 It is estimated that the system became a tropical depression at 0000 UTC on September 28, while located about to the south of Manzanillo, Mexico.The depression moved slowly toward the southwest and became better organized, despite a decrease in the coverage of deep convection.By late September 28 the depression was approaching tropical storm status; it turned to the northwest and attained winds of at 0600 UTC on September 29, at which time it was assigned the name Otis.