High Quality Content by WIKIPEDIA articles! Typhoon Choi-wan (International designation: 0914, JTWC designation: 15W, sometimes called Super Typhoon Choi-wan) was a powerful typhoon that became the first Category 5 equivalent typhoon to form during the 2009 Pacific typhoon season. Forming on September 11, 2009, about 1100 km (700 mi) to the east of Guam, the initial disturbance rapidly organized into a tropical depression. By September 12 ,the depression intensified into a tropical storm, at which time it was given the name Choi-wan. The following day, rapid intensification took place through September 14. Choi-wan attained its peak intensity on September 15, as it moved through the Northern Mariana Islands with the Japan Meteorological Agency reporting peak windspeeds of 195 km/h (120 mph 10-minute sustained). Additionally, the Joint Typhoon Warning Center reported the storm to have attained winds of 260 km/h (160 mph 1-minute sustained). The typhoon remained very powerful until September 17 when the storm`s outflow weakened. The typhoon underwent an eyewall replacement cyclone, leading to intensity fluctuations. By September 19, Choi-wan rapidly weakened as strong wind shear caused convection to diminish. The following day, the system transitioned into an extratropical cyclone and dissipated several hours later over open waters.