A composite study of 10 years of northwest Pacific rawinsonde data is used to analyze the large-scale structure of tropical cyclones. The temperature, height, moisture, wind and vertical motion fields are analyzed for various storm regions. Mean soundings for all regions from the eye through 12° radius are presented. Rainfall characteristics of the area inside 4° radius are discussed. Hurricane flight data are used to augment the analyses in the inner regions. Many important features are noted. Strong persistent asymmetries in storm structure exist, particularly at large radii. The storm circulation has very broad horizontal extent and appears to conform to a constant scale regardless of inner core intensity. Inflow in the middle troposphere is substantial from 4° outward. A mean subsidence region is observed from about 4–6° radius. Humidities are extremely high in the inner regions, and conditional instability exists everywhere outside the eye. Significant diurnal variations in rainfall and temp... Abstract A composite study of 10 years of northwest Pacific rawinsonde data is used to analyze the large-scale structure of tropical cyclones. The temperature, height, moisture, wind and vertical motion fields are analyzed for various storm regions. Mean soundings for all regions from the eye through 12° radius are presented. Rainfall characteristics of the area inside 4° radius are discussed. Hurricane flight data are used to augment the analyses in the inner regions. Many important features are noted. Strong persistent asymmetries in storm structure exist, particularly at large radii. The storm circulation has very broad horizontal extent and appears to conform to a constant scale regardless of inner core intensity. Inflow in the middle troposphere is substantial from 4° outward. A mean subsidence region is observed from about 4–6° radius. Humidities are extremely high in the inner regions, and conditional instability exists everywhere outside the eye. Significant diurnal variations in rainfall and temp...