A tropical system off the coast of Africa, which the National Hurricane Center was monitoring for several days, was upgraded to tropical depression status on August 21 and designated as Tropical Depression Four. Consequently, a tropical storm warning was immediately issued for the Cape Verde islands, as the system threatened to pass over or near the southern part of the archipelago. However, the system failed to strengthen into a tropical storm before passing the chain of islands, and the warning was discontinued the following morning.