfway between Newman and Jigalong.〔 With little extant convection and a shallow, exposed center, Lua deteriorated below tropical cyclone status early on 18 March near Wiluna. The cyclone's remnants later entered the Goldfields-Esperance region.〔 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 Lua」の詳細全文を読む スポンサード リンク
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