On October 9, 1993, observations were made from the NCAR Electra aircraft during a 7 hour flight towards a tropospheric low pressure system NW of Maui. A very bright (>50% intensity amplitude) OH wave (~200 km horizontal wavelength) was encountered ~900 km NW of Maui. The OH volume weighted Na column density measured by the lidar increased 4-fold at the same location. OH imagery showed the wave phase front was aligned NE-SW, similar to the tropospheric airmass boundary which was located ~2000 km NW of Maui. This 'wall' wave had an apparent phase velocity (vϕ) of 75 ms-1 toward the SE and was observed overhead Haleakala, Maui ~3 1/4 hours later. The 'wall' appeared to represent the southern boundary for an extensive short horizontal wavelength structure, with a similar phase front alignment. This structure had weak amplitudes initially but was fully developed ~1 hour after encountering the wall. The details of OH imagery, intensity, and Na structure associated with this event are summarized. ¿ American Geophysical Union 1995