Typhoon Dinah, known as Typhoon Luding in the Philippines, was the costliest tropical cyclone to form in the 1987 Pacific typhoon season. It also was the fourth typhoon to form during August 1987. An area of low pressure developed near Guam on August 19, and two days later, the low reached tropical storm intensity as it moved generally west. Intensification was initially gradual, with Dinah becoming a typhoon early on August 24, before it subsequently intensified at a faster pace. Dinah reached its highest strength on August 26 before turning northward on August 28 and into a less favorable conditions aloft, which prompted weakening. Dinah entered the Sea of Japan after passing near Okinawa on August 29, where Dinah leveled off in intensity. The system then began to recurve towards southwestern Japan, and after tracking through the area, Dinah transitioned into an extratropical cyclone on August 31, although the remnants could be traced for four more days as it approached the International Date Line.
Across Okinawa, one person was killed, and six more were injured; eight homes were destroyed or seriously damaged, and 13 boats sunk or were damaged. Damage exceeded $1.3 million (1987 USD). On the island of Kyushu, 250 homes were flooded and about 450,000 homeowners lost power. Throughout Japan, eight people perished, damage totaled $604 million and 89 were wounded. The typhoon destroyed nearly 40,000 dwellings and an additional 600 were flooded. In South Korea, 4,372 structures were destroyed, leaving more than 11,000 people homeless. Nationwide, the typhoon was responsible for flooding of crops. Property damage was estimated at $39.1 million.
Meteorological history
The origins of Typhoon Dinah can be traced back to a poorly organized area of disturbed weather that formed on August 18 close to Guam and was embedded in the monsoon trough, at the time situated near the equator. At 06:00 UTC on August 19, the Joint Typhoon Warning Center (JTWC) started tracking the system, as the system started to show signs of organization. Shortly thereafter, a low pressure area developed along the axis of the system, prompting the JTWC to issue a Tropical Cyclone Formation Alert and the Japan Meteorological Agency (JMA) to start keeping an eye on the low. Late on August 20, there was a rapid increase in the coverage of the thunderstorm activity, and satellite intensity estimates via the Dvorak Technique reached T2.0/. Based on this, the JTWC upgraded the system into a tropical depression at 00:00 UTC on August 21.
Shortly after the upgrade, the depression began to turn west in response to a subtropical high to its north. The system then moved beneath an upper-level high, resulting in improved outflow and decreased wind shear. Following an increase in Dvorak classifications, the JTWC classified the depression as Tropical Storm Dinah on the evening of August 21. Early the following day, the JMA also upped the cyclone into a tropical storm. However, strong wind shear prevented intensification at the climatological rate of one T number per day, as the storm passed roughly south of Guam. Midday on August 23, the JMA declared Dinah a severe tropical storm. Shortly after the upgrade, Dinah began to enter an area of lower shear, which accelerated intensification. After turning west-northwest and an increase in the storm's Dvorak intensity estimates, both the JTWC and JMA upgraded Dinah into a typhoon on the morning of August 24. At the time of the upgrade, Dinah was located about west of Guam. Despite a brief increase in shear, Dinah began to rapidly intensify over the ensuing 24 hours. At 06:00 UTC on August 25, the JTWC increased the intensity of the typhoon to , equal to Category 3 status on the United States-based Saffir–Simpson hurricane wind scale. Early on August 26, the JTWC estimated that Dinah, while continuing northwest at a steady clip, obtained maximum sustained wind speed, with , making it a super typhoon. Even though data from the JTWC suggested that Dinah began to weaken almost immediately thereafter, the JMA estimated that Dinah reached its maximum sustained wind speed and minimum barometric pressure of and , respectively, at noon on August 26. Around this time, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) also monitored the storm and assigned it with the local name Luding.