Well, the fluid dynamics and atmospheric dynamic people have known this for a long time. A Lee Wave occurs when a gravity propagates upwind of a mountain at the same rate as the mean flow. The wave also propagates vertically. Normally the stationary effect is vertical motion downwind of the obstacle to great altitudes. But, there are transient situations when the gravity waves propagates upwind faster than the mean flow, slowly enough, that one gets a fairly persistent "bow wave" effect. All of this is very sensitive to the stability, wind profile and boundary conditions. Explanation of this "Bow Wave" effect involves delving into papers in theoretical fluid dynamics and numerical model simulations. It's even difficult for me to understand clearly.

Bob Sharman NCAR has co-authored some articles on this. M Wurtele wrote some of the intial theoretical papers on Mountain Waves. He was a co-colaborator during the Sierra Wave Project in the 1950s.



Teddi Keller also wrote an interesting paper in 2012: Upstream-Propagating Wave Modes in Moist and Dry Flow over Topography

Sharman and Teddi are married and both work at NCAR. They both got their Ph'd at UCLA from Dr Wurtele. I saw both of them recently at the AMS convention in Phoenix.

Take a look at some of these references if you are into hydrodynamics and atmospheric dynamics:

Scholarly Paper - Lee Waves Ship Waves Sharman Keller
http://scholar.google.com/scholar?q=...0%2C5&as_vis=1

AMS Journals Online - Ship Waves and Lee Waves
http://journals.ametsoc.org/doi/abs/...W%3E2.0.CO%3B2

Lee Waves Benign and Malignant
http://www.nasa.gov/centers/dryden/p...ain_H-1890.pdf

NASA Wuertle Sharman 1993

Upstream Propagating Wave Modes in Moist and Dry Flow over Topography TeddieKeller_2012
http://journals.ametsoc.org/doi/pdf/.../JAS-D-12-06.1

RAL | RAL Staff | Robert Sharman
http://www.rap.ucar.edu/staff/sharman-staff.php

The Research Applications Laboratory (RAL)

Teddie Keller | staff.ucar.edu
https://staff.ucar.edu/users/tkeller