It had no official bounds; it ran year-round in 1990, but most tropical cyclones formed in the northwestern Pacific Ocean between May and November.
[1] These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
Tropical Storms formed in the entire west Pacific basin were assigned a name by the Joint Typhoon Warning Center.
A tropical disturbance trekked across the Philippines in mid June, upon entering the South China Sea a depression formed.
Paralleling the east coast of the Philippines, it reached a peak of 100 mph (155 km/h) winds before hitting Taiwan on June 23.
Typhoon Percy, which developed on June 20, reached a peak of 135 mph winds while located a short distance east of the northern Philippines.
Increasing vertical shear weakened Percy to a 95 mph typhoon before crossing extreme northern Luzon on the 27th, an area that felt the effects of Ofelia only days before.
[5] CMA 11 was a short lived system which hit Vietnam, bringing heavy rains, overall minimal damage.
On August 2, the remnant low of Tasha, as a patch of thunderstorms over northeastern China, was pushed to the east by a weather front from the west.
[8] The next day, the JTWC downgraded Aka into a tropical depression since it had lost convection due to persistent wind shear caused by a nearby TUTT.
On 12:00 UTC on August 15, the JTWC issued the last warning on the system,[citation needed] as it passed south of Wake Island.
Forming on August 23 from a tropical disturbance, the depression which would eventually develop into Typhoon Abe initially tracked in a steady west-northwestward direction.
As a result of an intense monsoon surge, the system's trajectory briefly changed to an eastward then northward path before returning to its original track.
[9][10] Typhoon Abe killed 108–195 people after it caused flooding and landslides in the Philippines and Taiwan, ravaged coastal areas of China, and brought high waves to Japan.
[9][11][12] Abe, which is responsible for killing 108 in China, affected half of Zhejiang's land area and a fourth of its population, leaving thousands homeless and causing ¥3.5 billion yuan (RMB, $741.5–743 million USD) to be lost in damages.
Typhoon Dot reached peak intensity of 85 mph before weakening slight before landfall on eastern Taiwan on 7 September.
After passing Taiwan Dot regained typhoon intensity in the Formosa Strait before making a final landfall in Fujian Province, China.
Vertical shear weakened it as it recurved to the northeast, and Flo hit Honshū, Japan, on the 19th as a 100 mph typhoon.
Gene then skimmed the coasts of Kyūshū, Shikoku and Honshū Islands in Japan before moving out to sea and turning extratropical.
Winds on 85 mph were recorded on Kyūshū and heavy rains fell across the region, resulting floods and landslides killed 4 people.
Hattie strengthened into a typhoon on 3 October while moving towards the northwest and reached a peak intensity of 105 mph the next day.
As Hattie accelerated towards Japan it was downgraded to a tropical storm before brushing pass Kyūshū and Shikoku before making landfall on Honshū Island.
Extreme rainfall, peaking near 31.5 in (800 mm) triggered extensive flooding that left some regions under 6 ft (1.8 m) of water.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration uses its own naming scheme for tropical cyclones in their area of responsibility.
Due to the severity of damage and loss of life caused by Mike, the name was retired and was replaced with Manny and was first used in the 1993 season.
This table summarizes all the systems that developed within or moved into the North Pacific Ocean, to the west of the International Date Line during 1990.