page_title: Cyclone Waka
section_title: Meteorological history
hierarchical_section_title: Cyclone Waka / Meteorological history
caption_attribution_description: English: Track map of Severe Tropical Cyclone Waka of the 2001–02 South Pacific cyclone season. The points show the location of the storm at 6-hour intervals. The colour represents the storm's maximum sustained wind speeds as classified in the Saffir-Simpson Hurricane Scale (see below), and the shape of the data points represent the nature of the storm, according to the legend below. Saffir-Simpson Hurricane Scale Tropical depression0–39 mph0–62 km/h Category 3111–129 mph178–208 km/h Tropical storm39–73 mph63–117 km/h Category 4130–156 mph209–251 km/h Category 174–95 mph119–153 km/h Category 5&gt;156 mph&gt;251 km/h Category 296–110 mph154–177 km/h Unknown Storm typeTropical cycloneSubtropical cycloneExtratropical cyclone / Remnant low / Tropical disturbance
context_page_description: Severe Tropical Cyclone Waka was one of the most destructive tropical cyclones ever to affect the South Pacific Kingdom of Tonga. Waka originated within the near-equatorial trough in mid-December 2001, although the system remained disorganized for more than a week. The storm gradually matured and attained tropical cyclone status on December 29. Subsequently, Waka underwent rapid intensification in which it attained its peak intensity as a Category 4 severe tropical cyclone on December 31, with winds of 185 km/h. Shortly thereafter, it passed directly over Vavaʻu, Tonga, resulting in widespread damage. By January 1, 2002, the cyclone began to weaken as it underwent an extratropical transition. The remnants of Waka persisted for several more days and were last observed near the Southern Ocean on January 6.
  Although the storm affected several countries along its path, Waka left the most significant losses in Tonga, where it killed one person and wrought 104.2 million paʻanga in damage. Hundreds of structures, including 200 in the island's largest city, and much of the nation's agriculture were destroyed.
context_section_description: In mid-December 2001, at the end of a Madden–Julian oscillation pulse, twin equatorial monsoonal troughs developed in the Northern and Southern Hemispheres. Although warm sea surface temperatures of 30 °C (86 °F) in the region favored development of a tropical cyclone, the southern trough developed substantially slower than the northern one. On December 19, the southern component was classified as Tropical Depression 03F by the Fiji Meteorological Service; at this time the depression was situated just east of the Solomon Islands. The northern component eventually developed into Typhoon Faxai, an extremely powerful Category 5 equivalent cyclone. Unlike Faxai, the precursor to Cyclone Waka developed slowly, mainly because of moderate wind shear in the region. Moving southeastward, the system gradually became more organized. On two occasions, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert; however, the agency later canceled them both times. By December 27, the depression had entered a region of lesser shear, favoring significant development of the system. The following day, the JTWC classified the system as Tropical Depression 07P, when the storm was situated roughly 640 km (400 mi) northwest of Pago Pago, American Samoa.
  Tracking towards the southwest in response to a mid-level ridge to the southeast, the depression quickly intensified, attaining gale-force winds on December 29. Upon doing so, it was upgraded to a tropical cyclone and given the name Waka. Shortly thereafter, the storm underwent rapid intensification; roughly 24 hours after being named, Waka attained sustained winds of 120 km/h (75 mph). During December 30, the center of the storm brushed Wallis Island before turning towards the southeast and accelerating due to an approaching trough from the northwest. Continuing to intensify, Waka passed directly over Niuafo'ou on December 31 with winds of 150 km/h (90 mph). Later that day, the cyclone attained its peak intensity as a Category 4 severe tropical cyclone with ten-minute sustained winds of 185 km/h (115 km/h) and a barometric pressure of 930 mbar (hPa; 27.46 inHg). The JTWC assessed the storm to have attained similar one-minute sustained winds upon peaking; however, this was due to discrepancies between the two warning centers. At this time, Waka displayed a well-defined, circular eye roughly 60 km (37 mi) in diameter. Shortly after attaining its peak intensity, the center of Waka passed over Vava'u.
  Continuing into the new year, Waka gradually weakened on January 1, 2002 as it entered a less favorable region for tropical cyclones. As a result, wind shear displaced convection from the center and its eyewall broke apart. Moving over decreasing sea surface temperatures, Waka began to undergo an extratropical transition, which it completed on January 2. Tracking southeastward, the remnant cyclone briefly slowed over open waters before again accelerating. Over the following few days, the system gradually weakened, with sustained winds decreasing below gale-force by January 5. The storm was last noted on January 6 near the Southern Ocean, about 2,200 km (1,400 mi) north-northwest of Antarctica, at which time it had a pressure of 972 mbar (hPa; 28.7 inHg).
caption: Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale
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