 A tropical wave , accompanied by a misshapen center of surface low pressure and a large area of disorganized showers and thunderstorms , emerged from the west coast of Africa on August 15 . The wave moved west @-@ northwestward along the southern periphery of a ridge to its north . The system quickly organized and its circulation became more defined , warranting its classification as a tropical depression early on August 15 . At the time , the depression was situated about 70 mi ( 110 km ) south of Praia , Cape Verde , prompting the issuance of tropical storm warnings for the southernmost islands . Deep convection continued to develop over the center and the depression intensified into Tropical Storm Erin six hours after its initial designation . However , dry air quickly became entrained into the circulation and convection waned . 
