Typhoon Abby, known as Typhoon Norming in the Philippines, was the second typhoon to affect Taiwan in a month during September 1986. A tropical depression developed on September 13 and the next day attained tropical storm status, upon which it was named Abby. Continuing to intensify, Abby moved west-northwest and became a typhoon on September 16. Two days later, the typhoon attained maximum intensity. On September 19, the typhoon made landfall in Taiwan as it turned towards the northwest. Rapid weakening occurred due to land interaction, and on September 20, Typhoon Abby transitioned into an extratropical cyclone. Its extratropical remnants were last noted on September 24 as they raced off to the northeast.
The typhoon claimed 13 lives in Taiwan. Around 2 million people lost power due to the storm while greater than 20 houses were destroyed. Over 59,895 ha (148,000 acres) of crops were damaged. Monetary damage totaled $81 million. In addition to effects on Taiwan, the extratropical remnants later brought heavy rains to Japan.
During late August and early September 1986, the Western Pacific monsoon trough became displaced to the east. Lower than normal pressures favored the building of convection over the trough. By the evening of September 9, a pronounced area of disturbed weather developed southwest of the Truk Atoll. Aided by low wind shear, the disturbance developed slowly, even though the Hurricane Hunters initially failed to find a well-defined center. The disturbance drifted towards the northwest, and early on September 12, the Japan Meteorological Agency (JMA) started monitoring the system.[nb 1] Based on ship reports, the Joint Typhoon Warning Center (JTWC) classified the system as a tropical depression at 06:00 UTC on September 13. Both the JMA and JTWC upgraded the depression into Tropical Storm Abby at 00:00 UTC on September 14.[nb 2]
On September 14, Abby, while moving west-northwest, began to develop a central dense overcast and thus began to intensify. On the morning of September 15, the JMA upgraded the system into a severe tropical storm. Despite reports from Hurricane Hunter aircraft indicating that low-and upper-level circulations were not properly aligned, both the JTWC and JMA estimated that Abby became a typhoon early on September 16.
At 06:00 UTC on September 18, the JMA reported that Abby attained its maximum intensity of 160 km/h (100 mph). Six hours later, the JTWC estimated that Abby reached its peak intensity of 175 km/h (110 mph). Moving northwest, the storm weakened slightly before making landfall in the eastern portion of Taiwan on September 19; the JTWC estimated winds of 170 km/h (105 mph) at the time of landfall. Due to land interaction, the storm rapidly weakened, with the low-level center re-curving towards the northeast. At 00:00 UTC on September 20, the JMA estimated that Abby weakened below typhoon intensity. Twelve hours later, the JTWC stopped monitoring the system while located 410 km (255 mi) southeast of Shanghai. Around this time, the JMA reported that Abby transitioned into an extratropical cyclone, although the JMA continued to track the system through the morning hours of September 24.