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Typhoon Kai-tak, known in the Philippines as Tropical Storm Helen, was a mild tropical cyclone that affected China, Vietnam and Laos. It was the seventh typhoon and the thirteenth named storm of the 2012 Pacific typhoon season. The storm killed up to 40 people and caused a sum of US$315 million in losses. Kai-tak can be tracked back to the broad area of disturbance embedded in a monsoonal trough that was first spotted, early on August 10. It was only at midnight, on August 16, when the JMA officially declared Kai-tak a typhoon. On the morning of August 17, the windpseed dropped to 60 knots (110 km/h; 69 mph) and was no longer a typhoon. The typhoon caused heavy damage in China's two provinces killing one person and causing a great economic loss. In Vietnam, Typhoon Kai-Tak has stormed across the country's north bringing high winds and floods to several areas including the capital Hanoi. Tropical Storm Kai-Tak slammed the northern Philippines triggering flash floods and landslides and killing at least three people, one week after deadly monsoon rains battered the country. ==Meteorological history== The origins of Kai-tak can be tracked back to the broad area of disturbance embedded in a monsoonal trough that was first spotted, early on August 10.〔(【引用サイトリンク】url=http://www.webcitation.org/69o9bBU5N )〕 By the next day, the convection deepened and a weak low-level circulation center was spotted with winds of up to . A Tropical Rainfall Measuring Mission pass revealed that the convection around the system was very loosely organised and the banding was relatively weak.〔(【引用サイトリンク】url=http://www.webcitation.org/69rBZScvQ )〕 By midnight, that day, the Japan Meteorological Agency (JMA) started tracking the system as a weak Tropical Depression with winds under 30 knots.〔(【引用サイトリンク】url=http://www.webcitation.org/69rBepaDC )〕 A couple of hours later, the Joint Typhoon Warning Center (JTWC) issued a Tropical cyclone formation alert (TCFA) estimating winds of up to .〔(【引用サイトリンク】url=http://www.webcitation.org/69siXr2n0 )〕 As the storm was also in the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA)'s area of Responsibility, they started issuing advisories on the system, thus naming it ''Helen''.〔(【引用サイトリンク】url=http://www.webcitation.org/69sjyaefC )〕 By noon, on August 12, the JMA confirmed that the depression has reached a windpseed of .〔(【引用サイトリンク】url=http://www.webcitation.org/69siPl1JI )〕 As opposed to this, in their first advisory on the system, the JTWC said that the storm had winds of up to 25 knots only.〔(【引用サイトリンク】url=http://www.webcitation.org/69sicl0mn )〕 Only late that night, did the JTWC confirm winds of 30 knots, based on new microwave imagery and satellite data. The storm was moving to the west at at the moment.〔(【引用サイトリンク】url=http://www.webcitation.org/69sicgwrL )〕 At midnight, the JMA reported winds of , stating that the depression had intensified into a tropical storm, thus officially naming it ''Kai-tak''.〔(【引用サイトリンク】url=http://www.webcitation.org/69siPWPVq )〕 At 09:00 UTC, on August 13, the JTWC confirmed the same.〔(【引用サイトリンク】url=http://www.webcitation.org/69uDMCVHg )〕 At that time, the system had a broad, partially exposed low-level circulation center (LLCC) with deep convection persisting along the western periphery.〔(【引用サイトリンク】url=http://www.webcitation.org/69uDNqKpY )〕 Later the same day, according to JMA, the storm reached a maximum sustained windspeed of , thus making it a Severe Tropical Storm.〔(【引用サイトリンク】url=http://www.webcitation.org/69xFWQupg )〕 The storm continued tracking northwestward and was located approximately northeast of Manila, Philippines. Infrared imagery revealed that deep convection persisted along the southwestern periphery of the LLCC. Though the storm entered warm watered off the Philippine coast, it failed to intensify rapidly as it was located along the southern periphery of a deep-layered subtropical ridge and was experiencing moderate vertical wind shear. The JTWC did not expect the storm to strengthen any further since it would start interacting with the nearby landmass.