The Cornell University Portable Radar Interferometer (CUPRI) observed two extremely strong layers of Polar Mesosphere Summer Mesosphere (PMSE) thirty minutes prior to the launch of Salvo C of the NLC-91 campaign. The lower layer exhibited a S/N rtio of 42 dB (the second strongest event of NLC-91), vertical velocities of a few m/s, and a narrow spectral width, suggesting that it was the result of partial reflections. The upper layer, in contrast, exhibited sinusoidal structures in vertical velocity with peak amplitudes greater than ¿10 m/s and wide spectral widths. These structures were observed to growth and steepen with altitude until they broke and produced turbulent radar scattering. We conclude that the rapid rate of growth of the wave with altitude was the result of a depressed mesopause temperature and a nearly adiabatic temperature gradient at PMSE heights and that the simultaneous measurement of both a low mesopause temperature and strong PMSE supports recent theories that find the presence of charged aerosols to be the key to the unique radar cross sections associated with PMSE. ¿American Geophysical Union 1993