page_title: Typhoon Caitlin (1991)
section_title: Meteorological history
hierarchical_section_title: Typhoon Caitlin (1991) / Meteorological history
caption_attribution_description: Saffir-Simpson Hurricane ScaleTDTS12345 English: Typhoon Caitlin 1991 track. Uses the color scheme from the Saffir-Simpson Hurricane Scale.
context_page_description: Typhoon Caitlin, known in the Philippines as Typhoon Ising, contributed to major drought relief in Okinawa. A tropical disturbance formed in the middle of July 1991 in the eastern portion of the Western Pacific monsoon trough, and while tracking to the west-northwest, was designated a tropical depression on July 21. Thunderstorm activity associated with the depression increased markedly on July 22, and two days later, the depression was upgraded into Tropical Storm Caitlin. The storm turned northward as it rounded a subtropical ridge while gradually intensifying. Caitlin became a typhoon on July 25 and peaked in intensity on July 27 near Okinawa. The typhoon began to weaken as it turned northeast over the Korea Strait. On July 30, Catlin transitioned into an extratropical cyclone as it entered the Sea of Japan.
  Across the Philippines, heavy rains triggered mudslides that claimed 16 lives and forced over 20,000 others to be evacuated. Due to the storm, reservoir levels in Okinawa on the island rose from only 35% to over 80% of its capacity and crop damage amounted to $7.4 million USD. On Kagoshima Prefecture, 72 homes were damaged and five million people were left without power.
context_section_description: The origins of Typhoon Caitlin can be traced back to a disturbance that formed in the middle of July in the eastern portion of the Western Pacific monsoon trough that extended south of Pohnpei in the eastern Caroline Islands. The disturbance moved west-northwestward, and although the low level center was initially displaced to the west of the deep convection, the Joint Typhoon Warning Center (JTWC) began tracking the system at 06:00 UTC on July 20. On the next day, the Japan Meteorological Agency (JMA) designated the system a tropical depression. Wind shear began to diminish on July 22, coinciding with falling pressures at Yap and increased convective activity. At 05:00 UTC on July 23, a Tropical Cyclone Formation Alert was issued by the JTWC, and eight hours later, the JTWC declared the system Tropical Depression 09W. On July 24, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) also started watching the storm and assigned it the local name Ising. A rapid increase in convection prompted both the JTWC and JMA to upgrade the depression into Tropical Storm Caitlin the same day.
  Tropical Storm Caitlin tracked west-northwestward until July 24, when a semi-permanent subtropical ridge weakened near 130°E, which caused the tropical storm to make a sharp northward turn; this turn was forecast well in advance by the Navy Operational Global Prediction System. Caitlin slowly intensified, and on the evening of July 24, the JMA classified Caitlin as a severe tropical storm. Satellite imagery depicted a cloud-filled eye, and midday on July 25, the JTWC upgraded Caitlin into a typhoon, with the JMA following suit that evening. At the time of the upgrade, Typhoon Caitlin was located around 440 km (275 mi) south of Okinawa. Continuing to intensify, Caitlin turned to the north-northwest. The typhoon passed 110 km (70 mi) west of Kadena Air Base at 15:32 UTC on July 27. Less than three hours later, the JTWC reported that Caitlin attained its peak intensity of 175 km/h (110 mph). Meanwhile, the JMA estimated a peak intensity of 145 km/h (90 mph) and a minimum barometric pressure of 940 mbar (28 inHg). After passing Okinawa, the typhoon tracked north-northeastward around the periphery of a broad subtropical ridge. On July 29, Caitlin, while weakening, accelerated towards the northeast through the Korea Strait, and gradually transitioned into a typhoon force extratropical low as it moved into the Sea of Japan. The JTWC issued its final warning was issued early on July 30 when satellite imagery indicated the system had lost most of its tropical characteristics. Six hours later, the JMA also declared Caitlin extratropical.
caption: Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale
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