Located over warm waters with fair upper level outflow, the depression quickly intensified and attained tropical storm status twelve hours after forming. Upon strengthening into a tropical storm, Fefa developed a curved cloud band over the southern and eastern portion of the center. The storm slowly strengthened as it tracked west-northwestward, a motion due to the presence of a high-pressure ridge to its north. Fefa initially strengthened slowly; on the day after it became a tropical storm the center was located on the western edge of the deep convection. On July 31, convection began increasing over the center, and it is estimated it intensified into a hurricane later that day while located about 710 miles (1,145 km) southwest of the southern tip of Baja California.