This paper reports a meteorological analysis of Typhoon Nari, and its hydrological impacts on Tamshui river basin. The analysis is based on meteorological and hydrological data from the Central Weather Bureau, Water Conservancy Agency, and observations from NCU that include satellite analysis, integrated sounding system (ISS), disdrometer, and VHF radar. Typhoon Nari is selected because of its unique track, slow moving speed, and associated rain size distribution and vertical velocity. These features caused a record-breaking 24-48 hour cumulative rainfalls in many parts of Taiwan. The huge amount of rainfall over northern Taiwan caused widespread floods, which in turn caused great loss of lives and properties. This pilot study reveals several fundamental factors influencing Nari, including influences of air-sea interaction and large-scale circulation on the track and intensity of typoons, role of microphysics and topography in rainfall estimate, and effect of high-resolution rainfall on hydrologic models.