 Nanmadol developed from an isolated area of convection south-southwest of Pohnpei that became classified as a tropical depression on November 28.Within highly conducive conditions for development, the system reached tropical storm intensity the following day, followed by typhoon intensity on November 30.Quickly pacing towards the north-northwest about the periphery of a nearby subtropical ridge, Nanmadol reached its peak intensity on December 1 with winds of 165 km/h (105 mph) and a minimum barometric pressure of 935 mbar (hPa; 27.61 inHg).