the origins of hurricane gilbert trace back to an easterly tropical wave—an elongated low-pressure area moving from east to west—that crossed the northwestern coast of africa on september 3, 1988. over the subsequent days, the wave traversed the tropical atlantic and developed a broad wind circulation extending just north of the equator. the system remained disorganized until september 8, when satellite images showed a defined circulation center approaching the windward islands. the following day, the national hurricane center (nhc) classified it as the twelfth tropical depression of the annual hurricane season using the dvorak technique, when it was located about 400 mi (640 km) east of barbados. the depression proceeded toward the west-northwest, and while moving through the lesser antilles near martinique, it gained enough strength to be designated as tropical storm gilbert.