〔(【引用サイトリンク】url=http://www.webcitation.org/69uDNibPn )〕 On August 14, the LLCC of the storm passed under the deepest convection, however, it failed to intensity because an anticyclone that was located to the northeast of Kai-tak. Albeit the ample outflow, no good convection developed to the northern half of the system due to the shear caused by the anticyclone. At this moment, Kai-tak was expected to rapidly drift eastward due to the persistent subtropical ridge. The JTWC expected Kai-tak to become a typhoon within 48 hours due to warm sea-surface temperatures, and then make landfall.〔(【引用サイトリンク】url=http://www.webcitation.org/69wCGDuhO )〕 By the night of August 14, Kai-tak tracked westward at and the LLCC became embedded within central dense overcast convection. The storm became more consolidated as a result. Fragmented concentric deep convection surrounded the LLCC. Also, the anticyclone to the east of the system weakened thus reducing the wind shear affecting Kai-tak. The windspeed then rose to approximately .〔(【引用サイトリンク】url=http://www.webcitation.org/69wCG2oVl )〕 By the next day, the Kai-tak accelerated towards the Philippines. The LLCC started interacting with the northern coast of the island nation. The deep convection continued to build along with the strong equatorward outflow. The storm, however, produced no poleward outflow. Due to the sudden rise in trackspeed, the JTWC estimated a landfall within 12 hours.〔(【引用サイトリンク】url=http://www.webcitation.org/69wCFtQQG )〕 On the night of August 15, the infrared satellite imagery showed that convective bands have deepened and wrapped tighter into the LLCC and an excellent equatoward outflow. The windspeed was estimated at , which is equivalent to a minimal category 1 tyhoon on the SSHS. Kai-tak was expected to continue intensifying before making landfall over China, and then decay rapidly due to land interaction.〔(【引用サイトリンク】url=http://www.webcitation.org/69xFg7RR5 )〕 According to reports the next morning, Kai-tak continued drifting westward at about . Though the bulk on convection remained to the southern semi-circle, deep convective rainbands have developed over the northern periphery. Over the past 12 hours, the storm rapidly moved west, into china and was expected to make landfall soon. Kai-tak was located along the southern periphery of a deep subtropical ridge positioned over southeast China.〔(【引用サイトリンク】url=http://www.webcitation.org/69yoUXv7g )〕 The storm continued speeding towards China and by the night of August 16, it was drifting west at nearly . Infrared imagery showed that the cloud-top temperatures were starting to drop. The vertical wind shear near Kai-tak had weakened dramatically. However, the storm maintained the same windspeed. The JTWC announced that the storm would start weakening rapidly within 12 hours due to land interaction.〔(【引用サイトリンク】url=http://www.webcitation.org/69yoUOZLo )〕 It was only at midnight, on August 16, when the JMA officially declared Kai-tak a typhoon.〔(【引用サイトリンク】url=http://www.webcitation.org/69yoHSg7y )〕 By then, the system sped up towards landmass. It was drifting west at over , poised to make landfall over the Leizhou peninsula over the next 12 hours, cross the Gulf of Tonkin, before making a second and final landfall into northern Vietnam to the east of Hanoi.〔(【引用サイトリンク】url=http://www.webcitation.org/69yoUK7lP )〕 At the same time, the PAGASA issued their last warning on Kai-tak, otherwise known as Helen, locally, as it left the Philippine area of Responsibility.〔(【引用サイトリンク】url=http://www.webcitation.org/69xFaNTaY )〕 On the morning of August 17, Kai-tak made landfall over the Leizhou peninsula, as expected. It maintained the same intensity and was expected to track west-northwestward under the influence of the subtropical ridge.〔(【引用サイトリンク】url=http://www.webcitation.org/6A0IuZvR6 )〕 Within 6 hours, Kai-tak made a second landfall over the northeast coast of Vietnam and has weakened slightly. The windpseed dropped to and was no longer a typhoon. Kai-tak was expected to weaken rapidly thereafter.〔(【引用サイトリンク】url=http://www.webcitation.org/6A0IuVKki )〕 Later that night, the JTWC issued their final warning on the system as it weakened further and sped up inland. They expected the system to dissipate within 24 hours.〔(【引用サイトリンク】url=http://www.webcitation.org/6A0IsK8kA )〕 However, the JMA stopped tracking the storm early the next morning, no longer considering it a tropical cyclone.〔(【引用サイトリンク】url=http://www.webcitation.org/6A0IihLmx )〕 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「Typhoon Kai-tak (2012)」の詳細全文を読む スポンサード リンク
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