 Subsequently, Ioke quickly strengthened, and by late on August 20 the storm developed a central dense overcast and the beginnings of an eyewall; early on August 21 the storm intensified into a hurricane, just 24 hours after first developing.Hurricane Ioke steadily deepened as it continued west-northwestward, with better definition of the eye and deepening of the eyewall convection.Near the International Date Line a frontal trough turned the hurricane to the northwest, and after a period of rapid deepening Ioke attained winds of early on August 22 while located about southeast of Johnston Atoll.