On August 15, the NHC first noted the potential for tropical cyclone development in the southwestern Gulf of Mexico from a tropical wave that was located over the central Caribbean Sea.[215] The low emerged over the Gulf early on August 19 producing disorganized showers.[216] Due to the threat the developing system posed to northeastern Mexico and South Texas, the NHC initiated advisories on it as Potential Tropical Cyclone Four at 21:00 UTC that same day.[217] As the disturbance moved northwestward toward the Gulf coast of Mexico on August 20, a Hurricane Hunters mission found that it was still a surface trough.[218] Later that day, it moved inland, striking the coast about 60 mi (95 km) southwest of the mouth of the Rio Grande.[219] With that, the window of opportunity for tropical development closed, and the NHC issued its last advisory on the system at 03:00 UTC on August 21.[220] The disturbance brought heavy rain to coastal Tamaulipas and coastal South Texas.[219]