page_title: Hurricane Ioke
section_title: Meteorological history
hierarchical_section_title: Hurricane Ioke / Meteorological history
caption_attribution_description: Typhoon Ioke started as all tropical cyclones do, as a depression—an area of low atmospheric pressure. After forming on August 19, 2006, the depression quickly developed into a tropical storm, the threshold for earning a name. Ioke is the Hawaiian word for the name Joyce. Storms and hurricanes in the central Pacific are unusual, but they occur often enough for there to be a naming convention, applied by the Central Pacific Hurricane Center in Honolulu. The last named central Pacific storm was Huko in 2002. Ioke rose all the way to hurricane strength in less than 24 hours. Ioke also performed another unusual trick, crossing the International Date Line on August 27, which by convention means the tropical cyclone was then called a typhoon instead of a hurricane. This photo-like image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite on August 28, 2006, at 1:30 p.m. local time (01:30 UTC). Typhoon Ioke at the time of this image had a well-defined round shape, clear spiral-arm structure, and a distinct but cloud-filled (or “closed”) eye. The University of Hawaii’s Tropical Storm Information Center reported that Typhoon Ioke had sustained winds of around 245 kilometers per hour (155 miles per hour) at the time this satellite image was acquired.
context_page_description: Hurricane Ioke, also referred to as Typhoon Ioke, had the highest Accumulated cyclone energy of any tropical cyclone on record. The first storm to form in the Central Pacific in the 2006 Pacific hurricane season, Ioke was a record breaking, long-lived and extremely powerful storm that traversed the Pacific for 17 days, reaching the equivalent of Category 5 status on the Saffir–Simpson hurricane scale on three different occasions. It was the most intense hurricane ever recorded in the Central Pacific, as well as the fifth-most intense Pacific hurricane on record, tied with 1973's Hurricane Ava.
  The cyclone developed in the Intertropical Convergence Zone on August 20 far to the south of Hawaii. Encountering warm waters, little wind shear, and well-defined outflow, Ioke intensified from a tropical depression to Category 4 status within 48 hours. Late on August 22 it rapidly weakened to Category 2 status before crossing over Johnston Atoll. Two days later favorable conditions again allowed for rapid strengthening, and Ioke attained Category 5 status on August 25 before crossing the International Date Line.
context_section_description: The Intertropical Convergence Zone (ITCZ) spawned a tropical disturbance with a low-level circulation far to the southeast of Hawaiʻi in the middle of August 2006. Under the influence of a strong westward-moving subtropical ridge to its north, the disturbance tracked nearly due westward, with deep convection in the region increasing and decreasing on a daily basis. It slowly became better organized, and early on August 20 the disturbance developed into Tropical Depression One-C while located about 775 mi (1,245 km) south of Honolulu, Hawaii. At the time, there was no convection associated with the ITCZ within 10° Longitude. With wind shear practically non-existent and sea surface temperatures of around 82 °F (28 °C), conditions favored strengthening, and operationally the cyclone was forecast to reach minimal hurricane status within four days before beginning to weaken. The depression attained tropical storm status within six hours of developing. The Central Pacific Hurricane Center designated the system with the name Ioke /iːˈoʊkeɪ/, Hawaiian for the name Joyce. 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 135 mph (215 km/h) early on August 22 while located about 280 mi (450 km) southeast of Johnston Atoll. After maintaining Category 4 status on the Saffir-Simpson Hurricane Scale for about 18 hours, southwesterly wind shear slightly disrupted the inner core of the hurricane, and Ioke quickly weakened to winds of about 105 mph (169 km/h). Late on August 22, the hurricane passed about 30 mi (48 km) south of Johnston Atoll, with the northeastern portion of the eyewall crossing the atoll early on August 23. After turning westward later in the day, wind shear began to decrease, allowing a second period of rapid deepening. By August 24 the hurricane maintained a 23 mi (37 km) closed eyewall, and on August 25 Ioke attained Category 5 status on the Saffir-Simpson Hurricane Scale while located about 970 mi (1,560 km) west-southwest of the Hawaiian Island of Kauaʻi.
  After maintaining Category 5 status for about 18 hours, Ioke weakened slightly due to an eyewall replacement cycle. Completing the cycle on August 26, the hurricane restrengthened to Category 5 status. The trough to its west tracked further away from the hurricane, allowing the subtropical ridge to build ahead of the hurricane which turned Ioke to the southwest. The overall environment remained very favorable for sustainment of the powerful cyclone. Strong upper-level cyclones far to its northwest provided outflow channels and light wind shear, with warm water temperatures along its path. With the conditions, the Geophysical Fluid Dynamics Laboratory hurricane model predicted Ioke to reach winds of 220 mph (350 km/h), with a predicted minimum pressure of 860 mbar (25 inHg). Early on August 27, the pressure dropped to 915 mbar (27.0 inHg), and shortly thereafter Ioke crossed the International Date Line, becoming a 160 mph (260 km/h) typhoon.
  Unofficially referred as a super typhoon by the Joint Typhoon Warning Center (JTWC), Ioke remained at the equivalence of a Category 5 hurricane for about 12 hours after crossing the Date Line. It then began a slight weakening trend on August 28, due to increased inflow from the ridge to its north. On August 29, the cyclone turned to the west and west-northwest while tracking around the periphery of the subtropical ridge, and Ioke again reached the equivalence of Category 5 status. The Japan Meteorological Agency (JMA) assessed Ioke as attaining peak 10‑minute sustained winds of 120 mph (195 km/h) on August 30. Later that day, the typhoon weakened to 
caption: Typhoon Ioke gaining strength after crossing the International Date Line on August 28
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