On August 11, a tropical wave moved off the west coast of Africa, and, encountering favorable conditions, quickly spawned Tropical Depression Four, roughly 520 miles (835 km) west-southwest of Cape Verde. The depression moved briskly westward, south of a deep layered ridge, and was upgraded to Tropical Storm Dean on August 14. The storm continued to strengthen overnight as it gained organization, and became the first hurricane of the season on August 16. On August 17 the eye of the hurricane passed into the Caribbean between the islands of Martinique and Saint Lucia as a Category 2 hurricane.