On July 29, 1987, a tropical wave emerged off the west coast of Africa into the Atlantic Ocean. Tracking westward along the southern edge of the Saharan Air Layer, a feature associated with large masses of dry air, little convective development took place over the following several days. Once near the Lesser Antilles in early August, atmospheric conditions became more favorable for development. Traveling across the Caribbean Sea, the system became increasingly organized and a mid-level circulation formed shortly before the wave moved inland over Central America on August 7. The following day, the northern portion of the wave interacted with a cold-core low over the Gulf of Mexico, resulting in the formation of a low-level circulation, exhibiting tropical characteristics, on August 9. Over the following two days, the system tracked in a general north-northwest direction towards the Texas coastline. Aided by an anticyclone aloft, outflow became pronounced and convection increased in coverage and intensity. Around 1200 UTC, the National Hurricane Center (NHC) estimated that the system developed into a tropical depression while located about 145 miles (235 km) south-southeast of Galveston, Texas.