1998 Pacific typhoon season

The 1998 Pacific typhoon season was the least active Pacific typhoon season on record, until it was surpassed 12 years later. It was also the third-latest starting Pacific typhoon season on record. The season produced 16 tropical storms, 8 strengthening into typhoons. The scope of this article is limited to the Pacific Ocean, north of the equator and west of the International Date Line. Storms that form east of the date line and north of the equator are called hurricanes; see 1998 Pacific hurricane season. Tropical Storms formed in the entire west Pacific basin were assigned a name by the Joint Typhoon Warning Center. Tropical depressions in this basin have the "W" suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric, Geophysical and Astronomical Services Administration or PAGASA. This can often result in the same storm having two names.

The 1998 season was very weak compared to the 1997 season; this was due to the strong El Niño in the previous season. During the 1998 season, a total of 28 tropical depressions developed across the western Pacific basin. Of those 28 depressions, a total of 18 strengthened into tropical storms of which 9 further intensified into typhoons. The first tropical cyclone developed on May 28, marking the third latest start to any Pacific typhoon season on record, and the last one dissipated on December 22. The Philippine region also set a record: with only eleven storms forming or moving into its area of responsibility, PAGASA had its quietest season on record, later tying with the 2010 and 2023 seasons. Overall inactivity was caused by an unusually strong La Niña, which also fueled a hyperactive Atlantic hurricane season that year.

Systems

Tropical Depression 01W (Akang)

The second tropical depression of the season developed out of a tropical disturbance which was first noted 1,080 km (670 mi) north-northwest of Palau on July 6. The disturbance gradually became better organized and was classified as Tropical Depression 01W at 1500 UTC on July 7. Upon becoming a depression, it marked the latest start for a Pacific typhoon season since reliable records began in 1959. The next day, 01W entered the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) area of responsibility and received the local name Akang. Slowly moving towards the northwest, the depression neared Taiwan. However, increasing vertical wind shear caused the convection associated with the depression to become displaced from the center of circulation. With the center exposed, 01W weakened. At 2100 UTC on July 10, the depression made landfall in northern Taiwan and dissipated shortly after. No known damage was caused by the depression.

Tropical Storm Nichole

As 01W intensified over the Philippine Sea, a broad area of low pressure developed in the South China Sea. The low slowly intensified as it moved towards the north-northeast and was declared Tropical Depression 02W early on July 8. Tropical Depression 02W slowly strengthened as northerly outflow was constricted. By late on July 8, the depression was upgraded to a tropical storm and given the name Nichole. The storm reached its peak intensity while just offshore southern Taiwan with winds of 95 km/h (60 mph 1-minute winds) according to the Joint Typhoon Warning Center (JTWC) and 65 km/h (40 mph 10-minute winds) with a minimum pressure of 998 hPa (mbar) according to the Japan Meteorological Agency (JMA). The combination of dry air, strong wind shear, and the storm's proximity to land caused Nichole to quickly weaken to a tropical depression twelve hours after reaching its peak intensity. The exposed remnants of Nichole executed a clockwise-loop offshore Taiwan before traveling north into mainland China and dissipating. Rough seas produced by the storm caused four container ships to run aground in Taiwans' Kaohsiung Harbor, none of the crew members were injured. Heavy rains in Taiwan flooded an estimated of crops.

Tropical Depression 03W

Operationally considered to have only been a tropical depression, Tropical Storm 03W developed out of a tropical disturbance along the eastern edge of a monsoon gyre on July 22. Tracking in a gradual northwest to northeast curve, the disturbance gradually intensified and was classified as a tropical depression while located 790 km (490 mi) east-northeast of Iwo Jima on July 25. The depression briefly intensified into a tropical storm, with a peak intensity of 85 km/h (50 mph 1-minute winds) as convection wrapped around the entire center of circulation. However, strong wind shear quickly blew away the associated convection, causing 03W to weaken to a tropical depression. Early on July 26, 03W degenerated into an exposed low before dissipating.

Typhoon Otto (Bising)

The first typhoon of the season developed out of a tropical low from a mesoscale disturbance in early August. Persistent convection developed around the low and early on August 2, the JTWC began issuing advisories on Tropical Depression 04W.

Storm signals were put in place in the Philippines prior to the storm's arrival on August 3. However, Otto turned away from the country and the signals were discontinued on August 5. Typhoon Otto produced heavy rains, amounting to at least 400 mm (15.7 in) in mountainous areas of Taiwan, caused flooding which killed five people. In all, damages in Taiwan amounted to NTD 25 million ($761,000 1998 USD). After traveling through the Taiwan Strait, the typhoon struck China, producing heavy rainfall which caused flooding in areas suffering from the worst flood in at least 45 years. Officials reported no damage or loss of life resulted from the storm in Fujian Province.

