Typhoon Nuri (2008) was 1 of approximately 120 typhoons in the past 60 years that passed through a narrow gap, the Luzon Strait, connecting the western North Pacific and the South China Sea (SCS). In total 70% of these storms, including Nuri, reached their maximum intensities over the warm waters east of Luzon and in the Kuroshio, then rapidly weakened in the SCS. Numerical experiments were conducted to understand the intensity change of Nuri. Westward across the Kuroshio in the Luzon Strait, the 26°C isotherm shallows rapidly by half. This and stronger mixing by wind-ocean resonance preferentially cooled sea surface temperature and weakened the typhoon in SCS. A positive-feedback mechanism is then described to explain the intensification of Nuri over the western North Pacific.