Sodium resonance lidar observations on the night of Nov 3, 1997 UT recorded a temperature inversion with 80 K amplitude moving downward from 90 to 83 km with the maximum temperatures exceeding 280 K. These are the highest temperatures and largest inversion layer observed in 10 years over Fort Collins, Colorado. The inversion can be decomposed into a 50 K peak-to-peak amplitude oscillation with an apparent 8-hr period and 25 km vertical wavelength plus a residual 30 K inversion layer. The temperature gradient above this maximum is near-adiabatic from 88--100 km for 4 hours with multiple super-adiabatic layers several km in depth. Streamlines derived from the sodium mixing ratio and the potential temperature both indicate a 10 km upward movement in the adiabatic region. Presumably, a large-amplitude upward-propagating wave saturated when it reached the inversion layer just below the mesopause and broke, leading to convective instabilities with large vertical and temporal scales.