Severe Tropical Storm Penny (Klaring)

A tropical disturbance formed on August 2 and strengthened into a tropical depression east of the Philippines. As Penny strengthened into a tropical storm, it made landfall over Northern Luzon, on August 7, and drifted into the South China sea on the same day. Strong vertical wind shear on August 8 caused Penny's convection to be displaced to south of the storm, and even exposed the level circulation center for a few hours. Penny was only located 165 kilometers from Hong Kong when it was at its closest distance to Hong Kong, and killed one person in Hong Kong. Penny soon made landfall over Maoming on August 11, and dissipated the next day.

Typhoon Rex (Deling)

An active Tropical Upper Tropospheric Trough allowed for the development of Tropical Depression 6W on August 22, east of Luzon. It moved westward initially, but as the trough weakened a ridge to the east, it moved northeastward where it became a tropical storm on the 23rd. Rex slowly intensified to become a typhoon on the 26th, followed by reaching a peak of winds on the 28th south of Japan. As it moved northward, it brought heavy flooding to Honshū, Japan, amounting to 13 deaths and moderate damage from mudslides across the island. Another trough pulled the storm eastward, saving Japan from a direct hit, and Rex continued northeastward to an unusually high latitude near 50°, when it became extratropical on the 9th near the Aleutian Islands, east of the International Date Line.

Due to heavy rains caused the weather front and Rex, 25 people were killed, 486 houses were destroyed, 13,927 houses were inundated in Japan. In Tochigi and Fukushima prefectures, experienced particularly heavy rains, with daily precipitation exceeded 600mm in Nasu (August 27). Losses from the fishing industry were ¥4.26 million (US$33,000).

Tropical Depression 07W

On August 26, a monsoonal trough formed over central China and drifted south. On August 29, the trough spawned an embedded low over Taiwan, and strengthened into a tropical depression on September 1. Tropical Depression 07W fully dissipated on September 6 due to vertical wind shear.

Severe Tropical Storm Stella

In northern Japan, near Wakkanai, Hokkaidō, severe damage to many homes took place. One person in the region was killed after being blown off his roof while trying to repair it and twelve homes were destroyed. Several rivers overflowed their banks after rainfall exceeding fell across Hokkaidō. Throughout Sōya Subprefecture, agricultural and fishing industry losses amounted to 23.1 million yen (US$171,213). Severe flooding took place in nearby Abashiri Subprefecture where hundreds of homes were inundated after rivers broke their banks. Over of farmland was lost. Large sections of roadways were washed away, including 14 bridges. Total losses in Abashiri reached 25 million yen (US$185,296), much of which was due to fishing industry damage.

Severe damage was sustained in Iwamizawa, Hokkaidō after torrential rains triggered widespread flooding. One person was killed in the city and 29 buildings were destroyed. Agricultural losses in the area amounted to 14.9 million yen (US$110,436). Some of the worst floods were in Obihiro, where nearly 230 million yen (US$1.7 million) in agricultural losses was sustained. A third fatality from Stella took place in the area.

Tropical Depression 09W

Tropical Depression 09W formed in the South China Sea on September 12, 1998. As the system tracked westward, it intensified and made landfall over Hainan Island, China, and subsequently Vietnam. The storm brought heavy rainfall and strong winds to these regions, causing significant damage and disruption. Although 09W was a relatively short-lived system, its impact on the affected areas was notable, highlighting the potential dangers of even minor tropical cyclones.

Typhoon Todd (Emang)

The monsoon trough spawned a low pressure system late on September 14, which developed into Tropical Storm Todd shortly thereafter. Interaction with a trough provided excellent outflow for the system, which explosively intensified over the following day, with 1-minute winds increasing from 50 knots to 130 knots in a 24-hour period ending at 06z on September 17. However, the upper-level low that had been providing Todd with enhanced outflow soon began to shear it as it catapulted the storm northward and then westward, and by the time it had made landfall in China, Todd had weakened back into a tropical storm with 10-minute winds of 45 knots per the JMA. Todd dissipated inland over China on September 20. Seven people were killed by Todd in Kyushu. Damage in southern Japan amounted to 31.9 million yen (US$236,436).

Typhoon Vicki (Gading)

Vicki developed in the South China Sea west of Luzon on September 17. Vicki moved east and crossed Luzon. After landfalling on Luzon, Vicki moved northeast and struck the Kii Peninsula in Japan on September 22 before becoming extratropical. The storm caused the deaths of 108 people. Insurance claims nationwide in Japan reached ¥159.9 billion (US$1.22 billion).

Tropical Depression 12W

Tropical Depression 12W formed in the South China Sea on September 16, 1998. It moved west-northwestward and tracked along the coast of Vietnam. Despite its relatively weak intensity, the system brought heavy rainfall and gusty winds to coastal areas, potentially causing localized flooding and disruptions. While 12W did not develop into a stronger storm, its impact on the region underscores the importance of monitoring even minor tropical disturbances, as they can still lead to significant weather events.

Tropical Storm Waldo

Tropical Storm Waldo was a tropical cyclone that formed in the western North Pacific Ocean during the 1998 typhoon season. While it didn't reach typhoon strength, it still brought significant impacts to the areas it affected.