Streamwise Evolution of African Easterly Waves

African easterly waves (AEWs) are generally attributed to hydrodynamic instability of the mid-tropospheric African easterly jet (AEJ). However, recent studies have shown that realistic amounts of damping renders the AEJ stable in numerical simulations. As such, normal mode instability of the AEJ may not be an accurate physical model for AEWs. Here, we examine the streamwise evolution of easterly wave packets to understand their formation and amplification. Using gridded analysis and idealized simulations, we examine the structure of the waves within zonally varying environmental flow.