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Tropical Storm Arlene, the first named storm of the 2011 Atlantic hurricane season, brought blustery conditions to much of eastern Mexico in late June to early July 2012. Arlene originated from an Atlantic tropical wave, which crossed the Yucatán Peninsula before emerging over warm waters in the Bay of Campeche. Despite moderate wind shear, the disturbance strengthened and developed a surface circulation, prompting the National Hurricane Center to declare it a tropical storm on June 28. Arlene remained vigorous for most of its existence; the storm peaked in intensity with winds of 65 mph (100 km/h) on June 30, just before making landfall on the coast of Veracruz. Crossing the mountains of eastern Mexico, Arlene weakened to a depression before dissipating early on July 1. The precursor disturbance to Arlene brought significant rainfall to parts of Central America, killing three people and triggering widespread flooding and landslides. Throughout Mexico, prolonged rains from Arlene and subsequent flooding affected hundreds of homes and several roads, causing many residents to seek shelter. At the height of the storm, power was lost to 285,000 homes. At least 22 people in Mexico were killed by Arlene. Elsewhere, rainfall from the storm alleviated ongoing drought conditions in southern Texas and Florida. == Meteorological history == The origins of Tropical Storm Arlene can be traced to a distinct tropical wave, embedded within an area of deep atmospheric moisture, that emerged off the coast of Africa on June 13, 2011. The wave tracked westward across the Atlantic for several days, reaching the western Caribbean Sea in late June. By June 24, it began interacting with the extension of a monsoon trough in the region, generating broad cyclonic flow and scattered convection in conjunction with an upper trough to its northwest. The amplified wave slowly proceeded west-northwestward along Central America, bringing heavy rainfall to the area. Initially, the disturbance's development was impeded by the trough aloft and adjacent land, though the National Hurricane Center (NHC) noted favorable conditions for tropical cyclogenesis over the Bay of Campeche, coupled with abating wind shear. On June 26, the disturbance moved inland over the Yucatán Peninsula, emerging into the bay the next day as it produced a surface low. Despite moderate shear, a Hurricane Hunters flight into the system revealed that a closed wind circulation had formed at sea level. Thunderstorm activity became more concentrated, and the NHC initiated advisories on Tropical Storm Arlene at midnight June 29, after the cyclone's surface winds increased to 40 mph (65 km/h) about 280 mi (450 km) south-southeast of Tampico, Tamaulipas. Over the following hours, deep convection increased around the broad storm, though its circulation center continued to lack in organization. Arlene curved to the west in response to a ridge of high pressure to its north and northwest. As the shear over the region further decreased, the large storm began to strengthen gradually, developing spiral convective bands closer to its center. Although forecast models supported intensification to hurricane status, significant development was compromised by a lack of distinguishable central features. On June 30, just before Arlene made landfall, Dvorak satellite estimates indicated the storm had reached a peak intensity of 65 mph (100 km/h) while accelerating off the coast of Veracruz. Arlene moved ashore near Cabo Rojo as a strong tropical storm by 09:00 UTC, with the severest winds confined to the north of the center. Farther inland, Arlene turned to the west-southwest along the building ridge. The storm decreased in strength upon doing so; its mid- and low-level circulations became increasingly decoupled, with the latter turning elongated and ill-defined. Early on July 1, the NHC downgraded Arlene to a tropical depression, and the cyclone dissipated over the high terrain of the Sierra Madre Mountains shortly thereafter. Arlene's remnants continued to produce heavy precipitation over central Mexico, and with high air pressures offshore a tight pressure gradient generated a strong easterly breeze along the country's Pacific coastlines. 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 Arlene (2011)」の詳細全文を読む スポンサード リンク
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