Abstract Detailed structure of the quasi-2-day oscillation observed in the active phase of the Madden–Julian oscillations during the intensive observation period of Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE IOP) was described. A variety of observational platforms is used including high-resolution GMS infrared histogram, rain-rate estimate from TOGA and MIT radar measurements, upper-air soundings, and boundary layer profiler winds from the Integrated Sounding System and surface data from the IMET buoy. The quasi-2-day mode had a westward propagation speed of 12°–15° day −1, a horizontal wavelength of 25°–30° longitude. A coupling with the westward-propagating n = 1 inertio–gravity waves was hypothesized from the space–time power spectral distribution of the cloud field. The wind disturbance structure was consistent with the hypothesis. The vertical wave structure had an eastward phase tilt with height below 175 hPa and vice versa above, indicating the wav...