Crestline Soaring Society

Terrain-induced Rotor Experiment, that is.

http://www.eol.ucar.edu/projects/trex/

Waves are probably more germane to sailplane flying, but there's some interesting stuff on this site, and the associated rotors do dip down below 20k MSL. The studies focus on Oct-May, because that's when there's enough moisture to form wave and rotor clouds.

The 'Publications' link leads to some good stuff, and 'The Rotor Flow in the Lee of Mountains' in documents is retro-cool. The pictures section is cool, and the
Sierra Rotors Project (SRP) links lead to interesting places as well.