 The origins of Olaf were from a tropical wave first noted over Central America on September 22 . It moved slowly through the eastern Pacific Ocean , and gradually developed an area of convection . <unk> , an upper @-@ level low @-@ pressure area moved from the Gulf of Mexico across Mexico into the Pacific , which produced wind shear across the region ; wind shear is the difference in wind speed and direction in the atmosphere , and is usually harmful to tropical cyclogenesis . The disturbance associated with the tropical wave persisted and developed outflow . This caused the upper @-@ level low to move away from the system . On September 26 , it was sufficiently organized to be classified Tropical Depression Seventeen @-@ E , while located about 345 miles ( 560 km ) south of the Gulf of Tehuantepec . 
