Formation of Tropical Storm Debby (2006) due to Thermal and Mechanical Forcing Associated with the Passage of the Pre-Debby African Easterly Waves over the Guinea Highlands

It is well known that African Easterly Waves (AEWs) play a major role in developing tropical cyclones in the Atlantic basin. However, the mechanisms which contribute to the maintenance and enhancement of the AEWs on the mesoscale near the western coast of Africa are less defined. These mechanisms contribute to the tropical cyclogenesis problem and make it difficult for numerical forecasting models to predict the development of tropical cyclones consistently. In this study, the Advanced Research WRF (WRF-ARW) model was used to simulate the pre-curser environment of Tropical Cyclone Debby (2006) (TC Debby). This study focuses on the evolving atmospheric dynamical processes and complex terrain interactions with the African Easterly Wave (AEW). The pre-Debby AEW system went under numerous transitions attributed to the forming and dying out of mesoscale convective systems (MCS) and convective cloud clusters (CCCs). However, the AEW did not become well organized until after its passage over the Guinea Highlands (GH), on the western side of Africa. Due to the interactions of the MCS and CCCs on the AEW as well as complex terrain interactions, a conceptual model of four distinct stages was proposed to describe the interactions of the AEW with the orographic effects of the GH and coupling of MCS as it continues to propagate westward towards the Atlantic Basin. The analysis will be completed to verify or disprove the conceptual model from the precursor environment of TC Debby (2006).